Optical homodyne for pulsed lasers

A homodyne method is presented for determining the degree of coherence of laser pulses. The method was first tested using computer generated data with varying amounts of noise to test the accuracy of the method in the determination of the phase drift programmed into the pulses. Analysis of the computer generated data also revealed the degree of sensitivity to timing jitter between the laser pulses. In order to eliminate the timing jitter, all analysis was completed on individual laser pulses. This was done by splitting the laser pulse into four beams with two traversing a variable path length to introduce a delay. A delayed pulse was overlapped with a pulse without delay and directed onto the entrance slit of a streak camera. The other two pulses were also directed to the streak camera at locations separate from each other and the two overlapping pulses. Results are presented for a single-longitudinal-mode nanosecond laser and the frequency-doubled output from a Nd:YAG amplified picosecond Nd:YVO$_4$ mode-locked oscillator.