塑料光纤耦合器的分析和研制

研究了一种新型的塑料光纤耦合器件.采用超声波熔接法制作塑料光纤耦合器,制作过程方便可行.分析了这种耦合器的长度和压缩厚度的变化对耦合比的影响,实验测试结果和计算机模拟分析基本一致.提出了降低工艺过程中的附加损耗的措施,实际制得的塑料光纤耦合器的耦合比和附加损耗能满足短距离通信上的使用要求.     

光纤耦合器及其应用

光纤耦合器是一种定向耦合器,是光纤通信系统中重要器件之一．虽然目前光纤耦合器的大部分应用还只涉及到它的线性特性,但是耦合器中的非线性效应自1982年起就开始研究,其中一个重要应用是全光开关．介绍了光纤耦合器的基本结构及工作原理,重点对光纤耦合器进行了线性与非线性理论分析,具体介绍了几种光纤耦合器的应用实例．     

带状线1/4波长耦合器误差分析

建立了在中心频率处带状线1/4波长定向耦合器S参数和驻波比的一阶近似式,根据灵敏度定义推导出耦合端和直通端幅度相对电路参数的灵敏度表达式,通过编程并与Ansoft公司仿真软件比较,结果显示了所推导公式的正确性和有效性.     

基于3×3平行排列耦合器的全光光开关的特性分析

提出了一种新型的基于3×3平行排列耦合器的全光光开关。此种光开关具有两个独立的输出端口且具有极好的偏振稳定性,消光比可达20dB。介绍了其工作原理,详细分析了信号光强度、控制光强度、光纤长度及耦合器分光比偏差等因素对各端口消光比的影响。比较了不同种类和长度光纤环的开关性能,首次得到了耦合器分光比偏差对消光比的影响曲线。     

基于双芯光纤耦合器的梳状滤波器及其CO2激光调节

基于光纤耦合器的波长特性,分析了光纤耦合器作为梳状滤波器的光谱特性;将长度不同的双芯光纤(twin-core fiber,TCF)熔接在两根单模光纤(single mode fibors,SMF)之间,实验制得具有不同峰值波长间隔的基于双芯光纤耦合器的全光纤型梳状滤波器,其消光比可达25 dB. 首次使用CO₂激光对其进行光谱调节,调节导致光谱向长波方向漂移和消光比的变化. 这种调节是基于CO₂与光纤相互作用时的残余应力释放和熔融变形机理,使用氢载TCF可以在相同实验参数下得到更大的波长调节激光. 关键词： 双芯光纤耦合器 梳状滤波器 2激光')" href="#">CO₂激光 残余应力     

Null Fiber Coupler with Ultra-high Splitting Ratio of 100000∶1 for All-fiber Acousto-optic Switch

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Mode selective directional couplers for overmoded waveguide systems

Two types of directional couplers for transverse electric (TE) modes are described: short and multihole couplers, respectively. They selectively pick one mode out of a mode mixture in an overmoded circular waveguide system. Unwanted modes are either statistically kept at low level or are suppressed by destructive interference in the coupling waveguide. Mode selectivity and directivity in multihole couplers oscillate up and down with an increasing number of holes, finally reaching a minimum of approximately 20 dB, unless there are competing modes with rational fractions of the beat wavelength. A multihole coupler for the TE₀₂ mode (28 GHz, 63.4 mm waveguide diameter, 41 holes) and a length of 1.6 m shows a calculated directivity of 68 dB and suppresses the unwanted modes TE₀₁ with 34 dB (24 dB), TE₂₂ with 37 dB (45 dB), and further modes TE_m (<5, m<6) with 17 dB to 34 dB in forward direction (figures in parentheses are for unwanted modes propagating in backward direction).A short directional coupler for the TE₀₁ mode (28 GHz, 63.4 mm waveguide diameter) with 16 holes and a length of 230 mm shows a directivity of 55 to 100 dB between 27.9 and 28.1 GHz, suppressing the TE₀₂ mode with 35 to 80 dB, the TE₀₃ mode with 30 to 65 dB, and the TE₂₂ mode with 30 to 70 dB.     

Improved directional couplers for overmoded waveguide systems

The performance of multihole directional couplers can be considerably improved by placing a second hole structure to the existing one. The improvement may be aimed at directivity or at suppression of certain unwanted modes propagating either in forward or backward direction.     

A Novel Acoustic Emission Fiber Optic Sensor Based on a Single Mode Optical Fiber Coupler

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A photonic wire-based directional coupler based on SOI

A photonic wire-based directional coupler based on SOI was fabricated by e-beam lithography (EBL) and the inductively coupled plasma (ICP) etching method. The size of the sub-micron waveguide is 0.34 μm × 0.34 μm, and the length in the coupling region and the separation between the two parallel waveguides are 410 and 0.8 μm, respectively. The measurement results are in good agreement with the results simulated by 3D finite-difference time-domain method. The transmission power from two output ports changed reciprocally with about 23 nm wavelength spacing between the coupled and direct ports. The extinction ratio of the device was between 5 and 10 dB, and the insertion loss of the device in the wavelength range 1520-1610 nm was between 22 and 24 dB, which included an about 18.4 ± 0.4 dB coupling loss between the taper fibers and the polished sides of the device.