Design of a MHz Repetition Rate Pulse Burst Laser System at Auburn University

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st change is that the pulse slicing is achieved using an acousto-optic modulator (AOM) rather than a pair of electro-optic Pockels cells. The AOM is less expensive (by ~90%) and is able to produce flexible bursts of pulses with variable pulse durations (as short as 10 nsec) at repetition rates ranging from DC to greater than 5 MHz. The energy of the pulses prior to amplification is estimated to be from 0.5 to 3.3 nJ for 10 to 50 nsec long pulses, respectively. The contrast ratio of the pulses produced by the AOM is ~800:1 before spatial filtering and ~15,000:1 after spatial filtering. The 2 nd major change in the design of the laser system is the temporal shape of the gain curve created by the power amplifier chain. The design of the flashlamp controller has been specified to produce approximately uniform gain over a 1 msec long period of time. This is contrast to previous designs, which had 100-200 μsec long gain curves with Gaussian shaped profiles. Preliminary measurements show that the total gain for the amplifier chain is approximately 10 7 resulting in individual pulse energies on the order of 10 mJ/pulse. This level of gain is expected to drop by only 10% over the 1 msec duration of gain envelope.