7 dB quadrature squeezing at 860 nm with periodically-poled KTiOPO4
  We observed -7.2 dB quadrature squeezing at 860 nm by using a sub-threshold continuous-wave pumped optical parametric oscillator with a periodically-poled KTiOPO4 crystal as a nonlinear optical medium. The squeezing level was measured with the phase of homodyne detection locked at the quadrature. The blue light induced infrared absorption was not observed in the experiment. 
Shigenari Suzuki, Hidehiro Yonezawa, Fumihiko Kannari, Masahide   Sasaki, and Akira Furusawa