  We investigate the generation of ultraviolet (UV) second-harmonic radiation
on the boundary of a UV transparent crystal, which is derived from the
automatic partial phase matching of the incident wave and the total internal
reflection. By adhering to another UV non-transparency crystal with larger
second-order nonlinear coefficient \chi^{(2)}, an nonlinear interface with
large disparity in \chi^{(2)} is formed and the enhancement of UV
second-harmonic radiation is observed experimentally. The intensity of enhanced
second harmonic wave generated at the nonlinear interface was up to 11.6 times
at the crystal boundary. As a tunable phase-matching method, it may suggest
potential applications in the UV, even vacuum-UV, spectral region.
