Abstract

Current techniques for the measurement of femtosecond laser pulses require an optical nonlinearity with a femtosecond response time. Common examples are a second harmonic generating crystal or a material with a Kerr nonlinearity. However, a need exists for measurement techniques for applications involving weak pulses and/or pulses in spectral regions where appropriate nonlinear crystals are not available (i.e. ultraviolet). Semiconductor detectors holds the promise of good sensitivity over a very broad bandwidth, but unfortunately, the fastest response times are still in the picosecond domain. Nonetheless, creative combinations of linear optics and fast electronic detection can be used to characterize optical fields on a femtosecond time scale. Our measurements employ a GaAs Schottky photodiode monolithically integrated with a microwave detector [1] to perform cross-correlations between the pulse to be measured and spectrally filtered slices of the same pulse [2]. To our knowledge, this is the first direct measurement of the amplitude and phase of a femtosecond pulse employing only an integrated opto-electronic circuit. Although demonstrated here for the meausrment of pulses from a standard Ti:sapphire laser, we believe this technique should also enable the complete characterization of ultraviolet pulses. In addition, we are studying various “single-shot” implementations.

© 1996 Optical Society of America