Intensity interference of ultrashort pulsed fluorescence

We extend the intensity interference experiments to a pulse envelope measurement of ultrashort incoherent optical pulses. The interfering fields can be mutually incoherent light pulses from independent sources. We show that the pulse envelope or width of ultrashort incoherent light pulses can be measured independently from the coherence time by using a combination of interferometer and two-photon coincidence counter. With this method we have measured the envelope autocorrelation of mutually incoherent femtosecond fluorescence from a solution of Nile Blue in dimethylaniline.