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All-fiber fused directional coupler for highly efficient spatial mode conversion

All-fiber fused directional coupler for highly efficient spatial mode conversion
All-fiber fused directional coupler for highly efficient spatial mode conversion
We model and demonstrate a simple mode selective all-fiber coupler capable of exciting specific higher order modes in two- and few-mode fibres with high efficiency and purity. The coupler is based on inter-modally phase-matching the propagation constants in each arm of the asymmetric fused coupler, formed by dissimilar fibres. At a specific coupler diameter, the launched fundamental LP01 mode is coupled into the higher order mode (LP11, LP21, LP02) in the other arm, over a broadband wavelength range around 1550 nm. Unlike other techniques, the demonstrated coupler is composed of a multimode fiber that is weakly fused with a phase matched conventional single mode telecom fiber (SMF-28). The beating between the supermodes at the coupler waist produces a periodic power transfer between the two arms, and therefore, by monitoring the beating while tapering, it is possible to obtain optimum selection for the desired mode. High coupling efficiencies in excess of 90% for all the higher order modes were recorded over 100 nm spectral range, while insertion losses remain as low as 0.5 dB. Coupling efficiency can be further enhanced by performing slow tapering at high temperature, in order to precisely control the coupler cross-section geometry.
1094-4087
11610-11619
Ismaeel, Rand
c1fb0984-a4c0-484a-8aef-625d48a62086
Lee, Timothy
beb3b88e-3e5a-4c3f-8636-bb6de8040fcc
Oduro, Bernard
09021c9e-9ead-4614-9891-bb7336865691
Jung, Yongmin
6685e51e-be47-4c96-8c4b-65aee3b5126d
Brambilla, Gilberto
815d9712-62c7-47d1-8860-9451a363a6c8
Ismaeel, Rand
c1fb0984-a4c0-484a-8aef-625d48a62086
Lee, Timothy
beb3b88e-3e5a-4c3f-8636-bb6de8040fcc
Oduro, Bernard
09021c9e-9ead-4614-9891-bb7336865691
Jung, Yongmin
6685e51e-be47-4c96-8c4b-65aee3b5126d
Brambilla, Gilberto
815d9712-62c7-47d1-8860-9451a363a6c8

Ismaeel, Rand, Lee, Timothy, Oduro, Bernard, Jung, Yongmin and Brambilla, Gilberto (2014) All-fiber fused directional coupler for highly efficient spatial mode conversion. Optics Express, 22 (10), 11610-11619. (doi:10.1364/OE.22.011610).

Record type: Article

Abstract

We model and demonstrate a simple mode selective all-fiber coupler capable of exciting specific higher order modes in two- and few-mode fibres with high efficiency and purity. The coupler is based on inter-modally phase-matching the propagation constants in each arm of the asymmetric fused coupler, formed by dissimilar fibres. At a specific coupler diameter, the launched fundamental LP01 mode is coupled into the higher order mode (LP11, LP21, LP02) in the other arm, over a broadband wavelength range around 1550 nm. Unlike other techniques, the demonstrated coupler is composed of a multimode fiber that is weakly fused with a phase matched conventional single mode telecom fiber (SMF-28). The beating between the supermodes at the coupler waist produces a periodic power transfer between the two arms, and therefore, by monitoring the beating while tapering, it is possible to obtain optimum selection for the desired mode. High coupling efficiencies in excess of 90% for all the higher order modes were recorded over 100 nm spectral range, while insertion losses remain as low as 0.5 dB. Coupling efficiency can be further enhanced by performing slow tapering at high temperature, in order to precisely control the coupler cross-section geometry.

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Accepted/In Press date: 23 April 2014
e-pub ahead of print date: 6 May 2014
Published date: 19 May 2014
Organisations: Optoelectronics Research Centre, Quantum, Light & Matter Group

Identifiers

Local EPrints ID: 365889
URI: http://eprints.soton.ac.uk/id/eprint/365889
ISSN: 1094-4087
PURE UUID: ba530a6b-817c-49e3-afe2-cccb810fe9c0

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Date deposited: 20 Jun 2014 12:44
Last modified: 16 Dec 2019 20:25

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Contributors

Author: Rand Ismaeel
Author: Timothy Lee
Author: Bernard Oduro
Author: Yongmin Jung

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