Great progress in optical storage has taken place in the last decade. The development of optical discs is always towards higher and higher storage density and data transfer rate in order to meet the ever-increasing requirements of applications in audio, video and image areas. It has been proved a logical and effective approach to employ laser light of shorter wavelength and lenses of higher numerical aperture for increasing storage density, as is shown by the evolution of optical disc from CD family to DVD family. At present, research and development of high density DVD (HD-DVD), blu-ray disc and advanced storage magneto-optical (AS-MO) disc are carried out very extensively. Meanwhile, miniaturization of disc size and use of multiplication techniques to increase the storage density and capacity have already given rise to new formats such as iD Photo disc and Data Play disc as well as multi-layer discs. Digital holographic storage (DHS) disc is also one of the research and development subjects of many companies and research institutions. Some new concept optical storage such as fluorescent multiplayer disc (FMD) is also under intensive development. All these have greatly promoted applications of optical discs in audio, video and image devices.

An azo dye, 2-(2-thiazolylazo)-5-diethylaminophenol(TAP), and its cobalt, copper and nickel chelates have been synthesized, which can be used as optical recording materials in DVD-R. The absorption spectra show a great difference in different metal chelates. This may be attributed to the different modes of coordination of metal ions to the azo dye. The structural consideration responsible for the difference are also discussed.

A new azo metal chelate thin film has been developed for digital versatile disk recordable (DVD-R) by means of a spin-coating. The absorption of the film matches very well with the wavelength of the GaAlInP semiconductor diode laser (0.63 approximately 0.65 μm). Thermal property of azo metal chelate indicates that the rapid decomposition of the dye happens in the narrow temperature zone. The optical recording performance of the azo nickel chelate thin film shows that high reflectivity contrast (34%) can be obtained at low writing power and short writing pulse-width using He-Ne laser (632.8 nm) irradiation. The average jitter of 5-in DVD-R disk after recorded with optimistic power on DVD-RT650 tester is less than 12%.

Subphthalocyanine (SubPc) thin films exhibit attractive characteristics in high-density optical storage applications. We have realized red-light (632.8 nm) recording on SubPc thin films previously. In this paper, novel subphthalocyanine thin films were developed by vacuum evaporation and spin-coating method. Their static and dynamic green-light (514.5 nm) recording performance were studied using self-developed short-wavelength optical disk testers. Sufficient reflectivity, reflectivity contrast and CNR can also be obtained at 514.5 nm if an appropriate multilayer structure was applied. It spread the dyes' traditional operating wavelength and provided a new clew for double-wavelength (even double short-wavelength) recording/reading and choosing short-wavelength recording materials.

The most important performance parameter for CD-R recording is the recording speed. We have achieved recording speeds of up to 56X on CD-R with a data-to-data jitter of 25 ns that is well within Orange Book specification. This jitter is achieved at zero asymmetry and with a write power margin of 20% of the optimum recording power. In this paper, we present results on a number of CD-R media. Furthermore, we discuss the influence of write strategy parameters, such as laser power level, laser pulse length, pulse shape, etc., on the recording performance of high speed CD-R.

Metallized azo dyes are paid much attention as recording media of digital versatile disc-recordable (DVD-R) due to their excellent optical and thermal properties within short wavelength (630 to approximately 650 nm). In this paper, a novel metallized azo dye has been synthesized. Smooth films on optical glass and single-crystal silicon were prepared by spin-coating method. The UV-Vis absorption spectra of the dye were measured in solution and in film. The optical constants (complex refractive index N=n+\ik) of the film on single-crystal silicon have been determined using scanning ellipsometer. The variation of the complex refractive index N with wavelength λ was obtained. Thermo-gravimetric analysis (TGA) of the dye showed clear threshold of thermal decomposition. Static optical recording tests were carried out to evaluate the performance of the optical recording medium. The results show that the dye is a promising candidate as a recording medium of DVD-R.

Optical data storage is a frontier in the information science. Currently, there are mainly two kinds of storage materials, i.e., thermal-optic and photonic materials. The storage methods are divided into serial and parallel modes. In the market, the mature technique is CD-RW, which uses the thermal-optic material and serial method. The storage density of the CD-RW is restricted by the size of material particles, the conduction of heat, etc. Besides, the recording speed is seriously limited by the process of heating. Photonic materials and parallel method will be the trend in the optical data storage. Because it is based on the photon reaction on the molecule scale, the storage density and speed will be greatly increased. In this paper, a new kind of organic photochromic material -- pyrrylfulgide was studied. A parallel optical data storage system was established. Using the pyrrylfulgide/PMMA film as a recording medium, micro-images and binary digital information could be recorded, readout and erased in this parallel system. The recorded information on the film can be kept for at least 8 months in dark at room temperature. So far, the storage density is 3 x 10⁷ bit/cm².

The dye coating is the most important process in CD-R replication technique, because the coating result has a significant effect on the final disc quality. Optical density (OD) curve represents the result of dye coating. In this paper an optical density curve model for dye coating is discussed. It can be used as an analysis tool of many important parameters in the coating process, thereby control the disc quality. The optical density curve of the disc after coating is measured with the Dr Schenk and then divided into several sections to line-fitting. The new curve has 4 characteristic points and 3 characteristic line sections, which can be used to make process analysis.

Two non-symmetric perfluorocyclopentene derivatives have been synthesized. The absorption bands of their closed forms are located at 400 to approximately 500 nm wavelength regions. They undergo thermally irreversible photochromic reaction and fatigue resistant. The closed-ring form remains thermally stable after several months. And the repeatable cycle number in hexane is more than 10³ times in the presence of air. It demonstrates that they are promising candidates for short wavelength recording.

Diarylethene has good applicative perspective in optical memories for its photochromic property. But, the most important problem, which prevents the diarylethene from practical application, is the Non-destructive readout capability. In this paper, we synthesized a diarylethene derivative -- compound 1 (See Figure 1) that has photochromic and electrochromic activity. It has good electronic gated reactivity in solution. And, we found the gel electrolytes based on PMMA are good materials of film for the compound 1. In this film, compound 1 shows almost the same phenomenon as that in solution. This gated reactivity capability provides a good support for the practical application of diarylethene.

Current applied optical storage technologies are all based on the heat effect of the recording laser, i.e., heat-mode optical storage. In the present work, photon-mode optical storage using photochromic diarylethene materials was investigated. Two diarylethene molecules dispersed into PMMA together was used as storage material. The recording layer was spin-coated on a glass substrate with Al reflective layer. Two laser beams of 532 nm and 650 nm were used in recording and readout by simultaneously writing and reading, and the reading lasers detected signals with high S/N ratio. Multi-wavelength storage was realized with the diarylethene PMMA film.

