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Chirality in Non-Hermitian Photonics
유선규,Xianji Piao,박남규 한국광학회 2019 Current Optics and Photonics Vol.3 No.4
Chirality is ubiquitous in physics and biology from microscopic to macroscopic phenomena, such as fermionic interactions and DNA duplication. In photonics, chirality has traditionally represented differentiated optical responses for right and left circular polarizations. This definition of optical chirality in the polarization domain includes handedness-dependent phase velocities or optical absorption inside chiral media, which enable polarimetry for measuring the material concentration and circular dichroism spectroscopy for sensing biological or chemical enantiomers. Recently, the emerging field of non-Hermitian photonics, which explores exotic phenomena in gain or loss media, has provided a new viewpoint on chirality in photonics that is not restricted to the traditional polarization domain but is extended to other physical quantities such as the orbital angular momentum, propagation direction, and system parameter space. Here, we introduce recent milestones in chiral light-matter interactions in non-Hermitian photonics and show an enhanced degree of design freedom in photonic devices for spin and orbital angular momenta, directionality, and asymmetric modal conversion.
유선규,홍동표,이기수 전북대학교 공업기술연구소 1995 工學硏究 Vol.26 No.-
This paper presents results from a computer based technique for the evaluation and graphic display of stress distribution in thermo plate when subjected to pressure. The simulation procedures provides a versatile and powerful means for the analysis and design of thermo plate subjected to pressure The main results on this study were as follows; 1. The stress distribution mode and maximum stress positions can be previously known in the step of a machine design. 2. seeking the weakest position in the step of a machine design, it is possible to modify it by the results before manufacturing.
격자 결합기를 이용한 금속 팁에서의 광 에너지 집속 최적화
박형열,구석모,유선규,박남규 한국물리학회 2010 새물리 Vol.60 No.1
The strong field enhancement at the end of a nanoscale metal tip, can be used to overcome the resolution limit of conventional near-field optical microscopy, and is thus believed to find future applications in high-resolution lithography or/and nanosensing area. In this paper, using a 3D finite-difference time domain (FDTD) analysis, we study the field enhancement factors at the metal tip, and optimize its structure with respect to the SPP excitation and tip-coupling efficiencies. The results show that it is possible to get factors higher field enhancement, by several orders of magnitude from the optimal structure, compared to the non-optimal cases, by adjusting the metal tip angle and employing blazed SPP grating couplers. 나노 스케일 크기의 금속 팁 구조에서의 강한 필드의 집속은 근접장 광학 현미경의 분해능 한계를 극복하는 방법으로 사용되며, 고해상도 전사법, 나노 센싱 등, 다양한 응용에서의 한계점을 극복할 수 있을 것으로 기대되고 있다. 이에 본 연구에서는 3차원 유한차분법 전산모사를 통해서 금속 팁에서 필드를 강하게 하기 위한 요소들을 분석하고, 금속 팁 끝에 모이는 표면 플라즈몬과 표면 플라즈몬을 발생시키는 결합기의 효율 증가를 위한 최적화 구조를 찾아보았다. 그 결과, 금속 팁의 각도의 최적화 값과 더불어 기울어진 격자 결합기의 도입을 통해 얻은 구조는 최적화되지 않은 구조에 비해 강한 필드가 집속되는 것을 확인할 수 있었다.