This paper theoretically investigates the dependence of leaky mode coupling between inner core fundamental mode and outer core defect mode on phase and loss matching in pure silica dual-core photonic crystal fibres wi...This paper theoretically investigates the dependence of leaky mode coupling between inner core fundamental mode and outer core defect mode on phase and loss matching in pure silica dual-core photonic crystal fibres with the multi-pole method. The complete mode coupling can take place when both the phase and loss matching conditions are satisfied at the avoided anti-crossing wavelength. It shows the influences of cladding structure parameters including the diameters of cladding air holes d1, diameters of outer core holes d2 and hole to hole pitch A on the characteristics of leaky modes coupling. The coupled-mode theory is used to analyse the mode transition characteristics and the complete coupling can be clearly indicated by comparing the real and imaginary parts of propagation constant of the leaky modes.展开更多
The generation mechanism of the first arrivals in the cased boreholes for the poorly bonded conditions is investigated. Based on the analyses of the Riemann surface structure of the characteristic function, the disper...The generation mechanism of the first arrivals in the cased boreholes for the poorly bonded conditions is investigated. Based on the analyses of the Riemann surface structure of the characteristic function, the dispersion features, excitation spectra and contributions of modes excited in the cased boreholes with different cementing types are studied. The phase velocity dispersion studies of leaky modes show that high-order modes form "plateau" regions with one approximate velocity denoted by v separated by their cutoff frequencies, in which the phase velocity changes little with a considerable frequency range, while the group velocity keeps a relatively constant high value. Usually, the operation frequency range of a specific cementing evaluation acoustic logging tool is covered by such a "plateau" region. Mode excitation and contribution analyses show that the first arrivals in the cased boreholes for the poorly bonded conditions are the contributions from leaky modes, where the traveling velocity of the first arrivals processed by slowness time coherence(STC) method is equal to the approximated velocity v. Analyses on generation of leaky modes in the cased boreholes supplement the understanding of the generation mechanism of the first arrivals.展开更多
ln tins paper we show that the antifterromagnetic slab wvavcguide Supports a slow TE wave. The Propagation propertics of the TE wave,TE and TM leaky waves in the antiferromagnetic slab arc discussed in detail.
Beam-frequency-scanning detection and point-to-point communication typically differ significantly in bandwidth and polarization characteristics,requiring two separate antennas in conventional designs.This paper propos...Beam-frequency-scanning detection and point-to-point communication typically differ significantly in bandwidth and polarization characteristics,requiring two separate antennas in conventional designs.This paper proposes a method to integrate a dual-mode radiation of narrowband circular polarization(CP)into a broadband linearly polarized(LP)beam-scanning leaky-wave antenna(LWA)using a full spoof surface plasmon polariton(SSPP)system.First,a grooved SSPP unit and its complementary structure are used with periodic mode modulation to achieve continuous vertically polarized(V-pol)dual-beam scanning from backward to forward.By periodically embedding spoof localized surface plasmon(SLSP)units,strong coupling between SLSPs and SSPPs is enabled under resonant conditions.Then,CP radiation is generated due to the rotating electric-field vectors of SLSPs.Experiment and simulation results demonstrate continuous V-pol beam scanning from−30°to 22°across 4.25–6.75 GHz,including effective broadside radiation.Notably,at 5.4 GHz,the antenna radiates right-handed circularly polarized(RHCP)and left-handed circularly polarized(LHCP)waves in opposite broadside directions.Compared with existing technologies,the insertable CP radiation allows the antenna to enable two significantly different operating modes,which can be applied in combined beam-scanning detection and narrowband satellite emergency communication,greatly improving system integration.展开更多
基金Project supported by the National Key Basic Research Special Foundation of China (Grant No. 2010CB327605)the National High-Technology Research and Development Program of China (Grant No. 2009AA01Z220)+2 种基金the Key Grant of the Chinese Ministry of Education (Grant No. 109015)the Discipline Co-construction Project of Beijing Municipal Commission of Education (Grant No. YB20081001301)the Open Fund of Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), Ministry of Education,and the Specialized Research Fund for the Doctoral Program of Beijing University of Posts and Telecommunications (Grant No. CX201023)
文摘This paper theoretically investigates the dependence of leaky mode coupling between inner core fundamental mode and outer core defect mode on phase and loss matching in pure silica dual-core photonic crystal fibres with the multi-pole method. The complete mode coupling can take place when both the phase and loss matching conditions are satisfied at the avoided anti-crossing wavelength. It shows the influences of cladding structure parameters including the diameters of cladding air holes d1, diameters of outer core holes d2 and hole to hole pitch A on the characteristics of leaky modes coupling. The coupled-mode theory is used to analyse the mode transition characteristics and the complete coupling can be clearly indicated by comparing the real and imaginary parts of propagation constant of the leaky modes.
