Pulsed, Single-Frequency, 2-um Seed Source for Coherent LIDAR Applications

The primary objective of the proposed Phase II effort is to develop and deliver a ruggedized, single-frequency, mJ-level, 2050-nm master oscillator?power amplifier system suitable for coherent LIDAR applications. The laser system is based on a low-average power, pulsed, single-frequency, 2-um Ho-laser source. Pulsed operation of the Ho-oscillator is achieved via passive Q-switching using robust Cr2+-doped saturable absorbers. Development of such pulsed seed sources enables the design of compact, rugged, reliable and efficient LIDAR transmitters based on all-amplifier architecture.Direct diode-pumping using the latest 1.9-um diode laser technology provides improved oscillator reliability and compactness. Efficient, Tm:fiber laser pumped, bulk Ho:YLF single-stage amplifier provides energy scaling to mJ level. The choice of a 2-um Ho-laser material (as opposed to 1.5-um Er-lasers) enables efficient power/energy scaling of the pulsed seed oscillator output in high-gain Ho-amplifiers. This approach decreases the number of amplifying stages, simplifies the overall design and packaging, and improves the electrical efficiency of the complete laser system as compared to the current technology.