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Published on: November 30, 2012
Impedance matching vertical optical waveguide couplers for dense high index contrast circuits
Rong Sun1, Mark Beals, Andrew Pomerene
1Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA. rsun@mit.edu
Abstract:
We designed and demonstrated a compact, high-index contrast (HIC) vertical waveguide coupler for TE single mode operation with the lowest coupling loss of 0.20 dB +/- 0.05 dB at 1550 nm. Our vertical coupler consists of a pair of vertically overlapping inverse taper structures made of SOI and amorphous silicon. The vertical coupler can suppress power oscillation observed in regular directional couplers and guarantees vertical optical impedance matching with great tolerance for fabrication and refractive index variations of the waveguide materials. The coupler furthermore shows excellent broadband coupling efficiencies between 1460 nm and 1570 nm.
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