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Proceedings Paper

Design and fabrication of indium phosphide air-bridge waveguides with MEMS functionality
Author(s): Wing H. Ng; Nina Podoliak; Peter Horak; Jiang Wu; Huiyun Liu; William J. Stewart; Anthony J. Kenyon
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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.

Paper Details

Date Published: 21 May 2015
PDF: 6 pages
Proc. SPIE 9517, Smart Sensors, Actuators, and MEMS VII; and Cyber Physical Systems, 95170A (21 May 2015); doi: 10.1117/12.2178612
Show Author Affiliations
Wing H. Ng, Univ. College London (United Kingdom)
Nina Podoliak, Univ. of Southampton (United Kingdom)
Peter Horak, Univ. of Southampton (United Kingdom)
Jiang Wu, Univ. College London (United Kingdom)
Huiyun Liu, Univ. College London (United Kingdom)
William J. Stewart, Univ. of Southampton (United Kingdom)
Anthony J. Kenyon, Univ. College London (United Kingdom)

Published in SPIE Proceedings Vol. 9517:
Smart Sensors, Actuators, and MEMS VII; and Cyber Physical Systems
José Luis Sánchez-Rojas; Riccardo Brama, Editor(s)

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