High-precision fiber Bragg gratings inscription by infrared femtosecond laser direct-writing method assisted with image recognition

For achieving high efficiency fiber Bragg gratings (FBGs) utilizing infrared femtosecond laser point-by-point inscription method, it is crucial to make the inscribed periodic structure perfectly in phase. It requires a perfect alignment between the micrometer-sized laser spot with the fiber along th...

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Veröffentlicht in:Optics express 2020-03, Vol.28 (6), p.8937-8948
Hauptverfasser: Yu, Yanjiang, Shi, Jindan, Han, Feng, Sun, Wenjuan, Feng, Xian
Format: Artikel
Sprache:eng
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Zusammenfassung:For achieving high efficiency fiber Bragg gratings (FBGs) utilizing infrared femtosecond laser point-by-point inscription method, it is crucial to make the inscribed periodic structure perfectly in phase. It requires a perfect alignment between the micrometer-sized laser spot with the fiber along the length. Here we report the highly precise fabrication of FBGs by infrared femtosecond laser point-by-point direct-writing method. Image recognition technique is applied to for automatically aligning the trace of the laser spot with the referenced central axis of the fiber along the whole FBG length. FBGs inscription with high spatial precision is confirmed by multiple approaches, including microscopic photographing and FBG spectroscopic measurement. 50 mm-long uniform FBGs with high reflectivity have been successfully demonstrated in a small-core single-mode silica fiber using auto-aligning technique.
ISSN:1094-4087
1094-4087
DOI:10.1364/OE.388393