Genetically Optimized Design of Ultra-Compact and Highly Efficient Waveguide Crossing, Optical Attenuator and Reflector

In this study, we present the design of ultra-compact and highly efficient photonic integrated devices by applying a meta-heuristic approach. Here, we integrated the three-dimensional finite-difference time-domain method into an evolutionary optimization algorithm to specifically design waveguide crossing, optical attenuator and reflector. The proposed devices have ultra-compact footprints of 2×2 μm ² with slab thickness of 220 nm and consist of 100×100 nm ² silicon or air cells on a SiO ₂ substrate. We demonstrate an ultra-compact waveguide cross on silicon photonic platform with transmission efficiency greater than 80% and with a negligible crosstalk. Also designed attenuator and reflector devices are providing 3 dB signal reduction and over 85% reflectivity, respectively. All of the devices are excited by a fundamental transverse-electric mode guided in a silicon waveguide with a width of 500 nm. Throughout the optimization process, fabrication constraints are taken into account to enable the realization of the designed devices in applications. The introduced design method can be further expanded to form either diverse photonic integrated devices or even plasmonic devices.