Continuously and widely tunable frequency-stabilized laser based on an optical frequency comb

Abstract

Continuously and widely tunable lasers, actively stabilized on a frequency reference, are broadly employed in atomic, molecular, and optical (AMO) physics. The frequency-stabilized optical frequency comb (OFC) provides a novel optical frequency reference, with a broadband spectrum that meets the requirement of laser frequency stabilization. Therefore, we demonstrate a frequency-stabilized and precisely tunable laser system based on it. In this scheme, the laser frequency locked to the OFC is driven to jump over the ambiguity zones, which blocks the wide tuning of the locked laser, and tuned until the mode hopping happens with the always-activated feedback loop. Meanwhile, we compensate the gap of the frequency jump with a synchronized acoustic optical modulator to ensure the continuity. This scheme is applied to an external cavity diode laser (ECDL), and we achieve tuning at a rate of about 7 GHz/s, with some readily available commercial electronics. Furthermore, we tune the frequency-stabilized laser only with the feedback of diode current, and its average tuning speed can exceed 100 GHz/s. Due to the resource-efficient configuration and the simplicity of completion, this scheme can be referenced and can find wide applications in AMO experiments.

Experimental realization of strong coupling between a cold atomic ensemble and an optical fiber microcavity

“…The first diffracted laser beam is used and focused through a 125 mm achromatic lens to a diameter of 30 μm onto the MOT, which can cover the optical cavity mode with a waist radius of 4.9 μm and avoid shining on the optical fiber microcavity. When focused into the optical cavity, the 1064 nm laser power at MOT goes down linearly from 4 W to 500 mW, which can reduce the thermal effect of the optical fiber microcavity caused by the high-power laser [57,58] . To precisely transport atoms, a programmable arbitrary waveform generator (AWG) is used to generate the microwave amplified by a microwave amplifier to drive the AOD and keep the diffraction efficiency above 75% throughout the transport process.…”