All-fiber amplifier based on chirally-coupled-core fibers for gravitational wave detectors

Publikation: Qualifikations-/StudienabschlussarbeitDissertation

Autoren

  • Sven Hochheim

Organisationseinheiten

Forschungs-netzwerk anzeigen

Details

OriginalspracheEnglisch
QualifikationDoctor rerum naturalium
Gradverleihende Hochschule
Betreut von
  • Benno Willke, Betreuer*in
Datum der Verleihung des Grades18 Jan. 2023
ErscheinungsortHannover
PublikationsstatusVeröffentlicht - 2023

Abstract

Für die Entwicklung neuartiger Gravitationswellendetektoren auf Basis interferometrischer Messungen werden spezielle Hochleistungslaser benötigt. Die Designstudie für das europäische "Einstein Teleskop" offenbarte, dass die optischen Leistungslevel aktuell verwendeter Lasersysteme für die zukünftig angestrebten Spezifikationen nicht mehr ausreichend sind. Die Entwicklung solcher leistungsstarken Lasersysteme ist daher ein weitreichendes Forschungsgebiet und von aktuellem Interesse geprägt. Insbesondere Faserverstärker sind durch ihre exzellente Strahlqualität auch bei höheren Leistungen in den letzten Jahren zunehmend in den Vordergrund gerückt. Die Leistungsskalierung solcher Lasersysteme über aktuelle Limitierungen hinaus ist das Konzept dieser Arbeit. Im Bereich von einfrequenten faserbasierten Lasersystemen stellt dabei der nichtlineare Effekt der stimulierten Brillouin-Streuung die grundlegende Limitierung dar. Insbesondere ist ein signifikantes Rauschen des Lasersystems oberhalb dieser Schwelle messbar. In diesem Zusammenhang wurde das Intensitätsrauschen genauer untersucht. Die Konversion von Phasen- zu Intensitätsrauschen spielt dabei eine entscheidende Rolle. Erstmals konnte die Charakteristik des zusätzlichen breitbandigen Rauschens basierend auf den Parametern eines asymmetrischen Brillouin Verstärkungsspektrums rekonstruiert werden. Die Leistungsskalierung von faserbasierten und einfrequenten Lasersystemen erfolgt beispielsweise durch die Vergrößerung der effektiven Kernfläche. Um die daraus resultierende Minderung der Strahlqualität in Faserverstärkern auszugleichen, wurde das Konzept der "chirally-coupled core" (3C®) Faser entwickelt. Dieser Fasertyp reduziert den Anteil geführter höherer Moden durch zusätzliche um den eigentlichen Kern rotierende Seitenkerne. Im Vergleich zu anderen Spezialfasertypen mit Mikrostrukturen weist diese Faser ein komplettes Glasdesign auf. Die lichtführenden Eigenschaften der 3C®-Faser wurden mit einem speziell entwickeltem S2-Aufbau untersucht und der hohe Anteil der geführten Grundmode im Faserkern experimentell bestätigt. Zum ersten Mal wurden optische Faserkomponenten direkt in solch einer 3C®-Faser integriert. Insbesondere die Herstellung von Signal und Pumplichtkopplern eröffnet neue Möglichkeiten für die Entwicklung neuartiger Verstärkersysteme. In dieser Arbeit wurde erstmals ein monolithisches einfrequentes Faserverstärker-Design realisiert, welches ein Leistungslevel von über 300W erreicht. Dieser erste Prototyp mit einer 3C®-Faser beruht auf dem Design, in der die optischen Faserkomponenten direkt in der Ytterbium-dotierten 3C®-Faser integriert wurden und somit auf die Notwendigkeit zusätzlicher Spleiße verzichtet werden konnte. Somit wurden bestmögliche Strahlparameter nach dem Verstärkungsprozess realisiert. Insbesondere in Hinblick auf den geführten Grundmodenanteil von über 90% unterstreicht diese Arbeit das hohe Potential von Faserverstärkern auf Grundlage von 3C®-Fasern als Laserquellen für die speziellen Anforderungen von Gravitationswellendetektoren.

