Abstract

The field localization associated with planar integrated optics makes a thin film an ideal medium for performing nonlinear optics phenomena with moderate total powers. To date, primarily second order processes^1–3 have been demonstrated. Coherent Anti-Stokes Raman Scattering, i.e. CARS (CSRS) is a third order process in which two photons at ω₁ combine with one photon at ω₂ (or vice-versa) to produce a photon at the frequency ω₃=2ω₁−ω₂ (or ω₃=2ω₂−ω₁). The resulting signal is enhanced when ω₁−ω₂ coincides with a vibrational Raman transition in the molecules which make up the medium and hence sweeping the difference frequency yields the Raman spectrum of the medium. This process promises sensitivities orders of magnitude larger than for spontaneous Raman scattering which has already been observed in thin film waveguides⁴.

© 1984 Optical Society of America