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Register a new userExposing and extending the interior waves field by transformation materials
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Based on transformation optics, a strategy is proposed to expose the inner one-dimensional space of a wave field inside a beam volume to the surface of the propagation medium and extend the space from one-dimensional to two-dimensional, allowing the corresponding field distribution to be detected directly and more subtly, which is important in optical signal processing. The method is applied to the quadratic graded index lens to construct a new graded index lens, and its enhanced chirpyness detection ability is demonstrated by numerical simulation.
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The propagation of electromagnetic surface waves guided by the planar interface of two isotropic chiral materials, namely materials $calA$ and $calB$, was investigated by numerically solving the associated canonical boundary-value problem. Isotropic chiral material $calB$ was modeled as a homogenized composite material, arising from the homogenization of an isotropic chiral component material and an isotropic achiral, nonmagnetic, component material characterized by the relative permittivity $eps_a^calB$. Changes in the nature of the surface waves were explored as the volume fraction $f_a^calB$ of the achiral component material varied. Surface waves are supported only for certain ranges of $f_a^calB$; within these ranges only one surface wave, characterized by its relative wavenumber $q$, is supported at each value of $f_a^calB$. For $mbox{Re} lec eps_a^calB ric > 0 $, as $left| mbox{Im} lec eps_a^calB ric right|$ increases surface waves are supported for larger ranges of $f_a^calB$ and $left| mbox{Im} lec q ric right|$ for these surface waves increases. For $mbox{Re} lec eps_a^calB ric < 0 $, as $ mbox{Im} lec eps_a^calB ric $ increases the ranges of $f_a^calB$ that support surface-wave propagation are almost unchanged but $ mbox{Im} lec q ric $ for these surface waves decreases. The surface waves supported when $mbox{Re} lec eps_a^calB ric < 0 $ may be regarded as akin to surface-plasmon-polariton waves, but those supported for when $mbox{Re} lec eps_a^calB ric > 0 $ may not.
Breaking the diffraction limit is always an appealing topic due to the urge for a better imaging resolution in almost all areas. As an effective solution, the superlens based on the plasmonic effect can resonantly amplify evanescent waves, and achieve subwavelength resolution. However, the natural plasmonic materials, within their limited choices, usually have inherit high losses and are only available from the infrared to visible wavelengths. In this work, we have theoretically and experimentally demonstrated that the arbitrary materials, even air, can be used to enhance evanescent waves and build low loss superlens with at the desired frequency. The operating mechanisms reside in the dispersion-induced effective plasmons in a bounded waveguide structure. Based on this, we constructed the hyperbolic metamaterials and experimentally verified its validity in the microwave range by the directional propagation and imaging with a resolution of 0.087 wavelength. We have also demonstrated that the imaging potential can be extended to terahertz and infrared bands. The proposed method can break the conventional barriers of plasmon-based lenses and bring new possibilities to the field of superresolution imaging from microwave to infrared wavelengths.
We theoretically investigate the existence and properties of hybrid surface waves forming at interfaces between left-handed materials and dielectric birefringent media. The existence conditions of such waves are found to be highly relaxed in comparison to the original hybrid surface waves, discovered by Dyakonov, in configurations involving birefringent materials and right-handed media. Hybrid surface waves in left-handed materials feature remarkable properties: (i) a high degree of localization and (ii) coexistence of several guided solutions. The existence of several hybrid surface waves for the same parameter set is linked to the birefringent nature of the medium whereas the strong localization is related to the presence of the left-handed material. The hybrid surface modes appear for large areas in the parameter space.
Abbes resolution limit, one of the best-known physical limitations, poses a great challenge for any wave systems in imaging, wave transport, and dynamics. Originally formulated in linear optics, this Abbes limit can be broken using nonlinear optical interactions. Here we extend the Abbe theory into a nonlinear regime and experimentally demonstrate a far-field, label-free, and scan-free super-resolution imaging technique based on nonlinear four-wave mixing to retrieve near-field scattered evanescent waves, achieving sub-wavelength resolution of $lambda/15.6$. This method paves the way for application in biomedical imaging, semiconductor metrology, and photolithography.
The coordinate transformation technique is applied to the design of perfect lenses and superlenses. In particular, anisotropic metamaterials that magnify two-dimensional planar images beyond the diffraction limit are designed by the use of oblate spheroidal coordinates. The oblate spheroidal perfect lens or superlens can naturally be used in reverse for lithography of planar subwavelength patterns.
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