Dynamic electromagnetic metamaterials

Fan, Kebin; Padilla, Willie J.

doi:10.1016/j.mattod.2014.07.010

Cited by 181 publications

(99 citation statements)

References 111 publications

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“…[14][15][16] Recently, much effort has been devoted to the development of dynamically tunable metamaterials (see refs. [17][18][19][20][21][22][23][24] and the references therein). Although the modulation of optical chiral effects is achieved by hybridizing chiral metamaterials with tunable media, [25,26] the effects demonstrated are highly dispersive since they are based on resonance shifts.…”

Section: Introductionmentioning

confidence: 99%

Polarization‐Induced Chirality in Metamaterials via Optomechanical Interaction

Liu

Powell

Guo

et al. 2016

Advanced Optical Materials

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manipulate the optical chiral effect, i.e., to not only control the strength but also the sign of chirality over the entire resonance band, one needs to dynamically and spatially control the structural symmetry at the subwavelength scale. This becomes challenging for metamaterial structures operating at infrared or optical frequencies, and introducing dielectrics to avoid the high losses of metals further increases the demands on the design.One of the promising approaches for reconfiguring all-dielectric metamaterials and metasurfaces is to exploit optomechanical effects. [27][28][29][30][31][32] As has been shown in the previous studies, the direction of an optical force acting on optomechanical structures is determined by the symmetry of the eigenmode profiles; [33][34][35] to generate an optical force acting in a certain direction, one needs to break the structural symmetry in that direction [28,31,36] -this is the case when the internal optical force of the system, originating from the near-field interaction within the system, dominates.However, in open systems like metamaterials, in addition to the internal force, there is also a non-negligible external force due to the interaction of incident light and the system, and the latter can be designed to be much stronger than the former. Importantly, since the external force has many degrees of freedom controlled by the incident wave, it provides a new possibility to generate an optical force and even to control its direction without the restrictions imposed by structural symmetry.Here, we introduce an optomechanical paradigm that allows full spatial control of metamaterials and metasurfaces working at infrared and optical frequencies. First, we show analytically that for a general two-resonator coupled system, the optical forces acting on the two resonators are asymmetric as long as the incident field can simultaneously excite the two normal modes of the system, i.e., the symmetric and antisymmetric modes. We propose a simple system based on nonparallel coupled dipole meta-atoms, which is inherently achiral (mirror symmetric). We show analytically and numerically that due to the interaction and the collective enhancement in the array structure, the external force acting on the dipole metaatoms can become highly asymmetric if the incident polarization explicitly breaks the mirror symmetry of the system, i.e., when it is not aligned with the symmetry axes of the system or becomes circularly polarized. This relative force is maximized around the antisymmetric mode, where the unusual phase response of the coupled meta-atoms leads to optical forces A novel type of metamaterial is introduced, where the structural symmetry can be controlled by optical forces. Since symmetry sets fundamental bounds on the optical response, symmetry breaking changes the properties of metamaterials qualitatively over the entire resonant frequency band. This is achieved by a polarized pump beam, exerting optical forces which are not constrained by the structural symmetry. This new concept ...

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Section: Introductionmentioning

confidence: 99%

Polarization‐Induced Chirality in Metamaterials via Optomechanical Interaction

Liu

Powell

Guo

et al. 2016

Advanced Optical Materials

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“…Recently, several researchers have attempted to combine the metamaterial with micromechanical structures 21 . By mechanically changing the geometry of the metamaterials, the optical properties can be modulated effectively, and several novel phenomena have been realized, such as state switching, anisotropy control, and resonance shifting [22][23][24] . However, most studies have focused on realizing actively tunable metamaterials, and the novel properties of photomechanical metamaterials, which may have numerous potential applications, for example, THz imaging, have been relatively less studied.…”

Section: Introductionmentioning

confidence: 99%

Photomechanical meta-molecule array for real-time terahertz imaging

Wen

Jia

et al. 2017

Microsyst Nanoeng

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Real-time terahertz (THz) imaging offers remarkable application possibilities, especially in the security and medical fields. However, most THz detectors work with scanners, and a long image acquisition time is required. Some thermal detectors can achieve realtime imaging by using a focal plane array but have the drawbacks of low sensitivity due to a lack of suitable absorbing materials. In this study, we propose a novel photomechanical meta-molecule array by conveniently assembling THz meta-atom absorbers and bi-material cantilevers together, which can couple THz radiation to a mechanical deflection of the meta-molecules with high efficiency. By optically reading out the mechanical deflections of all of the meta-molecules simultaneously, real-time THz imaging can be achieved. A polyimide sacrificial layer technique was developed to fabricate the device on a glass wafer, which facilitates the transmission of a readout light while the THz wave radiates onto the meta-molecule array directly from the front side. THz images and video of various objects as well as infrared images of the human body were captured successfully with the fabricated metamolecule array. The proposed photomechanical device holds promise in applications in single and broadband THz as well as infrared imaging.

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“…The EM behavior of metamaterial unit cell is modified intentionally using different reconfigurable methods such as mechanical, thermal and electrical. The metamaterial can be reconfigured mechanically by changing the distance between the metamaterial elements, or the distance between the metamaterial and the substrate, thus modifying the local dielectric environment and hence the resonance response but with increasing the complexity of the design and cost of fabrication [11]. On the other hand, many materials undergo a change of their EM properties as a function of temperature such as refractive index.…”

Section: Introductionmentioning

confidence: 99%

Reconfigurable Metamaterial Structure at Millimeter Wave Frequency Range

Esmail¹,

Majid²,

Abidin³

et al. 2017

IJECE

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In this paper, reconfigurable metamaterial structure at millimeter wave frequency range was designed and simulated for a future fifth generation (5G) mobile-phone beam switching applications. The new proposed structure was composed of a bridge-shaped resonator (BSR) in the front face and strip line at the back face of the unit cell which operates at 28GHz. First, nonreconfigurable low loss BSR unit cell was designed and subsequently, the reconfigurability was achieved using four switches formed in the gaps of the structure. The proposed structure achieves the lowest loss and almost full transmission among its counterparts by -0.06dB (0.99 in linear scale). To demonstrate the reconfigurability of the metamaterial, the reflection and transmission coefficients and real parts of the effective refractive index at each reconfigured frequency were studied and investigated. Simulation results showed that a high transmission and reflection peaks occur at each resonance frequency according to change the state of the switches. [6]. The study of the negative index metamaterials has been enhanced through various strategies and processes. However, few issues have been encountered such as the narrow bandwidths and losses that limit the spectrum and the range of their applications. Metamaterials suffer from high losses when the frequency is pushed to the higher range such as millimeter wave (MMW) bands [7]. However, the losses are very low and the unusual electromagnetic properties of the metamaterials can still be achieved within the microwave frequency region. The losses can give negative influences and adverse effects toward the realizations of the unique electromagnetic properties of the metamaterials. Throughout the years, the researchers had been proposed various technique to reduce such losses. Keyword: 5GA number of diverse techniques are extensively reported in the literature to compensate the metamaterials losses at microwave and terahertz such as tailoring geometry of metamaterial unit cell [8], using the electromagnetically induced transparency (EIT) at low frequency range [9], integrate an active

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Dynamic electromagnetic metamaterials

Cited by 181 publications

References 111 publications

Polarization‐Induced Chirality in Metamaterials via Optomechanical Interaction

Polarization‐Induced Chirality in Metamaterials via Optomechanical Interaction

Photomechanical meta-molecule array for real-time terahertz imaging

Reconfigurable Metamaterial Structure at Millimeter Wave Frequency Range

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