As one of the key components in scanning near-field optical microscopes (SNOM), optical fiber probes can be fabricated by use of either laser-heated pulling or chemical etching. For high-resolution near-field imaging, the near-field optical signal is rapidly attenuated as the aperture of probes decreases. It is thus important to fabricate probes optimized for aperture size and optical transmission. We present a two step fabrication method of 50 - 70% reproducibility to obtain probes with high optical transmission efficiency as well as small tip diameters. First, optic fiber probes with the transitional taper in hyperbolic or parabolic shape are produced by use of the simple home-made device for heating- pulling. Then, a rapid chemical etching with 40% buffered hydrofluoric acid is used to sharpen the tip while keeping the taper shape and the conic angle unchanged. The method renders us to achieve probes with tip diameters in the range of 20 nm - 200 nm and the tape angle near the tip apex in the range of 20 degree(s) - 60 degree(s). Particularly, the length of the non- propagating evanescent wave modes region decreases greatly to tens of micrometers or even less. In order to test the achieved probes, we give the photon tunneling decay curve and scanning near-field optical image of holographic grating by use of PSTM mode and collection-mode SNOM, respectively. In addition, an approach curve of shear force with hyperbolic probe is shown to verify its applicability to sample-tip distance regulation on basis of the principle of shear-force.

The operation principle and configuration of the Scanning Near-field Optical/Atomic Force Microscope (SNOAM) is introduced in the paper. DNA molecules were imaged in AFM mode and in SNOM mode. The topography images and the fluorescence images of single DNA molecule were obtained. The topography image in SNOM mode is of high resolution. The near-field fluorescence image shows the fluorescence distribution of DNA molecules. (lambda) DNA Molecules, in which YOYO-1 was intercalated, were imaged and characterized. For (lambda) DNA with 5 (mu) M YOYO-1, there is variation in the fluorescence intensity of the DNA and ratios of the fluorescence intensity showed almost integers in each region. As the fluorescence intensity correlated with the area of cross section in the DNA topography, it was suggested that YOYO-1 intercalated in the DNA homogeneously. Contrary, the fluorescence intensity of (lambda) DNA with 500 (mu) M YOYO-1 was heterogeneous and did not correlate with the area of topographic cross section. This suggested that YOYO-1 was not intercalated to (lambda) DNA uniformly in the concentration and intercalated partially and cooperatively.

In the paper we describe a completely new type of diode-pumped solid-state ring traveling-wave laser with two mirrors. Compared with traditional single-frequency laser, mode-locked laser and high power laser, this kind of novel ring traveling- wave lasers is more compact, reliable and affordable.

In this paper TiO₂ thin film was successfully prepared by mid-frequency alternative reactive magnetron sputtering technique with pure titanium target. Ellipsometry, AES, SEM, XRD and ultraviolet spectrophotometer were used to examine the thickness and refractive index, composition, surface morphology, microstructure and ultraviolet and visible absorption spectrum of the TiO₂ thin film, respectively. The effects of technological parameters on the properties of TiO₂ thin film were studied. The experimental results showed that the ratio of O to Ti in the thin film is very close to 2:1, which is almost independent of the oxygen partial pressure under the experiment flow rate range of oxygen in the work. The microstructure of TiO₂ thin film is mainly composed of anatase. The surface morphology of TiO₂ thin film is fine and dense. The optical properties of TiO₂ thin film are fairly good. Its transmittance is high up to 90%. The ultraviolet and visible absorption spectrum showed that the transmittance obviously decreased when oxygen flow rate was lowered from 10 sccm to 2 sccm.

In the paper, conductive and transparent indium tin oxide (ITO) films have been prepared by reactive magnetron sputtering using powder target of In₂O₃ with 10wt% SnO₂ in an Ar/O₂ atmosphere. The structural, composition, optical and electrical properties of the films deposited at different substrate temperature (150 approximately 350 degrees Celsius) have been investigated. Some interesting results obtained in this work, which might be somewhat new, are that the variations of oxide structure and concentration greatly influence the electrical properties of ITO films. X-ray diffraction patterns and X-ray photoelectron spectroscopy (XPS) show that the films deposited at substrate temperature 250 degrees Celsius or more are consist of In₂SnO₅ and In₂O₃ with no Sn₃O₄. When substrate temperature is lowered to 150 degrees Celsius, Sn₃O₄ occurs besides In₂O₃ in the films. The above result indicates the occurrence of Sn₃O₄ is unfavorable to the conductive properties. When substrate temperature is increased, Sn₃O₄ disappears, and oxygen vacancy and the electron donor Sn⁺⁴ concentration are increase, which result in a great improvement of the electrical and optical properties.

The cost per sensing point may be reduced by networking a number of gas sensors that shares the same tunable laser and/or the same signal processing electronics. In this paper we report on the use of a frequency modulated continuous wave (FMCW) technique for addressing the remote optical fiber gas sensor arrays. The sensor network is of a ladder topology and is interrogated by a tunable external-cavity semiconductor lasers. The system performance in terms of detection sensitivity and crosstalk between sensors is investigated. By using appropriate wavelength modulation/scanning coupled with low pass filtering, the coherent interferometric noise can be reduced greatly. Computer simulation shows that an array of 20 acetylene (C₂H₂) gas sensors with 2000 ppm (2.5 cm gas cell, or 50 ppm.m) detection sensitivity for each sensor may be realized. A two-sensor acetylene gas detection system is experimentally demonstrated with detection sensitivity of 165 ppm/(root)Hz (2.5 cm gas cell or 4 ppm.m/(root) Hz) and crosstalk of -25 dB.

