Digital laser frequency and intensity stabilization based on the STEMlab platform (originally Red Pitaya)

TL;DR

This paper presents a digital laser stabilization system using the STEMlab platform, achieving high bandwidth, low noise, and precise control of laser frequency and intensity with open-source hardware designs.

Contribution

It introduces a novel digital control system for laser stabilization based on STEMlab, with detailed characterization and open-source hardware layouts.

Findings

Laser linewidth reduced to 52 kHz (FWHM)

Intensity stabilization to 10^{-3} level

Bandwidth of 1.25 MHz limited by STEMlab system

Abstract

We report on the development, implementation, and characterization of digital controllers for laser frequency stabilization as well as intensity stabilization and control. Our design is based on the STEMlab (originally Red Pitaya) platform. The presented analog hardware interfaces provide all necessary functionalities for the designated applications and can be integrated in standard 19-inch rack mount units. Printed circuit board layouts are made available as an open-source project.\cite{APQGit_Lockbox,APQGit_IntStab} A detailed characterization shows that the bandwidth 1.25 MHz and the noise performance of the controllers are limited by the STEMlab system and not affected by the supplementary hardware. Frequency stabilization of a diode laser system resulting in a linewidth of 52(1) kHz (FWHM) is demonstrated. Intensity control to the $10^{-3}$ level with sub-microsecond rise and fall times based on an acousto-optic modulator as actuator is achieved.