Abstract

Since the first measurements of large nonlinear optical coefficients in -π-electron conjugated systems, such materials have been studied for all-optical applications.' Single crystal PTS seems to offer a very large n₂.² Often, however, associated with a large n₂, is strong two photon absorption, which can limit a material’s usefulness for all-optical devices. We report the first picosecond pulse, tunable, multi-photon absorption coefficient and nonlinear refraction measurements on single crystal samples of PTS. The complete spectra yield the two photon resonances obtained from near-resonant to off-resonant conditions. The resonant structure, in turn, reveals the locations of the two-photon states and unveils spectral regions where the two-photon figure of merit, T, may he suitable for all-optical switching.

© 1994 Optical Society of America