In order to design birefringent holey fiber with beat-length independent of wavelength, an asymmetric structure is introduced to reduce its wavelength-sensitivity. The influence of structural parameters on the modal b...In order to design birefringent holey fiber with beat-length independent of wavelength, an asymmetric structure is introduced to reduce its wavelength-sensitivity. The influence of structural parameters on the modal birefringence is calculated and analyzed. After optimizing the parameters, a flat dispersion curve of beat-length is obtained. The beat-length changes from 89.8 mm to 91.0 mm in wavelength range from 1.1 μm, to 1.7μm, and its relative variation is 1.38%. If this fiber is made into zero-order quarter wave plate, the phase delay can be easily controlled in （90±1）°.展开更多
The high power holey fiber is an efficient supercontinuum light source by using picosecond pulse,which is a less expensive laser source compared with low power and expensive femtosecond laser sources. In this paper, a...The high power holey fiber is an efficient supercontinuum light source by using picosecond pulse,which is a less expensive laser source compared with low power and expensive femtosecond laser sources. In this paper, a high power highly nonlinear holey fiber(HN-HF) with a low confinement loss is proposed for supercontinuum light sources. The finite difference method is used to calculate the different properties of the proposed HN-HF. High nonlinear coefficients are obtained at 1.06 μm, 1.31μm, and 1.55μm wavelengths with flattened chromatic dispersion and low confinement losses simultaneously. Moreover, numerical simulation results show that high power broad supercontinuum spectra with very short length of the proposed photonic crystal fiber are achieved.展开更多
The effects of high drawing speeds on parameters of holey fibers are presented. A holey fiber preform structure was made by using tube-in-tube method and was drawn at high speeds with an aim of mass production to meet...The effects of high drawing speeds on parameters of holey fibers are presented. A holey fiber preform structure was made by using tube-in-tube method and was drawn at high speeds with an aim of mass production to meet the demand of next generation communication systems. Transmission parameters such as numerical aperture and normalized frequency of the fabricated holey fibers have been measured and compared with theoretical values based on effective index method. Although the fabricated holey fibers were not of high quality, the analyses of the parameters have shown promising outlook for fabrication of such fibers.展开更多
Transmission loss of holey fiber is found to depend on its structure, and to be caused by Rayleigh scattering at glass surface. Under this loss dependence, most promising is optical wiring application, for which fiber...Transmission loss of holey fiber is found to depend on its structure, and to be caused by Rayleigh scattering at glass surface. Under this loss dependence, most promising is optical wiring application, for which fiber designs to realize bend-insensitivity and single-modedness are presented.展开更多
Erbium-doped holey fiber with hexagonal lattice was modeled by using effective index method. In order to calculate the equivalent step index of the periodic structure of the cladding holey optical fiber, all-vectorial...Erbium-doped holey fiber with hexagonal lattice was modeled by using effective index method. In order to calculate the equivalent step index of the periodic structure of the cladding holey optical fiber, all-vectorial fundamental space filling mode approach was utilized. By using EHll mode, we have numerically solved the rate equations of a three-level pumping scheme for a fiber laser. The obtained results have shown a good agreement with the other experimental results, recently. The results have predicted amplifiers with gain efficiencies as high as 10 dB/mW.展开更多
We numerically study the propagation of 1-ps laser pulse in three tapered holey fibers （THFs）.The curvature indices of the concave,linear,and convex tapers are 2.0,1.0,and 0.5,respectively.The central wavelength,loc...We numerically study the propagation of 1-ps laser pulse in three tapered holey fibers （THFs）.The curvature indices of the concave,linear,and convex tapers are 2.0,1.0,and 0.5,respectively.The central wavelength,located in the normal dispersion regime,is 800 nm.The nonlinear coefficient of the THFs increases from the initial 0.095 m-1· W-1 to the final 0.349 m-1·W-1.Wave breaking accompanied by oscillatory structures occurs near pulse edges,and sidelobes appear in the pulse spectrum.With the increase in propagation distance z,the pulse shape becomes broader and the pulse spectrum flattens.A concave THF is advantageous to the generation of wave breaking and enables easier achievement of super flat spectra at short lengths.展开更多
An index-guiding photonic crystal fibre with a small hole in the core is fabricated. The simulated results show that the first higher order mode possesses two zero-dispersion wavelengths, and the phase-matching is pos...An index-guiding photonic crystal fibre with a small hole in the core is fabricated. The simulated results show that the first higher order mode possesses two zero-dispersion wavelengths, and the phase-matching is possible in the anomalous dispersion regime between the two zero-dispersion wavelengths. Using 200 fs Ti： sapphire laser of 820, 830 and 840nm, the anti-Stokes line around 530nm can be generated efficiently. The maximum ratio of the anti-Stokes signal energy to the pump component in the output spectrum is estimated to be 1.03 and the conversion efficiency is above 50%.展开更多
