TROPICS with feedback

Summary form only given. In 1995, Y.J. Ding et al. proposed a novel optical parametric geometry which has since been assigned the acronym TROPICS: TRansverse Optical Parametric Infrared Conversion Structure. Other work has considered the large-signal regime, and examined the effects of a pump beam with a Gaussian profile, rather than a plane wave excitation. That investigation modeled the Gaussian pump beam as a sum of plane waves, each of which interacted with the generated signal and idler beams to provide the total output. Such an analysis is necessary in this configuration, because the generated beams traverse the pump beam wavefront. Of concern was the discovery that the multiple plane waves, some of which were not exactly resonant with the phasematched interaction, inhibited operation of the system as a true optical parametric oscillator. There was no physically realizable conversion of the pump beam without the insertion of at least some seed power at one of the generated wavelengths. This new work shows that the addition of facet mirrors to provide feedback at the generated wavelengths removes that restriction.