Ultra-Compact Waveguide Crossings using Cosine Tapers on a Monolithic Silicon Photonics Platform

A beam shaping approach has been implemented to realize high-performance waveguide crossings based on cosine tapers. Devices with a compact footprint of 4.7 µm × 4.7 µm are implemented on a GLOBALFOUNDRIES monolithic silicon photonics platform. Fabricated devices are found to be nearly wavelength-independent (± 0.035 dB for 1260 nm ≤ λ ≤ 1360 nm) with low insertion loss (~ 0.2 dB) and crosstalk (< -35 dB). The measured response of the devices is consistent with simulation results obtained by 3D FDTD computations. The design stability is confirmed by measuring the device insertion loss over nine chips, which is found to be 0.197 ± 0.017 dB at the designed center wavelength of 1310 nm.