To design and calculate the zero-dispersion wavelength is one of the important aspects for highly nonlinear photonic crystal fibres. By using the air filling fraction f defined as f = （ 6d） / （ 2π∧ ） here for th...To design and calculate the zero-dispersion wavelength is one of the important aspects for highly nonlinear photonic crystal fibres. By using the air filling fraction f defined as f = （ 6d） / （ 2π∧ ） here for the cladding effective index, and the step effective index model, the relationship between the properties of chromatic dispersion and the two different structures has been analysed. It is pointed that the variation of the zero dispersion wavelength is insensitive to the core diameter change in one range of core diameter D, while keeping the air filling fraction f constant. In the other range of core diameter D, the photonic crystal fibres have the best nearly-zero ultraflattened dispersion. These properties are significant to the design of chromatic dispersion and zero dispersion wavelength in photonic crystal fibres.展开更多
Fabricating electrodes with large specific surface area(SSA)and high permeability has been the longstanding target in redox flow batteries(RFBs).In this work,we propose a novel ZIF-8-assisted etching approach to form ...Fabricating electrodes with large specific surface area(SSA)and high permeability has been the longstanding target in redox flow batteries(RFBs).In this work,we propose a novel ZIF-8-assisted etching approach to form holey fibers in the electrospinning process of aligned electrode structures.The etching approach allows the formation of holey fibers with small pores of~50 nm,offering large active surface areas for redox reactions,while the aligned macrostructure with the holey fibers of 3–5 lm in diameter ensures a high permeability along the fiber direction.The application of the prepared electrodes to a vanadium redox flow battery(VRFB)enables an energy efficiency(EE)of 87.2%at the current density of 200 m A cm^(-2),which is 13.3%higher than that with conventional electrospun carbon electrodes.Even at high current densities of 300 and 400 m A cm^(-2),the battery still maintains energy efficiencies of 83.3%and 79.3%.More excitingly,the prepared electrode yields a high limiting current density of4500 m A cm^(-2) and a peak power density of 1.6 W cm^(-2).It is anticipated that the present electrospinning method combining the ZIF-8-assisted etching approach with a way to form ordered fiber structures will allow even more high-performance electrodes for RFBs in the future.展开更多
A novel equal diameter circular-hole photonic crystal fiber(PCF) with high birefringence is proposed and numerically analyzed by employing the finite-element method. The proposed PCF's birefringence is 10^(-3), wh...A novel equal diameter circular-hole photonic crystal fiber(PCF) with high birefringence is proposed and numerically analyzed by employing the finite-element method. The proposed PCF's birefringence is 10^(-3), which can reach 2 orders higher than that of traditional high birefringence fiber, and this equal diameter circular-hole structure reduces the difficulty of the actual drawing process. The effect of different parameters on the birefringence of this PCF is investigated, and the application of the Sagnac interferometer based on fiber filling technology in temperature sensing is studied. The result shows that the high birefringence PCF can be used in both optical communication and optical sensing fields.展开更多
A new type ultraflattened dispersion square-lattice photonic crystal fiber with two different air-hole diameters in cladding region is proposed and the dispersion is investigated using a compact 2-D finite difference ...A new type ultraflattened dispersion square-lattice photonic crystal fiber with two different air-hole diameters in cladding region is proposed and the dispersion is investigated using a compact 2-D finite difference frequency domain method with the anisotropic perfectly matched layers (PML) absorbing boundary conditions. Through numerical simulation and opti- mizing the geometrical parameters, we find that the photonic crystal fibers proposed can realize ultraflattened dispersion of 0±0.06 ps/(km·nm) in wa...展开更多
We propose a temperature-insensitive refractive index（RI） fiber sensor based on a Mach–Zehnder interferometer. The sensor with high sensitivity and a robust structure is fabricated by splicing a short photonic crys...We propose a temperature-insensitive refractive index（RI） fiber sensor based on a Mach–Zehnder interferometer. The sensor with high sensitivity and a robust structure is fabricated by splicing a short photonic crystal fiber（PCF） between two single-mode fibers, where two microcavities are formed at both junctions because of the collapse of the PCF air holes. The microcavity with a larger equatorial dimension can excite higher-order cladding modes, so the sensor presents a high RI sensitivity, which can reach 244.16 nm/RIU in the RI range of1.333–1.3778. Meanwhile it has a low temperature sensitivity of 0.005 nm/°C in the range of 33°C–360°C.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos.60777031, 11074164)the Shanghai Leading Academic Discipline Project (Grant No.S30108)
文摘In order to design birefringent holey fiber with beat-length independent of wavelength, an asymmetric structure is introduced to reduce its wavelength-sensitivity. The influence of structural parameters on the modal birefringence is calculated and analyzed. After optimizing the parameters, a flat dispersion curve of beat-length is obtained. The beat-length changes from 89.8 mm to 91.0 mm in wavelength range from 1.1 μm, to 1.7μm, and its relative variation is 1.38%. If this fiber is made into zero-order quarter wave plate, the phase delay can be easily controlled in （90±1）°.