The laser scattering particle size measurement technique is studied in this paper. An improved projection iterative algorithm is proposed to retrieve the particle size distribution from the scattering light energy. Experiments are made with spray droplet and standard multi-peak particles, which demonstrate the effectiveness of the measurement technique.

The ro-vibrational spectra of iodine molecule were studied extensively, nevertheless, the corresponding of hyperfine spectrum was few studied. In this paper, over 700 groups of stronger hyperfine transitions of iodine molecule were theoretically predicated to be available to diode laser frequency standard at 630 - 640 nm. According to theoretical predicated wavelength, we measured several groups of stronger transition hyperfine spectra with third derivative technique based on saturated absorption technique, in which three of them are reported in this paper. In the experiment, the S/N of the observed hyperfine spectra was from 70 to 400, which are available to be reference transitions for the visual diode laser frequency standard at red wavelength. Based on the high S/N of the new reference transition, the stabilization for the diode laser was performed with the above new observed hyperfine spectra. A preliminary iodine frequency stabilized tunable diode laser at new reference transitions was achieved with the frequency stability of 5 X 10^-11. Besides, the reason that the transition of band of 8 - 4 is stronger than the band of 6 - 3 were explained by the calculation of their Frank-Conden Factors, and the rule for assignment of the hyperfine spectra of Iodine molecule was also studied.

IFOG (Interferometric Fiber Optic Gyroscope) is the most promising angular velocity sensor in the inertial guidance market due to its attractive advantages, which is often regarded as the next generation gyro that can ultimately replace the traditional mechanical gyroscope. In order to improve the performance of IFOG, especially to low down the bias drift and angle random walk (ARW) of IFOG, it is valuable to research the noise characteristics of IFOG. In this paper, the ultra low frequency random noise and the relatively high frequency random noise has been investigated respectively. The experimental data of a practical open loop IFOG is obtained by different sampling frequency, through which the different frequency scope of the noise can be researched separately. The frequency spectral analysis of the noise deduces the follow result: (1) the relative high frequency (higher than about 0.001 Hz) random noise can be approximately modeled as Gaussian white noise (GWN), and its spectral range is determined by the system bandwidth of IFOG. The angle random walk of IFOG is determined by this kind of noise. (2) The ultra low frequency (lower than about 0.001 Hz) random noise can not be Gaussian white noise, which is much more great than other noises, and with the rise of frequency, the power of the relevant frequency component is lower down sharply. The ultra low frequency noise is often regarded as the source of bias drift of IFOG.

LiNbO₃ has excellent electro-optic, acousto-optic and nonlinear optical properties. In recent years, Rare-earth- doped LiNbO₃ is attractive since it allows a monolithic integration by combining amplifiers and lasers with modulators, filters, switches, etc., on the same chip. Acquiring the characteristics of the rare-earth-doped LiNbO₃ laser is the prerequisite of optimization and monolithic integration. This paper will present the theoretical modeling of Er-doped LiNbO₃ optical laser. The theoretical model is based on laser rate equations for an arbitrary rare-earth- doped laser host with multiple energy levels.

In this paper, we introduce a novel depolarizer, which is made of optical activity crystal. The equation of the degree of polarization is derived by using transfer matrix. The relationship of the degree of polarization and spectrum shape, thickness of the crystal is discussed. To demonstrate the analysis, we do some experiments using different kinds of crystals of different thickness. The results perfectly coincide with the analysis.

The temperature characteristic of components used in open-loop fiber-optic gyroscope (FOG) were studied independently and their relevant temperature models of thermal induced error were obtained A digital compensation method, in which a simple phase sensitive detection electric circuit and a microprocessor were adopted and the error compensation was realized with digital processing technology, was proposed. Experimental study showed that the bias drift of FOG tested was reduced abut 80% in the temperature range of 20 degrees Celsius - 55 degrees Celsius after compensation.

Silicon avalanche photodiodes operated int he Geiger mode are capable of detecting single photons in the near infrared regime. We have designed and tested two types of quenching circuit, with a dead time of about 1 microsecond in the passive quenching mode and 60 ns in the active quenching mode. The performance of our detectors under various operating temperatures has been investigated, and measurements down to liquid nitrogen temperatures are reported for the first time.

A new displacement measuring scheme based on simply supported beam is reported and demonstrated. The theoretical formula is derived and the experimental results are given. The scheme has many characteristics, such as simple structure, high sensitivity, large measuring range and good linearity. It is promising to be used into in-process displacement measurement.

For the first time the displacement remote measurement was realized in this paper, utilizing laser Doppler Effect. The Doppler shift of differential structure was analyzed theoretically. The system of differential optical-acoustic modulating structure, big aperture collecting backward scattering light, and compensating the losing signal by computer tracking software was designed. The displacement measurement of paper and metal at a distance of 10 meters long has been achieved with an accuracy of 0.4%.

A simple method to improve erbium-doped fiber ring laser's SNR is demonstrated. The laser's SNR is improved 5.2 dB. With the laser, transmission of 1.2 Gb/s RZ, 2.5 GHz analogue signal and 5 GHz analogue signal over 100 km was completed in a WDM system.

No Abstract Available

A novel and simple fiber Bragg grating (FBG) sensor for simultaneous displacement and temperature measurement is presented in this letter. The scheme used a specially constructed cantilever, and provided sensitivity coefficients of 8.22 X 104/mm and 8.86 X 105/°C for displacement and temperature measurement, respectively.

