A pulse width measurement system based on the second harmonic generation method is implemented for ultrashort semiconductor laser pulses. Second harmonics of GaAs diode laser pulses (about 100 ps pulse width) are generated by a Lithium Iodate single crystal, and the pulse width is estimated from their autocorrelation trace. The same GaAs laser pulse train is also measured by a high speed GaAs PIN photodiode (rise time 50 ps) and a sampling oscilloscope (resolution 25 ps) to compare with the estimated pulse widths.
