半导体垂直腔面发射激光器的微腔效应

应用腔量子电动力学和半导体物理学讨论了半导体垂直腔面发射激光器的微腔效应,得到了实际腔结构和注入载流子下的半导体生趣腔面发射激光器的自发发射谱,计算结果表明,半导体分布布拉格反射垂直腔激光器的单方向自发发射可以境强约２００倍。     

高速调制响应垂直腔面发射激光器中的微腔效应

应用微腔物理和量子阱物理，计算了量子阱垂直腔面发射激光器的自发发射谱和自发发射寿命，通过对半导体激光器传输函数的研究，发现缩短自发发射寿命是垂直腔面发射激光器实现高速调制响应的主要原因.     

基于环行腔激光器四波混频型可调谐波长转换的理论研究

建立了完整的基于半导体环行腔激光器四波混频型可调谐波长转换器的宽带理论模型.模型中考虑了半导体光放大器的材料增益谱、载流子的空间分布、光场的纵向空间分布和宽带放大自发发射等关键因素，并通过数值模拟，从理论上研究了这种波长转换器的各种性能与输入信号光功率、注入电流、输出耦合器的耦合比和环行腔激光器激射光波长的关系.理论上所得结论与文献中实验结果符合得很好. 关键词： 半导体环行腔激光器 四波混频 波长转换 放大自发发射     

语音信号调制的微腔半导体激光器的抗噪音性能

假定微腔半导体激光器输入调制信号为实际语音信号,伴随语音信号的噪音为加性白噪音,在小信号近似下,得到了电流调制和自发发射寿命调制下激光器的传递函数;在大信噪比的前提下,对激光器进行了频域分析,得到了不同参量下的信噪比增益.数值模拟结果表明,在偏置电流的变化范围内,存在极低信噪比增益区,大自发发射因子、小自发发射寿命有利于使该区变窄;语音信号的通带范围和功率谱密度分布特征参量的适当选取,可以使激光器的抗噪音性能在偏置电流的某段范围内得以提高.     

微腔半导体激光器的两种新调制方法

本文提出微腔半导体激光器的两种新调制方法:自发发射寿命调制和光子寿命调制。小信号近似分析的数值模拟结果表明,这两种调制方法的调制带宽大于同参数下的电流调制的带宽。     

二维导体微粗糙面与其上方金属平板的复合电磁散射研究

研究了二维导体微粗糙面与其上方金属平板复合电磁散射特征.应用互易性原理使求解二次散射场简化为求解包含平板上的极化电流和微粗糙面散射场的积分方程，从而降低了求解难度.应用物理光学近似和微扰法分别求解了平板上的极化电流和粗糙面的电磁散射场，得到了复合散射截面计算公式并进行了数值计算.尤其对该复合模型后向耦合电磁散射结果进行了详细分析和讨论. 关键词： 互易性原理 复合电磁散射 微粗糙面 平板     

有机薄膜电致发光器件的光学微腔效应

制备了以铝掺杂氧化锌（ＡＺＯ）透明导电膜为阳极的有机薄膜电致发光微腔器件，研究了垂直的光学法布里－珀罗微共振腔对有机器件的自发发射的微腔效应，发出了光谱窄化、发光强度增加及发射的角度依赖关系等现象。具有微腔结构的器件发射谱将高宽只有１４display status     

耦合结构有机微腔的光致发光特性

耦合光学微腔(Coupled optical microcavity,CMC)是一种特殊结构的微腔,在耦合微腔中,两个独立的微腔相邻耦合在一起.通常一个腔是无源的,另一个腔是有源的.首次研究了有机材料在耦合微腔中的自发发射特性.实验采用的有机发光材料为八羟基喹啉铝Tris(8-quinolinolato)aluminium(Alq₃),器件的结构为Glass/DBR_A/Filler/DBR_B/Alq₃/DBR_C.底部腔是无源的,组成为DBR_A/Filler/DBR_B.顶部腔是有源的,由DBR_B/Alq₃/DBR_C构成.其中反射镜DBR_A、DBR_B、DBR_C以及填充层(Filler)均由光学介质材料构成.通过结构设计使两个腔的谐振波长均位于530nm.耦合微腔器件与单层Alq₃薄膜相比较,Alq₃薄膜的光致发光光谱是峰值位于511nm的宽谱带,而在耦合微腔器件中观察到的是具有两个腔模式,峰值波长分别位于518,553nm的增强并窄化的光谱.这是由于两个腔的光场耦合引起了腔模式分裂.结果表明耦合微腔能极大地改变有机材料的自发发射特性,可以用来提高器件的发光效率.     

