title: Spot-size converter with a SiO(2) spacer layer between tapered Si and SiON waveguides for fiber-to-chip coupling.
abstract: We experimentally demonstrate low-loss and polarization-insensitive fiber-to-chip coupling spot-size converters (SSCs) comprised of a three dimensionally tapered Si wire waveguide, a SiON secondary waveguide, and a SiO(2) spacer inserted between them. Fabricated SSCs with the SiO(2) spacer exhibit fiber-to-chip coupling loss of 1.5 dB/facet for both the quasi-TE and TM modes and a small wavelength dependence in the C- and L-band regions. The SiON secondary waveguide is present only around the SSC region, which significantly suppresses the influence of the well-known N-H absorption of plasma-deposited SiON at around 1510 nm.
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Maegami
authors.forename: Ryohei
authors.initials: R
authors.lastname: Takei
authors.forename: Emiko
authors.initials: E
authors.lastname: Omoda
authors.forename: Takeru
authors.initials: T
authors.lastname: Amano
authors.forename: Makoto
authors.initials: M
authors.lastname: Okano
authors.forename: Masahiko
authors.initials: M
authors.lastname: Mori
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Kamei
authors.forename: Youichi
authors.initials: Y
authors.lastname: Sakakibara