Linien: A versatile, user-friendly, open-source FPGA-based tool for frequency stabilization and spectroscopy parameter optimization

TL;DR

Linien is an open-source FPGA-based tool that offers versatile, user-friendly laser frequency stabilization and spectroscopy parameter optimization, integrating machine learning and advanced modulation techniques.

Contribution

It introduces a modular, FPGA-enabled software platform with automatic lock point selection and parameter optimization for laser spectroscopy, adaptable to various hardware systems.

Findings

Supports sinusoidal modulation up to 50 MHz

Features FPGA-based automatic lock point selection

Utilizes machine learning for parameter optimization

Abstract

We present a user-friendly and versatile tool for laser frequency stabilization. Its main focus is spectroscopy locking, but the software is suitable for lock-in techniques in general as well as bare PID operation. Besides allowing for sinusoidal modulation (up to 50 MHz), triangular ramp scanning, IQ demodulation (1 $f$ to 5 $f$), IIR and PID filtering, Linien features two different algorithms for automatic lock point selection; one of them performs time-critical tasks completely on FPGA. Linien is capable of autonomously optimizing spectroscopy parameters by means of machine learning and can measure the error signal's power spectral density. The software is built in a modular way, providing both a graphical user interface as well as a Python scripting interface. It is based on the RedPitaya STEMLab platform but may be ported to different systems.