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[Springer Tracts in Modern Physics] Parity-time Symmetry and Its Applications Volume 280 || Parity-Time-Symmetric Optical Lattices in Atomic Configurations
摘要： In this chapter, we show how to theoretically design and experimentally construct exact parity-time (PT) symmetric optical lattices with gain and loss in atomic configurations. By making use of the advantages of light-induced atomic coherence in multi-level atomic systems, spatially extended gain and loss arrays with real-time reconfigurability and multiple-parameter tunability can be effectively obtained in hot atomic vapors. We have constructed periodically alternative gain-loss structures with two very different schemes based on spatially-arranged optical induction techniques. With the required symmetric/antisymmetric spatial distributions for the real/imaginary parts of the refraction index satisfied, PT-symmetric optical lattices can be achieved with easy controllability. The dynamic behaviors of light propagating inside the induced non-Hermitian optical lattices are investigated by measuring the relative phase difference between two adjacent gain and loss channels.
关键词： Light-Induced Atomic Coherence,Non-Hermitian Optical Lattices,Atomic Configurations,Parity-Time-Symmetric Optical Lattices,Gain and Loss
更新于2025-09-23 15:21:21
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[IEEE 2019 International Topical Meeting on Microwave Photonics (MWP) - Ottawa, ON, Canada (2019.10.7-2019.10.10)] 2019 International Topical Meeting on Microwave Photonics (MWP) - Widely Tunable Parity-Time-Symmetric Optoelectronic Oscillator Based on a Silicon Microdisk Resonator
摘要： A widely frequency-tunable parity-time (PT)-symmetric optoelectronic oscillator (OEO) based on a silicon microdisk resonator (MDR) is proposed and experimentally demonstrated. In the proposed OEO, two mutually coupled optoelectronic loops having an identical geometry with one having a gain and the other a loss, which are equal in magnitude, light implemented by employing the reciprocity of are propagation in an MDR, to form a PT-symmetric OEO. Thanks to the PT symmetry, single-frequency oscillation with low phase noise is implemented. The tuning of the frequency is realized by thermally tuning the MDR. The proposed OEO is demonstrated experimentally. A wide frequency tunable range from 2 to 12 GHz is realized. The phase noise is measured to be -105 dBc/Hz at a 10 kHz frequency offset, which can be further reduced if the loop length is increased.
关键词： Silicon photonics,Optoelectronic oscillator (OEO),Parity-time symmetric,Microwave photonic bandpass filter,Microwave photonics,microdisk resonator
更新于2025-09-16 10:30:52
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Tunable Unidirectivity of Metal-Dielectric-Metal Plasmonic Nanoantennas With PT-Symmetric Potentials
摘要： Parity-time (PT) symmetric photonic systems have attracted much attention due to their intriguing properties and asymmetric behaviors. In this paper, we propose a plasmonic nanoantenna with PT-symmetric potential for unidirectional scattering functionality. The studied plasmonic nanoantenna is comprised of three metallic layers separated by two dielectric layers. Such kind of system, with the same coefficient κ of loss and gain in each of the two dielectric layers, holds the characteristic of PT symmetry. We show that the unidirectional scattering is obtained for the passive structure (i.e., κ = 0), and the switching between forward and backward directionality can be achieved with a single structure by changing the excitation wavelength, when the induced electric dipole (ED) and magnetic dipole (MD) modes satisfy the first or second Kerker conditions, respectively. In addition, we find that the forward-to-backward ratio spectra can be strongly affected by the non-Hermiticity parameter κ. In particular, it is possible to reverse the radiation direction at the same wavelength in a wide spectra band by adjusting κ. Moreover, putting the nanoantennas in an array of transverse configuration can efficiently narrow the main lobe angular beam width to be <6?. These results contribute to the basic understanding of the optical properties of active-passive finite nanostructures with potential applications, and provide new ideas for the design of novel nanostructures displaying asymmetric and tunable responses.
关键词： parity-time symmetric,tunable,unidirectional scattering,Kerker condition,optical nanoantenna,metallic and dielectric hybrid
更新于2025-09-11 14:15:04