有机吸附物对多孔硅微腔发光的影响

理论上,采用Bruggeman有效介质近似,研究了有机吸附物对多孔硅微腔的折射率及其光致发光谱的影响.实验上,采用计算机控制的电化学腐蚀法制备了多孔硅微腔样品,并利用机械泵油的蒸气分子与该微腔样品进行相互作用.研究发现,多孔硅微腔发射的窄化光致发光谱对泵油蒸气分子的吸附与脱附很敏感,与之伴随的是该窄化光致发光谱发生明显的峰位移动(可达71nm)和强度变化.结合Bruggeman近似和表面态对多孔硅发光的影响,对实验结果进行了定性解释.实验结果与理论模拟结果符合较好. 关键词： Bruggeman近似 吸附物 多孔硅微腔 光致发光谱     

稳定和非稳定激光谐振腔中的自再现模讨论

本文通过菲涅耳-基尔霍夫衍射积分方法,推导了一般稳定和非稳定球面镜谐振腔中自再现模的解析表达式,揭示了从稳定腔变为非稳腔过程中自再现模的变化规律.进一步地,本文在几何光学近似条件下得到了非稳腔的自再现模,通过与衍射积分结果对比,发现基于几何光学近似得到的非稳腔最低阶偶对称模(即基模)和最低阶奇对称模的空间分布与衍射积分结果一致.而对于更高阶的自再现模,当非稳腔接近稳定腔时,几何光学近似得到的自再现模空间分布和衍射积分结果之间存在较大差异.本文的结果可以作为激光原理教学内容的重要补充.     

Approximate analytic expressions for calculation of spontaneous emission spectra for a quantum well embedded in a planar microcavity

The control of spontaneous emission is one of important characteristics of a planar microcavity. The integrals in the spherical coordinate for TE and TM modes spontaneous emission spectra of a quantum well (QW) embedded in a planar microcavity are derived with new variables dependent on wavelength and Taylor series including the two polarizations of the vacuum field. The approximate expressions of spontaneous emission in QW planar microcavities are obtained. The approximate results show that spontaneous emission spectra agree well with that in the numerical integral for planar semiconductor microcavities, in which Fermi-Dirac distribution functions of electrons and holes are considered. The main contribution to the spontaneous emission, radiated into all direction, has been found.     

Spontaneous emission coupling factors in planar micro-cavity lasers with distributed Bragg reflectors

In this article, a considerable value of spontaneous emission factor is estimated based on the spontaneous emission radiation patterns in micro-cavity lasers. After the spontaneous emission for a dipole in the micro-cavity is studied, the confinements of vacuum fields and electrons are considered together for a quantum well in the micro-cavity laser. The TE mode and TM mode spontaneous emission spectra are presented for a single quantum well embedded in a planar micro-cavity laser at 300 K. The results show that the TE mode spontaneous emission spectrum is enhanced, whereas the TM mode spontaneous emission is suppressed greatly. The maximum values obtained for the spontaneous emission coupling factors are 0.2 and 0.0055 for a dipole and a quantum well planar micro-cavity laser with distributed Bragg reflectors, respectively.     

由半导体激光器端面输出谱确定自发辐射谱

利用射线法和平均载流子分布近似，从理论上预言了用阈值以下半导体激光器的端面输出谱来确定自发辐射谱的可能性。在此基础上，通过实验测得的阈值以下半导体激光器的端面输出谱确定了自发辐射谱，并且对自发辐射谱和增益谱进行了比较和分析。     

Single-mode spontaneous emission from a single quantum dot in a three-dimensional microcavity

The spontaneous emission from an isolated semiconductor quantum dot state has been coupled with high efficiency to a single, polarization-degenerate cavity mode. The InAs quantum dot is epitaxially formed and embedded in a planar epitaxial microcavity, which is processed into a post of submicron diameter. The single quantum dot spontaneous emission lifetime is reduced from the noncavity value of 1.3 ns to 280 ps, resulting in a single-mode spontaneous emission coupling efficiency of 78%.     