On the basis of theory of electromagnetic field theory and fiber grating technology, a practical sensor of electric current is reported in this paper. The Bragg wavelength shift is linear to the electric current intensity, and the range of linear tuning is about 1.0 nm. The sensitivity of electric current sensor is up to 11.696 A/nm. The formulas have been derived theoretically, and the experimental results accord with the theoretical calculations.

The tunable external cavity laser diode by using fiber Bragg grating, which is adhered to a cantilever beam, is reported for the firstly in our knowledge in this paper. A tuning range 7 nm is achieved. The side mode suppression ratio about 39 dB is realized. The output power dependence on the drive current and the cooling current is discussed in detail.

In this paper, the mode-hop free tuning method and its construction of external cavity laser diode are reviewed. The mode-hop free tuning range is restricted by the positioning errors of the components under the laboratory conditions, which will be analyzed in detail for first time as our knowledge. Those are the important reference to the design and the assembly of mode-hop free tuning construction.

Based on the vacuum field in a quantum well vertical cavity surface emitting laser and the state of electron in a quantum well, the TE mode and TM mode spontaneous emission spectra are compared at 300 K. The results show that TE mode spontaneous emission in the direction perpendicular to the surface can be enhanced with a half-wavelength cavity, while TM mode spontaneous emission is suppressed greatly.

In this paper some results of a narrow-band tunable external- cavity semiconductor laser with the Littman set-up are reported. The laser system consists of a commercial semiconductor laser at wavelength of 803 nm, a blazed grating, and an external mirror. The output power 17.9 mW and sideband suppression ratio over 20 dB were obtained. The laser is tuned conveniently in a range greater than 10 nm. The laser is single frequency, has a narrow linewidth, and is tunable over a wide range. The laser beam has good directional stability when it is tuned.

A novel method with single-wavelength light is developed to determine the optical constants and the thickness of a thin metal film. It bases on a new geometry which consists of a coupling prism, a transparent coating layer directly deposited onto the prism base, a thin metal film (most often gold or silver), and air. The attenuated total reflection technique is employed in our configuration to excite two different kind of surface plasma waves simultaneously. One is the conventional surface plasma wave which propagates along the metal-air interface. The other is a modified long-range surface plasma wave which propagates along the nonsymmetrical structure (coating layer-metal and metal-air interfaces). The reflectivity shows to obvious surface plasmon resonance dips in a single-scan measurement. Every dip can be characterized by three main parameters: the position of the minimum, the peak height at the minimum, and the width of the resonance dip. These parameters provide enough information to determine the thickness, real and imaginary part of the optical constant of the thin metal film. Compared to conventional double- wavelength method and the double-medium technique, the present single-scan method not only avoids of the ambiguity of different conditions caused by two-scan technique, but also the dispersion problem with different light wavelength.

In common electro-optic modulators (EO), the inherent velocity mismatching between the optical wave and microwave is the major factor hampering efficient modulation. In this paper, we briefly compare periodically reversed electrode and domain reversal scheme (two ways of achieving quasi-velocity- matching), then we give the design principle of the EO modulator using domain reversal scheme. At last, we conclude that the bulk LiTaO₃ EO modulator can obtain quasi- velocity-matching at special frequency and make the modulation index increase proportionally to the interaction length. As an experiment, we use a 1.06 micrometer laser as a light source and a modulating microwave source at 6 GHz (16 W). We can expect that we will get at least 3.0 rads of modulation index.

Proton-exchanged waveguides of Y-cut MgO: LiNbO₃ and Z-cut LiNbO₃ are fabricated in benzoic acid. The effective refractive indices of guide modes are measured by prism coupling method at 632.8 nm. The refractive index profiles are obtained by the inverse WKB method and the surface refractive index increments are calculated. The results show that the waveguides have the linear-step index profiles and the slope coefficient of the profile for Y-cut MgO: LiNbO₃ is much smaller than that of Z-cut LiNbO₃ and indicate that the index profile of Y-cut MgO: LiNbO₃ waveguides is more like step. The theoretical mode indices are obtained on the basis of the dispersion equations with the simple step and linear- step index profiles respectively. It is found that the linear- step profile is more accurate. The effective diffusion coefficients, diffusion constant and activation energy are achieved with the diffusion law finally.

We present a method for sensing and inspecting acceleration by optic fiber gratings in this paper, the component a_i (i equals x, y, z) of one-dimensional acceleration to be linear with shift quantity (Delta) (lambda) _B of Bragg reflected wavelength in horizontal and vertical are obtained, inspectable minima values for acceleration components in every direction is 10^-5 m/s² order of magnitude; and the 3D acceleration in parallel and series connection forms to measuring are also given under the WDM way.

We have designed and constructed a white light optical sensor for optical particle counter (OPC). The optical system of the sensor is a right-angle scattering type optics. It consists of an illumination system and a collection system for scattered light. A large illuminating aperture angle of 24 degrees is obtained by applying an aplanatic singlet in the illumination system, and a large collecting aperture angle of +/- 44 degrees is achieved by a spherical mirror. With the two large apertures, high signal-to-noise ratio and good monotonic light scattering response have been gained.

Based on the corresponding relationship between the refractive index and the concentration of some solutions, and with the use of CCD, we present the principle of on-line measurement of solution concentration. It is verified by simulating test and proved to simple and convenient, and can be used for on-line automatic measurement of transparent solution concentration.

CCD device -- the photoelectric sensor of high sensitivity and high accuracy -- has been widely used in non-contact measuring and control system in industry. But the internal and external parameters and measuring system parameters of ordinary CCD camera vary with the working environment and condition, which affects the accuracy directly. According to rotary matrix, the mathematics model of measuring system of CCD camera is studied in the imagery way and the imagery model is given under the circumstances of non-parallel light. Based on this, the arithmetic is presented to demarcate the internal and external parameters and the measuring system parameters of ordinary CCD camera. It is not iterative, fast and accurate to demarcate. It has been applied in the measuring system of roller surface on line and produces better results.

