Dissertation / PhD Thesis

GSI-2024-00465

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png High-power frequency combs for precision spectroscopy in the extreme ultraviolet

Salman, H. S. (Corresponding author)HIJ*

2023
SUB Hamburg Hamburg

Please use a persistent id in citations: urn:nbn:de:gbv:18-ediss-118097

Abstract: Ultra-high-resolution spectroscopy provides the basis behind multiple scientific fields and in particular, for frequency metrology. The required techniques usually involve optical frequency combs, which are well established in the visible and infrared spectral regions. In contrast, the Vacuum- and Extreme Ultraviolet (VUV and XUV) are barely explored spectral ranges, mainly due to the lack of a suitable light source. However, many atoms and in particular ions of fundamental interest await to be analyzed. Additionally, prospective nuclear clocks based on optically driving the low energy 229Th nuclear transition (about 8.3 eV), set high demands on dedicated VUV sources. A possible solution can be provided by high-power frequency combs combined with cavity-enhanced high-harmonic generation (HHG). However, this combination represents a highly complex approach with great challenges if long-term stable, low-noise operation is required. This is particularly important should ultra-narrow transitions such as the 229Th transition be targeted. This dissertation addresses these challenges, describing the complete development of a fully-stabilized high-power femtosecond frequency comb centered at 1 μm wavelength with 65MHz comb line spacing and more than 70W output power. Furthermore, important features including a new oscillator design, wavelength tuning, adaptation for remote computer control and a technical interlock, which ensures fail-safe and stable long-term operation of the system, are implemented. The dissertation shows for the first time that a fully-stabilized high-power frequency comb can be operated continuously over multiple days without interruption, setting the stage for VUV conversion and ultra-high-resolution spectroscopy in this spectral region.

Note: Dissertation, Universität Hamburg, 2023

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Contributing Institute(s):

1. HIJ / HL (JHL)

Research Program(s):

1. 621 - Accelerator Research and Development (POF4-621) (POF4-621)

Experiment(s):

1. External experiment at external facility/ no experiment at GSI (other)

Appears in the scientific report 2023

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