title: Low-loss and low wavelength-dependence vertical interlayer transition for 3D silicon photonics.
abstract: This paper presents optimized design and measurement results for a low-loss broadband vertical interlayer transition (VIT) device located between lower and upper Si nano-photonic waveguides. The device comprises the lower c-Si taper, the upper a-Si:H taper, and a wide and thin SiON secondary core with a 0.6-μm-thick SiO₂ interlayer. The device structure facilitates the low loss VIT, giving insertion losses of 0.87 and 0.79 dB for quasi-TE and TM modes, respectively, at 1550 nm. Also, the evanescent coupling nature of the VIT device renders it wavelength- and polarization-insensitive, leading to loss variation of within 0.5 dB in the C-band.
authors.forename: Ryohei
authors.initials: R
authors.lastname: Takei
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Maegami
authors.forename: Emiko
authors.initials: E
authors.lastname: Omoda
authors.forename: Youichi
authors.initials: Y
authors.lastname: Sakakibara
authors.forename: Masahiko
authors.initials: M
authors.lastname: Mori
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Kamei