Ultra-broadband flat-top circular polarizer based on chiral fiber gratings near the dispersion turning point.
Opt Express
; 30(23): 41774-41783, 2022 Nov 07.
Article
em En
| MEDLINE
| ID: mdl-36366645
ABSTRACT
Based on the dual-resonance principle around the dispersion turning point, a scheme of chiral long-period fiber gratings (CLPGs) formed by twisting a high-birefringence (Hi-Bi) fiber is herein proposed to realise ultra-broadband flat-top circular polarizers. The coupling bandwidth is approximately seven times larger than that of traditional CLPGs. In addition, by introducing chirp characteristics in these CLPGs, an ultra-broadband flat-top circular polarizer with â¼200â
nm@3â
dB was conveniently achieved. Subsequently, by optimising the chirped CLPGs, a circular polarizer with a bandwidth extinction ratio of approximately 30â
dB and a high level of â¼100â
nm at 1â
dB was realised. It was shown that the mode-controlling performances of the CLPGs can be remarkably improved, which has significant applications in light-field regulation. Finally, for the first time, it was proved that the CLPG cannot generate a vortex beam.
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MEDLINE
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Ano de publicação:
2022
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Article