UV Solid-State Laser for Proliferation Detection

Compact laser systems are needed to interrogate possible sites of nuclear proliferation that, for strategic or political reasons, cannot be sampled and inspected directly. This laser system would be used with a nonlinear optical wavelength converter for remote spectroscopic analysis of effluents from suspected sites. This project will develop an advanced laser system that will be compact, lightweight, efficient, and suitable for deployment on a UAV. The laser system will be based on Yb:S-FAP, a relatively novel laser material with an upper state lifetime more than five times longer than Nd:YAG. For this particular application, the increased lifetime translates into a fivefold reduction in the number of pump diodes, leading to a more cost-effective and compact laser system. In Phase I, a full-scale, diode-pumped, Yb:S-FAP gain module was designed, fabricated, and tested. The module provided an output over 400 mJ in long-pulse quasi-cw operation as an oscillator, and a single-pass small signal gain of Go = 7.6 (gol = 2 nepers) in an amplifier configuration. A detailed analysis, along with the experimental results, showed that the approach was likely to meet the 200 mJ/pulse energy requirement. In Phase II, Yb:S-FAP slabs will be procured, and the system will be built and tested. Finally, the laser system will be configured into a rugged package suitable for airborne deployment. Commercial Applications and other Benefits as described by the awardee: Diode pumped solid-state lasers are used extensively in materials processing and other high value commercial applications. However, to date, these lasers have not achieved significant market penetration in high pulse energy (> 100 mJ) laser markets currently dominated by excimer and lamp pumped solid-state lasers. Despite their significant advantages, the use of diode pumped solid state lasers has been limited by the high cost of the diode laser pump sources. By using Yb:S-FAP, the diode cost (the main cost driver in high pulse energy systems) should be reduced by a factor of 4 to 5, compared with an Nd:YAG laser, resulting in a cost-effective solution for a wide range of commercial applications.