Coupling characteristics of high birefringence dual-core As2S3 rectangular lattice photonic crystal fiber

A type of As₂S₃ chalcogenide glass mid-infrared dual-core photonic crystal fiber has been proposed. The dual-core photonic crystal fiber (PCF) consists of two asymmetric cores. The high polarization property and the coupling characteristics have been studied by using the finite element method and mode coupling theory. Numerical results show that the birefringence at wavelength λ = 10 μm is up to 0.01386 and the coupling length can reach wavelength λ = 5 μm, 261 μm and 271.44 μm for x-polarized mode and y-polarized mode, respectively. It demonstrates that a 6.786-mm-long fiber can exhibit an extinction ratio of better than -10 dB and a bandwidth of 180 nm.     

Coupling characteristics of high birefringence dual-core As2S3 rectangular lattice photonic crystal fiber

A type of As2S3 chalcogenide glass mid-infrared dual-core photonic crystal fiber has been proposed.The dualcore photonic crystal fiber(PCF) consists of two asymmetric cores.The high polarization property and the coupling characteristics have been studied by using the finite element method and mode coupling theory.Numerical results show that the birefringence at wavelength λ = 10 μm is up to 0.01386 and the coupling length can reach wavelength λ = 5 μm,261 μm and 271.44 μm for x-polarized mode and y-polarized mode,respectively.It demonstrates that a 6.786-mm-long fiber can exhibit an extinction ratio of better than 10 dB and a bandwidth of 180 nm.     

Generation of a mid-infrared broadband polarized supercontinuum in As₂Se₃ photonic crystal fibers

A simplified structure of birefringent chalcogenide As 2 Se 3 photonic crystal fiber(PCF) is designed.Properties of birefringence,polarization extinction ratio,chromatic dispersion,nonlinear coefficient,and transmission are studied by using the multipole method,the finite-difference beam propagation method,and the adaptive split-step Fourier method.Considering that the zero dispersion wavelength of our proposed fiber is about 4 μm,we have analysed the mechanism of spectral broadening in PCFs with different pitches in detail,with femtosecond pulses at a wavelength of 4 μm as the pump pulses.Especially,mid-infrared broadband polarized supercontinuums are obtained in a 3-cm PCF with an optimal pitch of 2 μm.Their spectral width at 20 dB reaches up to 12 μm.In the birefringent PCF,we find that the supercontinuum generation changes with the pump alignment angle.Research results show that no coupling between eigenpolarization modes are observed at the maximum average power(i.e.,37 mW),which indicates that the polarization state is well maintained.     

Study on pulse compression in tapered holey fibres

This paper proposes three kinds of tapered holey fibres with a multi-layer of holes whose pitch of air holes at the end of untapered and tapered are 5.8 μm and 1.8 μm. The central wavelength which locates in the anomalous dispersion region is 1.55 μm. An adaptive split-step Fourier method is numerically used to study the pulse propagation in tapered holey fibres. For the considered convex tapered holey fibre, at a wavelength of 1.55 μm, a compression factor of 136.7 can be achieved by initial width of 800 fs propagation through a length of 0.8 m. It demonstrates that in anomalous dispersion region, pulse can be compressed with the increase of nonlinearity coefficient and the decrease of dispersion coefficient.     

反常色散锥形微结构光纤中高效率脉冲压缩研究

设计了一种沿光纤轴向线性变化的锥形微结构光纤,该光纤在1.55 μm波长处具有反常色散.利用自适应分步傅里叶方法求解非线性薛定谔方程,对中心波长为1.55 μm、初始脉宽为1 ps的脉冲在锥形微结构光纤中的传输进行了模拟,利用1 m长的锥形微结构光纤实现了光脉冲的高效压缩,获得了压缩因子为56.9、品质因子为27的脉冲压缩效果.从脉冲在光纤中的演化发现,在反常色散区基于非线性渐增、色散渐减的锥形微结构光纤有利于实现脉冲的高效率压缩.与普通非线性光子晶体光纤相比,锥形微结构光纤粗端具有较大的有效模式面积,这     

微结构纤芯对光子晶体光纤基本特性的影响

本文设计了两种具有微结构纤芯的光子晶体光纤（PCFs）——矩形芯和椭圆芯PCFs,利用电磁场散射的多极理论研究了这两种光纤的基本特性.发现在光纤包层气孔不变的情况下,仅通过调节纤芯气孔的大小就可以灵活地调节光纤的双折射、色散和非线性特性.随着纤芯气孔半径r₁的增大,两种纤芯结构的PCFs表现出如下特点：双折射度增大且最大双折射度对应的波长发生红移,零色散波长由一个增加到三个,短波段非线性系数增大而长波段非线性系数减小.r₁=0.4 μm的椭圆芯PCFs的三个零色 关键词： 微结构纤芯光子晶体光纤 双折射 色散 非线性     

Generation of a mid-infrared broadband polarized supercontinuum in As2Se3 photonic crystal fibers

A simplified structure of birefringent chalcogenide As 2 Se 3 photonic crystal fiber（PCF） is designed.Properties of birefringence,polarization extinction ratio,chromatic dispersion,nonlinear coefficient,and transmission are studied by using the multipole method,the finite-difference beam propagation method,and the adaptive split-step Fourier method.Considering that the zero dispersion wavelength of our proposed fiber is about 4 μm,we have analysed the mechanism of spectral broadening in PCFs with different pitches in detail,with femtosecond pulses at a wavelength of 4 μm as the pump pulses.Especially,mid-infrared broadband polarized supercontinuums are obtained in a 3-cm PCF with an optimal pitch of 2 μm.Their spectral width at 20 dB reaches up to 12 μm.In the birefringent PCF,we find that the supercontinuum generation changes with the pump alignment angle.Research results show that no coupling between eigenpolarization modes are observed at the maximum average power（i.e.,37 mW）,which indicates that the polarization state is well maintained.     

中红外高双折射高非线性宽带正常色散As2 S3光子晶体光纤

设计了一种中红外As₂S₃光子晶体光纤,利用多极法研究了这种光纤的双折射、色散和非线性特性.数值研究发现,该光纤在中红外波段λ = 3.625 μm处双折射B高达0.098;其x偏振方向的非线性系数γ_x达到了1.69 m^-1 ·W^-1, y偏振方向的非线性系数γ_y达到了0.78 m^{- 关键词： 光子晶体光纤 中红外波段 双折射 非线性}     

High birefringence, low loss terahertz photonic crystal fibres with zero dispersion at 0.3 THz

A terahertz photonic crystal fibre (THz-PCF) is designed for terahertz wave propagation. The dispersion property and model birefringence are studied by employing the finite element method. The simulation result reveals the changing patten of dispersion parameter versus the geometry. The influence of the large frequency band of terahertz on birefringence is also discussed. The design of low loss, high birefringence THz-PCFs with zero dispersion frequency at 0.3 THz is presented.