1.30μm／1.55μm SiGe多模干涉滤波器

用多模干涉原理分析和设计了光通信波长（１．３０μｍ～１．５５μｍ）的Ｓｉ１－ｘＧｅｘ／Ｓｉ滤波器，并用模的传播分析方法对其传输特性进行了研究。结果发现，在Ｇｅ含量ｘ＝０．０４时，干涉区的脊高和宽度分别为６．３５μｍ和８μｍ。如果多模干涉区长度ＬＭ＝２３０２．５μｍ，可滤１．３０μｍ而通１．５５μｍ的波长。且具有３１ｄＢ的对比度和０．０１ｄＢ的插入损耗；如果多模干涉区长度ＬＭ＝２５１２．５μｍ，可滤１．５５μｍ而通１．３０μｍ的波长。具有１６ｄＢ的对比度和０．０９ｄＢ的插入损耗。     

Numerical study of TE waves propagating in multibranch couplers

The evolution of TE-polarized waves propagating in the linear and nonlinear multibranch coupler is studied. The propagation of the waves in both directions is calculated by the beam-propagation method (BPM). The numerical results of simulation show that the minimum insertion loss of the nonlinear multibranch coupler is less than 0.088 dB, whereas that of the linear multibranch coupler is more than 3 dB.     

Numerical study of TE waves propagating in multibranch couplers

Abstract

The evolution of TE-polarized waves propagating in the linear and nonlinear multibranch coupler is studied. The propagation of the waves in both directions is calculated by the beam-propagation method (BPM). The numerical results of simulation show that the minimum insertion loss of the nonlinear multibranch coupler is less than 0.088 dB, whereas that of the linear multibranch coupler is more than 3 dB.     

Estimation of the performance of a 3-dB Y-junction optical coupler with a channel profile of proton-exchanged lithium niobate

A 3-dB optical coupler (power splitter) based on a Y-junction waveguide with a channel profile of proton-exchanged lithium niobate has been modeled. Finite difference beam propagation method has been used to investigate light wave propagation in axially varying waveguides. It is found that the structure splits the input power equally at the Y-junction with an efficiency of 99% and an average excess loss ?0.04 dB. The novelty of the coupling structure proposed is its capability to function as a wavelength-independent 3-dB coupler while maintaining very low-power imbalance for widespread optical communication wavelengths of 1.3 and 1.55 µm.     

Hollow-core tapered coupler for large inner diameter hollow-core optical fibers

A novel hollow-core tapered coupler has been theoretically designed and fabricated by fiber drawingmachine. The coupler's inner wall is coated with a polycrystalline GeO_2 film. The coupling loss ofhollow-core tapered coupler is about 0.2 dB. Hollow-core tapered coupler reduces the transmission loss ofhollow-core optical fiber(HCOF) by 0.5 dB/m, therefore the coupler is suitable for coupling high powerCO_2 laser in industrial application.     

熔锥型宽带耦合器的研制

介绍了全光纤熔融拉锥型3dB宽带耦合器的理论设计，根据理论设计制作了样品。应用耦合模理论分析了全光纤非对称熔融拉锥型耦合器的宽带特性；提出了3dB宽带耦合器的制作方案，在此基础上制作了样品；对样品进行测试，样品带宽大约为300nm(在1300nm～1600nm波长之间)，附加损耗小于0.5dB，完全达到了实用化的要求。     

反相电极聚合物定向耦合电光开关的优化设计

为了消除单节电极定向耦合电光开关的工艺误差对器件性能的不良影响,应用耦合模理论、电光调制理论、保角变换及镜像法,优化设计了一种两节交替反相电极聚合物定向耦合电光开关.模拟结果表明,该器件具有良好的开关性能:在1 550 nm的工作波长下,器件耦合区的长度为4 753.5 μm,交叉态电压为1.22 V,直通态电压为2.65 V,插入损耗小于2.21 dB,串扰小于-30 dB.通过微调状态电压,可以很容易地消除工艺误差对器件性能产生的不良影响.本文方法的设计结果与光束传播法的仿真结果符合得很好.     

