A Voigt laser operating on $^{87}$Rb 780 nm transition

TL;DR

This paper introduces a Voigt laser operating at 780 nm for $^{87}$Rb, demonstrating improved stability, immunity to current fluctuations, and tunability, suitable for compact optical standards in precise measurements.

Contribution

The paper presents a novel Voigt laser design using a Voigt anomalous dispersion optical filter, offering enhanced stability and tunability over traditional Faraday-based lasers.

Findings

Achieves frequency stability of 5×10⁻⁹ at 200 s

Maintains wavelength fluctuation within ±0.1 pm over 8 hours

Exhibits greater immunity to diode current fluctuations

Abstract

We report the development of laser systems -- a "Voigt laser" -- using a Voigt anomalous dispersion optical filter as the frequency-selective element, working at the wavelength of 780 nm of $^{87}$Rb-D2 resonance line. Compared with Faraday anomalous dispersion optical filter, the Voigt anomalous dispersion optical filter can generate a stronger and more uniform magnetic field with a compact size of magnet, and obtains a transmission spectrum with narrower linewidth and more stable lineprofile. In this case, the frequency stability of the Voigt laser reaches 5$\times$10$^{-9}$ at the averaging time of 200 s, and the wavelength fluctuation of 8-hours free operation is $\pm$0.1 pm. Besides, the Voigt laser has greater immunity to diode current than the Faraday laser, with a wavelength fluctuation of $\pm$0.5 pm in the current range from 73 mA to 150 mA. Finally, the Voigt laser frequency can be controlled by the cell temperature of the Voigt optical filter, which is expected to achieve a frequency detuning of 20 GHz. Consequently, the Voigt laser, whose frequency could correspond to the atomic transition frequency by tuning the cell temperature, obtains good robustness to the current and temperature fluctuation of laser diode, and could realize a compact optical standard for precise measurement once stabilized by modulation transfer spectroscopy.