This PDF file contains the front matter associated with SPIE Proceedings Volume 9673, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing.

Laser sintered thin layer graphene (Gr)-cubic boron nitride (CBN)-Ni nanocomposites were fabricated on AISI 4140 plate substrate. The composites fabricating process, composites microstructure and mechanical properties were studied. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy were employed to study the micro structures and composition of the composites. XRD and Raman tests proved that graphene and CBN were dispersed in the nanocomposites. Nanoindentation test results indicate the significant improvements were achieved in the composites mechanical properties.

A side-pumped Nd:YAG amplifier that can realize amplification and beam shaping simultaneously is reported. As a typical application, a Gaussian intensity profile of signal laser was amplified and converted into a flat-top distribution. The main parameters satisfying this requirement involved structural designation and optical parameters adjustment of the pumping laser diode LD, to obtain a specific gain distribution on cross section of the working material. Among them the key considerations include central wavelength of LDs and pumping radius to the centre of Nd:YAG rod. Take an example of 15mm-dameter Nd:YAG side-pumped rod amplifier, where 13.5kW laser diode bars were used, we simulated an uniform flat top laser profile by ray-tracing method. The following experiment shows a good agreement with the simulation. Moreover, gradual absorption coefficient of the working material could also be well compensated while realizing flat-top beam to flat-top beam amplification.

This study was based on the ferritic stainless steel SUS430. Under the parallel welding conditions, the critical penetration power values (CPPV) of 3mm steel plates with different surface-coating activating fluxes were tested. Results showed that, after coating with activating fluxes, such as ZrO₂, CaCO₃, CaF₂ and CaO, the CPPV could reduce 100~250 W, which indicating the increases of the weld penetrations (WP). Nevertheless, the variation range of WP with or without activating fluxes was less than 16.7%. Compared with single-component ones, a multi-component activating flux composed of 50% ZrO₂, 12.09% CaCO₃, 10.43% CaO, and 27.49% MgO was testified to be much more efficient, the WP of which was about 2.3-fold of that without any activating fluxes. Furthermore, a FeCl₃ spot corrosion experiment was carried out with samples cut from weld zone to test the effects of different activating fluxes on the corrosion resistant (CR) property of the laser welded joints. It was found that all kinds of activating fluxes could improve the CR of the welded joints. And, it was interesting to find that the effect of the mixed activating fluxes was inferior to those single-component ones. Among all the activating fluxes, the single-component of CaCO₃ seemed to be the best in resisting corrosion. By means of Energy Dispersive Spectrometer (EDS) testing, it was found that the use of activating fluxes could effectively restrain the loss of Cr element of weld zone in the process of laser welding, thus greatly improving the CR of welded joints.

The laser-induced damage of GaAs/Ge single heterojunction solar cells is investigated. The solar cells were irradiated by a continuous wave laser at the wavelength of 532 nm. Results indicate that the GaAs/Ge solar cells would mostly be damaged when laser is focused on its grid lines. Theoretically, the continuous wave laser at the wavelength of 532 nm is absorbed at the surface of solar cells. The continual temperature rise decomposed the material GaAs and melted the material Ge. The melted metal Ge connected the solar cells grid lines and the rear electrode, the solar cell became completely invalid. The major damage of continuous wave mainly comes from both the thermal melting and the thermal stress effects. The huge temperature gradient on the surface of the solar cells generated the crack, and even rupture. Concentric iridescent ring appeared on the damaged surfaces when observed with an optical microscope(OM) of broad spectrum. The damaged surface film was characterized by X-ray photoelectron spectroscopy(XPS) and the Contour Meter. The component of the concentric iridescent is GeO₂ film, when the light irradiated on the film and interfered, the concentric iridescent generated. The different ring indicated the thickness of oxide was different. When the film was corroded by HCl, the iridescent disappeared. The formation mechanism of the film and the cause of the concentric iridescent ring were analyzed. These experimental conclusions are tested and verified by scanning electron microscope with energy dispersive spectroscopy and X-ray photoelectron spectroscopy.

