Low-loss, high-bandwidth fiber-to-chip coupling using capped adiabatic tapered fibers

Published

May 1, 2020

Author(s)

Saeed Khan, Jeff Shainline, Richard Mirin, Sae Woo Nam, Sonia Buckley, Jeff Chiles

Abstract

We demonstrate adiabatically tapered fibers terminating in sub-micron tips that are clad with a higher-index material for coupling to an on-chip waveguide. This cladding enables coupling to a high-index waveguide without losing light to the buried oxide. A technique to clad the tip of the tapered fiber with a higher-index polymer is introduced. Conventional tapered waveguides and forked tapered waveguide structures are investigated for coupling from the clad fiber to the on-chip waveguide. We find the forked waveguide facilitates alignment and packaging, while the conventional taper leads to higher bandwidth. The insertion loss from a fiber through a forked coupler to a sub-micron silicon nitride waveguide is 1.1 dB and the 3 dB bandwidth is 90 nm. The coupling loss in the packaged device is 1.3 dB. With a fiber coupled to a conventional tapered waveguide, the loss is 1.4 dB with a 3 dB bandwidth extending beyond the range of the measurement apparatus, estimated to exceed 250 nm.

Citation

APL Photonics

Pub Type

Journals

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DOI Link

Citation

Khan, S. , Shainline, J. , Mirin, R. , Nam, S. , Buckley, S. and Chiles, J. (2020), Low-loss, high-bandwidth fiber-to-chip coupling using capped adiabatic tapered fibers, APL Photonics, [online], https://doi.org/10.1063/1.5145105 (Accessed April 26, 2024)