Linear and nonlinear waveguiding in rhodamine-doped epoxy films

Received October 23, 1990; revised manuscript received February 25, 1991 Planar waveguiding of 350-ps pulses, at a wavelength in the region of the long-wavelength tail of the absorption, is observed by coupling by prism into spun films of Rhodamine-B-doped epoxy films. In µ 13-grm-thick film=20 modes are supported at 633 nm. The angleof optimum coupling is seen to be intensity dependent; the angle increases with increasing intensity, indicating a positive real component of the material nonlinearity at all wavelengths investigated. The throughput of the guide is also seen to be strongly intensity dependent, indicating a strong intensity dependence of the transmission of the film.The observed behavior is compared with the intensity dependence of the unguided transmission, and the intensity-coupling efficienciesare estimated. As we know the coupling efficiency, we estimate the real component of the nonlinearity to’ be7.0 ± 0.5 × 10⁻²⁰ m2 V⁻² at 616 nm and 5.0 ± 0.5 × 10⁻²⁰ m2 V⁻² at 635 nm from the intensity dependence of the coupling angle.