The ferritic stainless steel SUS430 was used in this work. Based on a multi-component activating flux, composed of 50% ZrO₂, 12.09 % CaCO₃, 10.43 % CaO, and 27.49 % MgO, a series of modified activating fluxes with 0.5%, 1%, 2%, 5%, 10%, 15%, and 20% of rare earth (RE) element yttrium (Y) respectively were produced, and their effects on the weld penetration (WP) and corrosion resistant (CR) property were studied. Results showed that RE element Y hardly had any effects on increasing the WP. In the FeCl₃ spot corrosion experiment, the corrosion rates of almost all the samples cut from welded joints turned out to be greater than the parent metal (23.51 g/m² h). However, there was an exception that the corrosion rate of the sample with 5% Y was only 21.96 g/m² h, which was even better than parent metal. The further Energy Dispersive Spectrometer (EDS) test showed the existence of elements Zr, Ca, O, and Y in the molten slag near the weld seam while none of them were found in the weld metal, indicating the direct transition of element from activating fluxes to the welding seam did not exist. It was known that certain composition of activating fluxes effectively restrain the loss of Cr element in the process of laser welding, and as a result, the CR of welded joints was improved.

High-energy Laser weapon is a new-style which is developing rapidly nowadays. It is a one kind of direction energy weapon which can destroy the targets or make them invalid. High-energy Laser weapon has many merits such as concentrated energy, fast transmission, long operating range, satisfied precision, fast shift fire, anti-electromagnetic interference, reusability, cost-effectiveness. High-energy Laser weapon has huge potential for modern warfare since its laser beam launch attack to the target by the speed of light. High-energy Laser weapon can be deployed by multiple methods such as skyborne, carrier borne, vehicle-mounted, foundation, space platform. Besides the connection with command and control system, High-energy Laser weapon is consist of high-energy laser and beam steering. Beam steering is comprised of Large diameter launch system and Precision targeting systems. Meanwhile, beam steering includes the distance measurement of target location, detection system of television and infrared sensor, adaptive optical system of Laser atmospheric distortion correction.

The development of laser technology is very fast in recent years. A variety of laser sources have been regarded as the key component in many optoelectronic devices. For directed energy weapon, the progress of laser technology has greatly improved the tactical effectiveness, such as increasing the range and strike precision. At the same time, the modern solid-state laser has become the ideal optical source for optical countermeasure, because it has high photoelectric conversion efficiency and small volume or weight. However, the total performance is limited by the mutual cooperation between different subsystems. The optical countermeasure is a complex technique after many years development. The key factor to evaluate the laser weapon can be formulated as laser energy density to target. This article elaborated the laser device technology of optoelectronic countermeasure and Photoelectric tracking technology. Also the allocation of optoelectronic countermeasure was discussed in this article. At last, this article prospected the future development of high-energy laser.

To investigate the heat accumulation effect of the laser pulse train, a two dimensional finite element calculation model is established to calculate the temperature field of Aluminum target based on the Fourier heat transfer theory. Take account of the influence of the repetition rate of laser, four different repetition rates (5 kHz, 10 kHz, 50 kHz and 1 MHz) pulse laser train and continuous wave (CW) laser are analyzed in this study. The results indicate that under the same average power and irradiation time, the peak temperature and accumulative temperature increase with the decrease of the repetition rate. With the increase of the repetition rate, the heat accumulation effect is more closer to the CW laser. The heat accumulation effect of pulse laser train with lower repetitive rate is better.

In recent years, with the rapid development of the hardware and software of the three-dimensional model acquisition, three-dimensional laser scanning technology is utilized in various aspects, especially in space exploration. The point cloud filter is very important before using the data. In the paper, considering both the processing quality and computing speed, an improved mean-shift point cloud filter method is proposed. Firstly, by analyze the relevance of the normal vector between the upcoming processing point and the near points, the iterative neighborhood of the mean-shift is selected dynamically, then the high frequency noise is constrained. Secondly, considering the normal vector of the processing point, the normal vector is updated. Finally, updated position is calculated for each point, then each point is moved in the normal vector according to the updated position. The experimental results show that the large features are retained, at the same time, the small sharp features are also existed for different size and shape of objects, so the target feature information is protected precisely. The computational complexity of the proposed method is not high, it can bring high precision results with fast speed, so it is very suitable for space application. It can also be utilized in civil, such as large object measurement, industrial measurement, car navigation etc. In the future, filter with the help of point strength will be further exploited.

