title: Low-loss Si3N4 arrayed-waveguide grating (de)multiplexer using nano-core optical waveguides.
abstract: A 16-channel 200 GHz arrayed-waveguide grating (AWG) (de)-multiplexer is demonstrated experimentally by utilizing Si3N4 buried optical waveguides, which have 50 nm-thick Si3N4 cores and a 15 μm-thick SiO2 cladding. The structure with an ultra-thin core layer helps to reduce the scattering due to the sidewall roughness and consequently shows very low loss of about 0.4~0.8 dB/m. When using this type of optical waveguide for an AWG (de)multiplexer, there is no problem associated with gap refill using the upper-cladding material even when choosing a small (e.g., 1.0 μm) gap between adjacent arrayed waveguides, which helps to reduce the transition loss between the FPR (free-propagation region) and the arrayed waveguides. Therefore, the demonstrated AWG (de)multiplexer based on the present Si3N4 buried optical waveguides has a low on-chip loss. The fabricated AWG (de)multiplexer is characterized in two wavelength ranges around 1310 nm and 1550 nm, respectively. It shows that the crosstalk from adjacent and non-adjacent channels are about -30 dB, and -40 dB, respectively, at the wavelength range of 1310 nm. The Si3N4 AWG (de)multiplexer has a temperature dependence of about 0.011 nm/°C, which is close to that of a pure SiO2 AWG device.
authors.affiliation: Department of Electrical and Computer Engineering, University of California, Santa Barbara, CA 93106, USA. dxdai@ece.ucsb.edu
authors.forename: Daoxin
authors.initials: D
authors.lastname: Dai
authors.forename: Zhi
authors.initials: Z
authors.lastname: Wang
authors.forename: Jared F
authors.initials: JF
authors.lastname: Bauters
authors.forename: M-C
authors.initials: MC
authors.lastname: Tien
authors.forename: Martijn J R
authors.initials: MJ
authors.lastname: Heck
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Blumenthal
authors.forename: John E
authors.initials: JE
authors.lastname: Bowers