We have introduced a new approach to calculate the orbital angular momentum(OAM)of bound states in continuum(BICs)and below-continuum-resonance(BCR)modes in the rotational periodic system nested inside and outside by ...We have introduced a new approach to calculate the orbital angular momentum(OAM)of bound states in continuum(BICs)and below-continuum-resonance(BCR)modes in the rotational periodic system nested inside and outside by transforming the Bloch wave number from the translational periodic system.We extensively classify and study these BICs and BCR modes,which exhibit high-quality(high-Q)factors,in different regions relative to the interface of the system.These BICs and BCR modes with a high-Q factor have been studied in detail based on distinctive structural parameters and scattering theory.The outcomes of this research break the periodic limitation of interface state-based BICs,and realize more and higher symmetry interface state-based BICs and BCR modes.Moreover,we can control the region where light is captured by adjusting the frequency,and show that the Q factor of BICs is more closely related to the ordinal number of rings and the rotational symmetry number of the system.展开更多
We report the modeling and designing aspects of different types of photo-acoustic (PA) cell based on the excitation of longitudinal, radial and azimuthal mode using CW and pulse lasers. The results are obtained by emp...We report the modeling and designing aspects of different types of photo-acoustic (PA) cell based on the excitation of longitudinal, radial and azimuthal mode using CW and pulse lasers. The results are obtained by employing fluid dynamics equations along with Bessel’s function. The obtained results based on stimulation of longitudinal, radial and azimuthally resonance modes of the Photo acoustic signals in the suitable cavity. This is utilized to design highly efficient low volume PA detector for the spectroscopic studies of different types of atmospheric pollutants. We have also studied the dependence of the excited photo acoustic signals on various parameters such as cell radius, laser power, absorption coefficient, quality factor ‘Q’ along with the first longitudinal, radial, azimuthal mode and the pressure. The simulated results show the linearity of the PA signal with different concentration of the gas sample.展开更多
The distributed optical fiber surface plasmon resonance(SPR)sensors have attracted wide attention in biosensing and chemical sensing applications.However,due to the limitation of their sensing structure,it is difficul...The distributed optical fiber surface plasmon resonance(SPR)sensors have attracted wide attention in biosensing and chemical sensing applications.However,due to the limitation of their sensing structure,it is difficult to adjust their res-onant wavelength and sensitivity.Here,novel and flexible cascaded helical-core fiber[HCF)SPR sensors are proposed theoretically and experimentally for distributed sensing applications.It is shown that the resonant wavelength and sensitivity of the sensors can be conveniently controlled by adjusting the twist pitch of the helical core.A high sensitivity of 11,180 nm/RIU for refractive-index measurement ranging from 1.355 to 1.365 is realized experimentally when the twist pitch of the helical core is 1.5 mm.It is worth noting that the sensitivity can be further improved by reducing the twist pitch.For example,the sensitivity of the sensor with a twist pitch of 1.4 mm can theoretically exceed 20,000 nm/RIU.This work opens up a new way to implement multi-parameter or distributed measurement,especially to establish sensing networks integrated in a single-core fiber or a multi-core fiber.展开更多
We investigate the resonance modes of gold nanorods on an Indium tin oxide (ITO) coated glass substrate using spectroscopic ellipsometry. The unit cell of the structure investigated is composed of two gold nanorods wi...We investigate the resonance modes of gold nanorods on an Indium tin oxide (ITO) coated glass substrate using spectroscopic ellipsometry. The unit cell of the structure investigated is composed of two gold nanorods with differing lengths. In such a structure, we can excite the bright resoance and the dark resonance modes. Numerical simulation of the gold nanorod on substrate was performed with the bright resonance mode at 825.0 nm and the dark resonance mode at 1107.1 nm respectively. Using spectroscopic ellipsometry we optically characterize the fabricated gold nanostructure, with the bright resonance mode at 700.0 nm and the dark resonance mode at 1350.0 nm respectively. The experimental results from ellipsometry show a good agreement with the results from simulation.展开更多
The strong coupling between vibrational modes of molecules and surface plasmon resonance(SPR)modes in graphene makes them an ideal platform for biosensor techniques.In this paper,a new optical biosensor for molecule d...The strong coupling between vibrational modes of molecules and surface plasmon resonance(SPR)modes in graphene makes them an ideal platform for biosensor techniques.In this paper,a new optical biosensor for molecule detection based on silver metallic nanoparticles(MNPs)and graphene/gold MNPs in a terahertz frequency range is achieved.It is established that the nonlinear electrical properties of graphene can play a major role in realizing a biosensor for molecule detection.The performance parameters of the proposed device are reported with respect to the chemical potential μ of graphene,noting that the sensitivity of our device passes from 255 nm/RIU(nanometers/refractive index unit)for μ=1.21 e V to 2753 nm/RIU for μ=0.21 e V.Finally,this structure exhibits an optical sensing region that can be adjusted to meet the requirements of optical detection.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.61405058 and 62075059)the Natural Science Foundation of Hunan Province (Grant Nos.2017JJ2048 and 2020JJ4161)+2 种基金the Scientific Research Foundation of Hunan Provincial Education Department (Grant No.21A0013)the Open Project of State Key Laboratory of Advanced Optical Communication Systems and Networks of China (Grant No.2024GZKF20)the Guangdong Basic and Applied Basic Research Foundation (Grant No.2024A1515011353)。
文摘We have introduced a new approach to calculate the orbital angular momentum(OAM)of bound states in continuum(BICs)and below-continuum-resonance(BCR)modes in the rotational periodic system nested inside and outside by transforming the Bloch wave number from the translational periodic system.We extensively classify and study these BICs and BCR modes,which exhibit high-quality(high-Q)factors,in different regions relative to the interface of the system.These BICs and BCR modes with a high-Q factor have been studied in detail based on distinctive structural parameters and scattering theory.The outcomes of this research break the periodic limitation of interface state-based BICs,and realize more and higher symmetry interface state-based BICs and BCR modes.Moreover,we can control the region where light is captured by adjusting the frequency,and show that the Q factor of BICs is more closely related to the ordinal number of rings and the rotational symmetry number of the system.
