新型宽带单偏振单模光子晶体光纤的设计

基于折射率匹配耦合原理,提出并设计了一种新型宽带单偏振单模光子晶体光纤,阐述了工作原理并利用全矢量有限元法对其进行了数值模拟.当中间纤芯和边芯之间空气孔1和2的直径为2.4 μm时,波长在1.26～1.7μm的范围内,偏振相关损耗大于4.08 dB/m,单偏振单模的带宽高达440 nm;当空气孔1和2的直径为2.6 μ...     

金属包层单模光纤偏振器的分析

给出计算金属包层单模光纤偏振器中两种正交偏振模式的损耗系数，偏振器的消光比与插入损耗的微扰分析方法。本法计算较简便，且能分析光纤芯区被部分刻蚀的情况，此情况的分析尚未报道。其计算结果与实验结果符合。     

宽带空芯THz单模单偏振光纤

传统的THz单模单偏振光纤大部分都是基于实芯光纤设计的,增加了THz波的传输损耗。最近几年,也有一些关于空芯THz单模单偏振光纤的报道。但是,他们的带宽太窄,往往只能在单一频率附近工作,影响了单偏振器件在THz范围内的使用价值和技术优势。为了解决这些问题,设计了一种新颖结构的空芯THz单模单偏振器件。它拥有超过0.1 THz的带宽,工作频率范围从1.63 THz到1.73 THz。这种器件对于THz通信网络的建设和应用具有重要意义。     

单模光纤耦合器的偏振温度特性研究

理论分析并研究了温度变化对单模光纤耦合器的偏振特性的影响.推导了单模光纤耦合器输出消光比与输入消光比、模式耦合率的关系表达式.利用多个偏振特性不同的光源,进行了在快速温度变化条件下单模耦合器输出消光比随温度变化的测试实验,证明了采用低偏振的光源有利于降低单模耦合器中因温度变化引起的模式耦合效应.最后仿真计算了在光源输出消光比不同的情况下模式耦合引起的光纤陀螺输出误差的大小,为不同环境应用的光纤陀螺选取合适的光源提供了参考.     

低损耗大带宽双芯负曲率太赫兹光纤偏振分束器

设计了一种基于双芯负曲率光纤的新型低损耗大带宽太赫兹偏振分束器,该器件以环烯烃共聚物为基底,沿圆周等间距分布着12个含内嵌管的圆形管,通过上下对称的两组外切小包层管将纤芯分成双芯.采用时域有限差分法对其导模特性进行分析,详细研究了各个参数对其偏振分束特性的影响,分析了该偏振分束器的消光比、带宽、传输损耗等性能.仿真结果表明:当入射光频率为1 THz,分束器长度为6.224 cm时, x偏振光的消光比达到120.8 d B,带宽为0.024 THz, y偏振光的消光比达到63.74 d B,带宽为0.02 THz,传输总损耗低至0.037 d B/cm.公差分析表明结构参数在±1%的偏差下,偏振分束器仍然可以保持较好的性能.     

基于悬浮式双芯多孔光纤的太赫兹偏振分离器

提出了一种基于悬浮式双芯多孔光纤的低损耗、宽带太赫兹偏振分离器.通过纤芯的多孔结构实现器件的低损耗特性,利用两个纤芯微结构的正交关系实现宽带的单偏振模式匹配.结构参数设计采用折射率反转匹配耦合法;数值计算采用全矢量有限元法;光纤基底材料选择太赫兹波段低损耗环烯烃共聚物COC.首先对单芯高双折射悬浮式多孔光纤的色散、模式双折射、基模在空气中的能量分数、以及损耗等特性进行了分析,在此基础上,对悬浮式双芯多孔光纤偏振分离器的特性进行了详细研究.发现该偏振分离器的工作带宽超过1.5 THz(0.8 THz到2.3 THz).其偏振分离长度和吸收损耗随频率的增大而增大,在1 THz,分离长度仅为0.66 cm;x,y两偏振的消光比分别为-14.64 dB和-14.84 dB,两偏振模式的实际吸收损耗均小于0.12 dB.相对于其他双芯光纤偏振分离器设计,该结构具有宽带、低损耗、设计简单、拉制容易、以及抗环境干扰等优点.     

