The frequency stability of a 1560-nm diode laser, whose second harmonic was locked to <sup>87</sup>Rb sub-Doppler lines, was characterized by measuring the beat frequency relative to a 780-nm reference laser that was locked to sub-Doppler lines of another rubidium cell. The square root of the Allan variance reached a minimum value of 7.5 × 10<sup>−12</sup> in 1 s, which corresponded to frequency variations of 1.44 kHz for the 1560-nm laser. The frequency reproducibility of the system was ≈1 × 10<sup>−9</sup>. These values are better than those that can be achieved by locking to Doppler-broadened transitions at the 1550-nm wavelength band.
© 1998 Optical Society of America
(060.2330) Fiber optics and optical communications : Fiber optics communications
(130.4310) Integrated optics : Nonlinear
(140.0140) Lasers and laser optics : Lasers and laser optics
(300.6460) Spectroscopy : Spectroscopy, saturation
Ariel Bruner, Vered Mahal, Irena Kiryuschev, Ady Arie, Mark A. Arbore, and Martin M. Fejer, "Frequency Stability at the Kilohertz Level of a Rubidium-Locked Diode Laser at 192.114 THz," Appl. Opt. 37, 6410-6414 (1998)