An optical divide-by-3 system has been developed to phase lock a diode-pumped Tm:YAG laser at 148 THz (2022 nm) to a frequency near 1/3 that of an ultrastable diode laser system at 445 THz (674 nm). The 148-THz radiation is frequency doubled in angle-tuned AgGaS<sub>2</sub> and frequency differenced with the 445-THz radiation in noncritically phase-matched LiNbO<sub>3</sub> , generating two signals at 297 THz, which are mixed on a photodiode. An electronic servo system is used to control the frequency of the Tm:YAG laser and to phase lock it to the visible diode laser output. Phase-locking periods of several minutes are routinely obtained.
© 1999 Optical Society of America
(140.3480) Lasers and laser optics : Lasers, diode-pumped
(190.2620) Nonlinear optics : Harmonic generation and mixing
(300.6520) Spectroscopy : Spectroscopy, trapped ion
(350.4800) Other areas of optics : Optical standards and testing
J. E. Bernard, B. G. Whitford, and L. Marmet, "Phase-locked optical divide-by-3 system for visible radiation," Opt. Lett. 24, 98-100 (1999)