Four photochromic diarylethenes with different spectra in open and closed form were synthesized simultaneously. Irradiation of the open form with UV light results in essentially quantitative photocyclization to the closed form. The compounds show attractive optical properties and are expected to be used in optical storage and photoswitch.

Organometallic photochromic complexes, which are more stable than those traditional pure organic photochromic compounds, have a wide variety of potential applications in high-density optical storage. In this paper, Ag-TCNQ and Cu-TCNQ thin films were prepared by physical vapor deposition method. The proportion dependence of the spectral and optical properties of Ag-TCNQ thin films were studied and discussed. Multilayer film configuration was designed and prepared for optical memory study and its short-wavelength (514.5 nm) photochromic characteristics were reported. A recommendation of application of Metal TCNQ complexes for high-density and super high density optical storage was proposed as well.

Nickel phthalocyanine thin film was prepared by vacuum deposition, the absorption and transmission spectra, the thermal stability of the film were reported. And the static optical recording properties of the thin film were investigated with a self-developed short-wavelength optical tester with high NA objective lens. The results show that this film occupied suitable absorption and transmission properties for short-wavelength (514.5 nm) optical recording, excellent thermal stability and outstanding thermal decomposition characteristics. And high reflectivity contrast was obtained at low writing power and short writing pulse width using the Ar⁺ laser (514.5 nm) irradiation. The results indicate that metal phthalocyanine is not only qualified for traditional near infrared optical recording medium of CD-R, but also a promising candidate for the recording medium of green-light DVD-R.

Optical and morphological properties induced by laser irradiation in oxotitanium phthalocyanine (TiOPc) film were investigated at 650 nm wavelength with semiconductor laser. The reversible changes of spectra in the region of 610 - 730 nm wavelength were observed. The varieties of refractive index and extinction coefficient of the film before and after laser irradiation were detected. The morphological structure was investigated with transmission electron microscope (TEM) as well. The results suggest that the changes of the film optical properties are induced by photo-thermal processes, and this characteristic is significant to phthalocyanine film as promising candidate for DVD-rewritable recording medium (DVD-RW).

In this paper, spin-coated thin films of phthalocyanine dye were prepared. Absorption spectrum of the thin film shows a comparatively broad absorption at the wavelength region 630 - 770 nm and there is a steep absorption edge at the wavelength 750 nm, which is crucial to high reflectivity. Optical parameters of the thin film was measured by a spectroscopic ellipsometer. Extinction coefficient found to be very little at the wavelength 780 - 810 nm. 5-in CD-R discs made of this dye exhibit good performance after recorded in Yamaha 20 speed recorder. Jitters of land or pit are less than 35 ns and the 3T-11T's signals show very good quality. This dye is promising recording media for CD-R for much higher speed recording in the future.

This paper describes next generation technologies and future technologies of MO (Magneto-Optical) recording. A proximity optical head with blue laser, high NA lens and magnetic coil was developed. The head is kept at 30 μm height over media, using new optical feedback system. Front surface recording using the head and media well designed for blue laser achieved recording density of 17 Gb/in², giving 23 GB/120 mm media. As future technologies, an optical flying head was developed with 3 μm flying height. Combining the head and DWDD media, a density of 40 Gb/in² or 50 GB/120 mm media will be possible. &#les;

Domain wall displacement detection (DWDD) is the promising method for achieving very high-density magneto-optical disk. The resolving power can be expanded far beyond the optical limit which is determined by the light wavelength and the numerical aperture of the objective lens. Some technologies have been introduced to ensure the smooth wall motion which is the key to the high performance of DWDD. Very smooth surface is obtained by pretreatment of the substrate or by reactive ion etching process on a glass master. Reverse disk rotation for readout is effective in reducing the jitter because the front line for starting position of the wall displacement curves to the same direction as recorded crescent domains. A possibility of an areal density of 20 Gb/in² has been shown for the DWDD media using a blue-violet laser diode and a numerical aperture of 0.6.

Magnetic domains were thermomagnetically recorded on TbFeCo films using laser pulsed magnetic field modulation (LP-MFM) and light intensity modulation (LIM). The domains were observed with high resolution magnetic transmission X-ray microscopy (M-TXM) before and after the heat treatment in order to clarify the recording characteristics and the thermal stability of recorded domains. From the results of M-TXM images, it was found that isolated single marks whose lengths are much smaller than 100 nm can be recorded by LP-MFM but their mark lengths become often longer than designed. It was further confirmed that the heat treatment at 120 degree C for 50 hours does not influence significantly the crescent-shaped magnetic domains of 100 nm in width recorded using LP-MFM method and circular domains of 150 nm in diameter recorded using LIM method.

Temperature dependence of the properties of RE-TM thin films is very important for MO recording. In this paper, we studied the temperature dependence of the magnetic and magneto-optical properties of the amorphous LRE-HRE-TM single layer thin films and LRE-HRE-TM/HRE-TM couple-bilayered thin films. For LRE-HRE-TM single layer thin films, the temperature dependence of the magnetization was investigated by using the mean field theory. The experimental and theoretical results matched very well. With the LRE substitution in HRE-TM thin film, the compensation temperature T_comp decreased and the curie temperature Tc remained unchanged. Kerr rotation angle became larger and the saturation magnetization Ms at room temperature increased. For LRE-HRE-TM/HRE-TM couple-bilayered thin films, comparisons of the temperature dependences of the coercivities and Kerr rotation angles were made between isolated sublayers and couple-bilayered thin film.

Thermomagnetic recording process was simulated for Tb_x((Fe₇₈Co₂₂)_100-x media by using Huth's model modified to apply the magnetic field modulation (MFM) recording method. In the case of X = 17.6 (TM-rich) medium recorded with 1 μm laser spot and single pulse field, the recorded mark length becomes much longer than designed one when it becomes shorter than 100 nm. In the case of X = 21.7 (RE-rich) medium, the recorded mark lengths is not so much longer compared to those of X = 17.6 and 19.4, but it becomes difficult to record marks shorter than 40 nm due to the collapse of domains. The influence of magnetic parameters on the recording characteristics is also discussed.

In order to meet the requirements of high saturation magnetization (Ms) and large coercivity (Hc) at room temperature for hybrid recording, the TbCo/Cr films with perpendicular anisotropy were prepared by an r.f. magnetron sputtering system without applying bias voltage. The influence of sputtering conditions and the effects of Sm substitution on the magnetic and magneto-optical properties of TbCo/Cr films were studied. It was found that although the Hc of TbCo/Cr could be optimized by choosing suitable sputtering parameters, but the partial Tb substituted by Sm will directly affect the magnitude of saturation magnetization Ms and the Kerr rotation angle 0_k. This can be explained with the feeri-magnetical structure of RE-TM alloy. Under the optimized sputtering conditions, when the magnetic layer composition was (Sm_0.343Tb_0.657)₃₁Co₆₉, the Ms as high as 385emu/cm³ and the Hc as high as 4.7KOe at room temperature were obtained.

