Theoretical investigation of compact high-resolution interleaved arrayed waveguide gratings with multi-layer structures

Abstract

In this paper, a compact high-resolution two-stage interleaved arrayed waveguide grating (AWG) system with a 3D structure on a silicon nitride (Si3N4) platform is proposed. The device is comprised of a 7-channel primary AWG with a 0.4-nm resolution and seven 26-channel second-stage AWGs, each with a 2.8-nm resolution. Different arrayed waveguide widths are utilized to achieve the wavelength tuning of the second-stage AWGs. The AWGs have a greater fabrication tolerance than conventional AWGs. A taper-MMI input structure is utilized to make the -3 dB pass-band reach 0.4 nm, which is 100% of the channel spacing. Also, the horizontal slot arrayed waveguides are individually introduced into the AWG to reduce the inter-layer crossing and bending losses, which is also found to greatly reduce the footprint of the device. The proposed AWGs have an average crosstalk of about -24 dB in the 2-µm band, demonstrating the feasibility of the on-chip 3D optoelectronic integration design.