Simultaneous sampling of optical pulse intensities and wavelengths by four-wave mixing in a semiconductor optical amplifier

An all-optical sampling technique that allows the simultaneous measurement of optical pulse intensities and wavelengths with a temporal resolution of about 1 ps is introduced. Using four-wave mixing (FWM) in a semiconductor o ptical amplifier, the optical signal under test is cross correlated with ne arly transform-limited 1.4 ps optical sampling pulses. While the intensity of the generated FWM signal is used to determine the temporal shape of the signal intensity, the wavelength of the FWM signal yields time-resolved inf ormation about the signal wavelength (i.e., the frequency chirp). Using thi s technique, the correlation of intensity and wavelength dynamics of pulses generated by a self-Q-switched distributed-feedback laser is determined di rectly. (C) 1998 American Institute of Physics. [S0003-6951(98)03752-8].