Magnet-Free Optical Tesla Valve in Photonic Crystal Cavity-Waveguides and Experimental Demonstration
Abstract
The unidirectional transmission of electromagnetic (EM) waves based on Faraday rotation typically involves magnetic materials, which limits the integration of such devices at the chip level. Sparked by the wave-particle duality of electromagnetic waves in quantum theory and by the unidirectional transportation property of conventional fluidic Tesla valve (FTV), we proposed and demonstrated numerically and experimentally an optical Tesla valve (OTV) comprising photonic crystal cavity-waveguides entirely using magnet-free dielectrics. Spatial-reversal symmetry is broken, which, for a photon stream, is equivalent to apparent time-reversal symmetry breaking that is responsible for the unidirectional transmission property of the proposed OTV. The realized OTV exhibits a unidirectional transmission with a stopping factor of more than 40 dB at the microwave frequency. The proposed cavity-waveguide system is made of a single photonic crystal rather than multiple periodic structures. The experimentally demonstrated OTV has potential applications in optical, photonic, and quantum optics technologies, opening up a new way to control electromagnetic waves and other waves, such as acoustic waves, pressure waves, and soliton waves.