High-visibility Fabry-P<acute accent>erot interferometer fabricated in ULE® glass through fs-laser machining

• Type: Article in International Scientific Journal
• Date: 2024

Authors

Maia, JM (Author) Other; Marques, PVS (Author) FCUP

Journal

Title: Optics and Laser Technology

Vol. 176

ISSN: 0030-3992

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 0 Citations

Scopus - 0 Citations

Other information

Authenticus ID: P-010-8V9

DOI: 10.1016/j.optlastec.2024.110976

Abstract (EN): Low-finesse Fabry-Perot interferometers (FPI) with a plano-convex geometry are fabricated in ULE (R) glass through ultrafast laser machining. With this geometry, it is possible to overcome beam divergence effects that contribute to the poor fringe visibility usually observed in 100-mu m or longer planar-planar FPIs. By replacing the planar surface with a spherical one, the diverging beam propagating through the cavity is re-focused back at the entrance of the lead-in fiber upon reflection at this curved interface, thereby balancing out the intensities of both interfering beams and enhancing the visibility. The design of a 3D shaped cavity with a spherical sidewall is only made possible through fs-laser direct writing followed by chemical etching. In this technique, the 3D volume is reduced to writing of uniformly vertically spaced 2D layers with unique geometry, which are then selectively removed during chemical etching with HF acid. The radius of curvature that maximizes fringe visibility is computed using a numerical tool that is experimentally validated. By choosing the optimal radius of curvature, uniform visibilities in the range of 0.98-1.00 are measured for interferometers produced with cavity lengths spanning from 100 to 1000 mu m.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 8