A critical component for chip-scale integrated photonics would be a non-reciprocal optical waveguide allowing light to travel in only one direction while reflecting it in the opposite one. Inspired by concepts of parity-time-symmetric quantum theories, a periodically modulated dielectric waveguide displaying unidirectional reflection is now demonstrated, reflecting light at telecom frequencies in only one direction.
- Liang Feng
- Ye-Long Xu
- Axel Scherer
