On-chip optical diode based on silicon photonic crystal heterojunctions

TL;DR

This paper presents the design, fabrication, and testing of on-chip optical diodes using silicon photonic crystal heterojunctions, achieving unidirectional light transmission for integrated photonic circuits.

Contribution

It introduces a novel all-dielectric silicon photonic crystal heterojunction approach to realize on-chip optical diodes with directional bandgap mismatch.

Findings

Demonstrated significant unidirectional transmission in experiments

Achieved good agreement between measurements and simulations

Enabled potential for on-chip optical logical devices

Abstract

Optical isolation is a long pursued object with fundamental difficulty in integrated photonics. As a step towards this goal, we demonstrate the design, fabrication, and characterization of on-chip wavelength-scale optical diodes that are made from the heterojunction between two different silicon two-dimensional square-lattice photonic crystal slabs with directional bandgap mismatch and different mode transitions. The measured transmission spectra show considerable unidirectional transmission behavior, in good agreement with numerical simulations. The experimental realization of on-chip optical diodes using all-dielectric, passive, and linear silicon photonic crystal structures may help to construct on-chip optical logical devices without nonlinearity or magnetism, and would open up a road towards photonic computers.