基于“耦合-耦合-吸收”机理的超宽带单模单偏振微结构光纤

通过在高双折射微结构光纤包层构建缺陷并在其外侧空气孔镀金的方法，实现一种基于“耦合-耦合-吸收”滤波机理的新型单模单偏振微结构光纤（SMSP-MSF）。纤芯中需要滤除的偏振态模式能量通过“纤芯与缺陷芯耦合”和“缺陷芯与金缺陷耦合”两次耦合作用传递至镀金孔中，再利用金缺陷的等离子体共振效应对能量进行吸收，以实现宽带的单模单偏振传输。基于上述机理，利用全矢量有限元法，得到了两种宽带SMSP-MSF。所设计的正六边形晶格SMSPMSF的纤芯x偏振模式与缺陷芯模式、金层二阶表面等离子极化激元模式在多个波长分别谐振，实现380 nm的单模单偏振传输带宽。所设计的正方形晶格SMSP-MSF利用纤芯及缺陷芯相互垂直的排布方式，保证了纤芯与缺陷芯x偏振模式耦合，而y偏振模式不耦合，在1.55μm处实现了偏振消光比高达113 dB的高质量单模单偏振传输。     

新型单模光纤偏振器

本文介绍了新型D型微孔单模光纤偏振器的制作工艺及其性能参数。其工作波长为1.3μm,光纤偏振器的消光比优于40dB,插入损耗≤2.5dB.制作工艺较为简单,温度变化对器件的影响小,稳定性好,工作波长范围宽。     

基于金线填充的双芯光子晶体光纤偏振分束器

提出了一种基于金线填充的双芯光子晶体光纤超短偏振分束器,并进行了有限元分析.金线表面激发的表面等离子激元与双芯光子晶体光纤纤芯模之间的强烈耦合,导致更短的偏振分束器长度和更大的工作带宽.与同类的偏振分束器相比,所提出的偏振分柬器能同时实现较短的长度和较高的消光比.数值结果表明,长度为0.263 mm的偏振分束器,在波长1.55 μm处消光比达-70 dB,-20 dB消光比带宽为124 nm.     

基于金线填充的双芯光子晶体光纤偏振分束器（英文）

提出了一种基于金线填充的双芯光子晶体光纤超短偏振分束器,并进行了有限元分析.金线表面激发的表面等离子激元与双芯光子晶体光纤纤芯模之间的强烈耦合,导致更短的偏振分束器长度和更大的工作带宽.与同类的偏振分束器相比,所提出的偏振分束器能同时实现较短的长度和较高的消光比.数值结果表明,长度为0.263mm的偏振分束器,在波长1.55μm处消光比达-70dB,-20dB消光比带宽为124nm.     

Design and analysis of a novel single-mode single-polarization photonic crystal fibre based on polarization-dependent coupling and absorption effect

A novel single-mode single-polarization (SMSP) photonic crystal fibre has been proposed and analysed based on the polarization-dependent coupling and absorption effect via a full-vector finite element method with perfectly matched layers. The numerical results predict that very efficient SMSP operation can be achieved with both high bandwidth and high extinction ratio at low loss penalty. Effects of the fibre structural parameters on the SMSP bandwidth and extinction ratio have been explored, which will provide useful guide for the design and fabrication of the fibre. The results obtained will be instructive for the realization of new SMSP fibres with high performance.     

Single-polarization single-mode hollow-core negative curvature fiber with nested U-type cladding elements

Hollow-core negative curvature fibers (HC-NCFs) have become one of the research hotspots in the field of optical fiber because of their potential applications in the data and energy transmissions. In this work, a new kind of single-polarization single-mode HC-NCF with nested U-type cladding elements is proposed. To achieve the single-polarization single-mode transmission, we use two different silica tubes in thickness, which satisfy the resonance and anti-resonance conditions on the U-type cladding elements and the cladding tubes, respectively. Besides, the elliptical elements are introduced to achieve good single-mode performance. By studying the influences of the structure parameters on the propagation characteristics, the optimized structure parameters are obtained. The simulation results show that when the wavelength is fixed at 1550 nm, the single-polarization single-mode transmission is achieved, with the polarization extinction ratio of 25749 and minimum high-order mode extinction ratio of 174. Furthermore, the confinement loss is only 0.0015 dB/m.     