PbTe/CdTe量子阱光学性质的研究

PbTe/CdTe量子阱是一类新型异系低维结构材料,实验观察到具有强的室温中红外光致发光现象.建立了理论模型,计算了PbTe/CdTe量子阱的自发辐射率和光学增益.模型中量子阱分立能级的计算采用k·p包络波函数方法和有限深势阱近似,考虑了PbTe能带结构的各项异性和阱层中应变对能级的影响.计算了PbTe/CdTe量子阱自发辐射谱与带间弛豫和注入载流子浓度间的依赖关系,计算结果与实验观察到的光致发光峰相符合.自发辐射谱线峰位随着注入载流子浓度的增加而出现蓝移,当载流子浓度从2×1017cm-3增加到2.8×1018cm-3,基态发射峰从372 meV蓝移到397 meV,而第一激发态发射峰蓝移量为15 meV.上述蓝移现象是由载流子与载流子及载流子与声子间的相互作用引起的.与PbTe体材料相比.PbTe/CdTe量子阱结构具有更高的增益强度(提高近15倍)和更宽的增益区,因而该体系可能是实现室温连续工作的中红外激光器的理想材料.     

Controlling spontaneous emission and threshold-less laser oscillation with optical microcavities

We describe the alteration of spontaneous emission of materials in optical microcavities having dimensions on the order of the emitted wavelength. Particular attention is paid to one-dimensional optical confinement structures with pairs of planar reflectors (planar microcavities). The presence of the cavity causes great modifications in the emission spectrum and spatial emission intensity distribution accompanied by changes in the spontaneous emission lifetime. Experimental results are shown for planar microcavities containing GaAs quantum wells or organic dye-embedded Langmuir-Brodgett films as light emitting layers. Also discussed are the laser oscillation properties of microcavities. A remarkable increase in the spontaneous emission coupling into the laser oscillation mode is expected in microcavity lasers. A rate equation analysis shows that increasing the coupling of spontaneous emission into the cavity mode causes the disappearance of the lasing threshold in the input-output curve. Experimentally verification is presented using planar optical microcavities confining an organic dye solution. The coupling ratio of spontaneous emission into a laser mode increases to be as large as 0.2 for a cavity having a half wavelength distance between a pair of mirrors. At this point, the threshold becomes quite fuzzy. Differences between the spontaneous emission dominant regime and the stimulated emission dominant regime are examined with emission spectra and emission lifetime analyses.     

Intense laser field effects on the electron Raman scattering in a strained InGaN/GaN quantum well

The differential cross-section for an intersubband electron Raman scattering process in a strained InGaN/GaN quantum well in the presence of an intense laser field is studied. In the effective-mass approximation, the electronic structure is calculated by taking into account the effects of spontaneous and piezoelectric polarization fields on the confinement potential. Effects of laser field strength, indium composition and the well width on the differential cross-section of the strained quantum well are investigated. Results show that the position and the magnitude of the peaks of emission spectra considerably depend on the laser field strength as well as structural parameters.     

基于两端自发荧光辐射的808nm半导体激光器增益偏振特性实验表征和能带分析

通过半导体激光器两端的放大自发荧光辐射可以获取器件的光学增益信息. 本文利用这一新的增益实验测量方法, 开展了对连续运行的808nm GaAs/AlGaAs量子阱激光器横向电场 (TE)与磁场(TM)偏振增益特性的实验研究. 通过将实验结果与理论增益曲线对比, 分析了非应变GaAs量子阱TE和TM极化偏振对应的空穴子能带随注入电流的变化规律, 以及激光器在连续运行状态下的实际增益状态和影响因素. 关键词： 半导体激光器 增益测量 偏振 量子阱和能带