SINGLE-CRYSTALLINE EPITAXIAL ZNS WAVE-GUIDES FOR PHASE MATCHED 2ND HARMONIC-GENERATION DEVICES

A novel second harmonic generation (SHG) device using single-crystalline epitaxial ZnS waveguide was proposed. First, theoretical analyses were carried out. A possibility of mode-coupled phase matching was confirmed by calculating the mode dispersion curves. Optical crystalline orientation of the waveguide was theoretically determined. We found that the maximum conversion efficiency can be obtained when the crystalline orientation of the waveguide surface is (001) and the propagating direction is <110>. The output power was estimated as 4.9 mW (lambda = 0.42-mu-m) at the phase matched condition, assuming that the fundamental power is 100 mW and the waveguide length is 5 mm. Second, a ZnS waveguide having an optimized crystalline orientation was fabricated. The SHG in the waveguide was confirmed using YLF laser as a fundamental wave.