NEWS and LATEST RESEARCH
Wei Ting Chen, Joon-Suh Park, Justin Marchioni, Sophia Millay, Kerolos M. A. Yousef and Federico Capasso, "Dispersion-engineered metasurfaces reaching broadband 90% relative diffraction efficiency," Nature Communications 14, 2544 (2023).
I reported dispersion engineered nanostructures that enable broadband and polarization-insensitive metasurface components reaching 90% relative diffraction efficiency (normalized to the power of transmitted light) from 450 nm to 700 nm in wavelength. Relative diffraction efficiency is important at a system level – in addition to diffraction efficiency (normalized to the power of incident light) – as it considers only the transmitted optical power that can affect the signal to noise ratio.
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Jared Sisler, Wei Ting Chen, Alexander Y. Zhu and Federico Capasso, "Controlling dispersion in multifunctional metasurfaces," APL Photonics 5, 056107 (2020).
Conventional metasurfaces are usually designed at a wavelength to implement a target phase profile. In this paper, we report a more general design strategy by considering phase and group delay profiles at design wavelengths. This enables multi-functional metasurface devices with controlled dispersion characteristics. To proof the concept, we design and simulate metalenses with dual focal lengths and tailored focal length shifts in two discrete bandwidths in the visible spectrum as well as a metalens capable of achromatically focusing an incident plane wave to Airy disk and vortex spots for red and blue wavelengths.
W. T. Chen, A. Y. Zhu, J. Sisler, Z. Bharwani, F. Capasso, "A broadband achromatic polarization-insensitive metalens consisting of anisotropic nanostructures," Nat. Commun. 10, 355 (2019).
Polarization-insensitive metasurfaces usually comprise isotropic nanostructures. This greatly restricts the number of geometric parameters available in design. I demonstrated a polarization-insensitive metalens using otherwise anisotropic nanofins which offer additional control over the dispersion and phase of the output light. The polarization-insensitive metalens is achromatic across nearly the entire visible spectrum from wavelength λ = 460 nm to 700 nm with diffraction-limited performance. The metalens can image color objects, such as circular rainbow and letters of "R", "G" and "B" of three preliminary colors.
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