Evidence of cascaded emission in a dual-wavelength quantum cascade laser

Abstract

This letter reports on a quantum cascade laser that exhibits simultaneous dual-wavelength emission from two consecutive optical transitions in each active region. These “cascaded” transitions—a second-excited state to first-excited state and a first-excited state to ground state—yield light at ∼9.5 and ∼8.2μm, respectively, in good agreement with simulations. The two lasing wavelengths have similar thresholds at the leading edge of a current pulse.