Multi-color photonic integrated circuits based on homogeneous integration of quantum cascade lasers

We demonstrate an InP-based mid-infrared photonic integrated circuit processed from a wafer in which two distinct quantum cascade laser active regions are grown in different areas on the same InP crystal. A passive InGaAs waveguiding layer is epitaxially deposited on top of the entire InP substrate prior to the laser active region growth to optically couple the lasers emission and to multiplex their emission wavelengths to a single output waveguide. The method demonstrated in this work enables the creation of monolithic photonic integrated circuits with emission wavelength spanning the entire 3-15 µm spectral range and it is of interest for a wide range of applications.