GaAs基长波长量子点激光器增益和阈值电流密度的理论分析

基于谐振子模型的量子点能级,计算了包括和排除激子影响时多能级的增益谱.考虑了低温时非平衡载流子分布.得出了较宽温度范围内阈值电流密度的变化,包括负温度及振荡温度效应.研究了垂直层叠和p型掺杂对量子点激光器性能的改善,并讨论了获得极小阈值电流密度时的最佳量子点密度.     

InGaN量子阱激光器增益和阈值电流的理论计算

根据现有的材料参数，计算了Ｉｎ０．２Ｇａ０．８Ｎ／Ｉｎ０．０５Ｇａ０．９５Ｎ量子阱激光器的增益、阈值电流密度以及阈值与温度的关系。理论分析表明氮化物蓝绿光激光器的阈值电流密度是ＧａＡｓ材料的５倍以上，但其特征温度可接近５００Ｋ。     

Theoretical Analysis of Gain and Threshold Current Density for Long Wavelength GaAs-Based Quantum-Dot Lasers

Quantum dot gain spectra based on harmonic oscillator model are calculated including and excluding excitons.The effects of non-equilibrium distributions are considered at low temperatures.The variations of threshold current density in a wide temperature range are analyzed and the negative characteristic temperature and oscillatory characteristic temperature appearing in that temperature range are discussed.Also,the improvement of quantum dot lasers’ performance is investigated through vertical stacking and p-type doping and the optimal dot density,which corresponds to minimal threshold current density, is calculated.     

Differential Gain and Gain Compression in Quantum-Dot Lasers

The dynamics of optical gain in semiconductor quantum dots (QDs) is investigated. Simple analytical expressions are derived, which directly connect the laser dynamical response to capture and intradot relaxation rates. The effect of hole spreading in the valence band and spectral hole burning in the QD ensemble is also quantitatively assessed. The analysis shows that intradot relaxation constitutes the main limitation in the dynamics and points to possible routes towards the improvement of QD lasers     

Low Threshold Current Density and High Efficiency Surface-Emitting Lasers with a Periodic Gain Active Structure

We have achieved very low threshold current densities with high light output powers for InGaAs / GaAs surface-emitting lasers using a periodic gain active structure in which three quantum wells are inserted in two-wavelength-thick (2λ) cavity. Air-post type devices with a diameter of 20~40 μm exhibit a threshold current density of 380~410 A/cm². Output power for a 40 μm diameter device reaches over 11 mW. A simple theoretical calculation of the threshold and power performances indicates that the periodic gain structure has an advantage in achieving low threshold current density mainly due to the high coupling efficiency between gain medium and optical field. The deterioration of power, expected from the long cavity length of 2λ, is negligible.     

Ultrafast Gain Dynamics in Quantum-Dot Amplifiers: Theoretical Analysis and Experimental Investigations

Ultrafast gain dynamics in an optical amplifier with an active layer of self-organized quantum dots (QDs) emitting near 1.3$muhbox m$is characterized experimentally in a pump-probe experiment and modeled theoretically on the basis of QD Maxwell–Bloch equations. Experiment and theory are in good agreement and show ultrafast subpicoseconds gain recovery followed by a slower 5 ps recovery. This behavior is found to be mainly caused by longitudinal optical phonon scattering and strongly dependents on electronic structure and confinement energy of the dots. A low amplitude-phase coupling ($alpha$factor) is theoretically predicted and demonstrated in the experiments. The fundamental analysis reveals the underlying physical processes and indicates limitations to QD-based devices.     

单片集成GaAs基长波长谐振腔光探测器的研究

介绍了一种GaAs基的长波长谐振腔增强型(RCE)光探测器.通过两步生长法,在GaAs村底上异质外延生长了InP-InGaAs-InP的p-i-n光吸收结构和GaAs/AlAs的分布布拉格反射镜(DBR).所制备的器件在1 549.4 nm处获得了67.3%的量子效率和17 nm的光谱响应线宽,在1 497.7 nm处获得了53.5%的量子效率和9.6 nm的光谱响应线宽,而InGaAs吸收层厚度仅为200 nm.采用单片集成法,工艺简单、易于产业化,随着缓冲层技术的发展,此种RCE光探测器的性能还将获得进一步提升.     

长波长量子阱激光器的理论与应用

本文研究量子阱激光器的基础理论,并介绍生长长波长光电器件的工艺技术及设备。     

电调谐半导体激光器波长控制系统

研制了一种基于计算机控制的电调谐半导体激光器波长控制系统.通过调用系统中的半导体激光器"波长-电流"数据查询表,控制驱动单元的电流输出,实现对半导体激光器的输出波长控制.应用该系统对DBR激光器进行了波长控制实验,其波长控制误差不超过±0.02 nm.