The lifetime and reliability of optical media are discussed on the magneto-optical (MO) disk media. The experiments were applying the method conventionally used for MO disk. Based on accelerated aging experimental study, which the magneto-optical disk media are subjected to conditions of high temperature and high humidity, the reliability lifetime was obtained by analyzing the change of BER and CNR at high temperature experiment. The rate of failure was measured and the data were extrapolated to obtain rates of failure under the ambient conditions. We predicated the reliability life of MO disks by using the Weibull method. The research provided that the lifetime of magneto-optical disks was sufficiently long.

Nano-granular Fe₅₀Pt₅₀-Ag composite films are fabricated by annealing the precursor multilayer. Magneto-optical polar Kerr effect and optical constants of these films are measured with photon energy in the range of 1.4 eV to 6.8 eV. Upon considering the multiple reflection and optical interference effect caused by substrate, the diagonal and off diagonal elements of dielectric tensor are calculated out. Plasma resonance of Ag gives an absorption peak at around 3.8 eV. However, the Kerr effect does not show an obvious enhancement at this Ag plasma edge. The optical interference effect and granular structure of these films move the negative peaks in Kerr effect to the lower energy side.

The Bi₁Dy₂Fe_4.3Al_0.7O₁₂ films with perpendicular anisotropy were successfully prepared by citric acid complex type sol-gel method. The properties of Bi-substituted garnet films annealed at different temperatures were investigated. The results indicated the garnet films had high squareness. The coercive force of the films was about 1100 Oe. The figures of merit of 2° at 430 nm and 1.5° at 520 nm were obtained. The best crystallization temperature was 650°C.

In this paper AgO_x films for super resolution near-field structure application were prepared by reactive sputtering. The switching properties of AgO_x films were studied by analyzing the relationship between the transmittance and the laser power. We gained results that AgO_x films had excellent switching properties and the reaction (formula available in paper) was reversible. The structures of AgO_x films were investigated by X-ray diffraction and TEM.

The conventional TbFeCo magneto-optical medium has a relatively smaller kerr rotation angle in blue region than in the red. Consequently, intensive optimization of the RE-TM blue disk is needed. In this paper, optimization of magneto-optical properties and optical properties was carried out, and good results were obtained. We also calculated the temperature distribution of the recording layer, the results showed that the newly designed structure was successful in temperature controlling and had better thermal response.

The magnetic and magneto-optic properties of TbCo/Cr thin films were studied. A comparison of the MO properties was made between TbCo thin films with and without Cr underlayer. It was found that Cr underlayer helps to increase the Kerr rotation angle and to enhance the coercivities of TbCo thin films. The effects of the thickness of Cr underlayer and the gas pressure during Cr underlayer preparation on the magnetic and magneto-optic properties of TbCo layers were investigated, as well as the temperature dependence of these properties of TbCo/Cr thin films.

An image processing system for magneto-optical recorded domain has been built. Software based on the modern digital image processing techniques has been implemented, including image averaging, background subtraction, boundary detection and so on. With the system, the blurred domain image taken under difficult conditions due to poor contrast and signal-noise ratio can be enhanced and segmented from the background for further quantitative analysis.

The fatigue characteristic of the amorphous Sm-substituted DyFeCo magneto-optical alloy films fabricated by R.F. magnetron sputtering method were investigated by accelerated pulse training method under the condition of magnetic field modulation plus laser pulse irradiation. The evaluation of fatigue characteristic is determined from the static magneto-optical signal readout level after several writing/erasing repetitions compared with initial level. The experimental dependence of fatigue characteristics is in good agreement with the model based on the JMA equation. Furthermore, the Avrami factor can be derived from the model. Experimental results show that it is very effective in studying the writing/erasing ability of magneto-optical films employed the method of combined the accelerated pulse training with the JMA equation and Sm-substituted HRE-TM alloys can act as a practical medium for MO storage at short wavelength.

In the paper, the relationship among Kerr rotation angle (formula available in paper) thickness and refractive index of transparent dielectric layer on MO films has been deduced theoretically. A scheme based genetic algorithm (GA) for the optimization of dielectric thin film to enhance the magneto-optic effect has been fabricated. GA ameliorates the astringency and the convergent speed. According to the computing program flow chart, the designation of genetic operators was emphatically discussed.

Multi-layer optical recording is a promising technology for increasing a disc capacity using an optical pickup identical to that used for a single-layer optical disc. A capacity of 25 GB - 50 GB is required to record 2 - 4 hours HD-TV program. In this paper, the physical format of the dual-layer phase-change optical disc is studied and experimental results of an advanced dual-layer phase-change optical disc, of which first layer is characterized by a transmittance-balanced structure and prepared by a new replication process, are shown and discussed. The transmittance-balanced structure disc is realized by adopting Ge(Sn)-Sb-Te film that has appropriate optical constants and optimizing the thickness of dielectric layers. The signal of the second-layer in the transmittance-balanced structure disc is able to read and write without any influence of the first-layer. A capacity of over 50 GB is demonstrated by the transmittance-balanced structure disc.

For the materials of eutectic composition (AgInSbTe) using as the phase change optical memory, Sb rich recording layer have been utilized in order to the rapid crystallization. But, the mechanism of excess Sb addition has not been clear, because a eutectic material is thought to cause the phase separation in its solidification process. Recently, it was reported that a melt-quenched crystalline states of eutectic AgInSbTe and SbTe with excess Sb has a quasi-equilibrium sate with single phase hexagonal structure based Sb(R3m) and some Sb atoms are randomly replaced with Te atoms. In this paper, we report the excess Sb effect for the dynamics of rapid crystallization in eutectic amorphous films. This crystallization mechanism describe the propagation with high velocity in the interface separating the crystalline and amorphous phase for AgInSbTe and Ge(Sb..Te₃)+Sb materials. From these analysis, it is clear that the crystallization is grown up in the boundary of amorphous-crystalline region of eutectic materials, which is different from the stoichiometric Ge₂Sb₂Te₅ media. Under favorable conditions, a self sustained (explosive) process results by laser irradiation. Then, once crystallization has been initiated in the amorphous-crystalline region, the entire amorphous films has been crystallized.

A simulation model with spreadsheet to analyze the fractal crystallization in the eutectic materials of optical memory has been investigated, which is important for the high data rate in fast growth materials (AgInSbTe).

