查看更多>>摘要：In adaptive optics (AO) system, the phase compensation capability is limited greatly by the actuator number of the deformable mirror (DM). The actuator number of DM is mainly restricted by the manufacture techniques. The spatial correction capability of AO system can be improved by two or more combinational-DMs (CDMs) with conjugation relationship. The CDM AO system for wavefront correction is built, which consists of two 32-element DMs. The experimental results are in agreement with the numerical simulation results. It is indicated that the CDM AO system provides better correction performance than the single 32-element DM AO system.
查看更多>>摘要：We investigate the sensitivity enhancement of surface plasmon resonance (SPR) sensors through planar metallic film closely coupled to nanogratings. The effects of the thickness of metallic film and grating period on the refractive index sensitivity of the device are analyzed in detail. The refractive index sensitivity of nanograting-based SPR sensors is predicted to be about 540 nm per refractive index unit (RIU) using optimized structural parameters. Furthermore, the grating period can be used as a parameter to adjust the wavelength of resonance reflection. Our study on SPR sensors through planar metallic film closely coupled to nanogratings demonstrates the potential for significant improvement in refractive index sensitivity, since it shows much greater flexibility in terms of tuning the optical parameters of the device.
查看更多>>摘要：We have studied a function-lock strategy for all-optical logic gate (AOLG) utilizing the cross-polarization modulation (CPM) effect in a semiconductor optical amplifier (SOA). By monitoring the power of logic light, the strategy realized controllable methods to capture OR and NOR functions and switch between them. The strategy has been successfully applied in experiment with 10-Gb/s not-return-to-zero (NRZ) signals, which has a high success-rate above 95% and ensures the high extinction ratio of result light above 11.4 dB. Every step in the strategy has definite numeric evaluation, which provides the potential of automatic implementation.
查看更多>>摘要：A novel image fusion algorithm based on bandelet transform is proposed. Bandelet transform can take advantage of the geometrical regularity of image structure and represent sharp image transitions such as edges efficiently in image fusion. For reconstructing the fused image, the maximum rule is used to select source images' geometric flow and bandelet coefficients. Experimental results indicate that the bandelet-based fusion algorithm represents the edge and detailed information well and outperforms the wavelet-based and Laplacian pyramid-based fusion algorithms, especially when the abundant texture and edges are contained in the source images.
查看更多>>摘要：Based on the principle of spatial pyramid for signal, a multi-scale transform of two-dimensional (2D) interpolating pyramid is constructed by the nonlinear median operator. The transform properties of error diffuse halftoning noise on multiple scales are investigated and analyzed through experiments. According to these properties, a robust inverse halftoning method is proposed. The halftoning image is firstly pre-processed by a Gaussian low-pass filter, and decomposed by the one-scale transform. Then a Wiener filter is employed to the detailed coefficients. Finally an inverse image is reconstructed. Experimental results show that the proposed transform has the advantage of separating the halftoning noise and image detail over linear multi-resolution transform. The presented inverse halftoning method performs some excellent abilities on sharp edge, high peak signal-to-noise ratio (PSNR), and small memory requirement.
查看更多>>摘要：Coupling between subwavelength-diameter silica wires and silicon-based waveguides is studied using the parallel three-dimensional (3D) finite-different time-domain method. Conventional butt-coupling to a silica-substrated silicon wire waveguide gives above 40% transmission at the wavelength range from 1300 to 1750 nm with good robustness against axial misalignments. Slow light can be generated by counter-directional coupling between a silica wire and a two-dimensional (2D) silicon photonic crystal slab waveguide. Through dispersion-band engineering, 82% transmission is achieved over a coupling distance of 50 lattice constants. The group velocity is estimated as 1/35 of the light speed in vacuum.
查看更多>>摘要： B_2O_3-P_2O_5-SiO_2(BPS) three-dimensional (3D) high-organized polystyrene (PS) opals and inverse opals with large domain were fabricated and characterized. Scanning electron microscope (SEM) shows three or four small "windows", indicating that a very well interconnection between PS spheres of opal. The ultraviolet-visible (UV-vis) spectra indicate that the photonic band gaps (PBGs) are about 710 and 604 nm for 320- and 270-nm spheres respectively. While according to Bragg's equation, the simulation results should be 762 and 643 nm, which mean that 52 and 39 nm were shifted to blue region, respectively.
查看更多>>摘要：The diode-pumped Nd:KYW laser operated in the free-running mode at 1072 nm is demonstrated at room temperature. The laser output power of 102.6 mW with 12.07% optical-to-optical conversion efficiency and 13.16% slope efficiency is obtained. The laser threshold is about 110 mW. Such a low threshold is in agreement with the theoretical prediction.
查看更多>>摘要：1689-nm diode lasers used in medical apparatus have been fabricated and characterized. The lasers had pnpn InP current confinement structure, and the active region consisted of 5 pairs of InGaAs quantum wells and InGaAsP barriers. Stripe width and cavity length of the laser were 1.8 and 300 μm, respectively. After being cavity coated and transistor outline (TO) packaged, the lasers showed high performance in practice. The threshold current was about 13 ± 4 mA, the operation current and the lasing spectrum were about 58 ± 6 mA and 1689 ± 6 nm at 6-mW output power, respectively. Moreover, the maximum output power of the lasers was above 20 mW.
查看更多>>摘要：We investigate the transverse mode pattern in GaN quantum-well (QW) laser diode (LD) by numerical calculation. We optimize the current GaN LD structure by varying the n-GaN layer thickness. The n-type GaN layer is an important factor to determine the optical mode. Finally, we discuss the lasing performance of the GaN LD based on the transverse optical modes.
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