Fiber laser cutting of AZ31B magnesium alloy is considered. A three-dimensional (3D) finite element model (FEM) for simulation of the transient temperature field in laser cutting process is developed. The FEM take into account of the thermal physical parameters change with temperature, the moving heat source, the surface effect element, the reasonable boundary conditions, etc. The temperature evolution, the temperature gradient, the kerf shape and dimensions are simulated. Kerf width are measured using the Olympus optical microscopy and is compared with the predicted value. The microhardness near the kerf is measured by a Vickers microhardness tester. The results show that the maximum temperature gradually increased with the increase of cutting time. The workpiece temperature rise to 135.72°C from the room temperature. The simulated kerf width are in good agreement with measured results. The heat affected zone is not obvious and the microhardness change little perpendicular to laser cutting direction.

Atomic force microscope (AFM) is very useful in nano-scale force measurement. Lateral force is typically used in nanoscratch and surface friction measurement based on AFM. As one of the most important parameters to obtain lateral force, the lateral spring constant of AFM cantilever probe is of great significance and needs to be quantitative calibrated. Lateral torsion and lateral force of the cantilever are two parameters need to be measured in lateral spring constant calibration. In this article, we develop a calibration system and introduce a calibration method using an AFM head and an electromagnetic balance. An aluminium column with a known angel on top is placed on the weighing pan of the balance. The cantilever is precisely positioned in the AFM head, then approaches and bends on the aluminium column. During this procedure, the bending force and the lateral torsion of the cantilever are synchronously measured by the balance and an optical lever system, respectively. Then the lateral spring constant is calculated with a formula. By using this method, three kinds of rectangular cantilever are calibrated. The relative standard deviations of the calibration results are smaller than 2%.

Due to its low energy consumption, high efficiency and fast switching speed, light-emitted diode (LED) has been used as a new light source in optical wireless communication. To ensure uniform lighting and signal-to-noise ratio (SNR) during the data transmission, diffractive optical elements (DOEs) can be employed as optical antennas. Different from laser, LED has a low temporal and spatial coherence. And its impacts upon the far-field diffraction patterns of DOEs remain unclear. Thus the mathematical models of far-field diffraction intensity for LED with a spectral bandwidth and source size are first derived in this paper. Then the relation between source size and uniformity of top-hat beam profile for LEDs either considering the spectral bandwidth or not are simulated. The results indicate that when the size of LED is much smaller than that of reshaped beam, the uniformity of reshaped beam obtained by light source with a spectral bandwidth is significantly better than that by a monochromatic light. However, once the size is larger than a certain threshold value, the uniformity of reshaped beam of two LED models are almost the same, and the influence introduced by spectral bandwidth can be ignored. Finally the reshaped beam profiles are measured by CCD camera when the areas of LED are 0.5×0.5mm2 and 1×1mm2. And the experimental results agree with the simulations.

A new 4×4 point to point router is investigated with the transfer matrix method. Its routing paths and low loss of power are successfully demonstrated. The proposed design is easily integrated to a larger scale with less microring resonators, and the power loss from the input port to the output port is demonstrated to be lower than 10%. All of the microrings designed here have the identical radii of 6.98 μm, and they are all in resonance at a wavelength of 1550 nm. Both the gap between the microring and the bus waveguide and the gap between two neighbouring rings are 100 nm. The width of bus waveguide as well as the microrings is designed to be 200 nm. Free spectral range (FSR) is supposed to be around 17 nm based on the parameters above. A large extinction ratio (ER) is also achieved, which shows the high coupling efficiency to a certain extent. Thermal tuning is employed to make the microrings be in resonance or not, not including the two microring resonators in the middle. In other words, the two microrings are always in resonance and transport signals when the input signals pass by them. Hence, only two microrings are needed to deal with if one wants to route a signal. Although this architecture is blocking and not available for multicasting and multiplexing, it is a valuable effort that could be available for some optical experiments on-chip, such as optical interconnection, optical router.

