Whispering Gallery Modes and Spontaneous Emission in Compact VCSEL Structures

Semiconductors - The radiation power from active area into the planar waveguide has been studied theoretically in order to model VCSEL characteristics. Exact and simple quantitative connection...     

自发辐射因子对VCSEL在大信号调制下的分岔及混沌行为的影响

在SIMULINK平台下开发了垂直腔面发射激光器 (VCSEL)的动态仿真模型 ,实施高频大信号调制情形下的动态仿真 ,避免了大信号近似处理 ,提高了计算精度。选择自发辐射因子为控制参量 ,定量分析它对VCSEL稳定性和分岔点的影响。结果表明 ,在所选参量条件下 ,自发辐射因子数值在 5× 10 -3 ～ 5× 10 -5之间时 ,随着调制深度的加深 ,VCSEL峰值光子密度产生分岔 ,呈现双稳、多周期 ,最后回到单周期 ;当小于 10 -5时 ,进入混沌状态的演变过程。同时分岔点的移动依赖于自发辐射因子的大小 ,调控自发辐射因子可以抑制系统的非线性行为。仿真结果与文献实验结果吻合     

Amplified Spontaneous Emission in Slab Amplifiers

Amplified spontaneous emission (ASE) occurs in media with large gain, and affects both the magnitude and the spatial distribution of the inversion. In this work we theoretically study the effect of ASE in three-dimensional, rectangular slab amplifiers, using Monte Carlo type computer simulations. We found that in one-dimensional amplifiers ASE is always larger at the edges so that the inversion has a maxima at the center of the amplifier. However, in two- and three-dimensional amplifiers, the inversion has a minimum at the center of the amplifier for low gain, and a maximum at the center of the amplifier for high gain. Thus, the inversion profile can be changed by increasing the gain from a minimum at the center, through a plateau, to a maximum at the center. A simple analytical theory was developed and agrees with these results     

多段阵列式钕玻璃放大器中放大自发辐射问题的研究

由激光速率方程和泵浦速率的空间和时间分布出发，采用了二维光线追迹和蒙特卡罗法模拟了放大自发辐射，研究了多段阵列式钕玻璃放大器（ＭＳＡ）中间板条增益分布随时间和泵浦速率的变化。所得结果对大尺寸多段阵列式钕玻璃放大器的设计有参考价值     

光学速调管自发辐射谱的研究

介绍了储存环上为自由电子激光研究而建造的光学速调管的自发辐射谱的实验测量及数值模拟结果,并讨论了进一步改进自发辐射光谱调制深度以提高自由电子激光增益的途径     

Amplified Spontaneous Green Emission and Lasing Emission From Carbon Nanoparticles

In this work, the optical properties of carbon nanoparticles (CNPs) can be modulated by the dopant‐N atom and sp² C‐contents. CNPs prepared with the low urea mass ratio of 0.2:1 (CNP1) exhibit blue emission (maximum PL quantum yield: 15%). Increasing sp² C‐ and dopant‐N atom contents, as determined in CNPs prepared with high urea mass ratio of 2:1 (CNP2), lead to green emission (maximum PL quantum yield up to 36% in ethanol aqueous solution). Amplified spontaneous emission (ASE) can be observed only in CNP2 ethanol aqueous solution. Green lasing emission is achieved from CNP2 ethanol aqueous solution in a linear long Fabry‐Perot cavity, indicating the potential of CNP2 as a gain medium for lasing. CNP2 shows superior photostability compared with C545T dye. The green emission from CNP2 is speculated to arise from electron‐hole recombination (intrinsic state emission). The high PL quantum yield and small overlap between absorption and emissions of CNP2 ethanol aqueous solution are the key factors in realizing lasing emission.     

太赫兹光非对称解复用器中自发辐射噪声特性分析

提出了一个在超短脉冲注入半导体光放大器 (SOA)时 ,在考虑了半导体带间效应以及带内效应 ,包括载流子热效应、谱烧孔效应、双光子吸收效应以及超快非线性折射效应的自发辐射噪声的计算模型。并利用该模型计算了放大自发辐射 (ASE)噪声对太赫兹光非对称解复用器 (TOAD)开关性能的影响。数值结果表明 ,在考虑ASE噪声情况下 ,TOAD的开关窗口的边沿更陡 ,在开关窗口的尾部还会出现明显的小峰。结果还表明 ,在输入为理想孤子脉冲下 ,即使考虑ASE噪声 ,在TOAD处于开的状态时 ,其输出信号的信噪比也大于 2 5dB。     

掺镱单模石英光纤中放大的自发辐射

描述了掺镱单模石英光纤中正向和反向放大的自发辐射 (ASE)的差异以及ASE谱轮廓随抽运功率、激活光纤长度和抽运波长等量的变化 ,这些结果对于掺镱光纤激光器、放大器的设计有重要的指导意义。     

染料掺杂聚合物波导薄膜中的放大自发发射

利用简单的平板波导结构,在掺有机小分子激光染料ＤＣＭ的聚苯乙烯（ＰＳ）薄膜中,采用Ｎｄ：ＹＡＧ的三倍频激光束作泵浦源,在细条状增益区内,在脉冲激发能量为１２μＪ时,发生了增益窄化现象,在以５８０ｎｍ为中心处出现了光谱半高全宽（ＦＷＨＭ）只有２４ｎｍ的放大自发发射峰。     

InGaAs量子点的自发发射及光增益

研究了InGaAs量子点材料自发发射、放大自发发射及光增益特性.实验发现InGaAs量子点材料随着注入电流密度的增加,其自发发射及放大自发发射光谱峰蓝移,表现出明显的能带填充现象.由于量子点材料尺寸及形状等存在一定的分布,在光谱中没有明显的对应量子点激发态的谱峰.由单程增益放大自发发射得到了量子点材料在不同注入电流密度下的光增益谱.结果表明存在由于量子点大小分布造成的量子点态非均匀展宽引起的增益峰蓝移和增益谱展宽现象.     