An all-optical remote methane sensing system was developed. It combines long and low-loss optical fiber link with high radiant InGaAsP diodes and an interference light filter. The high sensitive technique is achieved by using the differential absorption method in the system. Based on the laboratory study of the v₂ + 2v₃ overtone band of CH₄ molecules at 1.33 micrometer, the system is used for remote detection in real time of low level gas. A methane monitor can detect concentration as low as 0.2%. The maximum is up to 100%.

This paper presents a monitoring temperature system in real time. The fluoroptic temperature could be detected quantitatively by the signals of PSD. When the optical fiber is 2 m long, the real-time temperature sensitivity is 0.1 degrees Celsius and the accuracy is 1%. The high sensitivity and high accuracy are partly due to the operation of the light source feedback, and partly due to the ratio of measurement and reference signals. This fluorescence temperature measuring system finds wide application fields where conventional techniques either cannot be used, or have proven to be unsatisfactory. It is especially useful for measurements in electrically hostile environments.

In this paper, the disadvantages of the traditional Current Transformer (CT) on high voltage power line are described. A new method to measure the high-voltage current is studied. A Practical Hybrid Fiber Optic Sensor for High-Voltage Current is developed and the result of the experiment and the errors are analyzed. This design consists of two parts. One is in the air attached with the high voltage power line and the other one is on the ground. In the upper part, a Rogowaski Loop is used to transform the current signal into voltage one, then a V/F converter is applied to change this voltage signal into frequency. After processed, the resulted frequency signal is fed to the LED, which turns the electrical signal into light one. Then, the light signal is lead along the optic fiber down to the ground. Here, the optic fiber is used for insulation purpose. On the ground the light signal is converted back into electrical signal with a photoelectric cell. After amplified and regulated, the electrical signal is fed to a F/V converter, which changes the frequency signal back into the original current signal.

The distributed optical fiber temperature sensing system based on the Raman back scattering has been widely used. By using the optical time domain reflection (OTDR) technique, the high intensity light pulse is coupled into optical fiber. By detecting and recording the variation of back scattering signal related to optical fiber temperature along with the time, the distribution measurement of environmental temperature is carried out. In order to ensure a certain intensity of the light pulse, it must have a certain width. In the meanwhile, the responding rate of the photoelectric components and the bandwidth of the digital collection systems cause the reduction of the space resolution. The signal coupling brought by the pulse width can be reduced and the space resolution of distributed optical fiber temperature sensing system can be improved by using self-adaptive wavelet nerve network which has a stronger ability of function approach and tolerant fault to process the data.

In this paper the dependence of the ranging performance for an airborne laser range finder (LRF) on atmospheric transmissivity, background noise and target characteristics is theoretically analyzed, in accordance with the system performance equations for the diffuse reflecting target. Based on LOWTRAN7 code, the ranging performance of the airborne laser range finder versus the surface visibility for atmosphere, the ranging path and the diffuse reflectance coefficient for target is numerically calculated and further discussed. On basis of the numerical results, an airborne LRF with excellent system performance is figured out.

This article has analyzed theoretically the characteristics of rotary double wedges about guide range, guide velocity and guide precision. It also has accomplished the design of rotary double wedges and given the calculating results and experimental data.

In this paper a variable grating mode liquid crystal optical sensor system performing intensity-to-spatial-frequency conversion is described. The system performs real-time, reconfigurable, and nonblocking, but nonbroadcasting, optical crossbar interconnections.

The big city is a center of the economic and political for every country and territory. The population is coarctation$DALindustry is focus and traffic is developed in the city. Especially, there are a lot of factories and cars. Burning coal for heating and life garbage are more too. It is a mostly cause beget atmosphere polluted. The Network can be availability inspects the buildup of the atmosphere, it's 3-D static state distributing and dynamic distributing. Also can be coarsely inspect at the car and helicopter. The network is low cost, high capability and facility using. It is commendably expand for every city.

In this paper a design method of the Micro Pulse Lidar (MPL) is introduced, that is a computer simulation of the MPL. Some of the MPL parameters concerned air scattered and the effects on the performance of the lidar are discussed. The design software for the lidar with diode pumped solid laser is programmed by MATLAB. This software is consisted of six modules, that is transmitter, atmosphere, target, receiver, processor and display system. The method can be extended some kinds of lidar.

The demand for incorporating sensor technology into the production environment is being driven by the increasing need to minimize manufacturing costs whilst simultaneously producing parts of high quality. A novel simple fiber-optic sensor based on the light beam reflection principle was presented for slopes measurement. With the optical probe arrangement like a wheel, the emitting single-mode finer (SMF) as the axle and eight receiving multi-mode fibers (MMF) as the spoke, the sensor can detect the surface slopes with two- coordinate as well as the offsets of displacement measurement can be compensated. The mathematical models were established based on the ABCD Law of Gaussian beam transmission matrix optics and in the case of paraxial approximation. Simulations were performed for verifying the proposed idea, and the preliminary experimental results were obtained and its performance coincided with the simulation. The resolution of slopes test was better than 0.02 degree over +/- 30 degree, and the displacement measurement vertical resolution stayed within 0.1 micron, the lateral resolution can reach 8 micron. And with the further development of this method, it can be absolutely used in complex surface measurement in Reverse Engineering.

