Zi-Xun Jia

Optical coherent thermal emission by excitation of magnetic polariton in multilayer nanoshell trimer.

A theoretical demonstration is given of coherent thermal emission via the visible region by exciting magnetic polaritons in isolated metal-dielectric-metal multilayer nanoshells and the collective behavior in a trimer comprising multilayer nanoshells. The dipolar metallic core induces magnetic polaritons in the dielectric shell creating a large enhancement of the emissivity, whose mechanism is different from that of film-coupled metamaterials. The coupling effect of the magnetic polaritons and the electric/magnetic modes of symmetric nanoparticle trimers is discussed to understand the collective behavior in self-assembled nanoparticle clusters with potential solar energy utilizations. The concept of hybridization is employed to understand the collective magnetic polaritons of a multilayer nanoshell trimer. The fundamental understanding gained herein opens up new ways to explore, control, and tailor spectral absorptance, thus facilitating rational design of novel self-assembled nanoclusters for energy harvesting.

Nanoparticle-crystal towards an absorbing meta-coating

In this paper, a double layer nanoparticle-crystal has been proposed, which shown incident and polarization angle, substrate independences for spectral absorptivity. Such phenomenon originates from the near-field light redistribution and excitation of internal collective oscillating. This kind of nanoparticle-crystal can be made of various types of metal with similar optical responses. A three oscillators mode has been proposed in this paper to understand the shift between global and internal collective oscillating, and verify the physical picture demonstrated. That kind of near-field redistribution result in a prototype of novel meta-coating, and facilitates the large scale application of metamaterial.

Double Directions Nanoscale Range Finding Using Fano Resonance in Coupled Gratings

In this paper, a theoretical demonstration is given of nanoscale range finding by exciting Fano resonance in coupled gratings. Metallic ridges induce oscillation mode, whose interference with surface plasmon polartions generate narrow Fano resonance. The concept of hybridization is employed to understand the coupling effect of surface plasmon polartions and the oscillation due to metallic ridges. Fano behavior in this structure is captured by using the temporal coupled-mode theory. The gained fundamental understanding opens up new ways to control nanoscale spacing distances and tailor Fano resonance, thus facilitating rational design of nanosensors to improve the performance of nanomotion control systems.

Responses transition in a monolayer Al-Al 2 O 3 nanoparticle-crystal due to oxidation

Nanoparticle is a promising candidate for large scale fabrication of metamaterial. However, optical responses for metamaterial made of abound metal like Al can be thoroughly changed due to oxidization. Especially for nanoparticle whose aspect ratio is extremely high, oxidation usually occurs. So to understand how the responses shift in a nanoparticle system due to oxidization is essential for large scale application of metamaterial. In this paper, we have concluded and quantified two general principles describing this transition in a monolayer Al-Al2O3 nanoparticle-crystal, which can be used in a thermophotovoltaic system. Square pattern, in which the unit of changing crystal is a square cell made up of Al and Al2O3 particles, is firstly demonstrated. A double oscillators model has been proposed to understand the interference between different absorption modes and their coupling. Using near-field distribution, equivalent inductor-capacitor model and dispersion relationship of surface Plasmon polariton, we have distinguished the resonance modes, concluded the transition principles in a simple case. Then the two principles are applied in a larger cell to verify its university. After detailed demonstration of symmetric square pattern, models and principles are extrapolated to more complex non-symmetric systems. The basic understanding gained here will help the design of robust large-scale metamaterial.

Graphene-Based Tunable Metamaterial Filter in Infrared Region

Abstract The extremely demanding fabrication precision has been a main block for real application of nanoscale metamaterial. To overcome this, a graphene-based tunable filter has been theoretically demonstrated to exhibit generally high filtering efficiency for the filter with mismatched geometry parameters. Rigorous coupled-wave analysis has been employed to investigate the transmission spectrum and electromagnetic field distributions for TM wave. The selectivity is understood as the excitations of surface plasmon polariton (SPP), magnetic polaritons (MP) and Fabry-Perot-like (FP) resonance. The dispersion relationship of SPP and inductor and capacitor of MP are utilized to quantitatively predict the resonance wavelengths. Moreover, the propagating electron wave on the conducting surface is employed to investigate the tuning effects. The fundamental understanding gained herein facilitates the rational design of novel graphene-based metamaterials.

Direct wavefront manipulating for a transverse electric wave microlens.

Due to the polarization nature of the transverse electric electromagnetic wave, manipulating it has been a difficult task and can be even more challenging for integrated on-chip optics. In this Letter, a transverse electric wave manipulating method based on direct wavefront bending and its physical picture have been proposed. Even with only five cells, the microlens can exhibit a focusing pattern and retrieve sub-wavelength spatial features. An analytical mode has been proposed to help understand the physical picture and verify the result. This Letter facilitates the basic understanding for transverse electric wave manipulating and the design of integrated optical elements.

Optical Bifacial Transmission by Asymmetric Charge-Oscillation-Induced Light Transmission Through a Plasmonic Structure

From first-principles computation, we reveal that optical bifacial transmission can be induced within an asymmetric metallic subwavelength structure. This phenomenon can be explained by a concrete picture in which the intensity of the driving forces for surface plasmon or charge wave is asymmetric for the two incident directions. Two distinguished different numerical methods, finite difference time domain (FDTD), and rigorous coupled wave analysis (RCWA) are utilized to verify that optical bifacial transmission can exist for linear plasmonic metamaterial. Previous results are also reviewed to confirm the physical meaning of optical bifacial transmission for a planar linear metamaterial. The incident light can provide direct driving forces for surface plasmon in one direction. While in the opposite direction, forces provided by the light diffraction are quite feeble. With the asymmetric driving forces, the excitation, propagation, and light-charge conversion of surface plasmon give the rise of bifacial charge-oscillation-induced transmission. In periodic a structure, the excitation of surface plasmon polariton can lead to the spoof vanish of such phenomenon. The transmissions for two incident directions get the same in macroscopic while the bifacial still exists in microscale.

2-Dimensional Microlens Based on Uniformed Plasmonic Pyramid Arrays

As a crucial optical element, many different kinds of microlens have been proposed and studied. In this paper, a 2-dimensional microlens has been achieved based on direct bending of wavefront. With only 25 elements, the microlens can achieve subwavelength imaging in a 2-dimensional case. Focusing pattern and sensitivity of object movement have been studied. The physical picture for focusing and imaging has been explained by the help of a Gauss dipole model. Current study can broaden the basic understanding on light-matter interaction and optical element design.