轨道角动量模传输的圆环形光子晶体光纤
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摘要
设计了一种新型轨道角动量模传输的圆环形光子晶体光纤,包层为排列有序的矩形空气孔围绕纤芯呈圆形排列,纤芯为大的空气孔,中间环形高折射率区为光子轨道角动量传输区。利用基于有限元法的COMSOL Multiphysics软件进行仿真分析,对光子轨道角动量模式在光纤中的传输特性进行了详细讨论。结果表明,该结构可实现1.2～2.0μm波段50个轨道角动量模式的有效分离和稳定传输,简并模式的有效折射率差大于10~(-4),保证了每个模式的稳定传输;限制损耗仅为10~(-9)dB·m~(-1),非线性系数低至0.833 km~(-1)·W~(-1)。该光纤可以应用于模分复用系统,将大大提高通信系统容量和频谱效率。
A new type of circular photonic crystal fiber supporting orbital angular momentum was proposed. The designed circular photonic crystal fiber is composed of well-ordered rectangular air hole rings in the cladding, a large air-core in the center and the annular high-index region for orbital angular momentum modes transmission. Utilizing the COMSOL Multiphysics software based on the finite element method, propagation properties of orbital angular momentum modes in fibers were discussed in detail. The results show that the designed circular photonic crystal fiber realizes effective segregation and stable transmission of 50 orbital angular momentum modes over the bandwidth from 1.2 μm to 2.0 μm. Large effective index differences(>10~(-4)) guarantee the stable transmission of every mode, confinement losses are lower than 10~(-9)dB·m~(-1), and nonlinear coefficients are as low as 0.833 km~(-1)·W~(-1). The proposed rectangular holes circular photonic crystal fiber applied in mode-division multiplexing fiber communication systems might greatly improve channel capacity and spectral efficiency.
A new type of circular photonic crystal fiber supporting orbital angular momentum was proposed. The designed circular photonic crystal fiber is composed of well-ordered rectangular air hole rings in the cladding, a large air-core in the center and the annular high-index region for orbital angular momentum modes transmission. Utilizing the COMSOL Multiphysics software based on the finite element method, propagation properties of orbital angular momentum modes in fibers were discussed in detail. The results show that the designed circular photonic crystal fiber realizes effective segregation and stable transmission of 50 orbital angular momentum modes over the bandwidth from 1.2 μm to 2.0 μm. Large effective index differences(>10~(-4)) guarantee the stable transmission of every mode, confinement losses are lower than 10~(-9)dB·m~(-1), and nonlinear coefficients are as low as 0.833 km~(-1)·W~(-1). The proposed rectangular holes circular photonic crystal fiber applied in mode-division multiplexing fiber communication systems might greatly improve channel capacity and spectral efficiency.
引文
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[14]Ramachandran S,Kristensen P,Yan M F.Generation and propagation of radially polarized beams in optical fibers[J].Optics Letters,2009,34(16):2525-2527.
[15]Brunet C,Vaity P,Messaddeq Y,et al.Design,fabrication and validation of an OAM fiber supporting 36 states[J].Optics Express,2014,22(21):26117-26127.
[16]Maji P S,Chaudhuri P R.Circular photonic crystal fibers:numerical analysis of chromatic dispersion and losses[J].Isrn Optics,2013,2013(4):1-9.
[17]Saitoh K,Florous N,Koshiba M.Ultra-flattened chromatic dispersion controllability using a defected-core photonic crystal fiber with low confinement losses[J].Optics Express,2005,13(21):8365-8371.
[18]Inci H D,Ozsoy S.Birefringence,dispersion and loss properties for PCFs with rectangular air-holes[J].Infrared Physics&Technology,2014,67:354-358.
[19]Jiang G,Fu Y,Huang Y.High birefringence rectangular-hole photonic crystal fiber[J].Optical Fiber Technology,2015,26:163-171.
[2]Gao Chunqing,Zhang Shikun,Fu Shiyao,et al.Adaptive optics wavefront correction techniques of vortex beams[J].Infrared and Laser Engineering,2017,46(2):0201001.(in Chinese)
[3]Bozinovic N,Ramachandran S.Terabit-scale orbital angular momentum mode division multiplexing in fibers[J].Science,2013,340(6140):1545-1548.
[4]Bu Jing,Zhang Lichao,Dou Xiujie,et al.Generation and application of optical vortices with arbitrary topological charges[J].Infrared and Laser Engineering,2017,46(6):0634001.(in Chinese)
[5]Gregg P,Kristensen P,Golowich S E,et al.Stable transmission of 12 OAM states in air-core fiber[C]//CLEO,2013:CTu2K.2.
[6]Ung B,Vaity P,Wang L,et al.Few-mode fiber with inverse-parabolic graded-index profile for transmission of OAM-carrying modes[J].Optics Express,2014,22(15):18044-18055.
[7]Brunet C,Ung B,Messaddeq Y,et al.Design of an optical fiber supporting 16 OAM modes[C]//OFC,2014:TH2A.24.
[8]Yue Y,Zhang L,Yan Y,et al.Octave-spanning supercontinuum generation of vortices in an As2S3 ring photonic crystal fiber[J].Optics Letters,2012,37(11):1889-1891.
[9]Wong G K,Kang M S,Lee H W,et al.Excitation of orbital angular momentum resonances in helically twisted photonic crystal fiber[J].Science,2012,337(6093):446.
[10]Zhang Lingxiang,Wei Wei,Zhang Zhiming,et al.Propagation properties of vortex beams in a ring photonic crystal fiber[J].Acta Physica Sinica,2017,66(1):14205.(in Chinese)
[11]Hu Z A,Huang Y Q,Luo A P,et al.Photonic crystal fiber for supporting 26 orbital angular momentum modes[J].Optics Express,2016,4(15):17285-17291.
[12]Tian W,Zhang H,Zhang X,et al.A circular photonic crystal fiber supporting 26 OAM modes[J].Optical Fiber Technology,2016,30:184-189.
[13]Lou Yan,Chen Chunyi,Zhao Yiwu,et al.Characteristics of Gaussian vortex beam in atmospheric turbulence transmission[J].Chinese Optics,2017,10(6):768-776.(in Chinese)
[14]Ramachandran S,Kristensen P,Yan M F.Generation and propagation of radially polarized beams in optical fibers[J].Optics Letters,2009,34(16):2525-2527.
[15]Brunet C,Vaity P,Messaddeq Y,et al.Design,fabrication and validation of an OAM fiber supporting 36 states[J].Optics Express,2014,22(21):26117-26127.
[16]Maji P S,Chaudhuri P R.Circular photonic crystal fibers:numerical analysis of chromatic dispersion and losses[J].Isrn Optics,2013,2013(4):1-9.
[17]Saitoh K,Florous N,Koshiba M.Ultra-flattened chromatic dispersion controllability using a defected-core photonic crystal fiber with low confinement losses[J].Optics Express,2005,13(21):8365-8371.
[18]Inci H D,Ozsoy S.Birefringence,dispersion and loss properties for PCFs with rectangular air-holes[J].Infrared Physics&Technology,2014,67:354-358.
[19]Jiang G,Fu Y,Huang Y.High birefringence rectangular-hole photonic crystal fiber[J].Optical Fiber Technology,2015,26:163-171.