半导体微腔激光器中的自发辐射耦合增强效应

针对半导体微腔激光器的结构特点,以及腔量子电动力学中自发辐射增强效应,采用光增益与载流子密度的对数关系,引入增益饱和项和非辐射复合项的贡献,指出即便是对于理想的封闭微腔,由于非辐射衰减速率的影响,光输出并不随泵浦线性变化。结合频谱和相图分析,给出了自发辐射耦合因子与微腔激光器的辐射阈值、开关延迟时间、驰豫振荡频率和光输出等参量关系的仿真结果,这对于微腔激光器的理论研究和优化器件结构有所裨益。     

半导体微腔中电偶极子的自发发射

由于反射电场的影响，电偶极子在微腔中的自发发射速度不同于自由空间中的自发发射速度。本文采用镜像法计算了理想平面微腔、金属平面镜组成的半导体微腔和由分布布喇格反射镜（DBR）作为谐振腔的垂直发射激光器（VCSEL）中电偶极子的自发发射速率。计算结果表明：由于微腔的调制作用，在某些情况下电偶极子自发发射速率增加，在一定腔长下电偶极子自发发射速度被抑制。     

InGaAs量子点的自发发射及光增益

研究了InGaAs量子点材料自发发射、放大自发发射及光增益特性.实验发现InGaAs量子点材料随着注入电流密度的增加,其自发发射及放大自发发射光谱峰蓝移,表现出明显的能带填充现象.由于量子点材料尺寸及形状等存在一定的分布,在光谱中没有明显的对应量子点激发态的谱峰.由单程增益放大自发发射得到了量子点材料在不同注入电流密度下的光增益谱.结果表明存在由于量子点大小分布造成的量子点态非均匀展宽引起的增益峰蓝移和增益谱展宽现象.     

Coherent Spontaneous Microwave Emission by Pulsed Resonance Excitation

This paper describes an investigation of the coherent microwave emission from pulse-excited ammonia molecules. Coherent and periodic pulses of near resonance frequency and 1-µsec duration excited the gas from its initial thermal equilibrium condition. Self-induced coherent emission (molecular ringing) continued after the excitation field was removed. This radiation was observed during a period of 10 µsec. In an actual experiment performed, a new Doppler bandwidth reduction method was used in the gas cell. The observed spectral width of the ammonia 7,7 line was about 5 kc. The emission was used to stabilize the excitation signal source to a short-term frequency stability of 2 X 10/sup -10/.     

放大自发辐射注入波长锁定法布里-珀罗激光器

波分复用无源光网络(WDM-PON)被认为是接入网的最终解决方案,基于放大自发辐射(ASE)注入波长锁定法布里-珀罗(F-P)激光器的WDM-PON由于其价格低廉和容易实现颜色无关操作而受到极大关注.实验研究了ASE注入波长锁定F-P激光器的ASE增益、边模抑制比(SMSR)和相对强度噪声(RIN)随F-P激光器注入电流和ASE注入功率的变化关系,理论模拟了ASE注入功率和增益一定时,F-P激光器注入电流随其前端面反射率的变化关系,并从实验上进行了验证.研究结果表明,当F-P激光器的注入电流为阈值电流的1.3～1.7倍时,能获得满足应用需要的相对强度噪声和边模抑制比.对于一定的ASE注入功率和输出功率,存在使注入电流最小的最佳前端面反射率.     

对自发发射过程的一点看法

自发发射是光学和辐射学中最基本的问题，也是量子光学的基础之一。它与许多辐射过程有关。本文围绕着这个过程是量子过程还是经典过程进行了讨论。虽然通常认为是量子的，但目前看来，认为经典过程能更全面地解释实验结果。从而填补了现有理论的不足，其应用推广更具意义。     

注入锁定铜蒸气激光器中自发辐射的影响

利用铜蒸气激光动力学模型模拟了注入锁定中注入光与放大自发辐射之间的竞争过程，分析了注入锁定效果与注入功率的关系，并就如何增强注入光对噪声光的抑制作用进行了讨论。     

Polarization-controlled single-mode VCSEL

Relative intensity noise (RIN) in a vertical-cavity surface-emitting laser (VCSEL) was greatly reduced through the use of polarization control to eliminate competition between two orthogonal polarization states by ensuring there was only one polarization state. Polarization was stable with optical feedback of up to 10%. Polarization control was achieved by inducing a small loss anisotropy in fundamental transversal mode VCSEL's. Anisotropic post structures, such as a rectangular post, an oblique post, or a zigzag-sidewall post, were found to be effective in creating loss anisotropy without serious degradation of other VCSEL characteristics such as light-output power or beam profile     

条形DH半导体激光器的自发发射因子

本文从理论上和实验上系统地研究了具有非自建增益波导的条形半导体激光器自发发射因子及其象散因子与波导尺寸、偏置电流和不同纵模等的关系.发现自发发射因子随电流变化并不是一常数,它在阈值电流附近有突变.采用自洽决定波导结构的方法得出增益波导的象散因子K只比折射率波导的K大几倍.指出从与实际不太符合的固定的复折射率分布模型出发是造成K大达两个量级的原因,并判明了目前尚有争论的两种象散因子表达式的正误.