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. Narrow-linewidth,
single mode operation and wide tunability are then gathered together on a single chip with high compactness and
intrinsic stability. 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 such as straight waveguides,
adiabatic couplers between active and passive waveguides, and echelle grating multiplexers, 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. Advantages are design flexibility, relatively simple processing and the need for one single epitaxial growth for
the entire structure. 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. The multiplexer is
based on an etched diffraction grating, covering the whole range of the 30 lasers of the array while keeping a very
compact size. 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.