Dual-band unidirectional reflectionlessness at exceptional points is investigated theoretically in a non-Hermitian plasmonic waveguide system, based on near-field coupling by using only two resonators. The system consists of a metal-insulator-metal waveguide end-coupled to two nanohole resonators. The reflectivity for the forward (backward) direction is ∼0 (∼0) at frequency 205.20 THz (194.56 THz), while for the backward (forward) direction it is ∼0.76 (∼0.78). Moreover, the quality factors of the dual-band unidirectional reflectionlessness for forward and backward directions can reach ∼132 and ∼137, respectively.
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http://dx.doi.org/10.1088/1361-6528/aaeef5 | DOI Listing |
Tunable dual-band unidirectional reflectionless phenomena in a one-dimensional waveguide coupled with a cavity optomechanical system driven by external driving fields were investigated. The results indicated that dual-band unidirectional reflectionlessnesses can be obtained by appropriately adjusting the strengths of the external driving fields, phase shift between the two optical cavities, coupling strengths of the optical cavities to the waveguide and decay rates of the two cavities and mechanical resonators. Moreover their peaks can be tuned by changing both the effective optomechanical coupling strengths and phase shift, which can achieve unidirectional reflectionlessness by adjusting the external driving fields when the phase shift is difficult to adjust precisely.
View Article and Find Full Text PDFNanophotonics
April 2022
Electrical Engineering and Electronics Department, Kyoto Institute of Technology, 1 Hashigami-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan.
Dual-band composite right/left-handed transmission lines with the nonreciprocal phase shift approximately proportional to the operating frequency are proposed and demonstrated by using normally magnetized ferrite microstrip lines. The nonreciprocal phase shift can be dynamically controlled by changing the externally applied dc magnetic field. Dynamic change in the nonreciprocal phase gradient along the line enables us to realize dual-band and unidirectional beam-scanning leaky-wave antennas without suffering from frequency-dependent change in the beam direction.
View Article and Find Full Text PDFTunable single-longitudinal-mode (SLM) ring Ho:YLF laser with intra-cavity isolator is investigated for 2.05 µm and 2.06 µm band based on single resonator, which is realized dual-band SLM laser conversion by a polarizer.
View Article and Find Full Text PDFA silicon trimer is explored to tailor unidirectional forward scattering at multiple wavelengths in the near-infrared region with low loss using theoretical calculations and numerical simulations, which leads to the dramatic enhancement in unidirectional forward scattering and suppression of backward scattering. The higher moments in the trimer can be properly excited and balanced by breaking the symmetry of the trimer. The generalized Kerker conditions at two different wavelengths can be achieved in the trimer to further improve the scattering directivity.
View Article and Find Full Text PDFNanotechnology
January 2019
Department of Physics, College of Science, Yanbian University, Yanji, Jilin 133002, People's Republic of China.
Dual-band unidirectional reflectionlessness at exceptional points is investigated theoretically in a non-Hermitian plasmonic waveguide system, based on near-field coupling by using only two resonators. The system consists of a metal-insulator-metal waveguide end-coupled to two nanohole resonators. The reflectivity for the forward (backward) direction is ∼0 (∼0) at frequency 205.
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