Polarization rotator for InP rib waveguide

A polarization rotator, suitable for integration in a polarization diversity optical receiver fabricated in InP technology, is proposed. The device, based on a two steps waveguide rotator, includes tapered input and output ports that provide very low insertion loss (<0.04 dB). An extinction ratio of 40 dB at 1550 nm wavelength is calculated, comparable or even superior to other state of the art polarization converters. The main advantage of the proposed design is the capability of implementation using a standard fabrication process with only two dry etch steps, significantly reducing complexity and cost.     

Compact polarization rotators for integrated polarization diversity in InP-based waveguides

We present the design, fabrication, and operation of a polarization converter based on angled waveguides in the InP/InGaAsP material system. By combining design elements from mode evolution and birefringent devices, the total device length is kept short (less than 50 microm) and the insertion efficiency high at 81%+/-19%, which corresponds to an insertion loss of 1 dB. Devices operate broadband, i.e., the polarization conversion exceeds 15 dB over a 100 nm wavelength range. A polarization rotator with these specifications is a prime candidate for use in an integrated polarization diversity scheme.     

Compact polarization rotator on silicon for polarization-diversified circuits

We demonstrate a polarization rotator based on adiabatic mode evolution on silicon for polarization-diversified circuits. The rotator has a device length of 420?μm, a polarization-conversion efficiency of more than 90%, and an insertion loss less than 1?dB for a wavelength range of 80?nm. Combining the rotator with a compact, broadband polarization beam splitter based on cascaded directional couplers enhances the polarization conversion extinction ratio to over 30?dB with less than 1.5?dB total insertion loss over a 60?nm spectral range.     

线圈型全光纤偏振器的研究

本文采用等效电流法对线圈型全光纤偏振器进行了分析计算.对应于保偏光纤中两正交传输基模的消光比,提出了一种分析保偏光纤弯曲损耗的新方法,这种方法基于将保偏光纤两个不同偏振模式分别等效为两个普通圆光纤的基模,等效参数通过测量不同偏振模式的模场半径来确定.实验证明这种理论计算方法与实验结果一致.最终,我们研制出的线圈型光纤偏振器在1.31μm工作波长下,实测消光比达30dB以上,工作偏振模式插入损耗≤3dB.     

一种高速率、高精度的全光纤偏振控制方法

提出了一种结构简单、高速率、高精度的全光纤偏振控制方法, 并对方案进行了详细的理论分析. 理论和实验结果表明:本方案可以自动补偿光纤系统由于环境变化使光纤发生形变产生的额外双折射效应, 提高了系统的抗干扰能力. 实验获得了31 dB消光比, 此方案有望在实际中得到广泛应用. 关键词： 光纤偏振控制器 双折射效应 法拉第旋转镜     

High-performance and fabrication friendly polarization demultiplexer

A compact and fabrication friendly polarization demultiplexer (P-DEMUX) is proposed and characterized to enable wavelength-division-multiplexing and polarization-division-multiplexing simultaneously. The proposed structure is composed of a polarization-selective microring resonator in ultrathin waveguide and two bus channels in the silicon nitride-silica-silicon horizontal slot waveguides. In the slot waveguide, the transverse electric (TE) mode propagates through the silicon layer, while the transverse magnetic (TM) mode is confined in the slot region. In the designed ultra-thin waveguide, the TM mode is cut-off. The effective indexes of the TE modes for ultrathin and slot waveguides have comparable values. Thanks for these distinguishing features, the input TE mode can be efficiently filtered through the ultra-thin microring at the resonant wavelength, while the TM mode can directly output from the through port. Simulation results show that the extinction ratio of the proposed P-DEMUX for TE and TM modes are 33.21 dB and 24.97 dB, and the insertion losses are 0.346 dB and 0.324 dB, respectively, at the wavelength of 1551.64 nm. Furthermore, the device shows a broad bandwidth ($>100$ nm) for an extinction ratio (ER) of $>20$ dB. In addition, the proposed P-DEMUX also has a good fabrication tolerance for the waveguide width variation of $-20$ nm$\le \Delta w_{\rm g}\le 20$ nm and the microring width variation of $-20$ nm$\le \Delta w_{\rm r}\le $20 nm for a low insertion loss of $<0.75$ dB and low ER of $<-18$ dB.     