With nano-level spatial and force resolution, atomic force microscope (AFM) becomes an indispensable nanoindentation measurement instrument for thin films and soft films. To do the research of size effect of the hardness property of thin films, indentation experiments have been done on a gold film with 200 nm thickness and a silicon nitride film with 110 nm thickness. It is possible to change the maximum load forces to get discrete residual depths on the film samples. The contact depths of the gold film are 15.91 nm and 26.67 nm respectively, while the contact depths of the silicon nitride film are 7.82 nm and 10.25 nm respectively. A group of nanoindentation force curves are recorded for the transformation into force-depth curves. Subsequently, a 3D image of the residual indentation can be obtained by in-situ scanning immediately after nanoindentation. The topography data is imported into a Matlab program to estimate the contact area of the indentation. For the gold film, the hardness parameters of 3.31 GPa and 2.57 GPa are calculated under the above two contact depths. And for silicon nitride film, the corresponding results are 6.51GPa and 3.58 GPa. The experimental results illustrate a strong size effect for thin film hardness. The correction of the residual indentation image of the gold film is also done as an initial study. Blind tip reconstruction (BTR) algorithm is introduced to calibrate the tip shape, and more reliable hardness values of 1.15 GPa and 0.94 GPa are estimated.

Based on the theory of information optics and the needs of perfect shuffle (PS) transform, a new method of achieving a PS transform is reported by using a subwavelength binary blazed grating (SBBG) array. Comparison the multilevel gratings, SBBG array can be fabricated only one step by photolithography and reactive ion etching (RIE). The SBBG array was designed to six channels PS transform, and transformation of two-neighboring channels was simulated by finite difference time domain (FDTD). The first order diffraction efficiency of SBBG designed here is larger than 80%, and has wide spectra and large incident angular tolerance by rigorous coupled-wave analysis (RCWA). The cross talk of neighboring channels was smaller than 3.24%. The theoretical analysis and computation show that PS transform using SBBG array has advantages of small size, compact structure, low loss and crosstalk, and easy to integrate with other photoelectric device. Consequently, it can be used in optical communication and optical information processing.

Optical data storage (ODS) represents revolutionary progress for the field of information storage capacity. When the thickness of data recording layer is similar to a few nanometer even atomic scale, the data point dimension can decrease to the minimum with stable mechanical property. Thus the new generation of ODS requires data recording layer in nanoscale to improve areal storage density, so that the more digital information can be stored in limited zone. Graphene, a novel two-dimensional (2D) material, is a type of monolayer laminated structure composed of carbon atoms and is currently the thinnest known material (the thickness of monolayer graphene is 3.35 Å). It is an ideal choice as a active layer for ODS media. Reduced graphene oxide, a graphene derivative, has outstanding polarization-dependent absorption characteristics under total internal reflection (TIR). The strong broadband absorption of reduced graphene oxide causes it to exhibit different reflectance for transverse electric (TE) and transverse magnetic (TM) modes under TIR, and the maximum reflectance ratio between TM and TE modes is close to 8 with 8 nm reduced graphene oxide films. It opens a door for a high signal to noise ratio (SNR) graphene-based optical data storage. Here, 8 nm high-temperature reduced graphene oxide (h-rGO) films was used for the ultrathin active layer of ODS. The data writing was performed on the h-rGO active layer based on photolithography technology. Under TIR, a balanced detection technology in the experiment converts the optical signals into electric signals and simultaneously amplifies them. The reading results show a stable SNR up to 500, and the graphene-based ODS medium has a high transparency performance.

The characteristics of laser scattering from sea surface have a great influence on application performance, from submarine communication, laser detection to laser diffusion communication. Foams will appear when the wind speed exceeds a certain value, so the foam can be seen everywhere in the upper layer of the ocean. Aiming at the volume-surface composite model of rough sea surface with foam layer driven by wind, and the similarities and differences of scattering characteristics between blue-green laser and microwave, an improved two-scale method for blue-green laser to calculate the scattering coefficient is presented in this paper. Based on the improved two-scale rough surface scattering theory, MIE theory and VRT( vector radiative transfer ) theory, the relations between the foam coverage of the sea surface and wind speed and air-sea temperature difference are analyzed. Aiming at the Gauss sea surface in blue-green laser, the dependence of back- and bistatie-scattering coefficient on the incident and azimuth angle, the coverage of foams, as well as the wind speed are discussed in detail. The results of numerical simulations are compared and analyzed in this paper. It can be concluded that the foam layer has a considerable effect on the laser scattering with the increase of wind speed, especially for a large incident angle. Theoretical analysis and numerical simulations show that the improved two-scale method is reasonable and efficient.

