Universal Non-Linear Optical Crystal based intense laser light systems (UNLOCK)

The primary goal of the project is the development of advanced active ion doped and passive nonlinear optical materials based on II-VI single crystalline layers for use in particularly compact integrated and robust mid-infrared laser systems operating in the mid-infrared wavelength region between 2 and 18 microns. This novel type of lasers will produce intense ultra-short light pulses characterized by ultra-broad spectra that can be used for sensing and imaging. Such compact integrated high power photonic light sources have never existed before. They can be compared only to semiconductor-lasers and provide a powerful alternative to quantum cascade lasers, the operation of which is limited due to relatively narrow achievable bandwidth (~5 THz vs. ~50 THz in this new class of lasers), on one hand, and to longer than 3.4 microns wavelength due to material reasons, on another hand. Compact microchip frequency combs are long sought after in industry and are of particular importance for biomedical applications, environmental sensing, oil and gas sensing and imaging in self-driving cars. The first fundamental studies and proof-of-principle of this technology have been carried out by the NTNU team. Also, the applicability of the envisaged laser sources towards important industrial problems, for example, to sensing in oil and gas industry, has been verified in the successfully completed feasibility study projects co-funded by the Norwegian industry, STATOIL (EQUINOR) and an NTNU spin-off ATLA Lasers AS. These works were primarily done on bulk crystalline materials. In the first project period we made remarkable progress in writing waveguides in crystals of ZnS, ZnSe and Si. For the first time we have created modifications inside the material that are smaller than the wavelength of the laser. It is also possible to create hollow structures inside the material. Combined with the recently developed by the applicants MBE method of producing these laser crystals this opens up an avenue towards new microchip laser design, and eventually, electrical pumping.

The primary goal of the project is the development of advanced active ion doped and passive nonlinear optical materials based on II-VI single crystalline layers for use in particularly compact integrated and robust mid-infrared laser systems operating between 2 and 18 microns and producing intense ultra-short pulses and frequency combs. Such compact integrated high power photonic light sources have never existed before. They provide a powerful alternative to quantum cascade lasers, the operation of which is limited due to relatively narrow achievable bandwidth (~5 THz vs. ~50 THz in Cr:ZnS/Se), on one hand, and to longer than 3.4 microns wavelength, on another hand. Compact mid-IR frequency combs are long sought after in industry and are of particular importance for biomedical applications, environmental sensing, oil and gas sensing and 3D-prototyping using polymers and composite materials. The first fundamental studies and proof-of-principle of this technology has been carried out in the previous completed NANOMAT project. Since then the applicability of the frequency comb sources towards important industrial problems – for example, to sensing in oil and gas industry – has been verified in the successfully completed by the applicant feasibility study projects funded by the Norwegian industry. These works were primarily done on bulk materials. Combined with the recently developed by the applicants MBE method of producing active ion doped single crystals this opens up an avenue towards novel laser design at the same time allowing using such advanced laser concepts as coherent beam combining, so far implemented only in fiber lasers but equally applicable to wave-guide structures. To realize such a compact and intense ultrashort-pulsed laser, the project will develop novel laser and nonlinear materials and micro-structures, advanced wave-guide laser architectures and deploy such an innovative concept as coherent beam combining of multiple wave-guides on a chip.