基于增益调控的连续超宽带波长调谐外腔面发射半导体激光器研究

Tunable semiconductor lasers have exhibited wide and prospective applications in the fields of optical communications and atmopheric environmental monitoring. However, the tunable wavelength range limited by the quantum well gain bandwidth has been a bottleneck in the further development of broad-band tuning range of semiconductor lasers.Thus, we are proposing a research project, which is about a new mechanism and method study of making the tunable wavelength range able to effectively break through the gain bandwidth limitation of the well from the gain spectrum broadening by the gain detuning and superposition control between different groups of quantum wells in the laser chip based on the external-cavity surface-emitting laser configuration. The concrete work involves: (1) analysis of the gain broadening mechanism from the gain detuning and superposition of the multi-periods of quantum wells, including the characteristics of the broadened gain spectra from the superposition, thermodynamics and laser physical effects; (2) design and fabrication of the laser chips with the superposed and broadened gain; (3) design of the cavity, wavelength filtering and selection technique as well as the relevant modulator preparation; (4) gain re-broadening mechanism with the multi-chip combination. In the near-infrared band of 900-1000 nm, more than 3 W of TEM00 output power and the tunable wavelength range over the gain bandwidth of the well by more than 100% are achieved.

可调谐半导体激光器在光通讯和大气环境监控等领域均已得到重要应用。然而，波长调谐范围长期受限于量子阱增益带宽成为了发展宽带波长调谐半导体激光器的瓶颈。针对上述问题，本项目提出以外腔面发射激光器结构为基础，通过对激光器增益芯片的多周期量子阱进行增益调控，使阱间增益谱形成频移复合展宽，波长调谐范围有效突破量子阱增益带宽极限的新方法和系统研究。具体包括：（1）基于多周期量子阱带隙梯度设计的增益调控及频移复合展宽机制分析，包括复合展宽增益谱的特性、热动力学和激光物理效应；（2）增益频移复合展宽芯片研制；（3）谐振腔设计、滤波选频技术及调制器研制；（4）多芯片组合增益谱二次展宽实验及机理研究。本项研究的代表性指标包括在900-1000 nm波段获得大于3 W基模输出功率并达到连续波长调谐宽度超过量子阱增益带宽极限100%以上的国际前沿水平。

面向大气光谱探测和光通讯等领域对可调谐半导体激光器的应用需求，为解决目前可调谐半导体激光器调谐范围和输出稳定性受限于增益带宽的技术瓶颈，本项目以外腔面发射激光器结构为基础，通过激光器增益芯片的多周期量子阱进行增益调控，使阱间增益谱形成频移复合展宽，波长调谐范围有效突破量子阱增益带宽极限，同时保持激光输出功率相对稳定。主要研究内容包括：1.多周期量子阱增益调控和增益频移复合展宽机制研究；2.增益频移复合展宽芯片研制；3.超宽波长调谐外腔面发射激光器实验系统设计及相关研究；4.二次增益复合展宽的新机制研究。项目研究工作按照原定研究目标和研究计划顺利开展，在激光波长调谐范围方面，在研究过程中发现了富铟岛阱增益展宽新机制，在调谐范围和功率稳定性方面获得突破，无需采用原定多芯片组合方案，简化了系统结构，完成了预期研究目标。项目取得成果总体情况为：对多周期量子阱分组和梯度带隙材料系统进行了研究，建立了增益频移复合展宽计算模型并完成了增益芯片样品制备与测试；设计并完成了外腔面发射激光器实验系统设计与搭建，实现960nm波段基模高功率激光输出；在材料生长与分析过程中发现了富铟岛阱引入增益展宽的新机制，对该机制进行了深入分析并进一步发展了基于阱岛复合量子限制结构使增益展宽，进而拓展光谱调谐范围的新方法。研制出光泵浦外腔面发射激光器最高连续输出功率达到1W，基于阱岛复合量子限制结构增益芯片成功实现激光光谱调谐范围>100nm，峰值波长调谐范围内功率波动不大于0.1dB。在光泵浦外腔面发射激光器结构设计、材料生长、器件研制以及相关新机理发掘方面获得系列进展，项目执行期间申请发明专利5项，其中授权发明专利2项，发表SCI、EI收录论文21篇，培养博士4人，硕士2人。