Room-temperature 2.95 μm quantum cascade laser sources based on intra-cavity frequency doubling

Reported are the design and performance of GaInAs/AlInAs/InP quantum cascade laser sources based on intra-cavity second-harmonic generation providing an output at 2.95 m wavelength. To produce frequency doubling, devices contain a passive heterostructure tailored for giant optical nonlinearity integrated on top of an active region and patterned for quasi-phase matching. The sources have a threshold current density of 2.2 kA/cm² and provide approximately 35 W of second-harmonic output at room temperature. The second-harmonic conversion efficiency is approximately 75 W/W².