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Mode junction photonics with a symmetry-breaking arrangement of mode-orthogonal heterostructures.
Yu, Sunkyu,Piao, Xianji,Koo, Sukmo,Shin, Jung H,Lee, Seung Hoon,Min, Bumki,Park, Namkyoo Optical Society of America 2011 Optics express Vol.19 No.25
<P>Junction structures provide the foundation of digital electronics and spintronics today. An equivalent, a photonic junction to achieve systematic and drastic control of photon flow is currently missing, but is mandatory for serious all-optical signal processing. Here we propose a photonic junction built upon mode-orthogonal hetero-structures, as a fundamental structural unit for photonic integrated circuits. Controlling the optical potential of mode-orthogonal junctions, the flow of photons can be dynamically manipulated, to complete the correspondence to the electronic junction structures. Of the possible applications, we provide examples of a photonic junction diode and a multi-junction half-adder, with exceptional performance metrics. Highly directional (41dB), nearly unity throughput, ultra-low threshold-power, high quality signal regeneration at 200Gb/s, and all-optic logic operations are successfully derived with the self-induced, bi-level dynamic mode-conversion process across the junction.</P>
One-way optical modal transition based on causality in momentum space.
Yu, Sunkyu,Piao, Xianji,Yoo, KyungWan,Shin, Jonghwa,Park, Namkyoo Optical Society of America 2015 Optics express Vol.23 No.19
<P>The concept of parity-time (PT) symmetry has been used to identify a route toward unidirectional dynamics in optical k-space: imposing asymmetry on the flow of light. Although PT-symmetric potentials have been implemented under the requirement of V(x) = V*(-x), this precondition has only been interpreted within the mathematical framework for the symmetry of Hamiltonians and has not been directly linked to unidirectionality induced by PT symmetry. In this paper, within the context of light-matter interactions, we develop an alternative route toward unidirectionality in k-space by employing the concept of causality. We demonstrate that potentials with real and causal momentum spectra produce unidirectional transitions of optical modes inside the k-continuum, which corresponds to an exceptional point on the degree of PT symmetry. Our analysis reveals a critical link between non-Hermitian problems and spectral theory and also enables multi-dimensional designer manipulation of optical modes, in contrast to the one-dimensional approach that used a Schrödinger-like equation in previous PT-symmetric optics.</P>
Bohmian Photonics for Independent Control of the Phase and Amplitude of Waves
Yu, Sunkyu,Piao, Xianji,Park, Namkyoo American Physical Society 2018 Physical Review Letters Vol.120 No.19
<P>The de Broglie-Bohm theory is one of the nonstandard interpretations of quantum phenomena that focuses on reintroducing definite positions of particles, in contrast to the indeterminism of the Copenhagen interpretation. In spite of intense debate on its measurement and nonlocality, the de Broglie-Bohm theory based on the reformulation of the Schrodinger equation allows for the description of quantum phenomena as deterministic trajectories embodied in the modified Hamilton-Jacobi mechanics. Here, we apply the Bohmian reformulation to Maxwell's equations to achieve the independent manipulation of optical phase evolution and energy confinement. After establishing the deterministic design method based on the Bohmian approach, we investigate the condition of optical materials enabling scattering-free light with bounded or random phase evolutions. We also demonstrate a unique form of optical confinement and annihilation that preserves the phase information of incident light. Our separate tailoring of wave information extends the notion and range of artificial materials.</P>
Plasmonic Structural-Color Thin Film With a Wide Reception Angle and Strong Retro-Reflectivity
Inchul Woo,Sunkyu Yu,Jae Sung Lee,Shin, J. H.,Mi Jung,Namkyoo Park IEEE 2012 IEEE photonics journal Vol.4 No.6
<P>We propose a plasmonic structural color in the form of a thin film with a monolayer of randomly dispersed silver nanoshells. By employing spatially isotropic optical dipole antenna nanoshells to achieve efficient couplings to obliquely incident field and by utilizing local frustration and interference of randomly dispersed scatterer phases, we successfully introduce plasmonic-driven unique traits of retro-reflection as an example of a plasmonic structural color. As compared to the natural counterpart, Morpho rhetenor , a much wider reception angle, up to 70<SUP>°</SUP>, and a stronger retro-reflectivity of 35-45% are achieved.</P>
Flexible, Angle‐Independent, Structural Color Reflectors Inspired by Morpho Butterfly Wings
Chung, Kyungjae,Yu, Sunkyu,Heo, Chul‐,Joon,Shim, Jae Won,Yang, Seung‐,Man,Han, Moon Gyu,Lee, Hong‐,Seok,Jin, Yongwan,Lee, Sang Yoon,Park, Namkyoo,Shin, Jung H. WILEY‐VCH Verlag 2012 ADVANCED MATERIALS Vol.24 No.18
<P><B>Thin‐film color reflectors inspired by Morpho butterflies</B> are fabricated. Using a combination of directional deposition, silica microspheres with a wide size distribution, and a PDMS (polydimethylsiloxane) encasing, a large, flexible reflector is created that actually provides better angle‐independent color characteristics than Morpho butterflies and which can even be bent and folded freely without losing its Morpho‐mimetic photonic properties.</P>