<div style="text-align:justify;"> Currently, coupled mode theory (CMT) is widely used for calculating the coupling coefficient of twin-core fibers (TCFs) that are used in a broad range of important app...<div style="text-align:justify;"> Currently, coupled mode theory (CMT) is widely used for calculating the coupling coefficient of twin-core fibers (TCFs) that are used in a broad range of important applications. This approach is highly accurate for scenarios with weak coupling between the cores but shows significant errors in the strong coupling scenarios, necessitating the use of a more accurate method for coupling coefficient calculations. Therefore, in this work, we calculate the coupling coefficients of TCFs using the supermode theory with finite element method (FEM) that has higher accuracy than CMT, particularly for the strong coupling TCF. To investigate the origin of the differences between the results obtained by these two methods, the modal field distributions of the supermodes of TCF are simulated and analyzed in detail. </div>展开更多
This paper presents an investigation of specific optical fiber core mode leakage behavior that occurs in high-power double-clad fiber lasers as a result of thermally-induced refractive index variations. A model of the...This paper presents an investigation of specific optical fiber core mode leakage behavior that occurs in high-power double-clad fiber lasers as a result of thermally-induced refractive index variations. A model of the power transfer between the core modes and the cladding modes during thermally-induced refractive index variations is established based on the mode coupling theory. The results of numerical simulations based on actual laser parameters are presented. Experimental measurements were also carried out, the results showed good agreement with the corresponding simulation results.展开更多
In the work of developing extrinsic fabry perot interferometric (EFPI), the key technology of polishing fiber optic endfaces and coating the multilayer of dielectric films on them is raised and resolved to settle the...In the work of developing extrinsic fabry perot interferometric (EFPI), the key technology of polishing fiber optic endfaces and coating the multilayer of dielectric films on them is raised and resolved to settle the disturbance and stability problem of EFPI, which simplifies the sensing system, improves the sensor performance and reduces the cost. In this paper, the relations between the output interferential light intensity and the F P cavity length are calculated based on the theory of mode field coupling. The EFPI fiber optic sensor is adhered to a distributed smart laminate beam to detect vibration frequency and axial strain value, the results coincident with the results tested by PZT.展开更多
In order to describe the time delay in the surface roughing process the Kardar Parisis-Zhang （KPZ） equation with memory effects is constructed and analysed using the dynamic renormalization group and the power count...In order to describe the time delay in the surface roughing process the Kardar Parisis-Zhang （KPZ） equation with memory effects is constructed and analysed using the dynamic renormalization group and the power counting mode coupling approach by Chattopadhyay [2009 Phys. Rev. E 80 011144]. In this paper, the scaling analysis and the classical self-consistent mode-coupling approximation are utilized to investigate the dynamic scaling behaviour of the KPZ equation with memory effects. The values of the scaling exponents depending on the memory parameter are calculated for the substrate dimensions being 1 and 2, respectively. The more detailed relationship between the scaling exponent and memory parameter reveals the significant influence of memory effects on the scaling properties of the KPZ equation.展开更多
The microring resonator based on lithium niobate on insulator(LNOI)is a promising platform for broadband nonlinearity process because of its strong second-order nonlinear coefficients,the capability of dispersion engi...The microring resonator based on lithium niobate on insulator(LNOI)is a promising platform for broadband nonlinearity process because of its strong second-order nonlinear coefficients,the capability of dispersion engineering,etc.It is important to control the energy transmitted into the resonator at different wavelengths,as this becomes difficult for two bands across an octave.In this Letter,we study the effect of different pulley bus-resonator configurations on phase mismatching and mode field overlap.We achieve the control of energy transmission coefficients at different wavebands simultaneously and provide a general design methodology for coupled structures for broadband applications.This paper can contribute to quantum and classical optical broadband applications based on LNOI microring resonators.展开更多
The wireless power transmission system based on nonlinear parity time symmetry is a robust sys-tem that can maintain high-efficiency transmission at a certain distance.Parity-Time Symmetry(PT symmetry)wireless power t...The wireless power transmission system based on nonlinear parity time symmetry is a robust sys-tem that can maintain high-efficiency transmission at a certain distance.Parity-Time Symmetry(PT symmetry)wireless power transfer system,due to its insensitivity to the position of the coupled resonant coil over a large range,can carry out constant power transfer to the load,and through coupled mode theory The PT symmetrical wireless power transmission circuit with S-P structure is analyzed,and the system has different transmission efficiencies in different coupling intervals,and the transmission effect of the structure at different distances is studied with the change of coupling coefficient.Then,the simulation is carried out by MATLAB and origin software.The final results show that the transmission efficiency does not change with the coupling coefficient in the strong coupling region and can maintain high-efficiency transmission.In the weak coupling region,the coupling coefficient has a great influence on the transmission efficiency of the system.展开更多
