[show abstract][hide abstract] ABSTRACT: This paper reports our recent progress in electron beam lithography for high resolution and highly dense metallic structures such as fish scale on both silicon and quartz. To observe photonic property in optical frequency, the pitch of 500 nm with both linewidth and gap of 50 nm gap in Al is demanded. For reliable lift-off process, adequate undercut in bilayer layer of resists is essential. Three different bilayers, PMMA/LOR, PMMA/copolymer and PMMA/PMMA (with different molecular weights) were compared and the most suitable bilayer was found to be the PMMA/PMMA with a difference in molecular weight between the top and bottom layer. With such a bilayer stack, dense fish scale pattern with minimum linewidth of 50 nm in Al were fabricated for both transparent and reflective configurations. Astonishing optical properties such as magnetic wall and asymmetric propagating waves through the chiral fish scale were observed.
[show abstract][hide abstract] ABSTRACT: We report on the development of photonic 2D- and 3D-chiral meta-materials with intriguing properties including giant rotary power and asymmetric transmission which are due to the excitation of chiral and enantiomeric sensitive plasmons.
[show abstract][hide abstract] ABSTRACT: We show that in the visible to near-IR part of the spectrum, normal incidence transmission of circularly polarized light through a nanostructured anisotropic planar chiral metamaterial is asymmetric in the opposite directions. The new effect is fundamentally different from the conventional gyrotropy of bulk chiral media and the Faraday effect. It has a resonance nature associated with a new type of excitation in the metal nanostructure: the enantiomerically sensitive plasmon.
[show abstract][hide abstract] ABSTRACT: We demonstrate a novel type of chiral photonic metamaterial based on pairs of physically separated mutually twisted planar metal patterns. It exhibits very strong gyrotropy (2500°/mm) in the visible, near-infrared and microwave spectral ranges.
[show abstract][hide abstract] ABSTRACT: The authors demonstrate a chiral photonic metamaterial with chirality provided by electromagnetic coupling between mutually twisted unconnected layers. In the visible and near-IR spectral ranges, the material exhibits polarization rotatory power of up to 2500°/mm and shows relatively low losses and negligible circular dichroism, making it a promising candidate for the development of chiral negative index media.
[show abstract][hide abstract] ABSTRACT: We demonstrate novel chiral photonic metamaterials consisting of physically separated mutually twisted planar metal patterns in parallel planes. Such metamaterials are shown to exhibit very strong gyrotropy (600°/mm) in the visible, near-IR and microwaves.
[show abstract][hide abstract] ABSTRACT: We report on the observation of enhanced microwave transmission through quasi-periodic hole arrays in metal films. The fraction of transmitted light reaches 50% in a self-standing metal film and approaches 90% when the film is sandwiched between thin dielectric slabs, while the holes occupy only 10% of the sample area. The maximum transmission is accompanied by zero phase change, rendering the film almost 'invisible' over a wide frequency range. The extraordinary transmission phenomenon is interpreted in terms of resonances in the self-consistent interaction between holes, which are represented by effective electric and magnetic dipoles. Comment: 4 pages, 2 figures
[show abstract][hide abstract] ABSTRACT: We report the first demonstration of an optical magnetic mirror achieved by nanostructuring a metal surface. It reverses the magnetic field of an incident wave upon reflection, acting as an 'optical frequency superconductor'.
Journal of Optics A Pure and Applied Optics 01/2007; 9(1). · 1.92 Impact Factor
[show abstract][hide abstract] ABSTRACT: This paper reviews our recent progress in nanoimprint lithography and hot embossing for the fabrications of planar photonic meta-materials and photonic gratings. With these technologies, dielectric, metallic chiral structures and dense gratings in sizes from sub micrometres down to sub-100 nm were successfully fabricated. Characterisations of these meta-materials and photonic structures indicate these materials and structures are functional. It can be concluded that nanoimporint lithography and hot embossing are capable of achieving large area planar optic meta-materials and photonic structures such as dense gratings. This progress suggests the great prospect of these techniques for fast speed patterning of important meta materials and photonic nanostructures with high throughput at low cost in mass production in the future.
Biophotonics, Nanophotonics and Metamaterials, 2006. Metamaterials 2006. International Symposium on; 11/2006
[show abstract][hide abstract] ABSTRACT: We report experimental evidence that electromagnetic coupling between physically separated planar metal patterns located in parallel planes provides for extremely strong polarization rotatory power if one pattern is twisted with respect to the other, creating a chiral object. In terms of a rotary power per sample thickness equal to one wavelength, the bilayered structure rotates 5 orders of magnitude stronger than a gyrotropic crystal of quartz in the visible spectrum.