Polarization beam splitter with wide bandwidth in air-hole-based periodic dielectric waveguides

A polarization beam splitter with wide bandwidth and simple structure in air-hole-based periodic dielectric waveguides has been proposed and designed. Operation principle of the device is based on different directional coupling properties of beams in TE and TM polarizations in parallel periodic dielectric waveguides. Performances have been evaluated by a finite-difference time-domain simulation. Results show that the polarization beam splitter provides a wide bandwidth of 113 nm with both a high extinction ratio (higher than 21 dB) and a low insertion loss (less than 1.5 dB) for optical communication wavelengths at ∼1.55 μm. Moreover, the performances of the polarization beam splitter are insensitive to longitudinal alignment errors in the coupling region, which is desirable for device fabrication and practical application.     

Design of a polarization splitter for an ultra-broadband dual-core photonic crystal fiber

A novel ultra-broadband polarization splitter based on a dual-core photonic crystal fiber (DC-PCF) is designed. The full-vector finite element method and coupled-mode theory are employed to investigate the characteristics of the polarization splitter. According to the numerical results, a graphene-filled layer not only broadens the working bandwidth but also reduces the size of the polarization splitter. Furthermore, the fluorine-doped region and the germanium-doped region can broaden the bandwidth. Also, the 4.78 mm long polarization splitter can achieve an extinction ratio of -98.6 dB at a wavelength of 1550 nm. When extinction ratio is less than -20 dB, the range of the wavelength is 1027 nm-1723 nm with a bandwidth of 696 nm. Overall, the polarization splitter can be applied to all-optical network communication systems in the infrared and near-infrared wavelength range.     

Theoretical simulation of a polarization splitter based on dual-core soft glass PCF with micron-scale gold wire

A polarization splitter based on dual-core soft glass photonic crystal fiber(PCF) filled with micron-scale gold wire is proposed. The characteristics of the polarization splitter are studied by changing the structural parameters of the PCF and the diameter of the gold wire with the finite element method(FEM). The simulation results reveal that the coupling length ratio of the soft glass-based PCF is close to 2 and the corresponding curve is more flat than that of the silica-based PCF.The broadband bandwidth is 226 nm in which the extinction ratio is lower than-20 d B by the soft glass-based PCF, i.e.,from 1465 nm to 1691 nm which is competitive in the reported polarization splitters, and the bandwidth is just 32 nm by the silica-based PCF. The insertion loss by our polarization splitter is just 0.00248 d B and 0.43 d B at the wavelength of 1.47 μm and 1.55 μm. The birefringence is obviously increased and the coupling length is decreased by filling gold wire into the soft glass-based or the silica-based PCF. Also the birefringence based on the silica-based PCF is much larger than that based on the soft glass-based PCF whether or not the gold wire is introduced. The fabrication tolerance of the polarization splitter is also considered by changing the structural parameters. The polarization splitter possesses broad bandwidth, low insertion loss, simple structure and high fabrication tolerance.     

Design and fabrication of a three-dimensional polymer optical waveguide polarization splitter

We present a design and fabrication of a three-dimensional polymer optical waveguide polarization splitter by taking into consideration of the induced birefringence effect of the polymer. We show that it is not possible to couple TM light from one waveguide to the other but evanescent coupling for TE light is possible. Hence the polarization splitter can be designed by considering TE mode coupling alone. This has an advantage of short interaction length of the device. Based on this consideration, we fabricated a polarization splitter with a TE extinction ratio of 15 dB and TM extinction ratio of 21 dB.     

反射式光学电压互感器光路建模及偏振误差分析

光路系统的偏振误差极大地制约着准互易反射式光学电压互感器的准确度.借助琼斯矩阵,建立了分立光学器件及光纤熔接点的传输模型,推导出完整的电压互感器光路系统的数学模型.以此模型为基础,对电压互感器中的偏振误差进行了仿真分析.结果表明：光源偏振度、起偏器消光比及起偏器与相位调制器的对轴角度主要影响系统的检测灵敏度|法拉第准直旋光器的旋光角度、法拉第准直旋光器与BGO晶体的对轴角度误差是主要的偏振误差源,影响系统的测量准确度及稳定性|根据电子式电压互感器IEC60044-7 0.2S级标准,法拉第旋光角度误差应该小于1.6°,旋光器与BGO晶体对轴角度误差小于1.85°.该研究对准互易反射式光学电压互感器光路设计和误差抑制具有一定的参考价值和指导意义.     

