Widely-tunable mid-infrared semiconductor lasers for spectroscopy applications and gas sensing

本项目旨在开发光辐射在3.05-3.45µm（87-98太赫兹）和4.25-4.65µm（64-71太赫兹）光谱区域的全半导体可调谐光源，用于检测和监测C2H2、CH4、C2H5、CH2O、CO、CO2和N2O等气体。提出的技术是在砷化铝镓中实现的电泵差频产生装置。epdfg的结构为腔内相位匹配的Bragg反射波导，其红外光是由嵌入波导芯内的电注入多量子阱二极管激光器泵浦和外部源传递的信号进行光混合产生的。EP-DFGs是红外吸收光谱中需要连续可调光源的潜在光源。现有的红外光源，如量子级联激光器，通常在几纳米的范围内继承波长可调性。EP-DFGs通过失谐泵浦波长、信号波长或同时失谐泵浦和信号波长，实现了数百纳米范围内的波长可调性。EP-DFG装置商业潜力的一个例子是对气体的连续传感和监测，其中波长可调性可以精确扫描分子及其同位素的吸收线。另一个应用是多组分气体分析，它需要可调谐激光器，因为它们可以访问宽光谱范围，通常包含分子的多条吸收线。EP-DFGs等单一可调谐激光设备的可用性可以取代几种传统激光器，从而降低成本和紧凑的组装组件。

This project aims to develop all-semiconductor tunable light sources with optical radiation in 3.05-3.45 µm (87-98 THz) and 4.25-4.65 µm (64-71 THz) spectral region for the detection and monitoring of gases including C2H2, CH4, C2H5, CH2O, CO, CO2 and N2O. The proposed technology is an electrically pumped difference-frequency generation device implemented in aluminum gallium arsenide. The structure of EP-DFG is an intra-cavity phase-matched Bragg reflection waveguide where the infrared light is generated by optically mixing the pump, which is an electrically injected multiple-quantum well diode laser embedded inside the waveguide core, and a signal which is delivered by an external source. EP-DFGs are potential sources for applications in infrared absorption spectroscopy where a continuously tunable source is desired. Available IR sources such as quantum-cascade lasers generally inherit wavelength tunability in range of few nanometers. EP-DFGs enable wavelength tunability in range of hundreds of nanometers offered by detuning the pump wavelength, the signal wavelength or detuning simultaneously both pump and signal wavelengths. An example of commercial potential of EP-DFG devices is continuous sensing and monitoring of gases where wavelength tunablity enables precise scanning of the absorption lines of the molecules and their isotopes. Another application is multi-component gas analysis which requires tunable lasers since they can access a wide spectral range that usually contains several absorption lines of the molecules. The availability of single tunable lasing devices such as EP-DFGs can replace several conventional lasers, resulting in reduced cost and compact assembly component.