The use of microdng resonators to assist in the evanescent field coupling between dissimilar waveguides is proposed and analyzed. Theoretical analysis based on the coupled mode theory and numerical example show that c...The use of microdng resonators to assist in the evanescent field coupling between dissimilar waveguides is proposed and analyzed. Theoretical analysis based on the coupled mode theory and numerical example show that complete cross power transfers can be obtained near the microring resonances. Applications of the device include power dividers, low-power thermo-optic or electro-optic switches, and modulators.展开更多
For the superstructure fiber grating （SFG） consisting of fiber Bragg grating （FBG） and long-period fiber grating （LPFG）, there exist three kinds of coupling： the contra-directional coupling between forward prop...For the superstructure fiber grating （SFG） consisting of fiber Bragg grating （FBG） and long-period fiber grating （LPFG）, there exist three kinds of coupling： the contra-directional coupling between forward propagating core mode and backward propagating core mode, the contra-directional coupling between core mode and cladding mode, and the co-directional coupling between core mode and cladding mode. By using the similarity transformation method for the coupled mode equations, the effects of three coupling coefficients κcoL, κclL, and κsL on the transmission and re- flection spectra of SFG have been investigated. The simulations show that the overall intensity of the transmission spectrum of SFG is decided by LPFG, that the main lobes of the transmission and reflectivity spectra of SFG are decided by coupling coefficients κcoL and κsL, and that the side lobes of the transmission and reflectivity spectra are decided by coupling coefficients κclL and κsL.展开更多
Propagation of light through curved graded index optical waveguides supporting an arbitrary high number of modes is investigated.The discussion is restricted to optical wave fields which are well confined within the c...Propagation of light through curved graded index optical waveguides supporting an arbitrary high number of modes is investigated.The discussion is restricted to optical wave fields which are well confined within the core region and losses through radiation are neglected.Using coupled mode theory formalism,two new forms for the propagation kernel for the transverse electric(TE)wave as it travels along a curved two-dimensional waveguide are presented.One form,involving the notion of“bend”modes,is shown to be attractive from a computational point of view as it allows an efficient numerical evaluation of the optical field for sharply bent waveguides.展开更多
A patterned monolayer graphene metamaterial structure consisting of six graphene blocks and two graphene strips is proposed to generate triple plasmon-induced transparency(PIT).TriplePIT can be effectively modulated b...A patterned monolayer graphene metamaterial structure consisting of six graphene blocks and two graphene strips is proposed to generate triple plasmon-induced transparency(PIT).TriplePIT can be effectively modulated by Fermi levels of graphene.The theoretically calculated results by coupled mode theory show a high matching degree with the numerically simulated results by finite-difference time-domain.Intriguingly,the high-sensitive refractive index sensing and excellent slow-light performance can be realized in the proposed graphene metamaterial structure.The sensitivity(S)and figure of merit can reach up to 5.7115 THz RIU^(-1)and 116.32,respectively.Moreover,the maximum group refractive index is 1036.Hence,these results may provide a new idea for designing graphene-based sensors and slow light devices.展开更多
We propose a novel bilayer graphene terahertz metamaterial composed of double graphene ribbons and double graphene rings to excite a dynamically adjustable triple plasma-induced transparency(PIT)effect.The coupled mod...We propose a novel bilayer graphene terahertz metamaterial composed of double graphene ribbons and double graphene rings to excite a dynamically adjustable triple plasma-induced transparency(PIT)effect.The coupled mode theory(CMT)is used to explain the PIT phenomenon,and the results of the CMT and the finite-difference time-domain simulation show high matching degree.By adjusting the Fermi levels of graphene,we have realized a pentafrequency asynchronous optical switch.The performance of this switch,which is mainly manifested in the maximum modulation depth(MD=99.97%)and the minimum insertion loss(IL=0.33 dB),is excellent.In addition,we have studied the slow-light effect of this triple-PIT and found that when the Fermi level of graphene reaches 1.2 eV,the time delay can reach 0.848ps.Therefore,this metamaterial provides a foundation for the research of multi-frequency optical switches and excellent slow-light devices in the terahertz band.展开更多
We present the design and optimization of evanescently coupled waveguide photodiodes（EC-WPDs） based on the coupling modes theory and the beam propagation method.Efficient focalization of the optical power in the abs...We present the design and optimization of evanescently coupled waveguide photodiodes（EC-WPDs） based on the coupling modes theory and the beam propagation method.Efficient focalization of the optical power in the absorber is achieved by an appropriate choice of index matching layers of EC-WPDs.Numerical simulation shows that high-speed（40 GHz）,high quantum efficiency（81%） and high linearity photodiodes can be achieved, and EC-WPDs are promising devices for future optical communication systems.展开更多