Atomic force microscope (AFM) is the most prevalent instrument in nanometer measurement. But the tip shape has a great influence on the measurements of surface topography. Blind tip reconstruction (BTR), established by Villarrubia, provides a good solution to this problem, nevertheless, with low precision if the tip characterizer is not appropriate. In order to explore the optimal tip characterizers for precision BTR, a serial of simulation experiments were carried out. First, a tip characterizer was simulated as the combination of a nanosized sphere with a square grating for the BTR of a conical tip. The results show that rotation structures are more suitable for conical tip reconstruction than prismatic structures. Second, a cylinder structure is chosen to verify the validity as an optimal feature for conical tip reconstruction. The simulation results show that if only the equivalent cone angle of the cylinder structure is no more than the tip, such structure is suitable as a tip characterizer. Tip characterizers need to have structure with smaller equivalent cone angle so as to make enough segments of the tip touched by the local maximum point of the sample. The local maximum point of the cylinder is just the top edge. From another point of view, the edge of the pillar has a zero equivalent radius, which is the sharpest feature but not obviously in scale.

We demonstrate an integrated Bragg grating filter using 60-nm-thick silicon-on-insulator strip waveguides. The ultrathin waveguides exhibit a propagation loss of 0.61 dB/cm. Upon thinning-down, the waveguide effective refractive index is reduced, making the fabrication of Bragg grating filter possible using the standard 248-nm deep ultra-violet (DUV) photolithography process. The Bragg grating filter exhibits a stopband width of 1 nm and an extinction ratio of 31 dB.

Precision measurement technology is the important measure of a nation's industrial technology level. However, with the rapid development of modern science and technology, metrological grating directly used for displacement measurement has could not meet the needs of contemporary people to the accuracy of measurement. So it is necessary to subdivide the grating sensor signal, especially the fine subdivision which has been increasingly concerned. Aiming at the constructor method used in the specific implementation process of the fine subdivision of the grating sensor signal, two schemes are put forward in this paper. Based on the analysis and comparison of the two methods, at last, the optimal design scheme will be determined.

How to improve the sensitivity of new pattern of gyroscope which is based on micro ring resonator is widely researched. And periodically modulating coupling coefficient and area are the two most common schemes. Moreover, when the area of the square difference is large enough, the precision of gyroscope of the latter is higher than that of the former by 1 to 2 orders of magnitude. But increasing modulation area will narrow the transmission band, it will impact on our measurement of the inertial rotation. What’s more, this modulation method is very sensitive to the coupling coefficient between the micro rings. Simultaneously, the slope of the center resonance peak will be quickly decayed with the increase of the coupling coefficient. Generally, there's no sense to our modulation when the coupled coefficient is over 0.1. In this paper, we use the way of combining the two schemes to study the performance of the gyroscope which includes it's precision and how to reduce interference when it applied to devices. We found that the accuracy of rotation produced by our scheme is higher than that of simply modulating coupling coefficient or coupling area. And the sensitivity of gyroscope achieved by the new method is times higher than that of the general of coupled resonator optical waveguide, and there is almost no limit to the coupled coefficient based on our coupling scheme. What’s more, the steepest transmission resonance of the transmission band appears at Ω = 0 and other resonance peaks around the center resonance are completely suppressed because of the effective superlattice structure, which will effectively reduce the interference during our measurement.

Polarization properties provide a controlled degree of freedom in the process of light propagation. Efficiently manipulating polarization states plays a pivotal role in the areas of electromagnetic wave detection and information communication. In this work, we propose a chiral metamaterial that is comprised of an array of 90°-twisted E-shaped resonators with incorporated vanadium dioxide films. The hybridized chiral metamaterial allows us to effectively modify the conductivity of vanadium dioxide utilizing a thermal trigger. A thermo-controlled cross-polarization conversion can be realized. The phase transition metamaterials may open an opportunity in the THz regime to acquire a variety of functionalities, such as tunable filters, modulators and switches.

