Picosecond all-optical switching in a Fabry–Perot cavity containing polydiacetylene

Abstract

Off-resonant nonlinear optical measurements have been made in a Fabry–Perot cavity containing a polydiacetylene (PTS) single crystal. The cavity length was controlled to select specific bias points on the Fabry-Perot fringe and the measurements were made by a pump-probe technique using 90 ps pulses at 1.06 μm wavelength. The changes in transmission at selected bias points were measured as a function of time delay between the pump and the probe. The measured response time was found to be pulse-width limited and the maximum changes in transmission were as large as 50% at low optical intensities (∼10 MW/cm2). The sign of n2 was determined from the direction of the fringe shift and was found to be negative. All-optical switching (82 MHz) at a picosecond time scale is demonstrated for an organic material.