Description: Deep-ultraviolet (DUV) Raman spectroscopy is a powerful method to isolate and extract the unique signatures of numerous chemical bonds present within complex samples. DUV (λ < 250 nm) excitation is critical for NASA missions because it shows an over 200-fold greater efficiency compared to commonly used 785 nm excitation and illumination as such short wavelengths minimizes the fluorescence background in the Raman spectra. The unavailability of compact, robust, and reliable deep-UV laser sources has constrained implementing DUV Raman spectroscopy in NASA's space-borne exploration and research. TIPD proposes to develop an ultrastable, compact, and robust DUV laser source for Raman spectroscopy based on our demonstrated capability in developing single-frequency fiber lasers and solid-state DUV laser sources. Cooperating with the University of Arizona, TIPD developed an ultrastable and compact single-frequency linearly polarized fiber laser system operating at 976 nm during the Phase I program. The team also developed a single-frequency fiber amplifier at 976 nm and single-pass frequency doubling of 976 nm light to demonstrate the viability of the compact design. Separately, the team has designed and delivered a 150 mW DUV laser for Raman spectroscopy operating at 244 nm using a BBO crystal and a resonant bow-tie cavity based upon a 976 nm VECSEL source. In phase II, the team will scale the power of the 976 nm fiber amplifier to achieve a 5-watt single-frequency output. The 5-watt single-frequency 976nm master oscillator power amplifier (MOPA) will act as the pump to build a 100-mW deep-UV laser prototype that will be delivered to NASA.

Benefits: Deep-UV Raman spectroscopy is a powerful tool to identify a variety of gas, liquid, and solid materials critical to understanding the evolution of the solar system and the universe. Compact and ultrastable DUV laser sources can be used for analysis of geological and mineralogical planetary composition, planetary habitability assessment, and for the search of past life on Mars, and for human protection in space.

Deep UV sources can be broadly used for Raman spectroscopy, laser cooling and trapping, laser inspection, optical data storage, metrology, biomedical applications, and laser lithography. The ultra-stable, high power, narrow-linewidth 976nm laser has applications beyond this program including laser sources for nonlinear wavelength conversion, and as a low noise laser pumps for a variety of lasers at 1 ??m and 1.5 ??m. The 488 nm blue laser, which is part of 244 nm system, has potential applications in submarine imaging, sensing, communications, data storage, undersea oil exploration, full color displays, and medicine.