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

The primary objective of the proposed Phase I effort is to develop and demonstrate a low-average power, pulsed, single-frequency, 2-um Ho-laser source for application as a front end in coherent LIDAR systems. Development of such pulsed seed sources is critical for the design of compact, rugged, reliable and efficient LIDAR transmitters based on all-amplifier architecture. Pulsed operation of the Ho-oscillator is achieved via passive Q-switching using robust Cr2+-doped saturable absorbers. Such seed oscillators allow generation of ns-width pulse trains at kHz repetition rates. Direct diode-pumping using the latest 1.9-um diode laser technology provides improved oscillator reliability and compactness. 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.