Title of Presentation: Recent Progress Made in the Development of High-Energy UV Transmitter

Primary (Corresponding) Author: Narasimha S. Prasad

Organization of Primary Author: NASA Langley Research Center

Co-Authors: Darrell J. Armstrong and Upendra N. Singh


Abstract: We are developing a high-energy Nd:YAG laser pumped nonlinear optics based UV converter that will be suitable for sensing of atmospheric ozone.  In this paper, recently obtained results of the effect of pump beam quality on the UV converter performance are discussed. The Nd:YAG pump laser is an all-solid-state, single longitudinal mode, and conductively cooled unit operating at 1064 nm wavelength. Currently, this pump laser provides an output pulse energy of >1J/pulse at 50 Hz PRF and a pulsewidth with of 22 ns.  Electrical-to-optical system efficiency of greater than 7% and a M2 value of ~2 have been achieved.  The spatial profile of the output beam is a rectangular super Gaussian. This Nd:YAG pump laser Has been developed to pump the nonlinear optics based UV converter arrangement to generate 320 nm and 308 nm wavelengths by means of 532 nm wavelength.  The 532 nm wavelength is obtained from the 1064 nm wavelength using a KTA crystal via second harmonic generation process.  The nonlinear optics arrangement consists of a novel optical parametric oscillator (OPO), known as Rotated Image Singly Resonant Twisted Rectangle (RISTRA) module and a sum frequency generation unit. The RISTRA configuration has demonstrated to provide enhanced output beam quality.  So far, the RISTRA OPO has demonstrated greater than 85% pump depletion and 24% IR to UV optical conversion efficiency with stable mode quality.  This high energy low repetition rate UV transmitter is being developed for atmospheric ozone profiling using differential absorption lidar (DIAL) technique suitable for space-based platforms.