Although the development of fluorescent fiber optic temperature measurement technology have overcome the difficulty of the surface temperature distribution measurement of a rotor of electric machine. The temperature of the conductor (or magnetic) strips which are buried under the surface of the rotor yet not be resolved. A new measuring scheme of fluorescent optical fiber is presented in this paper. It is fully suitable for the above measuring demands. Several fiber probes are assembled with the rotor. The sensor heads are buried under the rotor surface to touch the measuring points. The other ends of the fiber probes are terminated on an optical rotational coupling disc. The induced temperature signals then are sequentially transmitted out to the external of the rotor by another fix fiber. Finally the temperature of the strips is obtained. In this paper we will discuss the selection of light source, the design of light path and derive the theory analysis of dynamic coupling.

In this letter we report a novel 980 nm semiconductor laser array structure with nonabsorbing facets to avoid the COMD on facets. The 980 nm laser wafers are grown by MBE. Using quantum-well intermixing, we have fabricated nonabsorbing mirrors on the laser array's facets to resist COMD. The quantum intermixing process involves the deposition of a thin film (200 nm) of sputtered SiO₂ and a subsequent high temperature anneal (680 - 760 degrees Celsius). The cm bars are cleaved to lengths of 1 mm and their rear and front nonabsorbing facets are coated respectively with high and low reflectivity dielectric film by electron-beam. The devices are bonded p-side up onto copper heatsinks using indium solder and mounted on a water-cooled stage which is held at 18 degrees Celsius for all experiments. The emission wavelength of the laser arrays is 980 nm. Continuous wave (CW) output power of 8 W has been achieved.

The low frequency electrical noise and electric derivative (IdV/dI-I) are measured at different conditions. The correlation between the noise and device quality is discussed, the results indicate that the low frequency electrical noise of 808 nm high power semiconductor laser is mainly 1/f noise and has good relation with device quality.

Based on the theoretical analysis relating to the Heat Conducting Theory, the Thermal Strain Theory and the Mechanical Vibration Theory, the performance of the silicon microresonator with coating film are studied. The new models of resonant frequency and amplitude are presented by taking the coating film effect into full account, and the comparison between the theoretical values and experimental values shows that the models are more accurate.

In the view of the blindness of photoelectric measurement scheme argument and the danger of live shell measurement in shooting range, this paper provided a computer aided measurement method guiding the measurement scheme argument and equipment researching and producing and driving the measurement process visiblization and standardization. The computer aided measurement in shooting range can be divided into the mathematical simulation of targets moving, the mathematical simulation of measurement method, the mathematical simulation of photoelectric system, the animated displaying of measurement process, and so on. By adding random jamming, Gaussian white noise and so on, the live measurement environment and condition was built. By using mathematical discretization, the time series pictures was obtained. By controlling the time changing and time unifying of several equipment, the animated displaying of measurement process was built. The programming language was MATLAB. The method was proved through simulating the intersection measurement trajectory of antiaircraft gun's shell successfully.

In this paper, the principle of radiation sensor is introduced, the quantitative model for the relation of radiation & fiber loss was derived, and the relations among output-power loss were tested in variance circumstances.

Wavelength dependence and finite band width of reflectivity at the AR-coated facet have been taken into account to study the oscillation wavelength and threshold carrier density of one- fact antireflection semiconductor lasers. Analytic expressions for both the upper bound of the threshold carrier density and oscillation wavelength have been derived. Analysis shows the deviation between the wavelength of the AR-coated facet minimum reflectivity an that of the gain peak is a key parameter to reduce the Fabry-Perot oscillations.

This paper introduces the principle and characteristics of a sunlight tracking sensor. Application of the sunlight tracking sensor in optical fiber sunlight illuminating device is introduced too.

The operation principle, technique character and measuring method of 10 km LDOFTS are discussed. The testing result of 10 km LDOFTS is given in this paper.

A new sampling correct technology of distributed optical fiber temperature sensor (DOFTS) has been researched to eliminate the instability of DOFTS system that caused by the change of environment temperature, gain of amplifier and voltage of power supply. Put the optical sampling loop into a constant temperature thermostat. A computer automatically corrects signal voltage of every point. Thus the stability of the system is improved.

In this paper, a novel Eu³⁺ polymer named PRL basing on a new Eu-containing monomer was synthesized and was used as a red light-emitting material in our organic electroluminescent device with single layer structure of ITO/PRL/Al. This material had strong photoluminescence, good chromaticity and can transport both holes and electrons. Being a polymer, the device made by use simple spin-coating method in stead of the usual doped spin-coating and vacuum deposition. The brightness of 80 cd/m² was achieved at the voltage of 26 V. And we try to explain the mechanism of this EL device according to its photoluminescence, electroluminescence, B-V and I-V characteristic. And we also measured its mobility and explained the reason of its relatively high drive voltage and low luminescence

A new signal processing circuit for position sensitive detector (PSD) is proposed in this paper. Using this circuit, the photocurrents of PSD can be directly transformed into digital signals, and the signal-to-noise ratio can be greatly improved, but the measurement time is extended. The measurement results show that the agreement between theory and experiment is quite good.

Infrared Search and Track (IRST) system is one of the most typical airborne sensors for the remote target measurement, detection and tracking in the fighter planes. And the modeling of the measurement error is the basis of target recognition and tracking. For the purpose, this paper describes the important components of IRST system and their influence upon the measurement accuracy. After error propagation and conversion are considered, the total measurement error of IRST system can be obtained and compared with the calculations based on normal distribution model of the measurement error. Then a novel and more practical mathematical model of the measurement error is formed and the main parameters are defined. Finally data simulation is implemented, and the results demonstrate the new mathematical model of the measurement error is more effective.

