Fabrication of three-dimensional suspended, interlayered and hierarchical nanostructures by accuracy-improved electron beam lithography overlay

Nanofabrication techniques are essential for exploring nanoscience and many closely related research fields such as materials, electronics, optics and photonics. Recently, three-dimensional (3D) nanofabrication techniques have been actively investigated through many different ways, however, it is still challenging to make elaborate and complex 3D nanostructures that many researchers want to realize for further interesting physics studies and device applications. Electron beam lithography, one of the two-dimensional (2D) nanofabrication techniques, is also feasible to realize elaborate 3D nanostructures by stacking each 2D nanostructures. However, alignment errors among the individual 2D nanostructures have been difficult to control due to some practical issues. In this work, we introduce a straightforward approach to drastically increase the overlay accuracy of sub-20 nm based on carefully designed alignmarks and calibrators. Three different types of 3D nanostructures whose designs are motivated from metamaterials and plasmonic structures have been demonstrated to verify the feasibility of the method, and the desired result has been achieved. We believe our work can provide a useful approach for building more advanced and complex 3D nanostructures.114sciescopu

Geometric metasurface enabling polarization independent beam splitting

A polarization independent holographic beam splitter that generates equal-intensity beams based on geometric metasurface is demonstrated. Although conventional geometric metasurfaces have the advantages of working over a broad frequency range and having intuitive design principles, geometric metasurfaces have the limitation that they only work for circular polarization. In this work, Fourier holography is used to overcome this limitation. A perfect overlap resulting from the origin-symmetry of the encoded image enables polarization independent operation of geometric metasurfaces. The designed metasurface beam splitter is experimentally demonstrated by using hydrogenated amorphous silicon, and the device performs consistent beam splitting regardless of incident polarizations as well as wavelengths. Our device can be applied to generate equal-intensity beams for entangled photon light sources in quantum optics, and the design approach provides a way to develop ultra-thin broadband polarization independent components for modern optics.113Nsciescopu

A broadband optical diode for linearly polarized light using symmetry-breaking metamaterials

1151Ysciescopu

Complete amplitude and phase control of light using broadband holographic metasurface

Reconstruction of light profiles with amplitude and phase information, called holography, is an attractive optical technique to display three-dimensional images. Due to essential requirements for an ideal hologram, subwavelength control of both amplitude and phase is crucial. Nevertheless, traditional holographic devices have suffered from their limited capabilities of incomplete modulation in both amplitude and phase of visible light. Here, we propose a novel metasurface that is capable of completely controlling both amplitude and phase profiles of visible light independently with subwavelength spatial resolution. The simultaneous, continuous, and broadband control of amplitude and phase is achieved by using X-shaped meta-atoms based on expanded concept of the Pancharatnam-Berry phase. The first experimental demonstrations of complete complex-amplitude holograms with subwavelength definition are achieved and show excellent performances with remarkable signal-to-noise ratio compared to traditional phase-only holograms. Extraordinary control capability with versatile advantages of our metasurface paves a way to an ideal holography, which is expected to be a significant advance in the field of optical holography and metasurfaces

집속 이온빔 기술

2

MAXIM: Metasurfaces-oriented Maxwell simulation software with intuitive graphical user interfaces

We develop MAXIM which is electromagnetic wave simulation software based on rigorous coupled-wave analysis. The principal advantage of MAXIM is an intuitive graphical user interface drastically improving the accessibility of the software to who are not familiar with computer programming. Here, we present the basic formulation and computation methods that are incorporated in MAXIM. The computation performance is also evaluated for several didactic examples of dielectric metasurfaces which are the main application of MAXIM. The comparison of the calculation results with commercial software based on a finite-difference time-domain method confirms that the computation results of two programs coincide closely with each other within 1% difference. Considering the easy accessibility, wide availability and high reliability, MAXIM will serve the development of related research fields of metasurfaces and nanophotonics.11Nsciescopu

Metasurface-based reconfigurable visible light absorber

1

Dual-mode metasurface: Simultaneous control of phase and spectral responses

2

Dual-mode metasurface: Simultaneous control of phase and spectral responses

2