By investigating the influence of the difference of refractive index between core and cladding （nco - ncl）, normalized frequency （V） and core radius （α） on both the intramodal and intermodal nonlinear coefficie...By investigating the influence of the difference of refractive index between core and cladding （nco - ncl）, normalized frequency （V） and core radius （α） on both the intramodal and intermodal nonlinear coefficients （NCs） respectively, we design a novel weakly-coupled four-mode fiber with low nonlinearity. In general, under the premise of ensuring the low NCs between two non-degenerate modes, this design can reduce the intermodal NCs （〈 0.5 W-l·km^-1） between two degenerate modes and optimizes the parameters of differential group delays （DGDs） and chromatic dispersion. The optimized few mode fiber （FMF） is eligible for transmission and mode de-multiplexing in the receiver.展开更多
Weakly-coupled elliptic system arising in the two-predator, two-prey model is discussed. It is proved that there is no non-constant solution if diffusions or inter-specific competitions are strong, or if the intrinsic...Weakly-coupled elliptic system arising in the two-predator, two-prey model is discussed. It is proved that there is no non-constant solution if diffusions or inter-specific competitions are strong, or if the intrinsic growths of the prey are slow and the intrinsic drop rates of predator are fast.展开更多
In the paper,an optical fiber sensor based on a seven-core fiber composite structure is presented,which enables dual-parameter sensing of bending and temperature.The proposed structure is fabricated by combining the s...In the paper,an optical fiber sensor based on a seven-core fiber composite structure is presented,which enables dual-parameter sensing of bending and temperature.The proposed structure is fabricated by combining the strongly-coupled seven-core fibers(SC-SCFs)and a weakly-coupled seven-core fiber(WC-SCF).The SC-SCF acts as a beam coupler and enhances the Mach-Zehnder interference,while the WC-SCF serves as the enhanced section of another Mach-Zehnder interference.Therefore,the spectrum response of the fiber structure mentioned above exhibits a superposition effect of two Mach-Zehnder interferometers(MZIs).Among them,two dips corresponding to different MZIs are used to measure bending and temperature.The experimental results show the bending sensitivity and temperature sensitivity of the two MZIs are-4.238 nm/m^(-1),-2.263 nm/m^(-1),0.047 nm/℃,and 0.064 nm/,respectively.It proves℃that our sensor is very sensitive to bending.Through the dual-wavelength matrix method,the bending and temperature can be measured simultaneously.With the benefit of the composite structure,low cost,and ease of fabrication,the proposed sensor can be used in harsh environments.展开更多
A discrete sequential tunneling model is used for studying the influence of the doping density on the dynamical behaviors in weakly coupled GaAs/AlAs superlattices. Driven by the DC bias, the system exhibits self- sus...A discrete sequential tunneling model is used for studying the influence of the doping density on the dynamical behaviors in weakly coupled GaAs/AlAs superlattices. Driven by the DC bias, the system exhibits self- sustained current oscillations induced by the period motion of the unstable electric field domain, and an electrical hysteresis in the loop of current density voltage curve is deduced. It is found that the hysteresis range strongly depends on the doping density, and the width of the hysteresis loop increases with increasing the doping density. By adding an external driving ac voltage, more complicated nonlinear behaviors are observed including quasi- periodicity, period-3, and the route of an inverse period-doubling to chaos when the driving frequency changes.展开更多
基金supported by the National"973"Program of China(Nos.2010CB328204 and 2014CB340102)the National"863"Program of China(No.2012AA011301)+1 种基金the National Natural Science Foundation of China(Nos.61302085,61271191,and 61271189)the China PostDoctoral Foundation Project(No.2012M520207)
文摘By investigating the influence of the difference of refractive index between core and cladding （nco - ncl）, normalized frequency （V） and core radius （α） on both the intramodal and intermodal nonlinear coefficients （NCs） respectively, we design a novel weakly-coupled four-mode fiber with low nonlinearity. In general, under the premise of ensuring the low NCs between two non-degenerate modes, this design can reduce the intermodal NCs （〈 0.5 W-l·km^-1） between two degenerate modes and optimizes the parameters of differential group delays （DGDs） and chromatic dispersion. The optimized few mode fiber （FMF） is eligible for transmission and mode de-multiplexing in the receiver.
文摘Weakly-coupled elliptic system arising in the two-predator, two-prey model is discussed. It is proved that there is no non-constant solution if diffusions or inter-specific competitions are strong, or if the intrinsic growths of the prey are slow and the intrinsic drop rates of predator are fast.
基金supported by“Pioneer”and“Leading Goose”Research&Development Program of Zhejiang,China(Grant No.2022C03084)the Natural Science Foundation of China(Grant No.62205296)+1 种基金the Zhejiang Provincial Natural Science Foundation of China(Grant Nos.LQ22F050007 and LQ23F050004)the Ningbo Science and Technology Project,China(Grant No.2021Z030).
文摘In the paper,an optical fiber sensor based on a seven-core fiber composite structure is presented,which enables dual-parameter sensing of bending and temperature.The proposed structure is fabricated by combining the strongly-coupled seven-core fibers(SC-SCFs)and a weakly-coupled seven-core fiber(WC-SCF).The SC-SCF acts as a beam coupler and enhances the Mach-Zehnder interference,while the WC-SCF serves as the enhanced section of another Mach-Zehnder interference.Therefore,the spectrum response of the fiber structure mentioned above exhibits a superposition effect of two Mach-Zehnder interferometers(MZIs).Among them,two dips corresponding to different MZIs are used to measure bending and temperature.The experimental results show the bending sensitivity and temperature sensitivity of the two MZIs are-4.238 nm/m^(-1),-2.263 nm/m^(-1),0.047 nm/℃,and 0.064 nm/,respectively.It proves℃that our sensor is very sensitive to bending.Through the dual-wavelength matrix method,the bending and temperature can be measured simultaneously.With the benefit of the composite structure,low cost,and ease of fabrication,the proposed sensor can be used in harsh environments.
基金supported by the National Natural Science Foundation of China(Nos.11047108,11147197,11005003)the Research Project of Basic and Cutting-Edge Technology of Henan Province,China(No.112300410183)the Education Department of Henan Province, China(No.2011B140002)
文摘A discrete sequential tunneling model is used for studying the influence of the doping density on the dynamical behaviors in weakly coupled GaAs/AlAs superlattices. Driven by the DC bias, the system exhibits self- sustained current oscillations induced by the period motion of the unstable electric field domain, and an electrical hysteresis in the loop of current density voltage curve is deduced. It is found that the hysteresis range strongly depends on the doping density, and the width of the hysteresis loop increases with increasing the doping density. By adding an external driving ac voltage, more complicated nonlinear behaviors are observed including quasi- periodicity, period-3, and the route of an inverse period-doubling to chaos when the driving frequency changes.