文摘We report the modeling and designing aspects of different types of photo-acoustic (PA) cell based on the excitation of longitudinal, radial and azimuthal mode using CW and pulse lasers. The results are obtained by employing fluid dynamics equations along with Bessel’s function. The obtained results based on stimulation of longitudinal, radial and azimuthally resonance modes of the Photo acoustic signals in the suitable cavity. This is utilized to design highly efficient low volume PA detector for the spectroscopic studies of different types of atmospheric pollutants. We have also studied the dependence of the excited photo acoustic signals on various parameters such as cell radius, laser power, absorption coefficient, quality factor ‘Q’ along with the first longitudinal, radial, azimuthal mode and the pressure. The simulated results show the linearity of the PA signal with different concentration of the gas sample.
基金supported by the National Key R&D Program of China (No. 2017YFB0405501)the National Natural Science Foundation of China (Nos. 61705050, 61675052, 61965005, 61975038, and 61827819)the Guangxi Project (Nos. 2018AD19081 and 2018AA20001)
文摘The distributed optical fiber surface plasmon resonance(SPR)sensors have attracted wide attention in biosensing and chemical sensing applications.However,due to the limitation of their sensing structure,it is difficult to adjust their res-onant wavelength and sensitivity.Here,novel and flexible cascaded helical-core fiber[HCF)SPR sensors are proposed theoretically and experimentally for distributed sensing applications.It is shown that the resonant wavelength and sensitivity of the sensors can be conveniently controlled by adjusting the twist pitch of the helical core.A high sensitivity of 11,180 nm/RIU for refractive-index measurement ranging from 1.355 to 1.365 is realized experimentally when the twist pitch of the helical core is 1.5 mm.It is worth noting that the sensitivity can be further improved by reducing the twist pitch.For example,the sensitivity of the sensor with a twist pitch of 1.4 mm can theoretically exceed 20,000 nm/RIU.This work opens up a new way to implement multi-parameter or distributed measurement,especially to establish sensing networks integrated in a single-core fiber or a multi-core fiber.
文摘We investigate the resonance modes of gold nanorods on an Indium tin oxide (ITO) coated glass substrate using spectroscopic ellipsometry. The unit cell of the structure investigated is composed of two gold nanorods with differing lengths. In such a structure, we can excite the bright resoance and the dark resonance modes. Numerical simulation of the gold nanorod on substrate was performed with the bright resonance mode at 825.0 nm and the dark resonance mode at 1107.1 nm respectively. Using spectroscopic ellipsometry we optically characterize the fabricated gold nanostructure, with the bright resonance mode at 700.0 nm and the dark resonance mode at 1350.0 nm respectively. The experimental results from ellipsometry show a good agreement with the results from simulation.
文摘The strong coupling between vibrational modes of molecules and surface plasmon resonance(SPR)modes in graphene makes them an ideal platform for biosensor techniques.In this paper,a new optical biosensor for molecule detection based on silver metallic nanoparticles(MNPs)and graphene/gold MNPs in a terahertz frequency range is achieved.It is established that the nonlinear electrical properties of graphene can play a major role in realizing a biosensor for molecule detection.The performance parameters of the proposed device are reported with respect to the chemical potential μ of graphene,noting that the sensitivity of our device passes from 255 nm/RIU(nanometers/refractive index unit)for μ=1.21 e V to 2753 nm/RIU for μ=0.21 e V.Finally,this structure exhibits an optical sensing region that can be adjusted to meet the requirements of optical detection.
