Optimizing non-resonant frequency conversion in periodically poled media

Non-resonant frequency conversion into the blue, green, orange, and red spectral regions is reported. Fundamental light sources were continuous-wave non-planar monolithic single-mode ring Nd : YAG lasers as well as a standing-wave multi-mode Nd : YAG laser. Periodically poled KTiOPO4 was employed as the nonlinear medium, but the considerations could also be applied to other periodically poled materials. A multi-pass scheme resulted in a normalized conversion efficiency as high as 27.2 % W-1 for frequency doubling in the small-signal regime at 1064 nm.