optical parametric oscillator (OPO)

@[email protected] similar to a @[email protected], but based on 'non-linear optical gain' from @[email protected] rather than on @[email protected]
  1. The device is a powerful solid-state source of broadly tunable @[email protected] It consists of a crystal, usually BBO (BaB2O4), located inside an optical resonator and pumped by a very intense @[email protected] beam (typically provided by a pulsed @[email protected] or a @[email protected]). The pump beam (@[email protected] \(\lambda_{\text{p}}\) frequency \(\nu_{\text{p}}\)) is partially converted into two coherent beams, the signal and the idler, with wavelengths (\(\lambda_{\text{s}}\), \(\lambda_{\text{l}}\)) and frequencies (\(\nu_{\text{s}}\), \(\nu_{\text{l}}\)) such that \(\nu_{\text{s}} + \nu_{\text{i}} = \nu_{\text{p}}\). By simultaneous rotation of the crystal and adjustment of the optical resonator, the @[email protected] of the signal beam is continuously tunable, theoretically from \(\lambda_{\text{p}}\) to \(2 \times \lambda_{\text{p}}\) and practically over a slightly more reduced range.
  2. For example, for \(\lambda_{\text{p}} = 355\ \text{nm}\) (3rd harmonic of a Nd:YAG @[email protected]), \(\nu_{\text{s}}\) can be tuned from \(400\ \text{nm}\) (with \(\lambda_{\text{i}} \approx  3.15\ \unicode[Times]{x3BC}\text{m}\)) up to \(600\ \text{nm}\) (with \(\lambda_{\text{i}} \approx 870\ \text{nm}\)).
  3. This 'splitting of one photon into two photons' is the reverse of the 'sum frequency mixing' used, for instance, to generate the 3rd harmonic of a @[email protected] emission by mixing in a convenient crystal the fundamental and the frequency doubled beams (a way to get the 3rd harmonic much more efficiently than by pure frequency tripling as described under @[email protected]).
PAC, 2007, 79, 293. (Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)) on page 378 [Terms] [Paper]