Optical Parametric Oscillators
Optical parametric oscillators (OPOs) use parametric amplification in nonlinear crystals to produce optical gain. The output of an OPO can be varied over wide spectral ranges. The device consists of an optical resonator and a nonlinear optical crystal. OPOs use a nonlinear response of a medium to a driving field to convert photons of one wavelength to photons of longer wavelengths.
Image Credit: Olympusmicro
The bandwidth is determined by the bandwidth acceptance of the nonlinear crystal. Basic designs usually exhibits relatively broad bandwidth of about 15 cm-1. Introducing frequency selective elements into the cavity helps reduce bandwidth.
Optical parametric oscillators can be used in several applications including spectroscopy to cover very wide spectral regions, military applications including the generation of broadband high-power light for blinding heat-seeking missiles, and in digital projection displays.