Offset Lock with 440 GHz Range using Electro-Optic Modulation

TL;DR

This paper demonstrates a wide-range laser offset lock with a ±220 GHz range using electro-optic modulation and beat-note detection, significantly expanding the accessible frequency span for laser stabilization.

Contribution

The authors experimentally realize the largest known offset lock range of ±220 GHz using a novel beat-note and electro-optic modulation technique.

Findings

Achieved an offset range of ±220.1 GHz.

Maintained offset frequency fluctuations under 0.1 Hz.

Provided a simple setup for large-range laser offset locking.

Abstract

Offset locking is a popular method for stabilizing laser frequency, which is crucial to many physics experiments. Wide range offset locks are desirable, as they increase the span of usable frequencies in an experiment. Here, we experimentally realize a wide-range offset lock using a beat-note setup combined with electro-optic phase modulation. By using frequency down-conversion of the beat note and locking to sidebands generated by electro-optic modulation, we achieve an offset range of $\pm$ 220.1 GHz with offset frequency fluctuations under 0.1 Hz, enabling an optical heterodyne offset lock with the largest known range of any such lock. The relative simplicity of our setup provides a compelling method for locking at offsets in the hundreds of GHz range.