基金the National Natural Science Foundation of China(Grant Nos.11134011 and 41274134)
文摘The generation mechanism of the first arrivals in the cased boreholes for the poorly bonded conditions is investigated. Based on the analyses of the Riemann surface structure of the characteristic function, the dispersion features, excitation spectra and contributions of modes excited in the cased boreholes with different cementing types are studied. The phase velocity dispersion studies of leaky modes show that high-order modes form "plateau" regions with one approximate velocity denoted by v separated by their cutoff frequencies, in which the phase velocity changes little with a considerable frequency range, while the group velocity keeps a relatively constant high value. Usually, the operation frequency range of a specific cementing evaluation acoustic logging tool is covered by such a "plateau" region. Mode excitation and contribution analyses show that the first arrivals in the cased boreholes for the poorly bonded conditions are the contributions from leaky modes, where the traveling velocity of the first arrivals processed by slowness time coherence(STC) method is equal to the approximated velocity v. Analyses on generation of leaky modes in the cased boreholes supplement the understanding of the generation mechanism of the first arrivals.
文摘ln tins paper we show that the antifterromagnetic slab wvavcguide Supports a slow TE wave. The Propagation propertics of the TE wave,TE and TM leaky waves in the antiferromagnetic slab arc discussed in detail.
基金National Natural Science Foundation of China(62401133,62071117,62288101)111 Project(111-2-05)+3 种基金Natural Science Foundation of Jiangsu Province(BK20230192)Science and Technology Research Funds of Wuxi TaihuLight Program(K20231007)Sichuan Province Engineering Research Center for Broadband Microwave Circuit High Density IntegrationYoung Elite Scientists Sponsorship Program by Jiangsu Association for Science and Technology.
文摘Beam-frequency-scanning detection and point-to-point communication typically differ significantly in bandwidth and polarization characteristics,requiring two separate antennas in conventional designs.This paper proposes a method to integrate a dual-mode radiation of narrowband circular polarization(CP)into a broadband linearly polarized(LP)beam-scanning leaky-wave antenna(LWA)using a full spoof surface plasmon polariton(SSPP)system.First,a grooved SSPP unit and its complementary structure are used with periodic mode modulation to achieve continuous vertically polarized(V-pol)dual-beam scanning from backward to forward.By periodically embedding spoof localized surface plasmon(SLSP)units,strong coupling between SLSPs and SSPPs is enabled under resonant conditions.Then,CP radiation is generated due to the rotating electric-field vectors of SLSPs.Experiment and simulation results demonstrate continuous V-pol beam scanning from−30°to 22°across 4.25–6.75 GHz,including effective broadside radiation.Notably,at 5.4 GHz,the antenna radiates right-handed circularly polarized(RHCP)and left-handed circularly polarized(LHCP)waves in opposite broadside directions.Compared with existing technologies,the insertable CP radiation allows the antenna to enable two significantly different operating modes,which can be applied in combined beam-scanning detection and narrowband satellite emergency communication,greatly improving system integration.