The In-Zn oxide films with a laminated multilayer structure of each layer of In₂O₃ and ZnO were grown on glass substrates or polycarbonate disk substrates by pulsed laser deposition using a split target consisted of In₂O₃ and ZnO. For the disk sample with 60-layers, which was approximately 30 nm thick, fabricated at the trace ratio (the ratio of time required to irradiate each part of the split target) of In₂O₃:ZnO = 1:1, the CNR of approximately 60 dB was obtained for 3T signal (f = 58.5 MHz, λ = 406 nm, NA = 0.65).

The Blu-ray Disc (BD) optical recording system utilizes a blue laser (405 nm wavelength) in combination with a high-numerical-aperture (NA = 0.85) objective lens. This BD-format allows storing 23 - 27 GB on a single-layer and 46 - 54 GB on a dual-layer 12 cm disc at 36 Mbps user data rate. This paper reports on the design, manufacturing, and the recording performance of our dual-layer rewritable optical media. These media are based on the eutectic, fast-growth phase-change materials, which are promising candidates for high-speed applications. The performance of these materials in the case of dual-layer recording is discussed, with special attention for transmission balance for the semitransparent recording stack.

By using Si thin film to replace the Al reflective layer in conventional ROM, the recording pits with a diameter of 380 nm and a depth of 50 nm are read out on the dynamic measuring equipment with a laser wavelength λ of 632.8 nm and a NA of 0.40. In the course of reproduction, the readout power is optimized, and the velocity is 5 m/s. The optimum Si thin film thickness is 25 nm and the CNR is 35 dB.

The relationships among the recording laser power, laser pulse width, and the recording properties of Ag₅In₅Sb₄₇Te₃₃ thin films were investigated, and the morphology of the recording domains were directly observed by using the homemade apparatus. The results show that the clear and high reflectivity contrast recording domains can be obtained when the laser energy is in a certain range. By optimizing the recording condition, the recording domains with a diameter of 380 to 400 nm and reflectivity contrast of 22% are obtained under the recording power of 12 mW and pulse width of 90 ns.

Due to germanium doping in the AgInTeSb film, Ag₂Te phase was formed at minor doping and disappeared when the germanium content was high, AgInTe₂ phase changed into AgIn₂ phase, and Ge₂Sb₂Te₅ new crystalline phase appeared. The crystallization temperature of AgInTeSbGe increased manifestly with Ge addition. A doping amount of 4.1 at.% germanium increases the reflectivity contrast to be greater than 30% almost in the whole visible region.

Ge-Sb-Te phase change thin films are widely used as the recording media in rewritable optical storage. Doping of certain elements into Ge-Sb-Te films is an effective way to enhance their recording performance. In the present work effect of oxygen-doping on the optical constants of Ge-Sb-Te phase change thin films prepared by RF-sputtering were studied in the region of 400 to approximately 800 nm. The results show that the optical constants of the Ge-Sb-Te films change considerably with the doped oxygen content. With the increase in oxygen concentration, the extinction coefficients decrease monotonically. The calculated reflection spectra at normal incidence showed a good agreement with the measured values. With the optimal oxygen-doping, the reflectivity contrast between the crystalline and amorphous states of the Ge-Sb-Te films exceeds 30% throughout the whole visible region. The effect of the strain field induced by oxygen-doping on the optical properties is discussed.

In the two-color nonvolatile holographic data storage, ultraviolet light sensitization and visible light bleaching are two important processes. The selection of the wavelength of ultraviolet light and visible light has a profound impact on the recording and readout performance. We have studied experimentally the absorption spectra of some samples of typical doubly doped lithium niobate crystals, such as Mn:Fe:LN, Cu:Ce:LN, Cu:Fe:LN, etc., under the condition of ultraviolet light sensitization and visible light bleaching respectively. By choosing different wavelength of ultraviolet light and visible light, we have obtained some useful results of material properties. Finally, simple theoretical analysis are given and the appropriate wavelength of ultraviolet light and visible light for two-color nonvolatile holographic storage are suggested corresponding to each kind of crystal above.

Mg(3mol%):Mn:Fe:LiNbO₃ and Mg(7mol%):Mn:Fe:LiNbO₃ crystals have been grown by doping 3mol%, 7mol% MgO in Mn:Fe:LiNbO₃, respectively. It was found that light scattering resistance ability of Mg(7mol%):Mn:Fe:LiNbO₃ is two orders of magnitude higher than that of Mn:Fe:LiNbO₃ crystals. In Mg:Mn:Fe:LiNbO₃ crystal, Mn is deep level and Fe is shallow level. We selected Mg(3mol%):Mn:Fe:LiNbO₃ as the storage medium to carry the two-photon holographic storage experiment by using He-Ne laser as recording light and ultraviolet (UV) light as sensitizing light. The single photon recording and erasure curves as well as those of double photon were measured also. The recording speed of Mg:Mn:Fe:LiNbO₃ crystals is faster than that of Mn:Fe:LiNbO₃.

The congruent tri-doped Mg:Mn:Fe:LiNbO₃ crystals have been grown by Czochralski method in air atmosphere. The crystal samples are reduced in Li₂CO₃ powder at 500°C for 24 hours or oxidized for 10 hours at 1100°C in Nb₂O₅ powder. Compared with as-grown Mg:Mn:Fe:LiNbO₃, the absorption edge in UV-Vis. absorption spectrum of the oxidized sample or the reduced shifts to the red. The post-disposal, oxidation or reduction disposing has no effect on O-H vibration absorption peak in infrared region. In two coupling experiments we determine the writing time, maximum diffraction efficiency and the erasure time of crystal samples in the same conditions. The results indicate that oxidation and reduction disposing has great effect on the holographic recording properties of these crystals. The reduced crystal exhibits the fastest response time 145s and the biggest diffraction efficiency 67% among the crystal series. The mechanism of post-disposing effect on the holographic recording properties of Mg:Mn:Fe:LiNbO₃ crystals has been investigated.

The relationship of Bragg-mismatch and recording angles of holographic photopolymer was deduced, the calculated and experimental results were compared. It showed that the theory tallied with the experiment well. The result indicates that the Bragg-mismatch depends on the recording angles strongly, this result is important to the design of high-density photopolymer holographic memory system.

ASM method is an effective method for disk-type photopolymer high-density holographic storage that has a limited medium thickness. In this paper, the effects of recording angles of ASM method disk-type photopolymer high-density holographic storage on the recording capacity and density are studied theoretically. The calculation and analysis show that the recording density and capacity depend on the recording angles critically whether the spherical wave beam or plane wave beam is used as the reference beam. The results show that no matter spherical wave or plane wave is used as the reference beam the recording density and capacity increases monotonously with the increase of θ_s when θ_R is fixed. When the recording angle between two recording beams is large, it has an optimal incidence angle of reference beam to get the maximum recording density and capacity. By using this optimal recording angle we can get 3 - 4 times improvmeent of recording density and capacity.

