Abstract

We describe a new compact acousto-optically Q-switched diode-pumped solid-state (DPSS) intracavity frequency-tripled neodymium-doped yttrium vanadate laser capable of producing ~100 mW of 213 nm power quasi-continuous wave as 15 ns pulses at a 30 kHz repetition rate. We use this new laser in a prototype of a deep ultraviolet (UV) Raman standoff spectrometer. We use a novel high-throughput, high-resolution Echelle Raman spectrograph. We measure the deep UV resonance Raman (UVRR) spectra of solid and solution sodium nitrate (NaNO₃) and ammonium nitrate (NH₄NO₃) at a standoff distance of ~2.2 m. For this 2.2 m standoff distance and a 1 min spectral accumulation time, where we only monitor the symmetric stretching band, we find a solid state NaNO₃ detection limit of ~100 μg/cm². We easily detect ~20 μM nitrate water solutions in 1 cm path length cells. As expected, the aqueous solutions UVRR spectra of NaNO₃ and NH₄NO₃ are similar, showing selective resonance enhancement of the nitrate (NO₃⁻) vibrations. The aqueous solution photochemistry is also similar, showing facile conversion of NO₃⁻ to nitrite (NO₂⁻). In contrast, the observed UVRR spectra of NaNO₃ and NH₄NO₃ powders significantly differ, because their solid-state photochemistries differ. Whereas solid NaNO₃ photoconverts with a very low quantum yield to NaNO₂, the NH₄NO₃ degrades with an apparent quantum yield of ~0.2 to gaseous species.

Scalable approach for continuous-wave deep-ultraviolet laser at 213nm

Yushi Kaneda, Tsuyoshi Tago, Toshiaki Sasa, Masahiro Sasaura, Hiroaki Nakao, Junji Hirohashi, and Yasunori Furukawa
Opt. Express 27(6) 8021-8026 (2019)

750 mW continuous-wave solid-state deep ultraviolet laser source at the 253.7 nm transition in mercury

Martin Scheid, Frank Markert, Jochen Walz, Jiayu Wang, Martin Kirchner, and Theodor W. Hänsch
Opt. Lett. 32(8) 955-957 (2007)

Solid-state Raman laser generating discretely tunable ultraviolet between 266 and 320 nm

Richard P. Mildren, Hamish Ogilvy, and James A. Piper
Opt. Lett. 32(7) 814-816 (2007)

Solid-state tunable deep-ultraviolet laser system from 198 to 300 nm

T. Meguro, T. Caughey, L. Wolf, and Y. Aoyagi
Opt. Lett. 19(2) 102-104 (1994)

20 W, 2 mJ, sub-ps, 258 nm all-solid-state deep-ultraviolet laser with up to 3 GW peak power

Kun Liu, Hao Li, Shizhen Qu, Houkun Liang, Qi Jie Wang, and Ying Zhang
Opt. Express 28(12) 18360-18367 (2020)