Through a new manufacturing technology, achieved the machining of high precision composite radio panel. It adopts foil sticking in a vacuum, metal bonding, rubber precision compensation, stress release and other technology. Through designing the manufacturing process, and adopting a large number of experiment scheme to improve, finally summarized a technical route of high feasibility and accurate process parameters. At last, by the measurement of PGI Dimension red outside precision detector (the surface detection accuracy of which can reach 2 um) for surface precision of experimental panels, we verified the feasibility and reliability of this technique and provided the reliable data to support for practice application of this technology.

In lithography, online spectral metrology of excimer laser lithographic light sources is used as the evaluation and monitoring the quality of the output laser lithography equipment, through the spectrum measurement we can know the running status of lithography equipment. Center wavelength and Full-Width-At-Half-Maximum(FWHM) are two important indicators of online spectral metrology. Traditional way of accurately measuring laser spectrum is to use a high resolution grating spectrometers. These instruments can provide accurate spectral measurement ,but are very bulky and expensive. Fabry - Perot (FP) etalon is based on the principle of multi-beam interference, high spectral resolution can be done, is a modern high-resolution spectroscopy indispensable instrument. echelle has big blaze Angle, can achieve high The blazed order, realize high resolution(lower than etalon). This paper introduces a method of using Echelle and etalon, through the analysis of the diffraction line fringes of ArF laser and a series of algorithms to deal with data, realize the on-board measurement of center wavelength and FWHM .

This article studied the interference enhancement and modulation introduced by surface plasmon polaritons (SPPs) in a double-concentric-ring structure. Young’s double-slit interference experiment is a classic experiment in the history of physics, and has many modifications with deep impacts in many areas including physics, optics, and electromagnetics. In this work, to use the classic bull’s eye structure to produce the surface plasmon polariton effect, a double-concentricring- hole structure was used instead of the double-slit structure to generate optical interference, and the bull’s eye structure was applied in the surroundings to generate surface plasmonic wave for modulation of the interference. For structure details, a concentric double-ring-hole was etched in a silver film, with a series of periodic concentric-ringshaped shallow grooves etched in both the upper and bottom surfaces of the silver films. Simulation results showed that the interference of the double-ring-hole could be modulated by SPPs, generating new transmission spectra with desired peak positions and intensities. The transmission peak intensity could be enhanced by 2 to 6 times. The proposed structure can be used as a powerful and convenient tool to adjust the transmission spectra, which can have promising applications in the design and implementation of optical devices for filtering and sensing, especially in the sub-wavelength structure size range.

It is observed that light radiation can drive tangential micro/mili-scale flows in vicinity of the liquid-liquid interface between two immiscible liquids. Particle Image Velocimetry (PIV) study for these newly-reported phenomena shows that the strength of these light-driven flows strongly depends on the radiation power of the excitation light used, the inclination of the liquid-liquid interface, the thickness of the top-layer liquid, and the concentrations of the liquid involved. The effect occurs only in the case that the thickness of the top-layer liquid is sufficiently thin and positionally non-uniform. For a decane-water dual layer liquid system with a particular geometry, a Gaussian-type CW IR laser with a radiation power of several tens mili-watts can maintain a micro-scale flow with its maximum flow speed of several millimeter per second at the fastest point of the flow stream. The strength of the flows increases with inclination of the liquid-liquid interface but decreases with the thickness of the top-layer liquid. Adding another solute liquid into water in the decane-water system weakens the strength of the flows remarkably. For interpretation, Marangoni effect in association with an asymmetric deflection of the excitation light may be employed as a driving mechanism behind these phenomena. However, some characteristic behaviors of these flows revealed by PIV data also suggest that the recoil effects due to the abrupt change in the momenta of photons, which also occur associated with asymmetric light deflection at the inclined interfaces of liquid media, may also contribute significantly. In terms of application, these phenomena suggest a novel technological principle, based on which direct mechanical actuation and manipulation of liquids of extensive quantity using light beams may be accomplished.

