Monolithic integration of a widely-tunable mid-infrared source based on DFB QCL array and echelle grating

Abstract

In the mid-infrared (Mid-IR), arrays of distributed feedback Quantum Cascade Lasers (QCL) have been developed as a serious alternative to obtain extended wavelength operation range of laser-based gas sensing systems. In order to benefit from this extended wavelength range in a single output beam we have developed a platform for InP-based photonics. After the validation of all required building blocks, we are tackling the integration into a single monolithic device. We present the design, fabrication and performances of a tunable source, fully monolithic based on the echelle grating approach. The evanescent coupler has been designed to transfer all light adiabatically from the active region to a low loss passive waveguide, while taking advantage of the high gain available in the quantum wells. These results show the first realization of a monolithic widely tunable source in the Mid-IR and would therefore benefit to the development of fully integrated spectroscopic sensor systems.