Two-photon absorption in a commercial InGaAsP 1.3 mu m Fabry-Perot laser diode has been used for autocorrelation measurements of picosecond pulses at 1.5 mu m with average power peak-power products as low as 0.15 x 10(-3) (mW)(2). The laser diode has also been observed to possess a sub-nanosecond electrical response suitable for optical thresholding applications.