The backprojection-filtration (BPF) algorithm has become a good solution for local reconstruction in cone-beam computed tomography (CBCT). However, the reconstruction speed of BPF is a severe limitation for clinical applications. The selective-backprojection filtration (S-BPF) algorithm is developed to improve the parallel performance of BPF by selective backprojection. Furthermore, the general-purpose graphics processing unit (GP-GPU) is a popular tool for accelerating the reconstruction. Much work has been performed aiming for the optimization of the cone-beam back-projection. As the cone-beam back-projection process becomes faster, the data transportation holds a much bigger time proportion in the reconstruction than before. This paper focuses on minimizing the total time in the reconstruction with the S-BPF algorithm by hiding the data transportation among hard disk, CPU and GPU. And based on the analysis of the S-BPF algorithm, some strategies are implemented: (1) the asynchronous calls are used to overlap the implemention of CPU and GPU, (2) an innovative strategy is applied to obtain the DBP image to hide the transport time effectively, (3) two streams for data transportation and calculation are synchronized by the cudaEvent in the inverse of finite Hilbert transform on GPU. Our main contribution is a smart reconstruction of the S-BPF algorithm with GPU’s continuous calculation and no data transportation time cost. a 512³ volume is reconstructed in less than 0.7 second on a single Tesla-based K20 GPU from 182 views projection with 512² pixel per projection. The time cost of our implementation is about a half of that without the overlap behavior.

Silicon with various structural morphologies is widely used for solar cells and other optoelectronic devices. We present a new chemical etching process for nanoscale texturing of Si surfaces, which results in an almost complete suppression of the reflectivity in a broad spectral range, leading to black Si surfaces. The chemical etching process affects only the topmost 200-300 nm of the Si material. And it isn't dependent on the Si surface orientation and doping. Besides, the antireflective performance of reacted Si surface will highly improve with silver catalyst effect. Hence, it can be applied to various structural forms of bulk silicon as well as to thin Si films. The optical properties of various black Si samples are presented and discussed in correlation with the surface morphology, which are measured by atomic force microscope.

We investigate the influence of profile of one-dimensional (1D) Ag gratings on the enhancement factor (EF) of surface-enhanced Raman scattering (SERS). An optimized duty ratio of 1D Ag grating is found, and the SERS EF is experimentally obtained on the order of ~ 10⁴, while the finite-difference time-domain simulation shows that the SERS EF can be as high as ~ 10⁶. We ascribe the discrepancy between the simulated and the experimental results mainly to the fluctuation of Ag grating structure, which is confirmed by the topography measurement using scanning electron microscopy and atomic force microscopy.

It is interesting to investigate the nature of interactions between metal nanoparticles and graphene oxide (GO), which is the fundamental of the potential applications of the GO. Resonant Raman technique provides a useful way to explore the influence of metal nanoparticles on the electronic structure of GO. For this purpose, GO has been decorated by nanoparticles of metals such as silver (Ag), gold (Au) and palladium (Pd), and then measured using micro Raman spectroscopy. Several different laser lines are used in the experiment. There is a red shift in the D-band as well as the G-band in addition to the changes in the Raman bandwidth. Comparing the changes in the Raman spectra of the GO caused by the different metal nanoparticles, we find that the effect of Ag on GO is large. On the other hand, Au nanoparticles cause small changes. Such difference is related to the intrinsic properties of the metal nanoparticles which have different ionization energies. When the laser wavelength increases, the ratio between the intensities of the D-band and G-band (I_D/I_G) increases. And the Raman enhancement effects of Pd, Ag, and Au nanoparticles are different since they have different surface plasmon resonance frequencies.

We propose a tunable unidirectional long-range surface plasmon polaritons (LRSPP) launcher based on subwavelength metallic nanoslits in the visible range. The direction of the generated LRSPPs could be tuned simply by varying the incident angles. The extinction ratio reaches up to 28 dB with a wide angular width of 30º. The influences of the launcher geometry on its performance are investigated in this study as well. The broadband property of the launcher is also demonstrated.

The microstructure, optical properties, and magnetic properties of Fe-doped ZnO thin films prepared by direct current (DC) magnetron sputtering were studied in detail. The chemical composition were examined by Energy Dispersive x-ray Spectroscopy (EDS) and the charge state of Fe ions in the ZnO:Fe thin films was characterized by X-Ray photoelectronic spectrometry (XPS). X-ray diffraction (XRD) characterization of ZnO:Fe thin films confirmed the exclusive formation of the films with the wurtzite structure. The optical transmittance of the films decreased with the increasing of the iron concentration. Room-temperature magnetic measurements indicated that all the films are not ferromagnetic above 50 K. The effect of Fe doping was discussed and relevant mechanism was proposed by comparing with previous studies in ZnO systems.

