Hollow ARROW waveguides on self-aligned pedestals for high-sensitivity optical sensing

Evan J. Lunt; Brian S. Phillips; Jared M. Keeley; Aaron R. Hawkins; Philip Measor; Bin Wu; Holger Schmidt

doi:10.1117/12.841010

16 February 2010 Hollow ARROW waveguides on self-aligned pedestals for high-sensitivity optical sensing

Evan J. Lunt, Brian S. Phillips, Jared M. Keeley, Aaron R. Hawkins, Philip Measor, Bin Wu, Holger Schmidt

Proceedings Volume 7591, Advanced Fabrication Technologies for Micro/Nano Optics and Photonics III; 759109 (2010) https://doi.org/10.1117/12.841010
Event: SPIE MOEMS-MEMS, 2010, San Francisco, California, United States

Abstract

Antiresonant reflecting optical waveguides (ARROWs) provide a promising approach to realizing high-sensitivity sensing platforms on planar substrates. We have previously developed ARROW platforms that guide light in hollow cores filled with liquid and gas media. These platforms include integrated traditional solid waveguides to direct light into and out of sensing media. To improve the sensitivity of these platforms for optical sensing, hollow waveguide loss must be reduced. We are working towards this by using anisotropic plasma etching to create near-ideal hollow ARROW geometries. These structures rely on an etching mask that also serves as the sacrificial core for the waveguide. This self-aligned process creates a hollow waveguide on a pedestal which is surrounded by a terminal layer of air in three directions. We previously produced ARROWs by pre-etching the silicon substrate and aligning the sacrificial core to the pedestal. However, this necessitates using a pedestal which is wider than the core, leading to higher loss and poor reproducibility. We have also increased the hollow to solid waveguide transmission efficiency by using a design that coats the sides and top of the hollow core with a single layer of silicon dioxide. Using this design, we have demonstrated an interface transmission improvement of more than two times. A much improved optical sensor platform will incorporate both of these features, using the self-aligned pedestal process for most of the length of the hollow waveguides to decrease loss, and employing the single layer design only at the interfaces to improve hollow-solid waveguide coupling.

Citation Download Citation

Evan J. Lunt, Brian S. Phillips, Jared M. Keeley, Aaron R. Hawkins, Philip Measor, Bin Wu, and Holger Schmidt "Hollow ARROW waveguides on self-aligned pedestals for high-sensitivity optical sensing", Proc. SPIE 7591, Advanced Fabrication Technologies for Micro/Nano Optics and Photonics III, 759109 (16 February 2010); https://doi.org/10.1117/12.841010

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