Nonlinear optical processes in a polydiacetylene measured with femtosecond duration laser pulses

The temporal response of the third‐order nonlinear optical susceptibility in poly bis( p‐toluene sulfonate) of 2,4‐hexadiyne‐1,6 diol was determined by time‐resolved degenerate four‐wave mixing using tunable dye laser pulses with 300 fs duration. In the material’s absorption region these experiments were combined with saturated absorption techniques yielding a measurement for the excited state lifetime of 1.8 ps. Off resonance the nonlinear response was determined to be optical pulse width limited.