Ultra-broadband polarization splitter based on graphene layer-filled dual-core photonic crystal fiber

An ultra-broadband polarization splitter based on graphene layer-filled dual-core photonic crystal fiber(GDC-PCF)that can work in a wavelength range from 1120 nm to 1730 nm is proposed in this paper. Through optimizing fiber configuration, the polarization splitter has an extinction ratio of-56.3 dB at 1.55 μm with a fiber length of 4.8 mm.Compared with the photonic crystal fiber reported splitters, to our knowledge, the GDC-PCF splitter with the extinction ratio below-20 dB has a super wide bandwidth of 610 nm. Due to the excellent splitting characteristics, the GDC-PCF will be used in coherent optical communication systems in a wavelength range from infrared to mid-infraed.     

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。     

Compact efficient broadband grating coupler for silicon-on-insulator waveguides

We have designed a high-efficiency broadband grating coupler for coupling between silicon-on-insulator (SOI) waveguides and optical fibers. The grating is only 13 microm long and 12 microm wide, and the size of the grooves is optimized numerically. For TE polarization the coupling loss to single-mode fiber is below 1 dB over a 35-nm wavelength range when using SOI with a two-pair bottom reflector. The tolerances to fabrication errors are also calculated.     

硅基槽式微环谐振腔型偏振解复用器全矢量分析

提出一种紧凑型偏振解复用器, 其中两条常规硅基波导作为输入/输出信号通道, 居于其中的槽式微环谐振腔用于偏振态/波长选择组件. 采用全矢量频域有限差分法详细分析了硅基常规及槽波导的模式特性, 结果发现其横磁模的模场布及其有效折射率相似, 而其横电模相应的特性则差异明显, 结果输入横磁模能够在谐振工作波长下从下路端口输出, 而输入横电模与微环耦合可以忽略, 直接从直通端口输出, 从而实现两偏振态的高效分离. 采用全矢量时域有限差分法详细分析了该偏振解复用器的光波传输特性, 结果表明, 当微环半径为3.489 μm时, 在1.55 μm工作波长下, 横磁模与横电模的消光比与插入损耗分别为 ～ 26.12 (36.67) dB与 ～ 0.49 (0.09) dB. 另外, 论文详细讨论了器件关键结构参数的制作容差, 并给出了输入模场在器件中的传输演变情况.     

Integrated mode-evolution-based polarization splitter

A mode-evolution-based polarization splitter suitable for high-index-contrast systems and directly integratable with a recently reported on-polarization rotator is described and its performance verified through both finite-difference time-domain and eigenmode expansion simulations. For a device length of 200 microm, greater than 22 dB of extinction is obtained across a 1.45-1.75-microm bandwidth.     

1.3μm波长光纤偏振参数自动测试仪

本文介绍一种用于1.3μm波长的光纤偏振参数自动测试仪。它利用光路集成封装和计算机自动控制及信号处理等关键技术,方便、可靠、自动地进行1.3μm光纤及其器件偏振参数的测试,对于消光比为40dB以下的偏振态测量,误差优于0.3dB.     

Single polarization transmission in pedestal-supported silicon waveguides

In this Letter, properties of a pedestal-supported silicon waveguide are investigated, showing that it supports single polarization transmission. The pedestal is fabricated easily through a wet-etching process on strip waveguides. Theoretical analysis shows that this property is due to the leakage of quasi-TM mode when the pedestal width is small. A polarization extinction ratio larger than 20 dB at 1550 nm is measured in the pedestal waveguide sample, demonstrating single polarization transmission property experimentally. Thanks to its large single polarization transmission bandwidth, robustness in fabrication tolerance, and simple fabrication process, pedestal waveguides will have potential applications as simple silicon-integrated polarizers.     

A Microoptic Network Unit Using Planar Microlens Array

We propose a new concept for an optical network unit using planar microlens array for fiber to the home networks. It is expected from this modeling that an optical coupling loss of 2.5 dB, a polarization dependent loss of 0.5 dB and an extinction ratio larger than 50 dB can be achieved. The structure design and its fabrication method are discussed.     

基于半导体光放大器交叉偏振调制效应实现正、反相波长变换

利用琼斯矩阵,对基于半导体光放大器中的交叉偏振调制效应实现全光波长变换进行了理论分析.结果表明,利用这种机制可以实现同相与反相波长变换.在实验上同时实现了10Gb/s归零信号的正相与反相波长变换,输出消光比分别达到了6.9 dB和8.1 dB.