Zhongyuan Yu
State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing, China
Title: Designs of a reciprocal optical diode in silicon Waveguide
Biography
Biography: Zhongyuan Yu
Abstract
The optical diode, in which light asymmetrically propagates, has attracted great interest recently for its potential applications in integrated optical circuits. An optical diode can be built by either non-reciprocal or reciprocal structures. Typically, the non-reciprocal optical diode utilizes magneto-optical effect or optical nonlinearity. However, the external conditions and high input power limit the on-chip applications. Unlike non-reciprocal optical diodes, the reciprocity of the Lorentz theorem holds in a reciprocal optical diode. Here, we present three reciprocal optical diode designs based on both forward even-to-odd mode conversion and backward blockade of even mode. The functional region of first design consists of a tapered coupler, a narrow waveguide, and a silver surface plasmonic splitter. In order to obtain ±π phase shift, the refractive index of one of branches has been also modified. Secondly, the functional region comprises a tapered coupler, a narrow waveguide, a triangular prism and a partial depth etched cuboid. The mechanism is combining interference principle and the partial depth etching method. At last, we also design a reciprocal optical diode based on asymmetric spatial mode conversion by totally depth etching irregular shapes obtained by topological optimization. Unlike the other reported works, we do not expand the width of the slab silicon waveguide in the function region. These devices possess some satisfactory performances like high contrast ratio, large operational bandwidth and small footprint.