Cover slip external cavity diode laser

TL;DR

This paper presents a simple, economical, and robust external cavity diode laser design at 671 nm with a 40 GHz tuning range, fixed output pointing, and a linewidth under 30 MHz, suitable for spectroscopy.

Contribution

It introduces a novel cover slip external cavity design with feedforward current control for wide, mode-hop-free tuning of diode lasers.

Findings

Achieved 40 GHz mode-hop-free tuning range.

Laser linewidth smaller than 30 MHz.

Demonstrated use in lithium spectroscopy.

Abstract

The design of a 671 nm diode laser with a mode-hop-free tuning range of 40 GHz is described. This long tuning range is achieved by simultaneously ramping the external cavity length with the laser injection current. The external cavity consists of a microscope cover slip mounted on piezoelectric actuators. In such a configuration the laser output pointing remains fixed, independent of its frequency. Using a diode with an output power of 5-7 mW, the laser linewidth was found to be smaller than 30 MHz. This cover slip cavity and feedforward laser current control system is simple, economical, robust, and easy to use for spectroscopy, as we demonstrate with lithium vapor and lithium atom beam experiments.