Photogenerated voltage bias in optically pumped interband cascade lasers

Antimonide-based type-II W interband cascade lasers optimized for electrical injection were optically pumped and exhibited lasing at emission wavelengths ranging from 3.2 µm to 3.8 µm, with a maximum operating temperature of 200 K. As the optical pumping wavelengths increased from 1.8 µm to 1.9 µm, decreasing threshold pump intensity and increasing slope efficiency (external differential quantum efficiency) were observed. The generation of photovoltage under illumination and consequent achievement of lasing conditions will be discussed, including comparisons to physical operating principles in thermophotovoltaic interband cascade devices and conventional interband cascade lasers.