正三角形及正方形微光学腔模式特性研究

微谐振腔模式特性研究是利用微腔研制新型光电器件的基础．为了研制出能采用平面工艺制作的定向输出的微腔激光器，文章采用解析和数值模拟方法深入研究了正三角形及正方形光学微腔的模式特性，并得到与数值模拟结果符合非常好的解析场分布及模式波长．对正方形光学微腔，把模式组合成满足正方形对称性的场分布，发现其类WG模式只存在品质因子比它小一个数量级以上的偶然简并模式，因此正方形微腔有利于实现真正的单模工作．     

Experimental study of nonlinear mode mixing in dual-wavelength semiconductor lasers

New schemes for the generation of the sum, difference, and double frequencies in dual-wavelength injection lasers, based on an intracavity nonlinear mode mixing owing to a bulk nonlinearity, are experimentally investigated. Namely, the operation of the dual-wavelength laser diodes at the TE₀ and TE₁ modes, butt-joint laser diodes, and interband cascade lasers with tunnel junction are described.     

Laser theory for semiconductor quantum dots in microcavities

Quantum dots (QDs) used as active material in microresonators are currently of strong topical interest due to breakthroughs in growth and device structuring. From the theory side, however, atomic models are still used to analyse the emission from these semiconductor systems, despite known differences between QDs and atoms. We introduce a semiconductor laser theory based on a microscopic approach with the goal of better describing the characteristic behaviour of QD-based laser devices and to show differences from predictions based on atomic models.     

半导体断路开关实验研究

 介绍了半导体断路开关（SOS）特性参数测试平台和测试方法，并对半导体断路开关的截断阻抗、截断时间、电压增益、输出脉冲半高宽以及能量传递效率等参数进行了实验研究。结果表明，正、反向泵浦时间是影响半导体断路开关特性的最主要因素。实验获得了截断时间、电压增益和能量传递效率与正、反向泵浦时间的依赖关系以及SOS截断过程中的阻抗变化特性。     

双三角阵声靶测试系统研究

声靶容易构成较大的测试靶面,常用在大口径弹药的立靶密集度测试中。为了消除声波在空气中传播速度变化对声靶测试精度的影响,采用双三角阵声阵列模型使测量公式中不再引入声波速度。为了使测试系统紧凑、可靠,整个测试系统由双三角阵列、多通道数据采集仪、计算机系统构成。对测试系统进行了实弹射击实验,在2 m×2 m靶面内,弹着点测量误差为±10 mm。     

Nonlinear optics of coupled semiconductor microcavities

In a coupled microcavity configuration with Kerr optical nonlinearities in the external as well as in the central distributed Bragg reflectors, the energies of the closely spaced doublet of delocalized photon eigenmodes change with increasing light intensity. One beam optical bistability as well as all optical switching in a pump and probe configuration can be realized. The nonlinearity can induce a novel kind of Rabi anticrossing between a photonic mode and a nearly resonating quantum well exciton. Realistic numerical simulations of such effects in AlGaAs based microstructures are presented.     

半导体微腔中激子的光学效应

文章基于Fabry-Pérot半导体微腔,阐述了新型元激发--激子极化激元的基本概念和微观描述,讨论了其在光学放大器、光学开关和单光子源方面的潜在应用,概述了对其实现Bose-Einstein凝聚的实验研究,最后对将来的发展做了一个简单的展望.     

半导体微腔中激子的光学效应

文章基于Fabry-Pérot半导体微腔,阐述了新型元激发——激子极化激元的基本概念和微观描述,讨论了其在光学放大器、光学开关和单光子源方面的潜在应用,概述了对其实现Bose-Einstein凝聚的实验研究,最后对将来的发展做了一个简单的展望.     

Dynamic compression of exciton-polariton condensates in semiconductor microcavities

The evolution of probabilities of escape of hot and thermalized electrons from GaAs(001) with adsorbed cesium and oxygen layers to vacuum at the transition from positive to negative effective electron affinity is studied by the photoemission quantum yield spectroscopy. A minimum of the probability of escape of thermalized electrons near zero electron affinity is revealed and explained.     

Motion of spin polariton bullets in semiconductor microcavities

The dynamics of optical switching in semiconductor microcavities in the strong coupling regime is studied by using time- and spatially resolved spectroscopy. The switching is triggered by polarized short pulses which create spin bullets of high polariton density. The spin packets travel with speeds of the order of 10(6) m/s due to the ballistic propagation and drift of exciton polaritons from high to low density areas. The speed is controlled by the angle of incidence of the excitation beams, which changes the polariton group velocity.     