The methods based on the laser diffraction are more noticeable in the measurement of particle size distribution. In present laser particle sizing system, particles are treated as a group of spheres with various diameters, in order to inverse the particle size distribution. Actually, the shapes of most measured particles are non-spherical, so obvious differences would occur in the assumption of sphere. In this paper, after the description of the principle of laser particle sizing, problems existing in using above methods to measure the non- spherical particles are discussed. Then it is presented that the measurements based on the spherical, linear, rectangular particle diffraction would be applied to inverse the particle size distribution, according to the shape of measured particles. Through the measurement of samples, it is indicated that the results measured are consistent with those by the auto-electron microscope. In additionally, the values and diagrams obtained by these methods are presented, and the errors with different diffraction models are discussed in this paper.

In this paper, we analyze the performance of error probability of amplitude shift keying (ASK) system of coherent state signals and phase shift keying (PSK) system of squeezed state signals, in which we use a quantum receiver called square root measurement.

In this paper we present an edge detection method based on evolutionary techniques. The edge detection is casted as an optimization problem which minimizes cost function. Similar to the Bhandarkar's approach, the cost function is constrained by accurate localization, thinness, curvature, continuity and length. However, the proposed method uses evolutionary techniques not only for the search of minimum of the cost function, but also for the formulation of optimal structure of cost function. The usefulness of this method is demonstrated by showing experimental results of detected edges.

The photonics sensor with heterojunctions of TiO₂/PS/p-Si was prepared by coating the nano-sized thin film of TiO₂ on surface of the porous silicon substrate and was characterized by the surface photovoltage spectroscopy. The results showed that the photovoltage of porous silicon (PS/p- Si) was greatly increased two to three orders of magnitude by coating TiO₂ thin film. The enhancement of photovoltage may be attributed to the efficient absorption spectrum from near infrared till ultraviolet light of the double heterojunctions of TiO₂/PS/p-Si and the effective separation of the photoproduced electron-hole pairs due to the increment of the built-in electric field of the quasi- intrinsic porous silicon. Moreover, the back electric field generated by the potential difference between PS and p-Si may resist the diffusion of minority carrier toward the electrode, leading to the effective enhancement of photovoltage.

This paper presents a new development of sensor systems which use liquid crystal droplet materials. This material is a flexible plastic sheet which can be readily polymerized to any thickness, size or form. Sensors formed from the material do not require sealing and can be fabricated as large, flexible plastic sheets, which can be or trimmed. The high stability of these materials makes it possible for them to be used in electric field sensors. An electric field sensor is prepared using liquid-crystal droplet materials.

In this paper, the measurement of gravitational waves of the earth has been studied by using laser double beam interference method. We have discussed the measuring principle and precision. The results show that the precision is of 0.006 micrometer at (lambda) equals 6328 angstrom, length 25 m by modulating and counting of interferogram. So the method may be used to measure the gravitational waves of the Earth in tunnel.

The magneto-optic current and electro-optic voltage sensing technologies were combined into a single phase unit which provides a new solution for combined current and voltage sensing and relaying applications. It senses voltage and current by making utilities of Pockels electro-optic effect of a BGO(Bi₄Ge₃O₁₂) crystal and Faraday magneto-optic effect of a close-loop flint. The 220 kV high voltage is directly applied on the BGO crystal without capacitive dividers. This design permits true optical voltage measurement to be performed for the highest possible accuracy and stability. In the current sensor, a light beam circles around the current carrying conductor. The effect of the location movement of the conductor and external magnetic field are reduced. It has superior advantages of compact size, light- weight and better performance compared with conventional current and voltage transformers. Composite bushing consisting of a fiberglass tube support and silicone rubber that is filled with SF₆ gas is employed for HV insulation. Connections between the Combined Optical Transformers in the substation and the metering and protecting unit in the control house are via optical fiber cable. The fundamental principal, system design and test result of this new 220 kV Combined Optical Transformer will be introduced in this paper.

The stability of optical voltage transformers has been the main obstruction to its practical application. An optical voltage sensor is the core of an optical voltage transformer. This paper proposed a novel reflection-type transverse modulation optical voltage sensor with double light channels temperature compensation. The sensor is based on the Pockels effect in a Bi₄Ge₃O₁₂ (BGO) crystal. The measured voltage is applied to the crystal along the <001> direction with light wave passing through the crystal along the <110> direction. Theoretical analysis shows that this is an optimum configuration for a reflection-type transverse modulation optical voltage sensor. The novel optical voltage sensor was employed to develop a novel optical voltage transformer (OVT) for 220 kV power systems. There isn't any capacitor divider in the OVT. The measured high voltage is applied to the optical voltage sensor directly. Experiments showed that the sensor has good double light channels temperature compensation characteristic and the stability of the OVT could reach +/- 0.4% during two weeks. The principle, structure and test results of the OVT are presented in this paper.

It's usually known that the particle size and particle shape are two irrelevant concepts. But our research shows that the token of particle size is not only related to particle shape, but also related to particle measurement methods. This paper takes sheetlike graphite micropowder for example and gets the function relation between particle shape factor and particle size by analyzing the particle distribution data between laser diffraction and sedimentation. This research provides a new approach for the study of particle shape.

A photonic crystal is a periodic arrangement of dielectric or metallic materials. It may offer a possibility of eliminating electromagnetic wave propagation within a frequency band, i.e., a photonic band gap. The discovery of photonic band-gap materials and their use in controlling light propagation is a new and exciting development. It has vast implications for material scientists, electrical engineers, and physicists. Recently, photonic crystals have attracted particular interest due to their important applications in optical and tele- communications. In this paper, we present some of our recent works on photonic crystals and their applications.

