Tight focusing of polychromatic waves using angular spectrum compensation in spatially dispersive media

General method for focusing of waves using phase and amplitude compensation

A general method for focusing of waves, based on phase and amplitude compensation, is applied to monochromatic, polychromatic and diffusive waves. Monochromatic waves may form spatially localized waves in free space, whereas polychromatic waves form non-decaying traveling evanescent modes conned to subwavelength regions in media where the frequency depends on the wave vector. We suggest an analogy between the phase compensation method and the transformation of frequencies between inertial, relativistic coordinate systems.

Multiwavelength Achromatic Metasurfaces by Dispersive Phase Compensation

The replacement of bulk refractive optical elements with diffractive planar components enables the miniaturization of optical systems. However, diffractive optics suffers from large chromatic aberrations due to the dispersion of the phase accumulated by light during propagation. We show that this limitation can be overcome with an engineered wavelength-dependent phase shift imparted by a metasurface and demonstrate a design that deflects three wavelengths without dispersion. A planar lens without chromatic aberrations at three wavelengths is also presented. Our design is based on low-loss diel…

Localized and stationary light wave modes in dispersive media

In recent experiments, localized and stationary pulses have been generated in second-order nonlinear processes with femtosecond pulses, whose asymptotic features relate with those of nondiffracting and nondispersing polychromatic Bessel beams in linear dispersive media. We investigate on the nature of these linear waves, and show that they can be identified with the X-shaped (O-shaped) modes of the hyperbolic (elliptic) wave equation in media with normal (anomalous) dispersion. Depending on the relative strengths of mode phase mismatch, group velocity mismatch with respect to a plane pulse, an…

Strong group velocity dispersion compensation with phase-engineered sheet metamaterials

Resonant metamaterials usually exhibit substantial dispersion, which is considered a shortcoming for many applications. Here we take advantage of the ability to tailor the dispersive response of a metamaterial introducing a new method of group-velocity dispersion compensation in telecommunication systems. The method consists of stacking a number of highly dispersive sheet metamaterials and is capable of compensating the dispersion of optical fibers with either negative or positive group-velocity dispersion coefficients. We demonstrate that the phase-engineered metamaterial can provide strong g…

色散介质中加速界面的时空透镜效应

Space-Time Lensing by Accelerated Interfaces in Dispersive Media

研究色散介质中加速界面的时空透镜效应，通过逆设计程序实现准单色和多色脉冲聚焦，其时间反转可准直宽带脉冲，级联操作能抑制色散，全波模拟验证了相关效应。

Ultra-Broadband Dispersion-Manipulated Dielectric Metalenses by Nonlinear Dispersive Phase Compensation

Dispersion decomposes compound light into monochromatic components at different spatial locations, which needs to be eliminated in imaging but utilized in spectral detection. Metasurfaces provide a unique path to modulate the dispersion only by adjusting the structural parameters without changing the material as required for refractive elements. However, the common linear phase compensation does not conform to the dispersion characteristics of the meta-unit limiting dispersion modulation in broader wavelength bands, which is desired for ultra-broadband or multiband imaging. Here, we propose a …