Arbitrary Pulse Pattern Seed Laser and Amplifier (Topic 25c)

Pulsed fiber lasers are widely used in machining and material processing applications. Having control of the pulse width, pulse energy, and repetition rate allows flexibility in processing operations. This technology can be adapted for use in DoE facilities for applications such as high reliability, variable pulse-pattern, high-repetition-rate, intense near-IR lasers for neutralizing, notching, tailoring, and diagnosing H-minus beams. However, pulsed fiber lasers are peak power limited and can produce pulse energies of ~1 mJ. This SBIR will address these limitations by using a pulse and repetition rate agnostic fiber laser as a seed for a solid-state amplifier. The problem of creating a high reliability, flexible pulsed waveform laser source will be solved by a hybrid fiber/solid-state laser system. A continuous wave diode laser seed source will be modulated with an electro-optic modulator locked to an appropriate external clock to provide the desired pulse format. A fiber amplifier will be constructed to provide high small-signal gain of the modulated seed source. The final stage of amplification will be accomplished using bulk solid-state laser amplifiers to provide the desired pulse energy or average power. The Phase I program will model the performance of the hybrid amplifier with particular attention to nonlinear effects such as self-focusing, self-phase modulation, and stimulated Raman scattering. A seed source and high gain fiber amplifier will be constructed to benchmark its performance. The laser designed, constructed, and productized in this SBIR program would have application to precision machining applications where pulse flexibility is desirable for complex shapes. It would also have application to adaptive laser radar systems where pulse rates and pulse width flexibility offers advantages in ranging to moving targets.