Silicon nitride C-band grating couplers with reduced waveguide back-reflection

Abstract

We present a C-band grating coupler for the 800 nm silicon nitride platform with fully etched grates and suppressed back-reflection. By interrupting the first few grates in the center of the beam incoming from the waveguide and gradually increasing their span, waveguide-to-waveguide back-reflection is reduced by 5-12 dB in the C-band, at which the proposed grating coupler features an extra 2.7 dB insertion losses compared to the 5.8 dB of a standard reference design. Such grating couplers are expected to be particularly useful for applications sensitive to optical feedback, such as external cavity lasers.

Authors 3

1. Ibrahim Ghannam Aachen

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen Univ. (Germany)

2. Florian Merget Aachen

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen Univ. (Germany)

3. Jeremy Witzens Aachen

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen Univ. (Germany)