文摘<div style="text-align:justify;"> Currently, coupled mode theory (CMT) is widely used for calculating the coupling coefficient of twin-core fibers (TCFs) that are used in a broad range of important applications. This approach is highly accurate for scenarios with weak coupling between the cores but shows significant errors in the strong coupling scenarios, necessitating the use of a more accurate method for coupling coefficient calculations. Therefore, in this work, we calculate the coupling coefficients of TCFs using the supermode theory with finite element method (FEM) that has higher accuracy than CMT, particularly for the strong coupling TCF. To investigate the origin of the differences between the results obtained by these two methods, the modal field distributions of the supermodes of TCF are simulated and analyzed in detail. </div>
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61307057 and 61675114)
文摘This paper presents an investigation of specific optical fiber core mode leakage behavior that occurs in high-power double-clad fiber lasers as a result of thermally-induced refractive index variations. A model of the power transfer between the core modes and the cladding modes during thermally-induced refractive index variations is established based on the mode coupling theory. The results of numerical simulations based on actual laser parameters are presented. Experimental measurements were also carried out, the results showed good agreement with the corresponding simulation results.
文摘In the work of developing extrinsic fabry perot interferometric (EFPI), the key technology of polishing fiber optic endfaces and coating the multilayer of dielectric films on them is raised and resolved to settle the disturbance and stability problem of EFPI, which simplifies the sensing system, improves the sensor performance and reduces the cost. In this paper, the relations between the output interferential light intensity and the F P cavity length are calculated based on the theory of mode field coupling. The EFPI fiber optic sensor is adhered to a distributed smart laminate beam to detect vibration frequency and axial strain value, the results coincident with the results tested by PZT.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10674177)the Youth Foundation of China University of Mining & Technology (Grant No. 2008A035)
文摘In order to describe the time delay in the surface roughing process the Kardar Parisis-Zhang （KPZ） equation with memory effects is constructed and analysed using the dynamic renormalization group and the power counting mode coupling approach by Chattopadhyay [2009 Phys. Rev. E 80 011144]. In this paper, the scaling analysis and the classical self-consistent mode-coupling approximation are utilized to investigate the dynamic scaling behaviour of the KPZ equation with memory effects. The values of the scaling exponents depending on the memory parameter are calculated for the substrate dimensions being 1 and 2, respectively. The more detailed relationship between the scaling exponent and memory parameter reveals the significant influence of memory effects on the scaling properties of the KPZ equation.
基金supported by the National Key R&D Program of China(Nos.2019YFA0705000 and 2017YFA0303700)the Key R&D Program of Guangdong Province(No.2018B030329001)+4 种基金the Leading-edge Technology Program of Jiangsu Natural Science Foundation(No.BK20192001)the National Natural Science Foundation of China(Nos.51890861,11690031,11621091,and 11674169)the Guangdong Major Project of Basic and Applied Basic Research,Zhangjiang Laboratory(No.ZJSP21A001)the China Postdoctoral Science Foundation(No.2022M710068)the Jiangsu Planned Projects for Postdoctoral Research Funds(No.2021K259B)。
文摘The microring resonator based on lithium niobate on insulator(LNOI)is a promising platform for broadband nonlinearity process because of its strong second-order nonlinear coefficients,the capability of dispersion engineering,etc.It is important to control the energy transmitted into the resonator at different wavelengths,as this becomes difficult for two bands across an octave.In this Letter,we study the effect of different pulley bus-resonator configurations on phase mismatching and mode field overlap.We achieve the control of energy transmission coefficients at different wavebands simultaneously and provide a general design methodology for coupled structures for broadband applications.This paper can contribute to quantum and classical optical broadband applications based on LNOI microring resonators.
文摘The wireless power transmission system based on nonlinear parity time symmetry is a robust sys-tem that can maintain high-efficiency transmission at a certain distance.Parity-Time Symmetry(PT symmetry)wireless power transfer system,due to its insensitivity to the position of the coupled resonant coil over a large range,can carry out constant power transfer to the load,and through coupled mode theory The PT symmetrical wireless power transmission circuit with S-P structure is analyzed,and the system has different transmission efficiencies in different coupling intervals,and the transmission effect of the structure at different distances is studied with the change of coupling coefficient.Then,the simulation is carried out by MATLAB and origin software.The final results show that the transmission efficiency does not change with the coupling coefficient in the strong coupling region and can maintain high-efficiency transmission.In the weak coupling region,the coupling coefficient has a great influence on the transmission efficiency of the system.