Green light sensitive acrylamide-based photopolymer system has been prepared. The photosensitive medium was composed of monomer, photoinitiator, charge transfer agents and polymeric film-forming binder. The best Eosin Y, TEA, BAA and AA's concentration were got by optimization of acrylamide-based photopolymers composition. And diffraction efficiency as high as 55% with energetic sensitivity of 60 mJ/cm² has been obtained in the photosensitive films of 150 μm thickness. The principle of photopolymerization reaction was investigated in the paper, especially the function of charge transfer agents TEA and DPI were studied and we found that there existed a compensation effect between TEA and DPI in the polymerization process of photopolymer.

A series of Zn, Fe double-doped LiNbO₃ crystals were grown by Czochralski technique with 0.015wt% of Fe₂O₃ and with different concentration of ZnO. The defect structures of the Zn:Fe:LiNbO₃ crystals were studied by X-ray diffraction analyses and IR absorption spectra. The results indicated that the lattice constants of the Zn:Fe:LiNbO₃ increase with the concentration of ZnO increasing in the crystals. The result indicates that the absorption peaks of the IR transmission spectra shift to the shorter wavelength with the increasing of concentration of ZnO. The optical damage resistance ability of the Zn:Fe:LiNbO₃ crystals were investigated by straightly observing transmission facula distortion method, respectively. The results demonstrate that, compared with of Fe:LiNbO₃, the optical damage resistance ability of the Zn (7.0mol%):Fe:LiNbO₃ crystals is two orders magnitude higher than that of LiNbO₃ crystal. 6.0mol% of ZnO is the perfect doping concentration.

The absorption spectra and the optical damage resistance ability of the In:Fe:LiNbO₃ crystals grown by Czochralski method with different concentration of In₂O₃ were measured. The absorption edges of the absorption spectra of the In:Fe:LiNbO₃ crystals shift to the short wavenumbers with the concentration of the In₂O₃ in the crystal increasing. The optical damage resistance ability of the In(3.0mol%):Fe:LiNbO₃ crystal is two orders magnitude higher than that of Fe:LiNbO₃ crystal. The response speed of the In:Fe:LiNbO₃ crystals increases with the concentration of the In₂O₃ in the crystal increasing, on the contrary, the diffraction efficiency decreases.

Pr:LiNbO₃ crystal can be used in two-color gated storage process for its special energy-level structure. Compared with other crystals used as volume holographic storage media, it has a great merit that an image recording does not erase the recorded one in multiplex storage process. But its photorefractive effect appears weaker than other crystals in the same conditions. We doped photorefractive sensitizing element Ce into Pr:LibNO₃ to get Ce:Pr:LiNbO₃ crystal with Czochralski method. The structure of crystals has been determined by X-ray powder diffraction method. The results indicate Pr:LiNbO₃ and Ce:Pr:LiNbO₃ keep the same structural characteristics as pure lithium niobate. In the absorption spectra of Pr:LiNbO₃ and Ce:Pr:LiNbO₃ samples with non-polarized light in wavelength of 300 - 900 nm, the absorption edge of Ce:Pr:LiNbO₃ shifts to the red compared with that of Pr:LiNbO₃. The diffraction efficiency, writing time and especially erasing time of Ce:Pr:LiNbO₃ have been measured. We find that maximum diffraction efficiency of Ce:Pr:LiNbO₃ has increased without at cost of decreasing the erasing time. The effect of doping ions on the optical properties of Ce:Pr:LiNbO₃ crystal as holographic recording media has been studied systematically.

Stoichiometric Ce:Mn:LiNbO₃ crystal was grown by the TSSG method for the first time. The congruent Ce:Mn:LiNbO₃ (CCe:Mn:LiNbO₃) crystal was grown by the Czochralski method. The lattice constant was tested. The lattice constant of the stoichiometric Ce:Mn:LiNbO₃ (SCe:Mn:LiNbO₃) crystal was less than that of CCe:Mn:LiNbO₃ crystal. The absorption spectrum of the crystals was tested, the absorption edge of SCe:Mn:LiNbO₃ crystal has violet shift comparing with that of CCe:Mn:LiNbO₃ crystal. The exponential gain coefficient, the concentration of effective carrier, diffraction efficiency and response time were tested. Those properties of SCe:Mn:LiNbO₃ crystal mentioned above have been improved. SCe:Mn:LiNbO₃ crystal possesses the property of holographic storage for long.

Doped MgO and In₂O₃ in Fe:LiNbO₃ through Czochralski technology to grow Mg:In:Fe:LiNbO₃ crystal for the first time. The photo-scattering resistance ability of Mg(3mol%):In(3mol%):Fe:LiNbO₃ crystal were measured. It improves the two orders magnitude higher than that of Fe:LiNbO₃ crystal. The absorption spectra of the Mg:In:Fe:LiNbO₃ crystals were tested. The absorptive edge was found to shift to the short wavelength. The infrared spectra of the crystals were measured, when Mg²⁺ and In³⁺ reach their threshold concentration in crystal, the absorption peak shifts from 3484cm^-1 to 3520cm^-1. Two wave coupling method was used to test the diffraction efficiency and response time of the crystals. The response speed of the Mg:In:Fe:LiNbO₃ crystal is higher than that of the Fe:LiNbO₃ crystal.

Using Si-Mo Bar as the heater, potassium sodium barium strontium niobate (KNSBN) crystals doped with Ce and/or Eu have been grown by the Czochralski method. The exponential gain coefficients were measured by two-wave coupling light path, and in comparison with KNSBN, that of Ce:Eu:KNSBN is one time higher. Holographic associative storage principle is represented here and the holographic associative storage is realized by using Ce:Eu:KNSBN as the storage element and Mg:Fe:LiNbO₃ as the phase conjugator to feedback, fetch threshold and gain. The output images are integrated.

Congruent Eu:Fe:LiNbO₃ crystals doped with or without fluxing agent K₂O have been grown by TSSG method and the Czochralski method, respectively. The holographic storage properties, diffraction efficiency, response time and photoconduction, of the two Eu:Fe:LiNbO₃ crystals are characterized by two-wave coupling experiment. Eu:Fe:LiNbO₃ doped with fluxing agent K₂O (Eu:Fe:SLN) has the higher photorefractive performances than congruent Eu:Fe:LiNbO₃ (Eu:Fe:CLN). The nonvolatile holographic storage is realized in Eu:Fe:SLN crystals by using He-Ne laser as the light source and ultraviolet as the gating light.

