Development of a compact control circuit for voltage-controlled oscillator with applications in laser stabilization

Abstract

Experiments in atomic physics, spectroscopy, and metrology require the compulsory use of frequency- and/or power-stabilized laser beams. For this purpose, acousto-optic modulators (AOMs) or electro-optic modulators are commonly used. AOMs are the most widely employed because of their ability to not only control the frequency and amplitude but also manipulate the spatial deflection of the beam. The operation of AOMs requires stable radio frequency oscillators, which can be implemented using Direct Digital Synthesis (DDS) systems or Voltage-Controlled Oscillators (VCOs). DDS systems offer high precision and a wide range of operating frequencies but at a high cost and with a more complex experimental setup. However, VCO-based systems provide excellent resolution, are more cost-effective, and can be implemented more rapidly in the final application because of their low complexity. In this work, a detailed design of a compact system for controlling an AOM, which is easily constructed based on a VCO and some readily available discrete components, is presented. The constructed device was successfully used in two applications for controlling an extended cavity diode laser: one to reduce typical undesired fluctuations in laser intensity and the other for laser frequency stabilization to a hyperfine structure transition of the rubidium D2 line.