Very low threshold operation of quantum cascade lasers*
Yan Fang-Liang, Zhang Jin-Chuan†, Yao Dan-Yang, Liu Feng-Qi‡, Wang Li-Jun, Liu Jun-Qi, Wang Zhan-Guo
       
The cw power–current–voltage characteristic of an uncooled cw QCL. Inset shows the heat sink temperature as a function of injection electrical power.