Sub-threshold linewidth broadening factor of a 3.4 μm interband cascade laser operated at room temperature

摘要

Interband cascade laser (ICL) is a power-efficient mid-infrared semiconductor laser source. Linewidth broadening factor (LBF) is a crucial parameter of semiconductor lasers. This work investigates the sub-threshold LBF of a continuous-wave ICL operated at room temperature, using the Hakki-Paoli method. The carrier-induced gain variation of the ICL is extracted from the amplified spontaneous emission spectrum. The refractive index variation is determined by the optical wavelength change, and the thermal effect is carefully removed. It shows that the LBF of the ICL around the gain peak ranges from 1.1 to 1.4, depending on the operation wavelength.