Increasing the Q-factor of Fabry-Perot etalons using focused Bessel beam illumination

Dylan M Marques*, Oliver Sheppard, James A Guggenheim, Peter R T Munro

*Corresponding author for this work

Research output: Contribution to journalLetterpeer-review

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Abstract

Sensing and filtering applications often require Fabry-Perot (FP) etalons with an Interferometer Transfer Function (ITF) having high visibility, narrow Full Width at Half Maximum (FWHM), and high sensitivity. For the ITF to have these characteristics, the illumination beam must be matched to the modes of the FP cavity. This is challenging when a small illumination element size is needed, as typical focused beams are not matched to the FP cavity modes. Bessel beams are a potential alternative as their structure resembles the FP cavity modes while possessing a focused core. To study the feasibility of using Bessel beam illumination, in this Letter, ITFs of an FP etalon were measured using Bessel and Gaussian illumination beams. A Bessel beam with core size of 28 µm provided an ITF with visibility 3.0 times higher, a FWHM 0.3 times narrower, and a sensitivity 2.2 times higher than a Gaussian beam with waist 32 µm. The results show that Bessel beam illumination can provide ITFs similar to that of collimated beam illumination while also having with a focused core.

Original languageEnglish
Pages (from-to)6352-6355
Number of pages4
JournalOptics Letters
Volume48
Issue number24
Early online date1 Dec 2023
DOIs
Publication statusPublished - 15 Dec 2023

Bibliographical note

Funding.
British Heart Foundation (AA/18/2/34218); Engineering and Physical Sciences Research Council (EP/L015455/1); Royal Society (URF\R\191036, URF\R1\180435).

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