[show abstract][hide abstract] ABSTRACT: This paper reviews our recent progress of micro and nanolithography techniques for the fabrications of planar photonic meta-materials and other nano photonic structures. The nanotechnologies involved in this development include the state-of-the-art electron-beam lithography (EBL), nanoimprint lithography (NIL), hot embossing, soft lithography and hybrid lithography, which is the combination of different lithography processes. Using these technologies, various meta-materials in sizes from micrometres down to sub-100 nm were successfully fabricated. Characterisations of these meta-materials have revealed a wealth of novel phenomena in nanophotonics. This paper will also discuss the advantages, disadvantages and suitability of each technology involved, trying to give a fair judgement for the applicability of the developed techniques. It can be concluded that micro and nanolithography are capable of achieving functional planar optic meta-materials in both single layer and multiple layer. Especially the developed manufacture processes using nanoimprint lithography and hot embossing technique may lead to fast speed patterning for high throughput and low cost mass production for broad applications.
[show abstract][hide abstract] ABSTRACT: We report on a new type of composite metallic structure for nonlinear optics and nonlinear plasmonics, created by grain boundary penetration of gallium into an aluminum film. These composite films form mirrorlike interfaces with silica and show an exceptionally broadband phase-transition-based nonlinear response to optical excitation.
[show abstract][hide abstract] ABSTRACT: Simulations of Maxwell’s equations for electromagnetic waves interacting with planar chiral structures are shown to depend
on the polarization state of the exciting light field. These results illustrate generic features of light interaction with
planar chiral structures and imply broken enantiomeric symmetry for excitation with circularly polarized light.
Applied Physics B 07/2006; 84(1):97-101. · 1.78 Impact Factor
[show abstract][hide abstract] ABSTRACT: We report on the first observation of extraordinary transmission exhibited by arrays of holes arranged in a 2D quasicrystal in both microwave and optical parts of the spectrum, indicating a non-plasmon nature of the effect.
[show abstract][hide abstract] ABSTRACT: We report demonstration of an optical magnetic mirror achieved by nanostructuring a metal surface. In contrast to normal mirrors, it inflicts only small change to the phase of a reflected wave, offering intriguing applications.
[show abstract][hide abstract] ABSTRACT: The true three-dimensional finite element numerical solution of Maxwell's equations shows that the propagation of light through a thin flat free-standing metallic screen containing a hole of twisted shape is sensitive to whether the incident wave is left or right circularly polarized. The intensity map and polarization state of light are dramatically changed depending on the mutual direction of the hole's twist and the incident light's wave polarization handedness. We also observed a strong concentration of the transmitted field at the centre of the chiral hole when light in the object plane rotates against the twist of the investigated gammadion type structure.
Journal of Optics A Pure and Applied Optics 03/2006; 8(4):S98. · 1.92 Impact Factor
[show abstract][hide abstract] ABSTRACT: Electromagnetic wave reflected from a flat metallic mirror superimposed with a wavy structure with sub-wavelength features that resemble 'fish-scales' shows no phase change with respect to the incident wave
Lasers and Electro-Optics Society, 2005. LEOS 2005. The 18th Annual Meeting of the IEEE; 11/2005
[show abstract][hide abstract] ABSTRACT: This paper proposes to apply nanoimprint and soft lithography to the manufacture of large area planar chiral photonic meta-materials. Both dielectric and metallic chiral structures in nanometre order were replicated by nanoimprint lithography (NIL). To carry out the NIL, a nanofabrication process for imprint templates with chiral features was developed. For the dielectric chiral structures, a single layer of thick hydrogen silsequioxane (HSQ) was used, and for metallic chiral ones a bi-layer PMMA/HSQ technique was employed. The polarization conversion capabilities of planar chiral structures (PCS) imprinted in dielectric materials have been experimentally observed. This indicates that the developed nanoimprint processes in this work have the prospect of manufacturing planar photonic meta-media in high volume at low cost. A hybrid lithography combing nanoimprint and soft lithography is proposed for the constructions of chiral cavities inside dielectric materials.
[show abstract][hide abstract] ABSTRACT: Propagation of light through a thin flat metallic screen containing a hole of twisted shape is sensitive to whether the incident wave is left or right circularly polarized. The transmitted light accrues a component with handedness opposite to the incident wave. The efficiency of polarization conversion depends on the mutual direction of the hole's twist and the incident light's wave polarization handedness and peaks at a wavelength close to the hole overall size. We also observed a strong transmitted field concentration at the center of the chiral hole when the handedness of the chiral hole and the wave's polarization state are the same.