  We report on efficient generation of second harmonic laser and single-mode
vacuum squeezed light of 795 nm with periodically poled KTiOPO4 (PPKTP)
crystals. We achieved 111 mW of ultra-violet (UV) light at 397.5 nm from 191 mW
of fundamental light with a PPKTP crystal in a doubling cavity, corresponding
to a conversion efficiency of 58.1%. Using the UV light to pump an optical
parametric oscillator with a PPKTP crystal, we realized -5.6 dB of a maximum
squeezing. We analyzed the pump power dependence of the squeezing level and
concluded that the UV light induced losses limit the improvement of the
squeezing level. The generated squeezed light has huge potential application in
quantum memory and ultra-precise measurement.
