Woodworth S C, Cassidy D T, Hamp M J
Department of Engineering Physics, McMaster University, Hamilton, Ontario L8S 4L7, Canada.
Appl Opt. 2001 Dec 20;40(36):6719-24. doi: 10.1364/ao.40.006719.
We have developed a broadly tunable diode laser system by employing custom-designed asymmetric multiple-quantum-well (AMQW) InGaAsP lasers in an external cavity configuration. Feedback is provided by a diffractive optical element with high coupling efficiency and wavelength selectivity, allowing for single-mode tuning of the output wavelength by varying the external cavity length. This tunable laser system was used experimentally to perform absorption spectroscopy on weak CO2 lines over a broad wavelength region in the near infrared. An experimental tuning range of 80 nm has been observed for a laser cavity length of 600 micron, which is double the tuning range found with conventional, uncoated quantum-well lasers. We achieved a detection sensitivity of 5 x 10(-6) at 95% confidence over the wavelength range of 1.54-1.62 micron by employing a second-harmonic detection technique. The theoretical predictions of a broad gain profile from an ambipolar rate equation model are found to correspond to the experimentally observed increased tunability of the uncoated AMQW lasers.
我们通过在外部腔配置中采用定制设计的非对称多量子阱（AMQW）InGaAsP激光器，开发了一种宽可调谐二极管激光系统。反馈由具有高耦合效率和波长选择性的衍射光学元件提供，通过改变外部腔长度可实现输出波长的单模调谐。该可调谐激光系统通过实验用于在近红外的宽波长区域对弱CO2谱线进行吸收光谱分析。对于600微米的激光腔长度，观察到80纳米的实验调谐范围，这是传统未镀膜量子阱激光器调谐范围的两倍。通过采用二次谐波检测技术，在1.54 - 1.62微米波长范围内，我们在95%置信度下实现了5×10(-6)的检测灵敏度。发现双极速率方程模型的宽增益分布的理论预测与实验观察到的未镀膜AMQW激光器增加的可调谐性相对应。