Process of fabricating semiconductor microcavities and photon crystals

A process of fabricating microcavities and photon crystals in GaAs structures by means of electron lithography and reactive ion etching is described. Two types of structures, with micropillars and with photon crystals, are considered. The latter structures have the form of a square or hexagonal array of holes in a planar waveguiding structure. The minimal diameter of the micropillars is 100 nm, and their height is 700 nm. The size of the holes in the photon crystals and the photon crystal period are controllably varied from 140 to 500 nm and from 400 to 1000 nm, respectively. The etch depth of the crystals is more than 350 nm.     

Ellipsometric investigations and luminescence properties of semiconductor microcavities

Il Nuovo Cimento D - Luminescence investigations on MBE-grown AlAs/AlGaAs microcavities reveal position-dependent spectra from embedded GaAs quantum wells and from the reflector material. Because...     

Magnetic shielding property for cylinder with circular,square, and equilateral triangle holes

The shielding property of cylinder with circular, square, and equilateral triangle holes was investigated by finite element analysis(FEA). The hole area(S_(hole)) plays an important role in magnetic circuit on the surface of cylinder. When Sholeis less than the critical area(S_H), cylinder with three shapes of holes obtained the same remanent magnetization inside,indicating that the shielding property is unaffected by the shape of the hole. Hence, high-permeability material is the major path of the magnetic field. On the condition of S_(hole) S_H, the sequence of the shielding property is equilateral triangle square circular, resulting from magnetoresistance of leakage flux in air dielectric. Besides, the anisotropy of shielding property caused by hole structural differences of the cylinder is evaluated. We find that a good shielding effectiveness is gained in the radial direction, compared with the axis direction. This research focuses on providing a theoretical support for the design of magnetic shield and improvement on the magnetic shielding ability.     

Emerging opportunities for ultra-high Q whispering gallery mode microcavities

正Whispering gallery modes (WGMs) were first discovered for sound waves in the whispering gallery of St Paul’s Cathedral and explained by Rayleigh [1] in 1878. In 1961, Garrett et al.[2] applied the concept of WGMs to optical systems and realized stimulated emissions in Sm~(2+)-doped CaF_2 spheres.Since then, WGMs have been widely and intensively studied in a range of micro-sized systems, including microdroplets,microspheres, microtoroids, microdisks, and microtubes. In     

Polarization control of the nonlinear emission of semiconductor microcavities

The degree of circular polarization ( Weierstrass p ) of the nonlinear emission in semiconductor microcavities is controlled by changing the exciton-cavity detuning. The polariton relaxation towards K approximately 0 cavitylike states is governed by final-state stimulated scattering. The helicity of the emission is selected due to the lifting of the degeneracy of the +/-1 spin levels at K approximately 0. At short times after a pulsed excitation Weierstrass p reaches very large values, either positive or negative, as a result of stimulated scattering to the spin level of lowest energy (+1/-1 spin for positive/negative detuning).     

量子计算正三角形腔内的氢负离子光剥离截面

用传统量子力学方法研究了横截面为正三角形的腔内氢负离子光剥离, 得到了光剥离截面随能量变化的解析表达公式. 该公式还给出了剥离截面的阈值行为. 进一步研究发现, 当氢负离子处于正三角形一角附近时, 用量子力学方法得到的结果与氢负离子处于60°角域内时使用闭合轨道理论得到的结果一致.     

Optical properties of excitons in semiconductor superlattices and microcavities

The optical response of Mott–Wannier excitons is investigated in semiconductor superlattices and microcavities. p-Polarized light is considered to calculate the reflectivity R_pand dispersion relation of the collective normal modes in superlattices accounting for extrinsic Morse potential wells, andR_p in microcavities. Results of R_pexhibit well-defined peaks of the exciton bound states in the Morse potentials for both transverse and longitudinal modes. Comparisons ofR_p with experimental reflectivity data of light for semiconductor microcavities exhibit good qualitative agreement as well as Rabi splitting.     

Coherent control of polariton parametric scattering in semiconductor microcavities

In a pump-probe experiment, we have been able to control, with phase-locked probe pulses, the ultrafast nonlinear optical emission of a semiconductor microcavity, arising from polariton parametric amplification. This evidences the coherence of the polariton population near k=0, even for delays much longer than the pulse width. The control of a large population at k=0 is possible although the probe pulses are much weaker than the large polarization they control. With rising pump power the dynamics of the scattering get faster. Just above threshold the parametric scattering process shows unexpected long coherence times, whereas when pump power is risen the contrast decays due to a significant pump reservoir depletion. The weak pulses at normal incidence control the whole angular emission pattern of the microcavity.