Broadband integrated mid infrared light sources as enabling technology for point of care mid-infrared spectroscopy

This 1-year pilot project investigated the possibilities to transform recently developed narrow-linewidth, continuous-wave cw ZBLAN chip lasers into robust and miniaturized broadband light sources for sensing applications. Utilizing nanomaterials-based saturable absorbers, it was demonstrated the possibility of passively q-switched as well as passively q-switched mode-locked QML operation of those chip lasers. Further, a novel nematic liquid crystal cell was successfully employed as an active q-switching element in the same type of chip lasers. The short laser pulses that were generated in these experiments were finally launched into a highly nonlinear optical fiber for nonlinear frequency broadening and a maximum spectral bandwidth of close to 100 nm was obtained in the important 2 m region of the spectrum. Numerical simulations reveal that further spectral broadening to a full mid-infrared super continuum is feasible.