Interference filter based external-cavity diode laser with combined dual interference filters and largely adjustable feedback range

TL;DR

This paper presents a homemade 852-nm external-cavity diode laser using combined dual interference filters to achieve narrower linewidth and larger tuning range, suitable for precision spectroscopy and atomic physics applications.

Contribution

The study introduces a novel dual interference filter combination in an external-cavity diode laser to significantly reduce linewidth and enhance tunability.

Findings

Laser linewidth reduced from 176 kHz to 96 kHz with dual filters.

Narrower linewidth achieved using combined interference filters.

Increased feedback range improves wavelength tunability.

Abstract

External-cavity diode lasers (ECDL) are widely used as light sources in laser spectroscopy, atomic physics, and quantum optics. This study demonstrated a home-made 852-nm ECDL with variable feedback, using the combined dual narrow-band interference filters (IFs) as the laser longitudinal mode selection element. The combination of narrow-band IFs, mainly for the current commercially available narrow-band IFs with the full width at half maximum (FWHM) of approximately 0.5 nm for 780-895 nm. We designed different narrow-band IFs combinations to achieve a narrower FWHM, and applied them in the ECDL. The combination of the dual narrow-band IFs further reduces the laser linewidth. We measured the laser linewidth using a high-finesse Fabry-Perot cavity with a linewidth of approximately 10 kHz. The laser linewidth is approximately 176 kHz for the Single-IF-ECDL and 96 kHz for the Dual-IF-ECDL with the same feedback. In addition, we have experimentally verified the results of narrower laser linewidth and larger tuning range with increase in the feedback. The developed Dual-IF-ECDL has the capability of narrow linewidth and wavelength tunability and can be applied to precision spectroscopy, cooling and trapping of neutral atoms.