Narrow-linewidth external-cavity diode laser with dual narrow-band interference filters

External-cavity diode lasers (ECDL) are widely used as light sources in laser spectroscopy, atomic physics and quantum optics. This paper presents 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 about 0.5 nm for 780 to 895 nm. We design different narrow-band IFs combinations to achieve narrower FWHM, and apply them in ECDL. The combination of dual narrow-band IFs further reduces the laser linewidth. In our experiments, we measured laser linewidth using a high-finesse Fabry-Perot cavity with the cavity linewidth of about 10 kHz. The laser linewidth is about 176 kHz for the Single-IF-ECDL and about 96 kHz for Dual-IF-ECDL with the same feedback. In addition, we have experimentally verified the results of narrower laser linewidth and larger tuning range as feedback increases. The developed Dual-IF-ECDL has the capability of the narrow linewidth and wavelength tunability, and can be applied to precision spectroscopy and cooling and trapping of neutral atoms.
Comment: 15 pages, 13 figures