A Faraday laser locked to 87Rb D2 line

Abstract

We present a single-frequency Faraday laser utilizing a 5-Torr-Ar-mixed 85Rb atomic filter as a frequency-selecting element, and lock it to 87Rb D2 line via modulation transfer spectroscopy (MTS). The wavelength of the free-running Faraday laser fluctuated between 780.2457 and 780.2470 nm, which was limited within the ultra-narrow transmission bandwidth (700 MHz) of the atomic filter. When the Faraday laser was stabilized to 87Rb 52S1/2 F = 2 → 52P3/2 F′ = 3 hyperfine transition line, the output wavelength of the laser was approximately 780.24602 nm, and the fractional frequency Allan deviation measured by residual error signal arrived at 2.87 × 10−14 at 1 s, then reached 1.25 × 10−14 at 100 s. The laser system is easy to be locked to 87Rb D2 line within the current range of laser diode (LD) from 75 to 140 mA, which has the potential to achieve a “turnkey” systems and is suitable for laser-pumped rubidium atomic clocks and laser-cooling experiments.