Mainz 2026 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 41: Poster – Quantum Technologies II & Laser Technology
Q 41.24: Poster
Mittwoch, 4. März 2026, 17:00–19:00, Philo 2. OG
Laser frequency noise measurement close to the shot noise limit — •Christoph Raab1, Jonas Vogel3, Björn Lekitsch3, and Ferdinand Schmidt-Kaler2,3 — 1Hochschule Darmstadt, Darmstadt, Germany — 2QUANTUM, Universität Mainz, Mainz, Germany — 3neQxt GmbH, Erlenbach, Germany
Frequency-stabilized laser sources are used in many industrial or scientific applications like spectroscopy, frequency standard, interferometry and quantum technology. Typically, the freqency noise of a source is characterized by a beat note with a second laser. Here, we present a measurement setup to precisly characterise the frequency and phase noise of a cw laser without this significant overhead. The setup employes an interferometric approach to convert frequency fluctuations into an amplitude signal, detected by a photo diode. We find that the noise limit of the interferometer is dominated by the detection noise. Therefore, we carefully select and optimize the photodetector and the digitizing system, reaching a lower limit for the frequency noise density of a few Hz2/Hz or an equivalent laser linewidth of about 10 Hz. Our setup is optimzed for laser sources in the wavelength range of 620 nm to 870 nm, but the setup can be adapted over the entire range of visible to IR wavelengths.
Keywords: laser frequency noise; linewidth