Broadband frequency translation through time refraction in an epsilon-near-zero material
Abstract
Space-time duality in paraxial optical wave propagation implies the existence of intriguing effects when light interacts with a material exhibiting two refractive indexes separated by a boundary in time. The direct consequence of such time-refraction effect is a change in the frequency of light while leaving the wavevector unchanged. Here, we experimentally show that the effect of time refraction is significantly enhanced in an epsilon-near-zero (ENZ) medium as a consequence of the optically induced unity-order refractive index change in a sub-picosecond time scale. Specifically, we demonstrate broadband and controllable shift (up to 14.9 THz) in the frequency of a light beam using a time-varying subwavelength-thick indium tin oxide (ITO) film in its ENZ spectral range. Our findings hint at the possibility of designing (3 + 1)D metamaterials by incorporating time-varying bulk ENZ materials, and they present a unique playground to investigate various novel effects in the time domain.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- May 01, 2020
- Source ID
- 10.1038/s41467-020-15682-2
Entities
People
- Alan E. Willner
- Cong Liu
- Jeremy Upham
- M. Zahirul Alam
- Mohammad M. Karimi
- Orad Reshef
- Robert W. Boyd
- Yiyu Zhou
Organizations
- Natural Sciences and Engineering Research Council
- Office of Naval Research
- United States Department of Defense