APD (avalanche photodiode) is a very important photodetector, which is widely used in the fields of optical fiber communications and optical fiber sensors because of its high gain. But the thermo-performance of APD, which means that its gain is to vary with the temperature around, makes it difficult to be used more widely in the fields above. So the authors have done experiment research on the APD's thermo- performance and have solved this problem successfully. The thermo-performance of APD is systematically studied in this paper. The scheme of experiment system and experiment circuit which are used to measure to APD's temperature shift is introduced too, and the variation equation of its temperature shift is gained by linearizing the data got from our experiment. Moreover keeping the environment temperature constant and making compensation to the APD by adjusting the bias voltage are two key factors that should be carefully considered to research into the methods of compensating the effect of temperature shift. The two methods are discussed here too. And by these means the quite faint photoelectric signals, which has blent with the strong noise, can be picked up successfully. Our experiment conclusion is an important and valuable reference to using APD rightly and ensuring it to run steadily.

The use of opto-electronic Helmet Mounted Display And Sight System (HMDASS) will decrease responding time for fighter in near distance tussle. See-through type Helmet Mounted Display (HMD), instead of the simple graduation board display, will provide more information and so much as integrate the FLTR image. We research some questions of TFTLCD device in optic- electric HMDASS application, such as luminance, information content & format etc. This paper discuss the luminance question in perspective type LCD-HMD and put forward a display method to increase the reaction velocity for a pilot using opto-electronic Helmet Mounted Sight (HMS).

In the paper a multiplexing remote temperature measurement system based on the Internet is described. It includes the system project diagram, the configuration of hardware and software. This system can be used in the electric power station to inspect the potential defects of electric equipment. In the situation of full automatic operation, the temperature measuring results can be transmitted to the managed center through the Internet for monitor, in a nobody on duty status.

The mechanical sensing units made from piezoelectric composite materials, their structures and their performances are presented in this paper. Their sensing equations are deduced. The dynamic and static properties of the units are calibrated. The orthotropic piezoelectricity of them and advantages in properties make it possible to detect the stresses in Orthotropic material structures.

In this paper a novel opto-electric phase discriminator array implemented with CCD is presented. It has the potential application in scannerless three-dimensional imaging system. As it works, a sinusoidal light signal is detected by a CCD receiver. CCD's exposure is controlled with square wave that has the same frequency as incident light intensity. Thus the correlative operation is processed in CCD automatically. CCD's output signal contains phase information of input signal. In order to figure out the unique phase shift between the sinusoidal signal and the square wave signal, triple measurement methodology is adopted. In our experiment, the RMS error of measurement is about 0.2%.

A wide-angle single-mode 3-dB asymmetric Y-junction with a microprism is proposed. Symmetric Y-branches, useful for equal power splitting, have been widely investigated by various authors. Asymmetric Y-branches, however, are not as well studied as their symmetric counterparts. In this paper, the phase front mismatch caused by asymmetric branching will be discussed. The microprism is designed by its phase compensation rule (PCR), the phase front mismatch at the branching point is greatly eliminated, and the structure of the microprism can be varied in fixed microprism length or fixed index. By utilizing the PCR we proposed, each branch arm will have equal power. A conventional asymmetric Y-branch can be utilized as a 3-dB divider only under small and specific branching angles. To remove this disadvantage, a novel asymmetric Y-branch with microprism is proposed. This structure can divide the optical power almost equally into output branches under large-angle. Because the difference between the index of the film and the index of the substrate is very small, the proposed structure is weakly guiding. Therefore, device performance examined numerically by the semivectorial finite difference beam propagation method (SVFD- BPM) should be acceptable and always kept at satisfactory levels in this paper.

TiO₂/organically modified silane (ORMOSIL) optical waveguide thin films have been prepared at low temperature by the sol-gel technique by using y- Glycidoxypropyltrimethoxysilane and tetrapropylorthotitanate as precursors. Atomic force microscopy has been used to characterize the morphology and structural properties of the waveguide films. Waveguide properties of these composite thin films on III-V compound semiconductor substrates such as their refractive index, thickness, and propagation loss have been studied. It was experimentally demonstrated that grating structures could easily be fabricated for these composite thin films by using the embossing technique and we have successfully fabricated the grating by this method without baking. It was found that this method is specifically useful for the fabrication of diffractive grating and optical planar waveguides on sol-gel derived glass film coated on temperature sensitive substrates such as III-V compound semiconductors. As a preliminary result, the ridge waveguide and grating with a period of 1.102 micrometer and depth of 57.2 nm have been successfully fabricated.

We report the realization of the dynamic image of stress distribution by developing a remarkably strong mechanoluminescence (ML) material of Sr_0.975Al₂O_3.985:Eu_0.01(SAO- E), which can emit four orders of magnitude larger intensity than that of the reported strong ML material of quartz crystal. This ML material can be mixed in the target composite or coated on the surface to sense stress by emitting visible light. This method is applicable to the dynamic visualization of stress distribution in a solid not only in the atmosphere but also in an aqueous environment. A simulation result confirms that such a ML image successfully reflects the stress distribution. A kinetic model for ML of SAO-E is proposed.

