The development of an all-solid-state cw laser system for optical absorption measurements of the OH radical in the UV spectral range is described. The tunable output of a 1064-nm external-cavity diode laser is amplified by use of a Nd:doped, double-clad fiber amplifier. The amplified near-IR radiation is frequency doubled by a periodically poled lithium niobate crystal and then quadrupled in a beta-barium borate crystal. The design and operation of the system and measurements of OH absorption in the (2, 0) band of the A<sup>2</sup>Σ<sup>+</sup>– X<sup>2</sup>Π electronic transition are discussed.
© 2001 Optical Society of America
(140.2020) Lasers and laser optics : Diode lasers
(140.4480) Lasers and laser optics : Optical amplifiers
(190.2620) Nonlinear optics : Harmonic generation and mixing
(280.1740) Remote sensing and sensors : Combustion diagnostics
Gustavo J. Ray, Thomas N. Anderson, Jerald A. Caton, Robert P. Lucht, and Thomas Walther, "OH sensor based on ultraviolet, continuous-wave absorption spectroscopy utilizing a frequency-quadrupled, fiber-amplified external-cavity diode laser," Opt. Lett. 26, 1870-1872 (2001)