Short-wavelength InP quantum cascade laser sources by quasi- phase-matched intracavity second-harmonic generation

Short-wavelength quantum cascade laser (QCL) sources, based on transversely integrated giant nonlinearity have been designed and fabricated. Devices consist of an injectorless GaInAs/AlInAs/InP pump QCL and a passive two-well based nonlinearity grown on top of the pump active region. The nonlinearity was designed to possess a giant nonlinear response for the process of second-harmonic generation (SHG). For efficient SHG process, the wave-vector mismatch between the fundamental and the nonlinear signals was compensated by structuring the nonlinear layer into the 50% duty-cycle quasi-phase-matching gratings. Using this approach we were able to demonstrate room-temperature operation at 3.5 µm and 2.7 µm second-harmonic emission wavelengths with output power levels up to 30 µW. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)