We have investigated the triboluminescence (TrL) intensities of as-grown and thermally annealed ZnS thin films doped with manganese on quartz substrates. The ZnS:Mn thin films were deposited by rf magnetron sputtering and thermally annealed in a reducing gas (5% H₂/Ar) at 500 degrees Celsius, 600 degrees Celsius, 700 degrees Celsius and 800 degrees Celsius. The crystallinity and the triboluminescence intensities of the films were greatly enhanced by postannealing up to 700 degrees Celsius, accompanied by an increase in the adherent strength of the film. An X-ray diffractometer and a Scratch Adhesion Tester were used to study the crystallinity and adhesion of the as-grown and annealed films respectively. Results based on crystallographic and acoustic emission data were used to explain the failure mechanisms in the films during the triboluminescence measurement.

Results of our recent experiments relating to ZnTe homoepitaxial growth by atmospheric pressure metalorganic vapor phase epitaxy are described. The effects of substrate temperature, gas flow rate and VI/II ratio upon the growth rate of ZnTe layers have been investigated. The behavior of the growth rate is well explained with a simplified growth model, in which the diffusion in the boundary layer and the reaction-rate law described by Langmuir-Hinshelwood model are considered. We also deal with the results on the photoluminescence properties of ZnTe layers obtained under wide growth conditions covered from mass transport limited region to kinetically controlled one. The growth conditions close to the transition part between mass transport and surface kinetic regions led to ZnTe layer of high quality. Similar conclusion is also obtained for photo-assisted growth. Photo-assisted growth enlarges substrate temperature range for achieving ZnTe layer of good quality compared with thermal growth.

Indium nitride films were grown on (111)GaAs substrates by reactive magnetron sputtering using an indium target. It was found that the crystal quality of InN films depends strongly on the substrate temperature and sputtering gas pressure, and highly c-axis preferred wurtzite InN films can be obtained at growth temperature as low as 100 degrees Celsius. The influence of the substrate pretreatment on crystallinity of indium nitride films was also investigated. It was shown that the crystalline quality of InN layers grown on GaAs can be improved by presputtering the substrate in nitrogen plasma prior to the growth. By Auger electron spectroscopy and atomic force microscopy analysis we revealed that GaN islands form on the surface of GaAs substrate due to the presputtering. The optimum presputtering time for growing InN single crystal was assessed to be the time at which GaN islands cover the substrate surface entirely.

The temperature dependence of photoluminescence (PL) of rare- earth ions activated Y₂SiO₅ was investigated from room temperature to 573 K. Ion activators such as Eu³⁺, Ce³⁺, Sm³⁺, Tb³⁺, Tm³⁺ and some of their combinations were studied in this work. The most efficient blue, green and red phosphors at elevated temperature were found by doping the (Ce³⁺ + Tb³⁺), Tb³⁺ and Eu³⁺ respectively, in this material system. Meanwhile, the relationship between the unit cell volume of Re_x Y_2-xSiO₅ and the temperature dependence of PL was also revealed.

Electroabsorption (EA) modulator integrated with partially gain coupling distributed feedback (DFB) lasers have been fabricated and shown high single mode yield and wavelength stability. The small signal bandwidth is about 7.5 GHz. Strained Si_1-xGe_x/Si multiple quantum well (MQW) resonant-cavity enhanced (RCE) photodetectors with SiO₂/Si distributed Bragg reflector (DBR) as the mirrors have been fabricated and shown a clear narrow bandwidth response. The external quantum efficiency at 1.3 micrometer is measured to be about 3.5% under reverse bias of 16 V. A novel GaInNAs/GaAs MQW RCE p-i-n photodetector with high reflectance GaAs/AlAs DBR mirrors has also been demonstrated and shown the selectively detecting function with the FWHM of peak response of 12 nm.

The development of laser medicine in China is correlated with the development of laser science in China. After the first Chinese laser, ruby laser came into being in 1961, Chinese medical scientists began to do the studies about laser medicine in the middle 1960s. For example, ruby laser was adopted for the retina coagulation experiment in 1965. Since 1970s, through the free choice of utilizing Co₂, He-Ne, Nd:YAG argon, ruby lasers, laser surgery and medicine has been widely applied to the treatment for diseases of the eyes, ENT, dermatology, surgery, gynecology, tumors and diseases suitable to physical therapy or acupuncture with satisfactory effects. In June 1977, a nation-wide laser medicine symposium was held at Wuhan, Hubei Province with 200 participants including medical doctors and laser technologies from 23 provinces and municipal towns. Till the end of seventies, utilization of lasers has been extended to Nd glass laser, N laser and tunable dye lasers. The scope covered most of the clinical sections. After Dr. Thomas J. Dougherty developed the PDT for cancers in Roswell Park Memorial Institute in Buffalo in late 1970s and Professor Yoshihiro Hayata successfully applied the PDT in clinical treatment for lung cancer in 1980, Chinese pharmacists successfully produced the Chinese HpD and the first case of PDT, a lower eyelid basal cell carcinoma patient was treated with the Chinese laser equipment in 1981 in Beijing. Its success brought attention establishing a research group supported by the government in 1982. The members of the group consisted the experts on preclinical and clinical research, pharmaceutical chemistry, laser physicists and technologists. A systemic research on PDT was then carried out and obvious result was achieved. The step taken for PDT also accelerated the researchers on other kinds of laser medicine and surgery because the medical doctors had begun to master the knowledge about laser science. The prosperous situation of rapid development of laser science, bio-medical lasers, laser medicine and surgery as well as PDT was prolonged in the whole nineteen eighties.

The application of the wavelet transform to edge detection is discussed in general. In particular, two new wavelet transforms for edge detection as well as detecting the center of two edges are presented and discussed in detail. The proposed method is useful for lead inspection of surface mount devices in the electronic industry.