Terahertz semiconductor laser source at -12 C

Room temperature operation of Terahertz Quantum Cascade Lasers (THz QCLs) has been a long-pursued goal to realize compact semiconductor THz sources. The progress toward high-temperature operation in THz QCLs has been relatively slow compared to infrared QCLs owing to more significant challenges at THz frequencies. Recently, the maximum operating temperature of THz QCLs was improved to 250 K, and the achievement revitalized hope in the THz community in pursuit of higher temperature operations. In this paper, we report on further improvement in operating temperature to ~261 K (-12 0C) by judiciously optimizing key parameters and discuss the challenges ahead in achieving room temperature operation.