Presentation
28 April 2017 Independent control of function and chromatic dispersion in diffractive optical devices with metasurfaces (Conference Presentation)
Ehsan Arbabi, Amir Arbabi, Seyedeh Mahsa Kamali, Yu Horie, Andrei Faraon
Author Affiliations +
Proceedings Volume 10113, High Contrast Metastructures VI; 101130P (2017) https://doi.org/10.1117/12.2253726
Event: SPIE OPTO, 2017, San Francisco, California, United States
Abstract
Diffractive optical devices have many applications in various fields of optics. A fundamental property of all diffractive devices is their negative chromatic dispersion: a diffractive grating always disperses light in the opposite order compared to a refractive prism made of a material with positive (normal) dispersion. Unlike refractive devices, chromatic dispersion in diffractive devices stems from geometrical features, and cannot be controlled via the intrinsic material dispersion. In addition to the always negative sign, the amplitude of diffractive chromatic dispersion is set only by the function of the device. For instance, the angular dispersion of a grating is always given by dθ/dλ=tan⁡(θ)/λ (where θ is the deflection angle and λ is wavelength), or the focal distance dispersion of a diffractive lens is given by df/dλ=-f/λ. Therefore, the chromatic dispersion of diffractive devices has always been set by their function (e.g. by the deflection angle for a grating or the focal distance for a lens), and could not be controlled separately. Here, we present our work on breaking this fundamental relation between the function and chromatic dispersion of diffractive devices using metasurfaces providing independent control over phase and group delays. We use a reflective dielectric metasurface to experimentally demonstrate gratings and lenses that have positive, zero, and extraordinary negative chromatic dispersion. Apart from its fundamental scientific value, this concept expands the applications of diffractive devices as it enables various types of chromatic dispersions. For instance, a special case would be a dispersionless lens operating over a wide bandwidth with the same focal distance.
Conference Presentation
© (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Ehsan Arbabi, Amir Arbabi, Seyedeh Mahsa Kamali, Yu Horie, and Andrei Faraon "Independent control of function and chromatic dispersion in diffractive optical devices with metasurfaces (Conference Presentation)", Proc. SPIE 10113, High Contrast Metastructures VI, 101130P (28 April 2017); https://doi.org/10.1117/12.2253726
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KEYWORDS
Dispersion

Control systems

Optical components

Dielectrics

Prisms

Reflectivity

Current controlled current source

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