Abstract

In the last few years there have been numerous reports of χ⁽³⁾ measurements in polydiacetylenes; the most intensively studied materials are the toluene sulphonate polydiacetylene pTS and the urethane derivative polydiacetylene 4BCMU The time scale on which these measurements have been made ranges from nanoseconds to femtoseconds, and the techniques used have included degenerate four-wave mixing (DFWM),¹ third-harmonic generation,² photoacoustic spectroscopy,³ and pump-probe measurements.^4,5 In the literature there has been some uncertainty concerning the origin of nearresonant and off-resonant nonlinearities in pTS.^1,6

© 1991 Optical Society of America