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Four-port integrated waveguide coupler exploiting bi-directional propagation of two single-mode waveguides

Four-port integrated waveguide coupler exploiting bi-directional propagation of two single-mode waveguides
Four-port integrated waveguide coupler exploiting bi-directional propagation of two single-mode waveguides
We propose and numerically simulate a new and highly compact integrated 4x4 mode coupler based on two single-mode waveguides exploiting both forward and backward propagating directions to double the number of modes. The two parallel waveguides are coupled via long and short-period gratings to the co- and counter-propagating directions, respectively, of a single cladding mode of the device which acts as a bus between the waveguides. By connecting all end facets to optical circulators we construct a device with four input and output ports but only using two single-mode waveguides. Such a device can be fabricated in a single micromachined silica ridge structure. A photosensitive raised index layer is used for vertical confinement that supports multiple modes horizontally. We UV-write the waveguides and the Bragg gratings and provide a tilt angle to improve coupling. We have demonstrated this technology before for a polarizing waveguide-to-waveguide coupler and have simulated other unidirectional devices. We use coupled mode theory to simulate the system. By tailoring the grating parameters, we can achieve a wide variety of coupling ratios. Analytically, we find a set of solutions in which no light escapes via the cladding modes through the ends of the device and we have calculated device parameters to achieve a wide range of splitting ratios including coupling light from one input port equally into all output ports. Moreover, we derived analytically a set of parameters to implement a Walsh-Hadamard transformation and are investigating further options to implement a universal 4x4mode-coupler on this platform. We envisage that the device can be used for quantum information processing where two qubits are encoded in the waveguides using a photon in each propagation direction.
SPIE
Weisen, Mathias, John
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Gates, James
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Gawith, Corin
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Smith, Peter G.R.
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Horak, Peter
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Weisen, Mathias, John
6a6bd787-56ac-4902-80c4-b9e251338824
Gates, James
b71e31a1-8caa-477e-8556-b64f6cae0dc2
Gawith, Corin
926665c0-84c7-4a1d-ae19-ee6d7d14c43e
Smith, Peter G.R.
8979668a-8b7a-4838-9a74-1a7cfc6665f6
Horak, Peter
520489b5-ccc7-4d29-bb30-c1e36436ea03

Weisen, Mathias, John, Gates, James, Gawith, Corin, Smith, Peter G.R. and Horak, Peter (2020) Four-port integrated waveguide coupler exploiting bi-directional propagation of two single-mode waveguides. In Nanophotonics VIII. vol. 11345, SPIE.. (doi:10.1117/12.2555127).

Record type: Conference or Workshop Item (Paper)

Abstract

We propose and numerically simulate a new and highly compact integrated 4x4 mode coupler based on two single-mode waveguides exploiting both forward and backward propagating directions to double the number of modes. The two parallel waveguides are coupled via long and short-period gratings to the co- and counter-propagating directions, respectively, of a single cladding mode of the device which acts as a bus between the waveguides. By connecting all end facets to optical circulators we construct a device with four input and output ports but only using two single-mode waveguides. Such a device can be fabricated in a single micromachined silica ridge structure. A photosensitive raised index layer is used for vertical confinement that supports multiple modes horizontally. We UV-write the waveguides and the Bragg gratings and provide a tilt angle to improve coupling. We have demonstrated this technology before for a polarizing waveguide-to-waveguide coupler and have simulated other unidirectional devices. We use coupled mode theory to simulate the system. By tailoring the grating parameters, we can achieve a wide variety of coupling ratios. Analytically, we find a set of solutions in which no light escapes via the cladding modes through the ends of the device and we have calculated device parameters to achieve a wide range of splitting ratios including coupling light from one input port equally into all output ports. Moreover, we derived analytically a set of parameters to implement a Walsh-Hadamard transformation and are investigating further options to implement a universal 4x4mode-coupler on this platform. We envisage that the device can be used for quantum information processing where two qubits are encoded in the waveguides using a photon in each propagation direction.

Text
2003 SPIE-Photonics-EU_Abstract3_MatW - Accepted Manuscript
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More information

Published date: 6 April 2020
Venue - Dates: SPIE Photonics Europe 2020, France, 2020-03-29 - 2020-04-02

Identifiers

Local EPrints ID: 439349
URI: http://eprints.soton.ac.uk/id/eprint/439349
PURE UUID: ca23ffdc-1cb6-4852-874f-6bb8befef4ed
ORCID for Mathias, John Weisen: ORCID iD orcid.org/0000-0003-0387-972X
ORCID for James Gates: ORCID iD orcid.org/0000-0001-8671-5987
ORCID for Corin Gawith: ORCID iD orcid.org/0000-0002-3502-3558
ORCID for Peter G.R. Smith: ORCID iD orcid.org/0000-0003-0319-718X
ORCID for Peter Horak: ORCID iD orcid.org/0000-0002-8710-8764

Catalogue record

Date deposited: 17 Apr 2020 16:30
Last modified: 18 Feb 2021 16:59

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