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

B. Wiegand1, B. Leykauf1, R. Jördens2 and M. Krutzik1,3

Published in:

Rev. Sci. Instrum., vol. 93, no. 6, pp. 063001, doi:10.1063/5.0090384 (2022).


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 proportional-integral-derivative (PID) operation. Besides allowing for sinusoidal modulation (up to 50 MHz), triangular ramp scanning, in-phase and quadrature demodulation (1-5 f), infinite impulse response, and PID filtering, Linien features two different algorithms for automatic lock point selection; one of them performs time-critical tasks completely on field-programmable gate arrays. 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.

1 Institut für Physik, Humboldt-Universität zu Berlin, 12489 Berlin, Germany
2 QUARTIQ GmbH, Rudower Chaussee 29, 12489 Berlin, Germany
3 Ferdinand-Braun-Institut gGmbH, Leibniz-Institut für Höchstfrequenztechnik, 12489 Berlin, Germany


Field programmable gate array, Analog-to-digital converter, Infinite impulse response, Signal processing, Laser frequency stabilization, Machine learning, Spectroscopy, Graphical user interface

© 2022 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

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