Title: Lifetime Testing of a 355 nm, Space-Qualifiable Laser
Presenting Author: Floyd E. Hovis
Organization: Fibertek, Inc.
Co-Author(s): Fran Fitzpatrick, Joe Rudd, Michael Albert, Kent Puffenburger, Tom Schum, Slava Litvinovitch, Darrell Jones

Abstract:
A long-lived UV laser is an enabling technology for a number of high-priority, space-based lidar instruments. These include a next generation cloud and aerosol lidar that incorporates a UV channel, a direct detection 3-D wind lidar, and an ozone DIAL system. We have designed and built a TRL 6 demonstrator that has increased output power and space-qualifiable packaging that is mechanically robust, thermally-stable, and fully conductively cooled. Contamination control processes and optical coatings have been chosen that are compatible with multi-billion shot lifetimes. The diode pumped laser contains an essentially polymer free internal module that houses the third harmonic generator and expansion optics. When operated at 150 Hz the laser has demonstrated 275 mJ per pulse at 1064 nm, second harmonic conversion efficiencies of 70%, and third harmonic conversion efficiencies of 45%, thus meeting the 355 nm 100 mJ/pulse goal with margin. At this time we have successfully completed a full power 532 nm life test and a half power (50 mJ/pulse) UV lifetest. A full power (100 mJ/pulse @ 150 Hz) has been initiated and after 30 days (~400 million shots) there is no sign of optical degradation. Once the 4 month full power lifetest is complete, vibration and TVAC testing will be performed to demonstrate that the laser design is at TRL 6.