Mg:Fe:LiTaO₃ crystals were first grown by Czochralski method, and Fe:LiTaO₃ crystals, Fe:LiNbO₃ and Mg:Fe:LiNbO₃ crystals were also grown at the same time. The holographic storage properties of these crystals, such as the exponential gain coefficient, the diffraction efficiency and the response time, were measured by the two-wave coupling method. It was found that the response speed of Mg:Fe:LiTaO₃ crystal was five times faster than that of Fe:LiTaO₃. The light scattering resistance ability was also measured, and that of Mg:Fe:LiTaO₃ crystal was two orders of magnitude higher than that of Fe:LiTaO₃ as well as higher than that of Mg:Fe:LiNbO₃. The enhancement mechanism of the photorefractive properties for Mg:Fe:LiTaO₃ crystal was discussed for the first time.

CuO and Co₂O₃ were doped in KNSBN and Czochralski method was used to grow Cu:Co:KNSBN crystal for the first time. ZnO and Fe₂O₃ were doped in LiNbO₃ and Czochralski method was used to grow Zn:Fe:LiNbO₃ crystals. The diffraction efficiency and response time of the Zn:Fe:LiNbO₃ crystals were measured. The response speed of the Zn:Fe:LiNbO₃ crystal is four times higher than that of the Fe:LiNbO₃ crystal. The self-pumping phase conjugate reflectivity and respond time of the Cu:Co:KNSBN crystal were measured. The result shows that the self-pumping phase conjugate reflectivity of the Cu:Co:KNSBN crystal is two time higher than that of KNSBN crystal. Zn:Fe:LiNbO₃ and Cu:Co:KNSBN were used as storage element and self-pumping phase conjugate mirror, respectively, to make the holographic associative storage experiment. The excellent results were gained.

{[1-(2-methyl-5-(4-N,N-dimethylphenyl)),2-(2-methyl-5-(2-(1,3-dioxoane)))]-thien-3-yl}perfluorocyclopentene (1a) and {[1-(2-methyl-5-formyl),2-(2-methyl-5-(2,2'-dicyanovinyl))]-thien-3-yl}perfluorocyclopentene(2a) were synthesized and rewritable photo-mode optical recording by the use of them were performed. The results showed that both of the two diarylethenes are very sensitive responsing to the corresponding wavelength recording laser, and the readout signals with high S/N ratio which was up to 30 to approximately 50% were obtained. The destruction of the readout and the photochromic properties of these diarylethenes in hexane solution and PMMA films were also discussed.

Using a computer simulation, AgCl emulsions doped with [Fe(CN)₆]^4- complexes and a reference AgCl emulsion without dopants have been investigated at room temperature, and the free photoelectron decay time (FPT) was obtained. According to compare with the experimental results obtained by microwave absorption dielectric spectrum detection technology, the shallow electron traps (SETs) information was gotten. In this simulation, a model, which consists of a [Fe(CN)₆]^4- related SETs and intrinsic centers including two types of electron traps and a recombination center, is proposed. The model results in a set of differential equations that describe the kinetics of photographic generation, trapping, thermal detrapping and recombination processes. The FPT was simulated through solving these differential equations. Adjusting the simulation parameters of SETs to fit the experimental data, a number of important conclusions about SETs dopants were drawn from the simulation study.

Monolayer TeO_x thin films were deposited on K9 glass substrates or copper grids by vacuum evaporation. Structure of the as-deposited TeO_x thin film was determined by TEM and XPS. The TeO_x thin film was successfully recorded with a short-wavelength laser beam (514.5 nm). Atomic force microscopy (AFM) is used to study the microstructure of recorded marks. Micro-area morphology images show that the marks are deformed, and depressions and bulges have been imaged in the recorded marks. The level of the deformation is enhanced with the increase of writing power. AFM allows a precise determination of the mark size, the depression depth and the bulge height. The present setup allows the identification of individual marks through a specific location method and the correlation of the reflectivity contast, C, caused by a specific writing power to the morphology of the marks. According to the results of TEM analysis, there was no obvious difference between the phase state of as-deposited film and that of the recorded area. Based on the experimental results, the recording mechanism of TeO_x thin film was discussed.

Ce:Cu:BSO crystal co-doped with CeO₂ and CuO has been grown by the Czochralski method. The lattice constants, absorption spectrum, exponential gain coefficient, diffraction efficiency and respond time are measured. The lattice constants of Ce:Cu:BSO crystal are always larger than that of BSO crystal. Due to Ce and Cu ionic radii are larger than that of Bi³⁺ and Si⁴⁺, the lattice constants of doped crystal are larger than that of BSO crystal, thus make the absorption edge shift to the longer wavelength spectral range. The results indicate that the photorefraction of Ce:Cu:BSO crystal improves and the exponential gain coefficient and diffraction efficiency of Ce:Cu:BSO crystal improves two times compared with that of undoped BSO crystal. Furthermore, the photorefractive effect and the holographic storage effect of Ce:Cu:BSO crystal is better than that of undoped BSO crystal.

Ce:Fe:LiNbO₃ crystal co-doped with CeO₂ and Fe₂O₃ is grown by Czochralski method with Si-C bars as heaters. The exponential gain coefficient, diffraction efficiency and respond time of Ce:Fe:LiNbO₃ crystal are measured by two-wave-coupling technology. The results indicate that the exponential gain coefficient of Ce:Fe:LiNbO₃ is up to 22cm^-1 and the diffraction efficiency is 78% and the photorefractive effect is better than that of Fe:LiNbO₃ crystal. A thermal fixing experiment is carried on the Ce:Fe:LiNbO₃ crystal, which conditions are that the crystal is heated to 120°C, the activated energy and the developing efficiency of Ce:Fe:LiNbO₃ crystal are measured, and the decay time of a fixed grating is up to 110 years at the room temperature (20°C).

We describe a digital holographic storage system for the study on data storage format. Holograms are recorded with combined angle and spatial multiplexing in LiNbO₃:Fe by use of the 90° geometry, and reconstructions are detected with a 40-frame/s CCD camera. The data storage format and addressing method that take advantage of the unique characteristics of our volume holographic memory are discussed.

An optimum design scheme for a new 3 Dimensions Magneto-Optical Disc information storage system is proposed. By the use of the Polarization Preserving Fiber (P.P.F) integrated optical head, the small objective lens of the P.P.F. optical head can be moving at high speed, the average access time of the storage system can be reduced effectively. The wave division multiple technology can be used to realize multi-wavelengths optical fiber signals transmission in parallel mode, so the 3 dimensions storage system possesses the advantages of huge density, and the access time will be further decreased. According to the laser diffraction theory, an optical expert system software is set up to analyze the aberrations of the integrate optical head, and to compute the pick-up signals by computer simulation.