All-fiber single polarized Yb-doped fiber laser with a high extinction ratio

We present an all-fiber design for a single polarization Yb-doped fiber laser with all-fiber connections spliced. Single polarization with a high extinction ratio was achieved by the design of a laser cavity consisting of a fiber Bragg grating inscribed on a single-polarization fiber as a high reflective mirror and a piece of end-cleaved single-polarization fiber as an output coupler. The fiber laser operates at 1063.25 nm with an output power of 1.7 W, an optical signal- to-noise ratio of 70 dB and a narrow bandwidth of 54 pm. The laser output has a polarization extinction ratio of 700:1 or 28 dB, and a very stable power output.     

Broadband single-polarization photonic crystal fiber

We demonstrate a single-mode photonic crystal fiber that supports only one polarization state in a 220-nm-broad spectral region centered at 727 nm. The fiber has a mode-field diameter of 15.5 microm and background losses of < 15 dB/km in the single-polarization region. To our knowledge, these are the broadest bandwidth and the largest mode size yet reported for a single-polarization fiber.     

Single-polarization fiber with a high extinction ratio

An elliptical-core hole assisted single-polarization fiber was designed, fabricated, and characterized. Numerical modeling based on the vectorial Maxwell equation reveals the dependence of the single-polarization bandwidth on core delta and air-hole size. Several single-polarization fibers based on this design with their single-polarization operating windows centered between 0.9 and 1.5 microm were successfully demonstrated. A correlation between fiber birefringence and single-polarization operating bandwidth is qualitatively confirmed. A single-polarization bandwidth as high as 55 nm was observed. These fibers also show very high extinction ratios of 60 dB or higher at lengths much shorter than 1 m. Other properties such as the dependence on length of the single-polarization operating window were also measured.     

Versatile control of geometric birefringence in elliptical hollow optical fiber

A novel optical fiber fabrication technique was developed by converting the symmetry of the silica substrate into the germanosilicate ring core to efficiently introduce geometric birefringence in an elliptical hollow optical fiber. Due to high ellipticity in the hollow ring core, the fiber provides an extremely high group birefringence of 2.35 x 10(-3) at 1550 nm. Single-mode single-polarization guidance was also experimentally confirmed, with a bandwidth of approximately 35 nm. The generic adiabatic mode conversion capability in the taper also provided a stable fusion splice to conventional single-mode fiber with low loss and high tensile strength.     

Characterization of single-polarization single-mode photonic crystal fiber using full-vectorial finite element method

A modal solution approach based on the powerful, finite element method (FEM) using a full-vectorial H-field formulation has been used to determine the single-mode operation of a photonic crystal fiber (PCF). The modal solution of the fundamental space-filling mode has also been obtained to identify the cutoff conditions of the waveguide modes. The FEM, with the perfectly matched layer boundary condition, has been developed and employed to characterize the leakage loss and the differential loss between the polarized modes of a PCF. The design approach for a single-polarization and single-mode PCF has also been discussed.     

Fabrication of tapered fiber based ring resonator

Tapered fiber based ring resonators are fabricated and its optical characteristic is investigated in detail. The ring resonator is fabricated by coiling the tapered fiber, which is firstly made by heating and stretching a piece of optical fiber, after the polymer protective cladding has been removed The comb filter with a constant free spectral range (FSR) and the maximum extinction ratio of 4.2 dB is achieved by a single-mode fiber based ring resonator. The FSR of ring resonator can be adjusted by controlling the diameter of the ring. The extinction ratio is improved in the polarization maintaining fiber based ring resonator where the maximum extinction ratio of 14 dB is achieved at 1531 nm region.