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Title: Controlling the sign of chromatic dispersion in diffractive optics with dielectric metasurfaces

Diffraction gratings disperse light in a rainbow of colors with the opposite order than refractive prisms, a phenomenon known as negative dispersion. While refractive dispersion can be controlled via material refractive index, diffractive dispersion is fundamentally an interference effect dictated by geometry. Here we show that this fundamental property can be altered using dielectric metasurfaces, and we experimentally demonstrate diffractive gratings and focusing mirrors with positive, zero, and hyper-negative dispersion. These optical elements are implemented using a reflective metasurface composed of dielectric nano-posts that provide simultaneous control over phase and its wavelength derivative. In addition, as a first practical application, we demonstrate a focusing mirror that exhibits a five-fold reduction in chromatic dispersion, and thus an almost three-times increase in operation bandwidth compared with a regular diffractive element. This concept challenges the generally accepted dispersive properties of diffractive optical devices and extends their applications and functionalities.
Authors:
 [1] ;  [2] ;  [1] ;  [1] ;  [1]
  1. California Inst. of Technology (CalTech), Pasadena, CA (United States). T. J. Watson Lab. of Applied Physics
  2. California Inst. of Technology (CalTech), Pasadena, CA (United States). T. J. Watson Lab. of Applied Physics; Univ. of Massachusetts, Amherst, MA (United States). Dept. of Electrical and Computer Engineering
Publication Date:
Grant/Contract Number:
SC0001293; 1512266
Type:
Accepted Manuscript
Journal Name:
Optica
Additional Journal Information:
Journal Volume: 4; Journal Issue: 6; Journal ID: ISSN 2334-2536
Publisher:
Optical Society of America
Research Org:
California Inst. of Technology (CalTech), Pasadena, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF); Defense Advanced Research Projects Agency (DARPA) (United States)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; beam steering; diffraction gratings; diffractive optics; effective refractive index; Fresnel zones; reflection coefficient
OSTI Identifier:
1467089