Multi-wavelength photochromic storage is a new optical storage with high storage capacity based on photochromic principle. The storage mechanism, system structure and disc structure of multi-wavelength photochromic storage are presented. An experimental system with 3-wavelength lasers used to accomplish 3-wavelength photochromic storage is presented. Experiments on the 3-wavelength photochromic storage system have been carried out. The results show that two materials used in the experiment can be used in 3-wavelength photochromic storage and contrast of the readout signal is high. The results also show that little crosstalk between two materials generates, but a little crosstalk generates irradiated by 780 nm laser and the crosstalk do not affect the recognition of the information stored in the recording layer.

The paper suggests a new scheme of hybrid recording by high refractive index optical waveguide. A recording bit will be determined by thermal gradient and magnetic field gradient, thermal field gradient be used to determine recording track width, and magnetic field gradient will determine recording bit width. In the scheme thermal gradient will be obtained by laser from an optical waveguide. The optical waveguide is flat structure and composed by three materials. The core is high refractive index material, and the clad is low refractive index material. The paper research relationship between track-width and structure of optical waveguide and analyses influence to track density by material refractive index and core thickness of optical waveguide. In theory the scheme can support 500kPTI track density.

In order to increase storage capacity and data transfer rates, a sophisticated optical storage technology - Multi-layer and Multi-wavelength photochromic storage technology - has been developed. Based on the characteristics of Photochromic medium, Multi-laser can do parallel reading or writing. In this case, the error-correcting code of conventional Compact Disc could not adapt to the Multi-layer storage. This paper put forward an error-correcting code for the two-layer storage. And some simulations were carried out.

The signal distortion can result in unacceptable bit error rate in data storage system. The low-pass nature of system is one of the significant sources of the signal distortion in the volume holographic memory (VHM). The current research interesting is how to improve the signal performance and enhance the reliability of VHM.A reduced channel model is developed to investigate the low-pass nature of the VHM. Specially, the influence on the signal from the low-pass nature of VHM is characterized by the inter-pixel interference (IPI) in a data page. Recently, some reseachers has adopted and proposed the linear transversal filter in order to cope with the IPI. However, the intensity measurement derived from the CCD is not a simple linear combination of the data. In some cases, its performance can't approach to the optimal solution. In this works, a new multiplayer percpetion based on nonlinear equalizer is introduced to counter IPI, the simulation result show that the performance of such a nonlinear equalizer is superior to that of the linear equalizer.

The paper does simulating calculation for power loss problem of waveguide probe by using vector BPM method. The paper got following results: (1) The refractive index difference of core and clad of waveguide probe is one important factor of affecting output power of waveguide probe. (2) The shape of waveguide probe is another factor of effecting the output energy.

In the multi-wavelength optical storage system, multiple data streams should be processed simultaneously. Thus a group of symmetric finite impulse response (FIR) filters are designed to meet this requirement. Unlike those conventional ways that FIR filters are implemented by digital signal processing (DSP) microprocessors or application-specific integrated circuits (ASIC), those filters are implemented on a single field programmable gate array (FPGA) integrated chip to obtain an efficient and compact solution. Since FPGAs are reconfigurable, a flexible and cost efficient platform is provided for developing the multi-signal processing subsystem. The paper presents the design and implementation of an FIR filter for the signal-processing platform using the Xilinx's SRAM-based FPGA technology. The structure and the bit serial approach of the FIR filter on an FPGA chip are also presented.

Volume holography is currently the subject of widespread interest as a fast-readout-rate, high-capacity digital data-storage technology. However, due to the effect of cross-talk noise, scattering noise, noise gratings formed during a multiple exposure schedule, it brings a lot of burst errors and random errors in the system. Reed-Solomon error-correction codes have been widely used to protect digital data against errors. This paper presents VLSI implementations of an 16 errors correcting (255,223) Reed-Solomon decoder architecture for volume holographic storage. We describe the Reed-Solomon decoders using modified Euclidean algorithms which are regular and simple, and naturally suitable for VLSI implementations. We design the speedily multiplication for GF(28) and pipeline structure to solve hardware complexity and high data processing rate for the Reed-Solomon decoders. We adopt high speed FPGA and have a data processing rate of 200 Mbit/s.

Higher recording density demands constant flying height over the entire recording area of the disk, however, in the recording procedure, the head doesn't always keep constant flying height, the flying height variation influences the recording density. This paper studies the head-disk coupling in waveguide probe near-field recording, and derives the relationship curve between half amplitude wide of static light distribution as well as static recording density and near-field coupling gap by computer simulation. After defining statistical recording density, we discuss the relationship between flying height variation of the flying optical head and statistical recording density in near-field optical recording.

Evanescent energy can be used to get extremely small optical spots. For the data storage applications, optical near field is defined in terms of Evanescent coupling between the system used to read or write data and recording layer. Near-field techniques can be applied to optical data storage systems to greatly increase recording density. So near-field recording technique has great potential in optical disc recording system and hybrid recording system. The characteristic of near-field recording spot is of vital importance in the data storage system basing the near-field theory, so it is absolutely necessary to be analyzed and measured. This paper analyses characteristic of near-field spots. The heat response time of the near field to overcome super paramagnetic effect is calculated basing the heat transfer theory. A novel measuring method for the diameter of near-field recording spot is also presented. Since the grain of the recording media is tiny enough, with the aid of atomic force microscope (AFM), near-field optical lithography can be accomplished. The diameter of near-field recording spot can be obtained by specifically designed computer either. So the relationship between the near-field recording spot diameter and the probe size of near-field recording system, the near field recording distance coupling between head and disc can be got.

Volume holography is currently the subject of widespread interest as a fast-readout-rate, high-capacity digital data-storage technology. However, due to the effect of cross-talk noise, scattering noise, noise gratings formed during a multiple exposure schedule, it brings a lot of burst errors and random errors in the system. Reed-Solomon error-correction codes have been widely used to defend digital data against errors, but the speed of Reed-Solomon decoder for volume holographic storage system application is a challenge. This paper presents a high-speed VLSI decoder architecture implementation for decoding (255,223) Reed-Solomon codes with the Modified Berlekamp-Massey algorithm for volume holographic storage. In contrast to conventional Berlekamp-Massey architectures, the speed bottleneck is eliminated via a series of algorithmic transformations that result in a fully systolic architecture in which a single array of processors computes both the error-locator and the error-evaluator polynomials. The proposed architecture requirs approximately 25% fewer multipliers and a simpler control structure than the architectures based on the popular extended Euclidean algorithm. By adopting high speed CPLD, a data processing rate over 200 Mbit/s is realized. Moreover, for block-interleaved Reed-Solomon codes, embedding the interleaver memory into the decoder results in a further increase of the throughput.