文摘The high power holey fiber is an efficient supercontinuum light source by using picosecond pulse,which is a less expensive laser source compared with low power and expensive femtosecond laser sources. In this paper, a high power highly nonlinear holey fiber(HN-HF) with a low confinement loss is proposed for supercontinuum light sources. The finite difference method is used to calculate the different properties of the proposed HN-HF. High nonlinear coefficients are obtained at 1.06 μm, 1.31μm, and 1.55μm wavelengths with flattened chromatic dispersion and low confinement losses simultaneously. Moreover, numerical simulation results show that high power broad supercontinuum spectra with very short length of the proposed photonic crystal fiber are achieved.
文摘The effects of high drawing speeds on parameters of holey fibers are presented. A holey fiber preform structure was made by using tube-in-tube method and was drawn at high speeds with an aim of mass production to meet the demand of next generation communication systems. Transmission parameters such as numerical aperture and normalized frequency of the fabricated holey fibers have been measured and compared with theoretical values based on effective index method. Although the fabricated holey fibers were not of high quality, the analyses of the parameters have shown promising outlook for fabrication of such fibers.
文摘Transmission loss of holey fiber is found to depend on its structure, and to be caused by Rayleigh scattering at glass surface. Under this loss dependence, most promising is optical wiring application, for which fiber designs to realize bend-insensitivity and single-modedness are presented.
文摘Erbium-doped holey fiber with hexagonal lattice was modeled by using effective index method. In order to calculate the equivalent step index of the periodic structure of the cladding holey optical fiber, all-vectorial fundamental space filling mode approach was utilized. By using EHll mode, we have numerically solved the rate equations of a three-level pumping scheme for a fiber laser. The obtained results have shown a good agreement with the other experimental results, recently. The results have predicted amplifiers with gain efficiencies as high as 10 dB/mW.
基金supported by the National Natural Science Foundation of China (No.10874145)the Specialized Research Fund for the Doctoral Program of Higher Education (No.20091333110010)+1 种基金the Nature Science Foundation of Hebei Province (No.F2009000481)the China Postdoctoral Science Foundation (Nos.20080440014 and 200902046)
文摘We numerically study the propagation of 1-ps laser pulse in three tapered holey fibers （THFs）.The curvature indices of the concave,linear,and convex tapers are 2.0,1.0,and 0.5,respectively.The central wavelength,located in the normal dispersion regime,is 800 nm.The nonlinear coefficient of the THFs increases from the initial 0.095 m-1· W-1 to the final 0.349 m-1·W-1.Wave breaking accompanied by oscillatory structures occurs near pulse edges,and sidelobes appear in the pulse spectrum.With the increase in propagation distance z,the pulse shape becomes broader and the pulse spectrum flattens.A concave THF is advantageous to the generation of wave breaking and enables easier achievement of super flat spectra at short lengths.
基金Supported by the National Key Basic Research Programme of China under Grant No 2003CB314905, and the National Natural Science Foundation of China under Grant No 60637010.
文摘An index-guiding photonic crystal fibre with a small hole in the core is fabricated. The simulated results show that the first higher order mode possesses two zero-dispersion wavelengths, and the phase-matching is possible in the anomalous dispersion regime between the two zero-dispersion wavelengths. Using 200 fs Ti： sapphire laser of 820, 830 and 840nm, the anti-Stokes line around 530nm can be generated efficiently. The maximum ratio of the anti-Stokes signal energy to the pump component in the output spectrum is estimated to be 1.03 and the conversion efficiency is above 50%.
