Degenerate four-wave mixing using wave pump beams near the critical angle: two distinct behaviors

Picosecond degenerate four-wave mixing in a planar quasi-waveguide made of poly(vinyl alcohol) film doped with rhodamine 6G dye is reported. The four-wave mixing geometry consists of a probe beam incident from above a prism-film structure which is pumped by two oppositely propagating quasi-guided or evanescent waves. Such fourwave mixing signals are obtained both in reflection and in transmission. It is shown that the reflected signal can be optimized by varying both the pump and the probe angles. With this configuration four-wave mixing reflectivities of nearly 0.1 percent were obtained.