UV integrated optics devices based on beta-barium borate

We report on our recent progress in development of ultraviolet (UV) integrated optics devices based on beta-barium borate (BBO). Planar optical waveguides with a thickness of a few micrometers have been formed by the implantation of He+ ions with energies of around 2 MeV. Two alternative methods based on the femtosecond-laser assisted micromachining and lithographic structuring for the fabrication of ridge-type channel optical waveguides in implanted BBO crystals have been developed, and the transmission properties of the obtained waveguides have been studied. We demonstrate a big potential of the fabricated channel waveguides for the second harmonic generation of continuous-wave deep-UV laser light with a power of the order of 1 mW, exploiting the nonlinear optical properties of BBO crystal. In addition, a low-voltage electro-optic waveguide modulator for the deep-UV light (half-wave voltage times electrode length Vπ × l = 43 V cm at 257 nm) was realized for the first time.