Abstract

The strong enhancement of optical electromagnetic fields inside microcavities based on laser or nonlinear optical (NLO) materials opens promising perspectives in terms of reduction or even cancellation of laser threshold or demonstration of highly efficient frequency conversion in very thin nonlinear samples. We report here on the elaboration and optical characterization of Fabry-Perot (FP) type microcavities made of 4-Nitrophenyl-L-prolinol (NPP) crystal, and experimentally evidence cavity-enhanced second harmonic generation (SHG) around 1.15 µm. The FP cavity is made of a NPP crystalline layer (thickness 11 µm) sandwiched between two dielectric mirrors (maximal reflectivity R = 95% centered at 1.15 µm). After capillary filling, the polycrystalline sample is placed inside a furnace with a transparent window allowing for microscope observation of the corresponding area, which creates a «cold » zone where recrystallization may be seeded. Large single crystalline domains (5×2mm²) are obtained at the outcome of the cooling process.

© 1998 IEEE