20 W CW 589 nm sodium beacon excitation source for adaptive optical telescope applications

Abstract Operation of a doubly resonant sum-frequency generation (SFG) ring containing a lithium triborate (LBO) crystal has been demonstrated. It is pumped by 1.064 and 1.319 μm Nd:YAG injection-locked ring lasers and produces a 20 W, diffraction-limited, single-frequency, continuous wave, 589 nm beam. Nearly 60% conversion of pump laser power is obtained. Such a device produced a guidestar in the mesospheric sodium layer that can provide improved sky coverage for adaptive optical telescope applications. “First light” on the sky for the laser source was 21 November 2002 at the Starfire Optical Range, Kirtland AFB, New Mexico.