Zitieren

All-fiber amplifier based on chirally-coupled-core fibers for gravitational wave detectors. / Hochheim, Sven.
Hannover, 2023. 133 S.

Publikation: Qualifikations-/StudienabschlussarbeitDissertation

Hochheim, S 2023, 'All-fiber amplifier based on chirally-coupled-core fibers for gravitational wave detectors', Doctor rerum naturalium, Gottfried Wilhelm Leibniz Universität Hannover, Hannover. https://doi.org/10.15488/13572
Hochheim, S. (2023). All-fiber amplifier based on chirally-coupled-core fibers for gravitational wave detectors. [Dissertation, Gottfried Wilhelm Leibniz Universität Hannover]. https://doi.org/10.15488/13572
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title = "All-fiber amplifier based on chirally-coupled-core fibers for gravitational wave detectors",
abstract = "High-power lasers are required for the development of novel gravitational wave detectors based on interferometric measurements. The design study for the European {\textquoteright}Einstein Telescope{\textquoteright} revealed that the optical performance of current used laser systems is no longer sufficient for the desired specifications of advanced detector designs. The development of such powerful laser systems is therefore a wide field of research and is of current interest. In particular, fiber amplifiers have increasingly come to the fore in recent years due to their excellent beam quality, even at higher power levels. The power scaling of such laser systems beyond current limitations is the concept of this work. In the area of single-frequency fiber-based laser systems, the non-linear effect of stimulated Brillouin scattering represents the fundamental limitation. In particular, a significant excess noise level of the laser system can be measured above this threshold. In this context, the intensity noise was investigated in more detail. Here, the conversion of phase to intensity noise plays a crucial role. For the first time, the characteristics of the additional broadband noise was reconstructed based on the parameters of an asymmetric Brillouin gain spectrum. The optical output power of fiber-based single-frequency laser systems is scaled, for example, by increasing the effective mode area of the fiber. For the compensation of the resulting reduction of the beam quality in fiber amplifiers, the special concept of the {\textquoteright}chirally-coupled core{\textquoteright} (3C{\textregistered}) fiber was developed. This fiber type reduces the content of guided higher order modes through additional side cores rotating around the actual signal core. Compared to other specialty fiber types with micro-structures inside, this fiber features an all-solid design. The light-guiding properties of the 3C{\textregistered}-fiber were examined with a specially developed S2-setup and the high content of the guided fundamental mode in the fiber core was experimentally confirmed. For the first time, optical fiber components were integrated directly into such a 3C{\textregistered}-fiber. Especially, the manufacturing of signal and pump light couplers opens up new possibilities for the development of advanced fiber amplifier systems. In this work, a first monolithic single-frequency fiber amplifier design was realized, which achieves a power level of over 300 W. This prototype is based on a 3C{\textregistered}-fiber without the need for additional fusion splices, because the optical fiber components were integrated directly into the Ytterbium-doped 3C{\textregistered}-fiber. So, the optimal beam parameters were realized after the amplification process. In particular with regard to the guided fundamental mode content of over 90%, this work emphasizes the high potential of fiber amplifiers based on 3C{\textregistered}-fibers as laser sources for the special requirements of gravitational wave detectors.",
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Download

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T1 - All-fiber amplifier based on chirally-coupled-core fibers for gravitational wave detectors

