Vertically emitting distributed-feedback quantum-cascade lasers

Quantum cascade lasers (QCLs) have been established as versatile light sources in the mid-infrared. On the one hand their multilayer heterostructure offers great flexibility in emission wavelengths and allows for the integration of nonlinear light conversion mechanisms. On the other hand the bigger waveguide dimensions, when compared to band-gap lasers, make advanced cavity designs, such as various distributed feedback designs, photonic crystals and microcavities more readily accessible. We present surface emitting QCLs operating around 10mum with optical peak power levels in the Watt range. By nonlinear light generation in the laser cavity, we generate frequency-doubled light that is extracted from the surface of the device by grating coupling, while the fundamental radiation is blocked.