Distributed Bragg reflector laser(1.8 μm) with 10 nm wavelength tuning range

We report a 1.8 μm two-section distributed Bragg reflector laser using butt-jointed In Ga As P bulk material as the waveguide core layer. The threshold current is 17 m A and the output power is 8 m W on average. The threshold current, output power, and emitting wavelength dependences on temperature are measured. The obtained wavelength tuning range is 10 nm. This device has potential applications in simultaneous multiple-gas detection.     

数字正交锁相放大器的研制及其在甲烷检测中的应用

利用可调谐二极管激光吸收光谱技术检测气体浓度时,为了从红外传感信号中提取一次及二次谐波信号来表征气体浓度,研发了一种基于数字信号处理器的数字正交锁相放大器.介绍正交锁相放大原理,设计谐波提取算法,给出数字正交锁相放大器的软硬件实现方案.利用配备的浓度为1%~5%的甲烷样品以及研制的锁相放大器,开展气体实验.实验结果显示,当甲烷浓度为5%时,在二次谐波对应的频率点处,测得的系统信噪比为34dB,表明设计的锁相放大器具有较好的性能;测得的二次与一次谐波信号峰峰值的比值与气体浓度成线性关系;考虑动态配气以及气体沿管道传输的时间,检测系统的响应时间约为96~98s;气体浓度为20 000ppm时,测试浓度波动范围为-92ppm~+118ppm;根据Allan方差预测的系统检测下限为29.52ppm.与模拟锁相放大器以及商用锁相放大器相比,本文研制的数字正交锁相放大器硬件结构简单、体积小、成本低、易于集成,在红外气体检测领域具有很好的应用前景.     

Growth of High-Quality GaAs on Ge by Controlling the Thickness and Growth Temperature of Buffer Layer

In the last two decades, m-v compound semi- conductor materials grown on elemental semiconduc- tor substrates have attracted much attention due to their potential applications in high-efficiency so- lar cells, photodetectors, quantum-dot （QD） lasers, and metal-oxide-semiconductor field-effect transistors （MOSFETs）. Due to their extremely high electron mobility, III-V semiconductors such as GaAs, InGaAs and InAs are believed to be chan- nel materials for future complementary metal-oxide- semiconductor （CMOS） technology.CMOS tran- sistors on Ge substrates with high mobility In- GaAs/Ge channels have already been fabricated by using a wafer bonding technique, which is a promis- ing step for such a device on Si.     

Electrically and Optically Bistable Operation in an Integration of a 1310 nm DFB Laser and a Tunneling Diode

We experimentally demonstrate an In P-based hybrid integration of a single-mode DFB laser emitting at around 1310 nm and a tunneling diode. The evident negative differential resistance regions are obtained in both electrical and optical output characteristics. The electrical and optical bistabilities controlled by the voltage through the tunneling diode are also measured. When the voltage changes between 1.46 V and 1.66 V, a 200-mV-wide hysteresis loop and an optical power ON/OFF ratio of 17 dB are obtained. A side-mode suppression ratio of the integrated device in the ON state is up to 43 dB. The tunneling diode can switch on/off the laser within a very small voltage range compared with that directly controlled by a voltage source.     

1.82-μm distributed feedback lasers with InGaAs/InGaAsP multiple-quantum wells for a H2 O sensing system

High-strained InGaAs/InGaAsP multiple quantum wells （MQWs） distributed feedback （DFB） lasers, fabricated using metal organic chemical vapor deposition, are presented at 1.82 μm with a high side-mode-suppression ratio of 49.53 dB. The current- and temperature-tuning rates of the DFB mode wavelength are 0.01 nm/mA and 0.13 nm/℃, respectively. A characteristic temperature of 51 K is also confirmed. The DFB laser demonstrates good performance and can be applied to H₂ O concentration sensing.