Injectorless quantum cascade lasers for room-temperature short-wavelength emission by efficient second-harmonic generation

In this paper we demonstrate RT second-harmonic generation around 2.7 μm with peak output powers close to 10 μW at current densities of around 2 kA/cm2. We also discuss possible device structures for wavelengths around 3.5 μm and a future development strategy for single-mode, two-color tunable laser sources.