title: Ultra-compact broadband mode converter and optical diode based on linear rod-type photonic crystal waveguide.
abstract: In this paper, we present extremely compact designs of both broadband mode converter and optical diode in linear rod-type photonic crystal (PhC) waveguide with functional region consisting of only 4 × 1 unit cells of perfect PhC. The dielectric distribution inside functional region are optimized by combining geometry projection method and method of moving asymptotes. Bidirectional mode converter realizes above 60% transmission efficiency within bandwidth 0.02c/a, where c and a represent light velocity and PhC lattice constant respectively. Optical diode achieves above 19 dB unidirectionality for even mode within bandwidth 0.01c/a. Moreover, the proposed designs have reasonable tolerance of rod boundary fluctuation. We expect the results will help developing recipes for future PhC devices in all-optical integrated circuits.
authors.forename: Han
authors.initials: H
authors.lastname: Ye
authors.forename: Donglin
authors.initials: D
authors.lastname: Wang
authors.forename: Zhongyuan
authors.initials: Z
authors.lastname: Yu
authors.forename: Jinqiannan
authors.initials: J
authors.lastname: Zhang
authors.forename: Zhihui
authors.initials: Z
authors.lastname: Chen