Composite-cavity ring laser for missile defense coherent LADAR

The Q-Peak Division of Physical Sciences Inc. proposes to develop an innovative composite-cavity ring laser that will improve significantly on the performance of non-planar ring oscillators (NPRO), without requiring an amplifier, and which is amenable to space qualification or other high-reliability applications through its multiply-redundant pumping scheme. Our open design with individual optical components has several advantages over the monolithic NPRO, starting with robust unidirectional oscillation due to its TGG/crystal quartz optical diode, enabling high-power operation (multi-Watts)and operation with Nd:YVO4 or YLF (both birefringent materials not amenable to out-of-plane designs); low pump-induced frequency noise because the laser crystal makes up a small fraction of the total cavity length (further enhanced by using YLF); and excellent passive thermal stability due to making the resonator from low-expansion materials, further enhanced with re-entrant mirror mounting. In addition, the laser can be frequency tuned or modulated in a variety of ways, over a wide range of bandwidths and total frequency excursions. In Phase I we will compare the performance of two laser hosts in a partially-ruggedized version of our ring-laser design and develop and demonstrate several frequency-tuning approaches. The designs will be suitable for construction and delivery under a potential follow-on effort.