Simple three-stage frequency-stabilized diode laser system using injection-locking and tapered amplifier

Abstract

We developed a three-stage, amplifying, tunable diode laser system that comprises a master laser in a Littrow configuration, frequency-stabilized by dichroic atomic vapour laser lock, acousto-optic frequency shifter, injection-locked slave laser, and tapered amplifier. The slave amplifies the injected frequency-shifted master beam while suppressing (within 0.5  %) the strong dependence of its intensity on the acousto-optic frequency shifter carrier frequency, thus acting as a strongly saturated optical limiting amplifier with constant output power. The resulting beam is then amplified in a tapered amplifier. The system provides an output power above 700 mW at a wavelength of 780 nm, with a time-averaged linewidth of 0.6 MHz, and a frequency drift below 2 MHz/h. Dichroic atomic vapour laser lock enables frequency stabilization in the range of 400 MHz around D2 lines of rubidium. The mode-hop-free tuning range amounts to 2 GHz. Determined by the acousto-optic frequency shifter model used, the fine-tuning range (precision of few tens kHz) spans 70 MHz. A description of the system was presented and its performance was tested. The basic components have been designed in our laboratory.