Simulation of Optical Devices Using Parallel FDTD Method

On this paper, we investigate the algorithm and efficiency of simulation of optical devices using parallel computing method, implement some real wavelength division multiplexing (WDM) components such as resonators to test the method's possibility and efficiency.     

EPR and optical studies on transition metal doped LiRbB4O7 glasses

Electron paramagnetic resonance and optical investigations of copper and chromium doped LiRbB₄O₇ glasses are carried out. From the results and discussions, it is predicted that both the transition metal ions exhibit octahedral environment. In the case of Cr³⁺, the site symmetry is near octahedral, whereas in the case of Cu²⁺, it is tetragonally distorted octahedral environment. Crystal field, spin-Hamiltonian and bonding parameters are evaluated. The bonding parameters are suggesting ionic.     

Temperature variation of the fundamental absorption edge in AgGaSe2

Optical absorption measurements were made in the temperature range 9–300 K on the chalcopyrite semiconductor compound AgGaSe₂ and the optical energy gap E_G determined as a function of temperature T. In order to obtain the values of E_G as a function of T, the Elliot-Toyozawa model [R.J. Elliot, J. Phys. Rev. 108 (1957) 1384; D.D. Sell, P. Lawaets, Phys. Rev. Lett. 26 (1971) 311] was employed to perform the analysis of the optical absorption spectra. The resulting E_G vs. T curve was fitted to a semi-empirical model that takes into account both the thermal expansion and the electron–phonon interaction contributions. The results have been used to estimate values of the deformation potentials of the valence and conduction bands of the compound.     

Fluorescence characteristics of Dy/CdS nanocrystals doped silica xerogel

Cadmium sulfide semiconductor nanocrystals along with dysprosium ions were incorporated in silica xerogels through sol-gel route. The fluorescence properties were analyzed for samples annealed at different temperatures. The incorporation of the CdS semiconductors as nanocrystallites was confirmed from the HRTEM measurements. The fluorescence intensities were compared for Dy³⁺, CdS and Dy³⁺/CdS-doped silica xerogels. Enhanced blue emission was observed for codoped samples annealed up to 100 °C.     

A novel technique for measurement of self-generated magnetic fields and the plasma density in laser produced plasmas from the Faraday rotation using two color probes

Diagnostic information about the self-generated magnetic fields (SGMF) generated in laser produced plasmas is normally obtained by measuring the Faraday rotation angle (FRA) of a linearly polarized laser probe beam passing through the plasma. Simultaneous recording of the corresponding interferogram is required to get the density information necessary for estimating the magnetic field. The problem with this method is that the visibility of the fringes in the interferogram can be poor, and the SGMF cannot be calculated in the regions where the interference fringes are not observable. In this paper, we propose a new method to obtain the density distribution and the SGMF from two simultaneous measurements of FRA using two probe beams of different colors, which allows one to calculate the SGMF without the need of interferometry.     

Trapping a dark soliton pulse within a nano ring resonator

We propose the interesting results that a dark soliton pulse can be localized within a nonlinear nano-waveguide. The system consists of nonlinear micro and nano ring resonators, whereas the dark soliton can be input into the system and trapped within the nano-waveguide. A dark soliton pulse is input into a ring resonator and chopped to be the smaller pulses. The required pulse is filtered and amplified, which can be controlled and localized within the nano-waveguide. The localized bright soliton is also reviewed and discussed.     

Performance analysis of optical wavelength switching network using multiple output light source

In this paper a 32×32 optical wavelength switching network using the multi-channel and multi-wavelength spectrum-sliced light source is presented where the 2×2 optical-switching elements are utilized in dilated Benes and modified dilated Benes configurations, respectively. The system performances in bit-error rate, especially for the effects of intraband crosstalk, are analyzed in details for the two type networks. Through the simulation studies, the dilated Benes shows better performances than the modified dilated Benes configuration.     

Comparative study on structural and optical properties of CdS films fabricated by three different low-cost techniques

Highly crystalline and transparent cadmium sulphide films were fabricated at relatively low temperature by employing an inexpensive, simplified spray technique using perfume atomizer (generally used for cosmetics). The structural, surface morphological and optical properties of the films were studied and compared with that prepared by conventional spray pyrolysis using air as carrier gas and chemical bath deposition. The films deposited by the simplified spray have preferred orientation along (1 0 1) plane. The lattice parameters were calculated as a = 4.138 Å and c = 6.718 Å which are well agreed with that obtained from the other two techniques and also with the standard data. The optical transmittance in the visible range and the optical band gap were found as 85% and 2.43 eV, respectively. The structural and optical properties of the films fabricated by the simplified spray are found to be desirable for opto-electronic applications.     

光学实验的计算机仿真

基于计算机仿真技术,以光学干涉实验和滤波实验为研究对象,应用Matlab软件数值模拟了杨氏双缝干涉实验和多光束干涉实验干涉图形和光强分布图,数值模拟了光学滤波实验字母滤波后的频谱图和字母成像图,结果表明,计算机仿真结果能够清晰的表达出实验和理论的效果。研究结果为光学实验的课堂教学提供了参考。     

Optical Measurement of φ750 mm Telescope System

为了探测更高轨道的空间目标,研制了一台通光口径为φ750 mm的望远镜.该望远镜为主焦点光学系统,由一片二次非球面反射元件和四片透射元件组成,具有大视场(4°),大相对孔径(1∶1.32)和宽光谱(500～800 nm)的特点.本文以该望远镜的研制为基础,介绍了其光学系统各个元件的单独检测和系统装调完成后的整体检测方法和过程.采用样板法对系统中的球面透射元件进行了单独检测,采用透射无像差补偿器法对二次非球面反射镜进行了单独检测,采用反射无像差补偿器法对组合起来的透射校正镜组进行了检测,并且对系统装调对准之后的光学系统进行室内平行光管和室外对星观测两种方法进行检测,测量结果均满足设计要求,其中球面透镜的面形误差小于0.1个光圈,反射元件和透射元件非球面表面的面形误差均优于λ/30(λ=632.8 nm),透射校正镜组的波像差优于λ/30(λ=632.8nm).光学系统整体检测结果表明,室内和室外检测结果一致,其像面的80％能量集中度直径在4°的全视场范围内均小于2个像元,达到了设计的成像要求.