Function expansion based topology optimization of NRD guide device using hybrid method of harmony search and gradient method

In recent years, optimization technique has attracted a lot of attention to develop high performance electromagnetic devices and various kinds of design strategies have been reported. Among them, topology opti-mization method has potential to develop innovative devices. In this paper, the function expansion based topology optimization method, which has been developed for design of photonic devices, is extended to be applied to design of nonradiative dielectric waveguide (NRD guide) devices. In the optimal design of NRD guide devices, solution search sometimes tends to fall into local minimum compared with the design of photonic devices. Therefore, we develop a novel hybrid optimization method combining har-mony search which is one of the evolutionary algorithm and gradient method using adjoint variable method for robust and efficient design of NRD guide devices.