Quantum cascade lasers: from sketch to mainstream in the mid and far infrared

<正>Electrically-pumped semiconductor lasers based on monolithic chip configuration possess plenty of advantages such as small volume, light weight, long lifetime and stable performance. Nevertheless this type of lasers rely on the interband transition, which sets the bounds for emission wavelength typically below4μm,and state of the art performance has been attained below 3μm. Attempts to employ small bandgap meterials like antimonide or lead salts ended with poor performance mainly due to imperfect crystal quality and severe Auger recom-