文摘To design and calculate the zero-dispersion wavelength is one of the important aspects for highly nonlinear photonic crystal fibres. By using the air filling fraction f defined as f = （ 6d） / （ 2π∧ ） here for the cladding effective index, and the step effective index model, the relationship between the properties of chromatic dispersion and the two different structures has been analysed. It is pointed that the variation of the zero dispersion wavelength is insensitive to the core diameter change in one range of core diameter D, while keeping the air filling fraction f constant. In the other range of core diameter D, the photonic crystal fibres have the best nearly-zero ultraflattened dispersion. These properties are significant to the design of chromatic dispersion and zero dispersion wavelength in photonic crystal fibres.
基金financially supported by the grant from the Research Grants Council of the Hong Kong Special Administrative Region,China(T23-601/17-R)the National Natural Science Foundation of China(21703263)HKUST Fund of Nanhai(FSNH-18FYTRI01)。
文摘Fabricating electrodes with large specific surface area(SSA)and high permeability has been the longstanding target in redox flow batteries(RFBs).In this work,we propose a novel ZIF-8-assisted etching approach to form holey fibers in the electrospinning process of aligned electrode structures.The etching approach allows the formation of holey fibers with small pores of~50 nm,offering large active surface areas for redox reactions,while the aligned macrostructure with the holey fibers of 3–5 lm in diameter ensures a high permeability along the fiber direction.The application of the prepared electrodes to a vanadium redox flow battery(VRFB)enables an energy efficiency(EE)of 87.2%at the current density of 200 m A cm^(-2),which is 13.3%higher than that with conventional electrospun carbon electrodes.Even at high current densities of 300 and 400 m A cm^(-2),the battery still maintains energy efficiencies of 83.3%and 79.3%.More excitingly,the prepared electrode yields a high limiting current density of4500 m A cm^(-2) and a peak power density of 1.6 W cm^(-2).It is anticipated that the present electrospinning method combining the ZIF-8-assisted etching approach with a way to form ordered fiber structures will allow even more high-performance electrodes for RFBs in the future.
基金supported by the National Natural Science Foundation of China(Nos.61301124,61471075 and 61671091)the Basic Research Project of Chongqing Science and Technology Commission(Nos.cstc2014gjhz40001,cstc2015jcyj BX0068,cstc2014jcyj A1350,cstc2015jcyj B0360 and KJZH17115)+3 种基金the University Innovation Team Construction Plan of Smart Medical System and Core Technologythe Enhancement Plan of Chongqing Key Laboratory of Photoelectronic Information Sensing and Transmitting Technologythe Scientific and Technological Research Program of Chongqing Municipal Education Commission(No.KJ1704091)the Funds of Chongqing University of Posts and Telecommunications(No.A2016-72)
文摘A novel equal diameter circular-hole photonic crystal fiber(PCF) with high birefringence is proposed and numerically analyzed by employing the finite-element method. The proposed PCF's birefringence is 10^(-3), which can reach 2 orders higher than that of traditional high birefringence fiber, and this equal diameter circular-hole structure reduces the difficulty of the actual drawing process. The effect of different parameters on the birefringence of this PCF is investigated, and the application of the Sagnac interferometer based on fiber filling technology in temperature sensing is studied. The result shows that the high birefringence PCF can be used in both optical communication and optical sensing fields.
基金supported by the National Natural ScienceFoundation of China (Grant Nos. 60637010 and 60671036)the National Basic Research Program of China (Grant No.2007CB310403).
文摘A new type ultraflattened dispersion square-lattice photonic crystal fiber with two different air-hole diameters in cladding region is proposed and the dispersion is investigated using a compact 2-D finite difference frequency domain method with the anisotropic perfectly matched layers (PML) absorbing boundary conditions. Through numerical simulation and opti- mizing the geometrical parameters, we find that the photonic crystal fibers proposed can realize ultraflattened dispersion of 0±0.06 ps/(km·nm) in wa...
基金supported by the Ministry of Science and Technology of China (MOST) (No. 2015AA043504)the National Natural Science Foundation of China (NSFC) (Nos. 91323301 and 51575053)
文摘We propose a temperature-insensitive refractive index（RI） fiber sensor based on a Mach–Zehnder interferometer. The sensor with high sensitivity and a robust structure is fabricated by splicing a short photonic crystal fiber（PCF） between two single-mode fibers, where two microcavities are formed at both junctions because of the collapse of the PCF air holes. The microcavity with a larger equatorial dimension can excite higher-order cladding modes, so the sensor presents a high RI sensitivity, which can reach 244.16 nm/RIU in the RI range of1.333–1.3778. Meanwhile it has a low temperature sensitivity of 0.005 nm/°C in the range of 33°C–360°C.
