Subharmonic lock-in detection and its optimisation for femtosecond noise correlation spectroscopy

Fuente: arXiv
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Autori principali: Weiss, M. A., Herbst, F. S., Eggert, S., Nakajima, M., Leitenstorfer, A., Goennenwein, S. T. B., Kurihara, T.
Natura: Preprint
Pubblicazione: 2024
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author Weiss, M. A.
Herbst, F. S.
Eggert, S.
Nakajima, M.
Leitenstorfer, A.
Goennenwein, S. T. B.
Kurihara, T.
author_facet Weiss, M. A.
Herbst, F. S.
Eggert, S.
Nakajima, M.
Leitenstorfer, A.
Goennenwein, S. T. B.
Kurihara, T.
contents Although often viewed as detrimental, fluctuations carry valuable information about the physical system from which they emerge. Femtosecond noise correlation spectroscopy (FemNoC) has recently been established to probe the ultrafast fluctuation dynamics of thermally populated magnons by measurement of their amplitude autocorrelation. Subharmonic lock-in detection is the key technique in this method, allowing to extract the pulse-to-pulse polarisation fluctuations of two femtosecond optical pulse trains transmitted through a magnetic sample. Here, we present a thorough technical description of the subharmonic demodulation technique and of the FemNoC measurement system. We mathematically model the data acquisition process and identify the essential parameters which critically influence the signal-to-noise ratio of the signals. Comparing the model calculations to real datasets allows validating the predicted parameter dependences and provides a means to optimise FemNoC experiments.
format Preprint
id arxiv_https___arxiv_org_abs_2403_09829
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Subharmonic lock-in detection and its optimisation for femtosecond noise correlation spectroscopy
Weiss, M. A.
Herbst, F. S.
Eggert, S.
Nakajima, M.
Leitenstorfer, A.
Goennenwein, S. T. B.
Kurihara, T.
Optics
Other Condensed Matter
Instrumentation and Detectors
Although often viewed as detrimental, fluctuations carry valuable information about the physical system from which they emerge. Femtosecond noise correlation spectroscopy (FemNoC) has recently been established to probe the ultrafast fluctuation dynamics of thermally populated magnons by measurement of their amplitude autocorrelation. Subharmonic lock-in detection is the key technique in this method, allowing to extract the pulse-to-pulse polarisation fluctuations of two femtosecond optical pulse trains transmitted through a magnetic sample. Here, we present a thorough technical description of the subharmonic demodulation technique and of the FemNoC measurement system. We mathematically model the data acquisition process and identify the essential parameters which critically influence the signal-to-noise ratio of the signals. Comparing the model calculations to real datasets allows validating the predicted parameter dependences and provides a means to optimise FemNoC experiments.
title Subharmonic lock-in detection and its optimisation for femtosecond noise correlation spectroscopy
topic Optics
Other Condensed Matter
Instrumentation and Detectors
url https://arxiv.org/abs/2403.09829