Optical properties of non-linear crystal grown from the melt GaSe–AgGaSe2

Modified GaSe single crystal was grown from the melt with charge composition GaSe+10 mass% of AgGaSe2. Lattice structure, visible to mid-IR and further THz range optical properties, as well as Raman spectra were studied in details. The grown crystal was identified as ε-GaSe:Ag (0.04 mass%). This silver content in GaSe has resulted in 6% decreased non-linearity that was over compensated in CO2 laser SHG efficiency by vanished of bulk damages and 10–20% improved surface damage threshold. About 30% increased microhardness is promising for cut and polishing at arbitrary direction and ε-GaSe:Ag applications in out-of-door systems.