基金funded by the Tsinghua National Laboratory for Information Science and Technology (TNList)
文摘The use of microdng resonators to assist in the evanescent field coupling between dissimilar waveguides is proposed and analyzed. Theoretical analysis based on the coupled mode theory and numerical example show that complete cross power transfers can be obtained near the microring resonances. Applications of the device include power dividers, low-power thermo-optic or electro-optic switches, and modulators.
基金Supported by the Cultivation Fund of the Key Scientific and Technical Innovation Project, Ministry of Education of China (708064)Natural Science Foundation of Wuhan University of Technology (471-38650024)
文摘For the superstructure fiber grating （SFG） consisting of fiber Bragg grating （FBG） and long-period fiber grating （LPFG）, there exist three kinds of coupling： the contra-directional coupling between forward propagating core mode and backward propagating core mode, the contra-directional coupling between core mode and cladding mode, and the co-directional coupling between core mode and cladding mode. By using the similarity transformation method for the coupled mode equations, the effects of three coupling coefficients κcoL, κclL, and κsL on the transmission and re- flection spectra of SFG have been investigated. The simulations show that the overall intensity of the transmission spectrum of SFG is decided by LPFG, that the main lobes of the transmission and reflectivity spectra of SFG are decided by coupling coefficients κcoL and κsL, and that the side lobes of the transmission and reflectivity spectra are decided by coupling coefficients κclL and κsL.
文摘Propagation of light through curved graded index optical waveguides supporting an arbitrary high number of modes is investigated.The discussion is restricted to optical wave fields which are well confined within the core region and losses through radiation are neglected.Using coupled mode theory formalism,two new forms for the propagation kernel for the transverse electric(TE)wave as it travels along a curved two-dimensional waveguide are presented.One form,involving the notion of“bend”modes,is shown to be attractive from a computational point of view as it allows an efficient numerical evaluation of the optical field for sharply bent waveguides.
基金supported by National Natural Science Foundation of China:61605018,11904032,61841503Science and Technology Project Foundation of the Education Department of Jiangxi Province:GJJ150815
文摘A patterned monolayer graphene metamaterial structure consisting of six graphene blocks and two graphene strips is proposed to generate triple plasmon-induced transparency(PIT).TriplePIT can be effectively modulated by Fermi levels of graphene.The theoretically calculated results by coupled mode theory show a high matching degree with the numerically simulated results by finite-difference time-domain.Intriguingly,the high-sensitive refractive index sensing and excellent slow-light performance can be realized in the proposed graphene metamaterial structure.The sensitivity(S)and figure of merit can reach up to 5.7115 THz RIU^(-1)and 116.32,respectively.Moreover,the maximum group refractive index is 1036.Hence,these results may provide a new idea for designing graphene-based sensors and slow light devices.
基金Project supported by National Natural Science Foundation of China(NSFC)(61605018,11904032,61841503)。
文摘We propose a novel bilayer graphene terahertz metamaterial composed of double graphene ribbons and double graphene rings to excite a dynamically adjustable triple plasma-induced transparency(PIT)effect.The coupled mode theory(CMT)is used to explain the PIT phenomenon,and the results of the CMT and the finite-difference time-domain simulation show high matching degree.By adjusting the Fermi levels of graphene,we have realized a pentafrequency asynchronous optical switch.The performance of this switch,which is mainly manifested in the maximum modulation depth(MD=99.97%)and the minimum insertion loss(IL=0.33 dB),is excellent.In addition,we have studied the slow-light effect of this triple-PIT and found that when the Fermi level of graphene reaches 1.2 eV,the time delay can reach 0.848ps.Therefore,this metamaterial provides a foundation for the research of multi-frequency optical switches and excellent slow-light devices in the terahertz band.
基金Project supported by the State Key Development Program for Basic Research of China(No.2011CB301702)the National Natural Science Foundation of China(Nos.61006041,61001121,60736036,60932004)the Fundamental Research Funds for the Central Universities
文摘We present the design and optimization of evanescently coupled waveguide photodiodes（EC-WPDs） based on the coupling modes theory and the beam propagation method.Efficient focalization of the optical power in the absorber is achieved by an appropriate choice of index matching layers of EC-WPDs.Numerical simulation shows that high-speed（40 GHz）,high quantum efficiency（81%） and high linearity photodiodes can be achieved, and EC-WPDs are promising devices for future optical communication systems.
