Beam shaping for ultra-compact waveguide crossings on 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 4.7µ×4.7µ were fabricated on the GLOBALFOUNDRIES 45 nm monolithic silicon photonics platform (45 CLO technology). Fabricated devices are found to be nearly wavelength independent (±0.035 for 1260≤≤1360) with low insertion loss (∼0.2) and crosstalk (-35). The measured response of the devices is consistent with the three-dimensional finite-difference time-domain simulation results. The design stability is validated by measuring the device insertion loss on eight chips, which is found to be 0.197±0.017 at the designed center wavelength of 1310 nm.