Polarization-insensitive nonlinear-optical devices

Zincblende semiconductors, such as GaAs, GaP and others, show great potential for quasi-phase-matched nonlinear optical frequency conversion. In addition to broad infrared transparency and high nonlinear coefficient of zincblende materials, the symmetry of their nonlinear optical tensor allows operating nonlinear-optical devices with the following unusual features: second harmonic generators which are not sensitive to the direction of linear polarization, optical parametric oscillators which can be pumped by circular and even random polarization, and optical parametric amplifiers of randomly-polarized radiation.