Transport properties of optical fibres with high numerical apertures

0535619 - ÚPT 2021 RIV US eng C - Konferenční příspěvek (zahraniční konf.)
Tyc, Tomáš - Simpson, Stephen Hugh - Čižmár, Tomáš
Transport properties of optical fibres with high numerical apertures.
Complex Light and Optical Forces XIV 2020. Proceedings of SPIE. Vol. 11297. Bellingham: SPIE, 2020, č. článku 112970Y. ISBN 978-151063357-5. ISSN 0277-786X.
[Complex Light and Optical Forces 2020 /14./. San Francisco (US), 04.02.2020-05.02.2020]
Grant CEP: GA MŠMT EF15_003/0000476; GA MŠMT(CZ) LO1212; GA MŠMT ED0017/01/01
Institucionální podpora: RVO:68081731
Klíčová slova: optical fibre * polarization * spin-orbit coupling
Obor OECD: Optics (including laser optics and quantum optics)

We theoretically examine the transport properties of non-ideal optical fibres with high numerical aperture. Using a simple spectral method, we derive the modes in perturbed or non-ideal fibres from the numerically evaluated modes of circularly symmetric fibres. We then consider the propagation through the fibre of Gaussian spots, projected onto the distal fibre end. The incident spots are of uniform, arbitrary polarization and positioned at any point on the fibre facet. We then evaluate the effect of propagation through the fibre in terms of various indices. In particular, we consider the motion of the centre of energy, the average polarization state and the average spin and orbital angular momentum. The study includes both step index and graded index optical fibres with symmetric and chiral deformations. We observe a fundamental difference between propagation in step index and graded index optical fibres: in the latter case, the centre of energy converges to the fibre axis as the light propagated along the fibre and in the former it moves erratically about the transverse plane. In addition, we find that circular polarization states are preserved for cylindrically symmetric fibres, of arbitrarily high numerical aperture. However, this property is destroyed by relatively weak deformations of the fibre.We theoretically examine the transport properties of non-ideal optical fibres with high numerical aperture. Using a simple spectral method, we derive the modes in perturbed or non-ideal fibres from the numerically evaluated modes of circularly symmetric fibres. We then consider the propagation through the fibre of Gaussian spots, projected onto the distal fibre end. The incident spots are of uniform, arbitrary polarization and positioned at any point on the fibre facet. We then evaluate the effect of propagation through the fibre in terms of various indices. In particular, we consider the motion of the centre of energy, the average polarization state and the average spin and orbital angular momentum. The study includes both step index and graded index optical fibres with symmetric and chiral deformations. We observe a fundamental difference between propagation in step index and graded index optical fibres: in the latter case, the centre of energy converges to the fibre axis as the light propagated along the fibre and in the former it moves erratically about the transverse plane. In addition, we find that circular polarization states are preserved for cylindrically symmetric fibres, of arbitrarily high numerical aperture. However, this property is destroyed by relatively weak deformations of the fibre.
Trvalý link: http://hdl.handle.net/11104/0313585