Silica microballs have a wide range of applications in the field of optics, electronics, biotechnology，chemical industry, and so on. In this work, a new approach, electrospraying, was used to coat the silica microballs onto the glass substrate, and the coating results were compared to spin-coating and dip-coating. Good microball size control could be achieved using the electrospraying method. X-Ray Diffraction (XRD) results showed that amorphous silica microballs were obtained. From Scanning Electron Microscopy (SEM) images, we can see that uniform microball size was achieved. In general, the results are better than what can be achieved by spin-coating, and comparable to that of dip-coating. However, electrospraying has great potential in mass production, especially for large-area fabrication.

The influence of pulse-separation (τ_s) between a pair of temporally separated femtosecond laser pulses (with near ablation-threshold energy) on surface ablation of SiO₂ were experimentally studied. A τ_s range of τ_s≤20 ps was considered. It was shown that a τ_s-independent/-dependent crater ablation area can be flexibly controlled. Once the pulse energy of the pulse pair exceeds a threshold value, crater ablation area become quasi-τ_s-independent at τ_s> ~1 ps. This τ_s-independent phenomenon can even be observed when each pulse within the double-pulse pair has a sub-threshold energy, which leads to a further reduction in ablation size. The experimental findings have not only confirmed our previous calculation based on a modified model, but also greatly extended the results both quantitatively and qualitatively. A dominant amount of seed electron from photoionization of self-trapped excitons (STEs) is responsible for the appearance of τ_s-independent phenomena. For physical interest, it is inferred that destruction of STEs will tend to break the τ_s-independent ablation phenomena. Experiments performed on CdWO₄, a material exhibiting similar electron dynamics to that in SiO₂ but a faster decay in STE population, support this conjecture. A possible improvement for the relevant theoretical modeling is also suggested based on the experimental findings.

Titanium dioxide thin film plays an important role in thin film solar cells, and has promising future in everyday applications including air cleaning and self-cleaning glass. With the concepts of flexible solar cells and wearable devices being more and more popular, there is increasing interest to coat titanium dioxide thin films on flexible substrates, such as aluminum foils. Many methods have been used to fabricate titanium dioxide thin films, such as dip-coating, spin coating, aerosol spray, plasma-assisted coating, electrospraying, and so on. Among them, electrospraying is especially suitable for thin film deposition on flexible substrates. This work reports fabrication of dense and uniform titanium dioxide thin films on glass as well as flexible aluminum foil using multi-jet electrospraying technique.

The thermo-optic properties of CdSe/ZnS quantum dots (QDs) are investigated in this paper. Two CdSe/ZnS QDs-doped samples are fabricated and the closed aperture Z-scan data were obtained by a single-beam Z-scan setup with a continuous laser as the exciting source. With the measured curves the coefficient of nonlinear refractive index n2 (caused by thermal effect) and the thermo-optic coefficient were achieved. CdSe/ZnS QDs-doped materials show larger thermooptic coefficients than the glass materials by 2 orders of magnitude.

Because of excellent superiorities, triple-electrode carbon nanotube sensor acts good in the detection of multi-component mixed gas. However, as one of the key factors affecting the accuracy of detection, the electrode separation of carbon nanotube gas sensor with triple-electrode structure is very difficult to decide. An optimization method is presented here to improve the mixed gas measurement accuracy. This method optimizes every separation between three electrodes of the carbon nanotube sensors in the sensor array when test the multi-component gas mixture. It collects the ionic current detected by sensor array composed of carbon nanotube sensors with different electrode separations, and creates the kernel partial least square regression (KPLSR) quantitative analysis model of detected gases. The optimum electrode separations come out when the root mean square error of prediction (RMSEP) of test samples reaches the minimum value. The gas mixtures of CO and NO₂ are measured using sensor array composed of two carbon nanotube sensor with different electrode separations. And every electrode separation of two sensors is optimized by above-mentioned method. The experimental results show that the proposed method selects the optimal distances between electrodes effectively, and achieves higher measurement accuracy.