Optical Parametric Oscillator, a resonator around a second-order nonlinear crystal in which each pump photon splits into a signal and an idler photon whose energies add up to the pump's. Changing crystal angle, temperature or poling period tunes the output across wide ranges, especially into the mid-infrared. Like a laser it has a threshold, but its output wavelengths are set by phase matching rather than by an atomic transition.
Idler out of the OPO is at 3.4 microns now, just tweak the PPLN temperature to sit on the methane line.
Also heard as
- optical parametric oscillator
Related terms
Quasi-phase matching
Phase matching by periodically flipping a crystal's nonlinear orientation instead of relying on birefringence.
Phase matching
Keeping interacting waves in a nonlinear crystal in step so the generated light builds up instead of canceling.
SHG
Second Harmonic Generation: converting light to exactly double its frequency, half its wavelength, in a nonlinear crystal.
Lasing threshold
The pump level at which gain exactly balances resonator losses and laser output begins.