This report introduces a New Tracking Technique that extends the radial tracking range to more than several tracks. This New Tracking Technique is a major improvement in the tracking servo's response to mechanical disturbances such as shock and vibration. An added closed loop Quadrature servo conditions the tracking error signal to provide a continuous negative feedback tracking signal over several tracks. This report also describes the ease with which this Quadrature servo is incorporated into current optical disc products and the many advantages offered by its use in optical disc products.

The light intensity distribution at the pupil of the objective lens, the numerical aperture of the objective lens, the retardation inside optical pickup heads (PUHs) and the wavefront aberration of the lase beam radiated from the objective lens are dominant factors, which affect the drive to drive variation in DVD (Digital Versatile Disc) signal quality testing. The impact of each factor on the jitter measurement is experimentally analyzed. According to these analyses, a tester PUH was developed. The consistency comparison of jitter measurement between the consumer players and DVD testers are demonstrated.

In complicated structures it is difficult to determine causes of vibration because of non-linearity and variation of the system. Though Operating vibration signal has a strong similarity to dynamic characteristics of the structure in static state, it is too early to conclude that resonance of the structure brings out vibration of the structure without source identification. In vibration source identification it is important to decide not only the location and the number of sources but also rankings of sources. With this information one can know vibration generation mechanisms and devise counter plans. This research demonstrates the application for vibration source identification in optical disk drives. There are many vibration sources such as the external disturbance, the disk vibration, airflow, the motor vibration, and the chassis vibration in optical disk drives. These vibration sources are inputs of the system. And focus error signal is an output of the system. Therefore optical disk drive can be defined as a MISO system. In this research, the multiple coherence function between the output and all inputs is evaluated experimentally. The partial coherence functions are used to show which source is the major sources of focus error signal.

This paper proposes the designs of liquid crystal diffractive optical elements (LCDOEs) and their applications in optical pickup heads for advanced high-density and high-speed optical storage.

This paper presents a digital servo system using general digital signal processor (DSP) and gives the constitution of the servo system. The authors principally discuss the design method of digital servo algorithm. The repetitive control scheme is adopted to enhance the system performance to periodic disturbance.

The characteristic parameters of DVD optical heads have an important influence on the control accuracy, ability and quality of DVD system. Therefore, to test and evaluate such characteristic parameters is the necessary prerequisite for optical head production and application. This paper classifies these characteristic parameters and analyzes the factors affecting on them, discusses some methods to test and evaluate some key parameters according to actual experimental results.

Dynamic self-adaptive technology makes it possible to adjust the spindle motor speed of optical disc drive based on the different quality of optical discs. It guarantees the read process have the optimal speed to read data smoothly and protect the optical-head components. This paper presents a dynamic self-adaptive technology based on disc quality which uses fussy logic control to make the speed adjusting process fast. It is applied to the servo system of high-speed CD-ROM driver system and good results are obtained.

We propose a novel multi-pickup and multi-disk drive, in which multiple optical disks are mounted on a spindle at a equal spacing and multiple optical pickups, whose quantity is equal to that of the data surfaces of the optical disks, simultaneously read or write data in parallel. The key part of the drive is its servo-control system, which controls these optical pickups in parallel to implement the focusing servo-control and the tracking servo-control of each optical pickup in real-time in order to ensure the correct data read or write. The drive is important solution to offer super-large-capacity and quick-data-access information storage.

This paper clarified the relationship between the radial dynamical characteristic of optical drivers and disks firstly. Then the specific parts comprising the radial dynamical characteristic of optical drivers (or disks) were identified. The statistical expectation and variance of the error due to specific clamping processes were studied thoroughly. At the end of the paper, the schematic of a practical measuring system was shown.

iSCSI builds on SCSI command for storage and TCP/IP protocols for networking. As a new storage technology, VHS has advantage of huge capability and fast data transfer rate. This paper presents a detailed design, based on Intel's network processor and embedded Linux OS, to implement embedded VHS system in which unites iSCSI and VHS technologies.

This paper presents a new approach to realize the redundant array of independent DVD libraries (RAID-LoIP) by using the iSCSI technology and traditional RAID algorithms. Our design reaches the high performance of optical storage system with following features: large storage size, highly accessing rate, random access, long distance of DVD libraries, block I/O storage, long storage life. Our RAID-LoIP system can be a good solution for broadcasting media asset storage system.

Both the requirement of the application and the development of the technology have promoted the research of the new network protocols in network storage, and currently IP-based SAN has become new focus of study. The main network protocols used in IP-based SAN are: iSCSI, FCIP, iFCP and mFCP. They all implement the transmitting of block level storage data over TCP/IP. To understand and master the protocols deeply, this paper elaborates the latest development of these protocols, and analyzes and compares them intensively in regards of protocol stack, implementation model, naming, addressing, discovery and routing etc.

The steady and fast increase of data intensive application is violently driving the demand for more data storage capacity and new storage architecture. The server-attached storage approach is being replaced by storage area networks (SANs), whose primary purpose is the transfer of data between computer systems and storage elements or among storage elements, allowing storage devices to be shared among multiple servers. In this paper, we mainly analyze the different characters of Fibre Channel, iSCSI and InfiniBand used within the SANs environment. This paper discusses the issues of protocol performance, protocol scalability, the security mechanism, the interoperability and adaptability with SAN environments, the cost of investment of each architecture and so on. Comparing the performance of traditional direct attached storage, the findings show that all Fibre Channel, InfiniBand and iSCSI are the competent gigabit networking technology for storage area networks. Each protocol has its own advantages and disadvantages. Due to the overwhelming benefits of economy, covenience and high performance/cost ratio, more enterprise can deploy iSCSI SAN based on mature and existing TCP/IP infrastructure.

On the commercial available server, the great workloads on CPU generally limit the performance of Input/Output (I/O) or delay the response time. A Network-Attached Storage Device (NASD) is developed to meet the scalability requirement of mass multimedia storage. The evaluating experiments in this paper indicate that the bottleneck of data transmission is not the capability of CPU, but the network and reading/recording speed of physical storage devices. To improve the performance of multimedia storage system, a scheme of NASD-based multi-port storage area network is presented. In the new system composed of one manager and several NASDs, the manager only assigns the task of data processing to the NASDs. The NASDs can dynamically generate the virtual files and sent them to clients directly. Act as a virtual server, the storage system can provide the multi-port service for the different clients and different requirements.

In the view of string controller utilization of fiber channel RAID, this paper builds SPN model of RAID and calculates the utilization of string controller in different parameters. As a conclusion: average utilization of two string controllers is higher than that of three string controllers in distributed data storage system.