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Design and fabrication of indium phosphide air-bridge waveguides with MEMS functionality

Design and fabrication of indium phosphide air-bridge waveguides with MEMS functionality
Design and fabrication of indium phosphide air-bridge waveguides with MEMS functionality
We present the design and fabrication of a dual air-bridge waveguide structure integrated with MEMS functionality. The structure is designed to function as a tunable optical buffer for telecommunication application. The optical buffer structure is based on two parallel waveguides made of high refractive index material with subwavelength dimensions. They are suspended in air, and are separated by a sub-micron air gap. Due to the fact that the size of the waveguides is much smaller than the wavelength of light that propagates in the structure, a significant fraction of the optical mode is in the air gap between the waveguides. By changing the size of the air gap using MEMS techniques, we can vary this fraction and hence the effective refractive index of the waveguide structure, thus generating tunable optical delay.

The optical buffer structure was grown on an InP substrate by molecular beam epitaxy, and the device layer was made of InGaP. An InGaAs layer was sandwiched between the device layer and the substrate to serve as a sacrificial layer. The sub-micron waveguides, their supports in the form of side pillars with tapered shapes in order to minimize optical losses, and the MEMS structures were patterned using electron beam lithography and plasma etching. Electrodes were integrated into the structure to provide electrostatic actuation. After the sample patterning, the waveguide structure was released using HF etch. Our simulations predict that by varying the waveguide separation from 50 nm to 500 nm, we could achieve a change in propagation delay by a factor of two.
optical buffer, waveguide, III-V semiconductors, MEMS, MOEMS, optical delay, actuation
Ng, W.H.
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Podoliak, Nina
0908b951-00a7-48a5-bc82-631640910b9c
Horak, P.
520489b5-ccc7-4d29-bb30-c1e36436ea03
Wu, J.
5a0119e5-a760-4ff5-90b9-ec69926ce501
Liu, H.
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Stewart, W.J.
bbe93aab-9477-4f08-9042-a0c453aeb7a5
Kenyon, A.J.
e2e3bbbc-23b6-4c67-832d-9a16abf4aa31
Ng, W.H.
8d085a91-7054-4571-986b-4d6723f901ea
Podoliak, Nina
0908b951-00a7-48a5-bc82-631640910b9c
Horak, P.
520489b5-ccc7-4d29-bb30-c1e36436ea03
Wu, J.
5a0119e5-a760-4ff5-90b9-ec69926ce501
Liu, H.
c9560e2b-c593-4209-8578-39bd481ee456
Stewart, W.J.
bbe93aab-9477-4f08-9042-a0c453aeb7a5
Kenyon, A.J.
e2e3bbbc-23b6-4c67-832d-9a16abf4aa31

Ng, W.H., Podoliak, Nina, Horak, P., Wu, J., Liu, H., Stewart, W.J. and Kenyon, A.J. (2015) Design and fabrication of indium phosphide air-bridge waveguides with MEMS functionality. SPIE Microtechnologies conference, Barcelona, Spain. 04 - 06 May 2015. 6 pp .

Record type: Conference or Workshop Item (Paper)

Abstract

We present the design and fabrication of a dual air-bridge waveguide structure integrated with MEMS functionality. The structure is designed to function as a tunable optical buffer for telecommunication application. The optical buffer structure is based on two parallel waveguides made of high refractive index material with subwavelength dimensions. They are suspended in air, and are separated by a sub-micron air gap. Due to the fact that the size of the waveguides is much smaller than the wavelength of light that propagates in the structure, a significant fraction of the optical mode is in the air gap between the waveguides. By changing the size of the air gap using MEMS techniques, we can vary this fraction and hence the effective refractive index of the waveguide structure, thus generating tunable optical delay.

The optical buffer structure was grown on an InP substrate by molecular beam epitaxy, and the device layer was made of InGaP. An InGaAs layer was sandwiched between the device layer and the substrate to serve as a sacrificial layer. The sub-micron waveguides, their supports in the form of side pillars with tapered shapes in order to minimize optical losses, and the MEMS structures were patterned using electron beam lithography and plasma etching. Electrodes were integrated into the structure to provide electrostatic actuation. After the sample patterning, the waveguide structure was released using HF etch. Our simulations predict that by varying the waveguide separation from 50 nm to 500 nm, we could achieve a change in propagation delay by a factor of two.

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More information

Published date: May 2015
Venue - Dates: SPIE Microtechnologies conference, Barcelona, Spain, 2015-05-04 - 2015-05-06
Keywords: optical buffer, waveguide, III-V semiconductors, MEMS, MOEMS, optical delay, actuation
Organisations: Optoelectronics Research Centre, Quantum, Light & Matter Group

Identifiers

Local EPrints ID: 384460
URI: http://eprints.soton.ac.uk/id/eprint/384460
PURE UUID: f3faa83b-d74d-4fe8-be19-cbc68d5fc190
ORCID for Nina Podoliak: ORCID iD orcid.org/0000-0002-3146-0355
ORCID for P. Horak: ORCID iD orcid.org/0000-0002-8710-8764

Catalogue record

Date deposited: 02 Dec 2015 10:10
Last modified: 15 Mar 2024 03:36

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Contributors

Author: W.H. Ng
Author: Nina Podoliak ORCID iD
Author: P. Horak ORCID iD
Author: J. Wu
Author: H. Liu
Author: W.J. Stewart
Author: A.J. Kenyon

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