Rao Gottipaty N, Karpf Andreas
Department of Physics, Adelphi University, Garden City, New York 11530, USA.
Appl Opt. 2011 Feb 1;50(4):A100-15. doi: 10.1364/AO.50.00A100.
Since the first quantum cascade laser (QCL) was demonstrated approximately 16 years ago, we have witnessed an explosion of interesting developments in QCL technology and QCL-based trace gas sensors. QCLs operate in the mid-IR region (3-24 μm) and can directly access the rotational vibrational bands of most molecular species and, therefore, are ideally suited for trace gas detection with high specificity and sensitivity. These sensors have applications in a wide range of fields, including environmental monitoring, atmospheric chemistry, medical diagnostics, homeland security, detection of explosive compounds, and industrial process control, to name a few. Tunable external cavity (EC)-QCLs in particular offer narrow linewidths, wide ranges of tunability, and stable power outputs, which open up new possibilities for sensor development. These features allow for the simultaneous detection of multiple species and the study of large molecules, free radicals, ions, and reaction kinetics. In this article, we review the current status of EC-QCLs and sensor developments based on them and speculate on possible future developments.
大约16年前第一台量子级联激光器（QCL）问世以来，我们见证了QCL技术以及基于QCL的痕量气体传感器取得了大量有趣的进展。QCL在中红外区域（3 - 24μm）工作，能够直接探测大多数分子种类的转动振动带，因此非常适合用于高特异性和高灵敏度的痕量气体检测。这些传感器在众多领域都有应用，包括环境监测、大气化学、医学诊断、国土安全、爆炸物检测以及工业过程控制等等。特别是可调谐外腔（EC）-QCL具有窄线宽、宽调谐范围和稳定的功率输出，为传感器的发展开辟了新的可能性。这些特性使得能够同时检测多种物质，并研究大分子、自由基、离子以及反应动力学。在本文中，我们综述了EC-QCL的现状以及基于它们的传感器发展情况，并对未来可能的发展进行了推测。
