An Ultra-High Stability, Low-Noise Laser Current Driver with Digital Control

Abstract

We present a low-noise, high modulation-bandwidth design for a laser current driver with excellent long term stability. The driver improves upon the commonly-used Hall-Libbrecht design. The current driver can be operated remotely by way of a micro-processing unit, which controls the current set point digitally. This allows precise repeatability and improved accuracy and stability. It also allows the driver to be placed near the laser for reduced noise and for lower phase lag when using the modulation input. We present the theory of operation for our driver in detail, and give a thorough characterization of its stability, noise, set point accuracy and repeatability, temperature dependence, transient response, and modulation bandwidth.