Dual-pulse pump laser for trace gas detection

A high-energy, dual-pulse, injection seeded pump laser operating at 1064 nm is an enabling technology for several airborne and space-based trace gas lidar systems. In a NASA SBIR funded Phase I effort we performed proof of principle testing of an approach to building such a laser. During Phase I, we successfully demonstrated the following key technical objectives. 1. Operation of a single-frequency oscillator that achieved high beam quality, 30 mJ dual-pulse output at 50 Hz. The 30 mJ pulse pairs had an M2 of 1.5 and a pulse spacing of 100 μs. Our current approach to dual pulse operation allows pulse spacings in increments of 100 μs. Future implementations will increase the flexibility of the pulse spacings. 2. Efficient amplification of the dual-pulse oscillator output with existing in-house amplifiers to 120 mJ each while still maintaining an M2 of 1.9. 3. Further amplification of the output with a traditional on-axis Brewster angle slab to 280 mJ/pulse with an optical-to-optical efficiency of 18%. We anticipate achieving >20% efficiency in the future by incorporating an updated off-axis amplifier design. In the next development phase, our goal is to mature the technology and demonstrate a path to a space-qualifiable, injection-seeded laser system capable of producing two closely spaced (~100-200 μs), 600 mJ pulses at 50 Hz.