Self-heterodyne mixing method of two inter-mode beat frequencies for frequency stabilization of a three-mode He-Ne laser

Abstract

We present a robust self-heterodyne mixing method of two inter-mode beat frequencies suitable for frequency stabilization of a three longitudinal-mode (3-mode) He-Ne laser at 633 nm. A high-contrast frequency discrimination signal with a broad locking range of 244 MHz is obtained by using a self-heterodyned double balanced mixer operating at the inter-mode beat frequency of 607 MHz. We show that the central-mode frequency of the 3-mode He-Ne laser could be stabilized to the center of the gain profile with a frequency fluctuation less than +/- 5 MHz for more than 12 h. Copyright 2012 Author(s). This article is distributed under a Creative Commons Attribution 3.0 Unported License. [http://dx.doi.org/10.1063/1.4733344]