Abstract

Coherent anti-Stokes Raman spectroscopy (CARS) is a form of nonlinear-optical spectroscopy that is useful for spectroscopic sensing of high-temperature media. Earlier research¹ evaluated optical parametric oscillator (OPO) devices as an alternative to dye lasers in providing tunable coherent light for this purpose. Further development of the OPO CARS theme follows demonstrations^2,3 of how to control the optical bandwidth and output wavelengths of a pulsed OPO with a passive ring cavity, injection-seeded by a single-mode external-cavity diode laser (ECDL). We have succeeded in injection seeding a single pulsed OPO at two separate optical frequencies that fall within its intrinsically broad optical bandwidth, using a pair of ECDLs. This OPO-based strategy enables single-shot, two-colour multiplex CARS measurements⁴ that can be used for combustion diagnostics, as has previously been demonstrated with dye-laser sources.⁵

© 1996 IEEE