Topology optimization of waveguide bends with wide, flat bandwidth in air-bridge-type photonic crystal slabs

Abstract

We employed the topology optimization (TO) method to improve the transmission bandwidth of waveguide bends in air-bridge-type, two-dimensional photonic crystal slabs. We experimentally confirmed that bend loss at longer wavelengths in the vicinity of the band edge was suppressed by using TO. The optimized bends showed good performance, comparable to that of straight waveguides.