AU - Hochheim, Sven

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PY - 2023

Y1 - 2023

N2 - High-power lasers are required for the development of novel gravitational wave detectors based on interferometric measurements. The design study for the European ’Einstein Telescope’ revealed that the optical performance of current used laser systems is no longer sufficient for the desired specifications of advanced detector designs. The development of such powerful laser systems is therefore a wide field of research and is of current interest. In particular, fiber amplifiers have increasingly come to the fore in recent years due to their excellent beam quality, even at higher power levels. The power scaling of such laser systems beyond current limitations is the concept of this work. In the area of single-frequency fiber-based laser systems, the non-linear effect of stimulated Brillouin scattering represents the fundamental limitation. In particular, a significant excess noise level of the laser system can be measured above this threshold. In this context, the intensity noise was investigated in more detail. Here, the conversion of phase to intensity noise plays a crucial role. For the first time, the characteristics of the additional broadband noise was reconstructed based on the parameters of an asymmetric Brillouin gain spectrum. The optical output power of fiber-based single-frequency laser systems is scaled, for example, by increasing the effective mode area of the fiber. For the compensation of the resulting reduction of the beam quality in fiber amplifiers, the special concept of the ’chirally-coupled core’ (3C®) fiber was developed. This fiber type reduces the content of guided higher order modes through additional side cores rotating around the actual signal core. Compared to other specialty fiber types with micro-structures inside, this fiber features an all-solid design. The light-guiding properties of the 3C®-fiber were examined with a specially developed S2-setup and the high content of the guided fundamental mode in the fiber core was experimentally confirmed. For the first time, optical fiber components were integrated directly into such a 3C®-fiber. Especially, the manufacturing of signal and pump light couplers opens up new possibilities for the development of advanced fiber amplifier systems. In this work, a first monolithic single-frequency fiber amplifier design was realized, which achieves a power level of over 300 W. This prototype is based on a 3C®-fiber without the need for additional fusion splices, because the optical fiber components were integrated directly into the Ytterbium-doped 3C®-fiber. So, the optimal beam parameters were realized after the amplification process. In particular with regard to the guided fundamental mode content of over 90%, this work emphasizes the high potential of fiber amplifiers based on 3C®-fibers as laser sources for the special requirements of gravitational wave detectors.

AB - High-power lasers are required for the development of novel gravitational wave detectors based on interferometric measurements. The design study for the European ’Einstein Telescope’ revealed that the optical performance of current used laser systems is no longer sufficient for the desired specifications of advanced detector designs. The development of such powerful laser systems is therefore a wide field of research and is of current interest. In particular, fiber amplifiers have increasingly come to the fore in recent years due to their excellent beam quality, even at higher power levels. The power scaling of such laser systems beyond current limitations is the concept of this work. In the area of single-frequency fiber-based laser systems, the non-linear effect of stimulated Brillouin scattering represents the fundamental limitation. In particular, a significant excess noise level of the laser system can be measured above this threshold. In this context, the intensity noise was investigated in more detail. Here, the conversion of phase to intensity noise plays a crucial role. For the first time, the characteristics of the additional broadband noise was reconstructed based on the parameters of an asymmetric Brillouin gain spectrum. The optical output power of fiber-based single-frequency laser systems is scaled, for example, by increasing the effective mode area of the fiber. For the compensation of the resulting reduction of the beam quality in fiber amplifiers, the special concept of the ’chirally-coupled core’ (3C®) fiber was developed. This fiber type reduces the content of guided higher order modes through additional side cores rotating around the actual signal core. Compared to other specialty fiber types with micro-structures inside, this fiber features an all-solid design. The light-guiding properties of the 3C®-fiber were examined with a specially developed S2-setup and the high content of the guided fundamental mode in the fiber core was experimentally confirmed. For the first time, optical fiber components were integrated directly into such a 3C®-fiber. Especially, the manufacturing of signal and pump light couplers opens up new possibilities for the development of advanced fiber amplifier systems. In this work, a first monolithic single-frequency fiber amplifier design was realized, which achieves a power level of over 300 W. This prototype is based on a 3C®-fiber without the need for additional fusion splices, because the optical fiber components were integrated directly into the Ytterbium-doped 3C®-fiber. So, the optimal beam parameters were realized after the amplification process. In particular with regard to the guided fundamental mode content of over 90%, this work emphasizes the high potential of fiber amplifiers based on 3C®-fibers as laser sources for the special requirements of gravitational wave detectors.

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