1 × 4 coupler based on all solid five-core photonic crystal fibers

An improved 1 × 4 coupler based on all solid multi-core photonic crystal fiber is proposed and analyzed. The expressions to calculate the coupling length and the coupling efficiency are deduced based on the coupled-mode equations firstly. Then a full-vector finite element method (FEM) is used to calculate the coupling length and the coupling efficiency. Next, the propagation characteristics and the performances of the coupler are analyzed through using a full vector beam propagation method (BPM). Research shows that the results derived by FEM agree with that by BPM. The coupling length of the coupler is 4.1 mm at λ = 1.55 μm. A maximum coupling efficiency of 24.96% can be obtained. The coupling ratio is more than 22.5% over a wavelength range of 100 nm. The polarization-dependent loss at λ = 1.55 μm is equal to 0.73 dB. Finally, the influences of the micro-variation of structure parameters and the material refractive index on the working performances of the coupler are investigated.     

An efficient directional coupling from dielectric waveguide to hybrid long-range plasmonic waveguide on a silicon platform

The silicon-based three-dimensional hybrid long-range plasmonic waveguide not only supports long-range propagation distance (~mm) but also has an ultra-small modal area (~10^?2 μm²) at 1.55 μm. Here, we propose a directional coupler for effective coupling from a dielectric slab-waveguide to the hybrid plasmonic waveguide on a silicon platform. Our simulation results show that the coupler is able to excite hybrid long-range plasmonic mode with short coupling length, low insertion loss, and high extinction ratio. With the arm separation of 0.3 μm, the coupling length can be made 5.2 % of the propagation length of the hybrid plasmonic waveguide, while the insertion loss and extinction ratio are ?0.12 and 22.4 dB, respectively. This coupler offers the potential applications in signal routing between the hybrid long-range plasmonic waveguide and dielectric waveguide in the photonic integrated circuits.     

Four-wavelength DBR laser array with waveguide couplers fabricated using selective MOVPE growth

We have developed an integrated multiwavelength laser with waveguide couplers using a novel selective metal-organic vapor-phase epitaxy (MOVPE) technique. The lasing wavelength was controlled by modulating the effective refractive index of distributed Bragg reflector (DBR) waveguides. Array lasing wavelengths were distributed from 1548.0 to 1553.5 nm with an average spacing of 1.8 nm. The propagation loss of the waveguide coupler was about 16 dB for inner ports and 20 dB for outer ports with a 6 dB splitting loss. Four-wavelength laser outputs were coupled into a single-mode fibre.     

Fiber devices using polarization- maintaining fibers

Fiber devices using polarization-maintaining fibers called PANDA fibers are presented. They are polarization-maintaining couplers and polarization-splitting couplers, optical isolators and optical circulators, and multi/demultiplexers designed for 1.3 μm wavelength. Crosstalk of-32 dB and excess loss of 0.03 dB for the polarization-maintaining coupler, and polarization-splitting ratio of 17 dB and excess loss of 0.5 dB for the polarization-splitting coupler have been fabricated by a fusion-elongation method. A fiber polarizer with the extinction ratio of more than 40 dB has been presented by using the difference of bending loss between the orthogonal modes in the PANDA fibers. Multi/demultiplexer with narrow band-pass of 1.4 nm utilizing combination of PANDA fiber polarization dispersion and the polarization-splitting coupler has been realized. An optical isolator consisting of fiber polarizers and a spherical YIG with a lens function and an optical circulator consisting of polarizing-splitting couplers and spherical YIGs have been achieved.     

Fiber devices using polarization- maintaining fibers

Fiber devices using polarization-maintaining fibers called PANDA fibers are presented. They are polarization-maintaining couplers and polarization-splitting couplers, optical isolators and optical circulators, and multi/demultiplexers designed for 1.3 μm wavelength. Crosstalk of-32 dB and excess loss of 0.03 dB for the polarization-maintaining coupler, and polarization-splitting ratio of 17 dB and excess loss of 0.5 dB for the polarization-splitting coupler have been fabricated by a fusion-elongation method. A fiber polarizer with the extinction ratio of more than 40 dB has been presented by using the difference of bending loss between the orthogonal modes in the PANDA fibers. Multi/demultiplexer with narrow band-pass of 1.4 nm utilizing combination of PANDA fiber polarization dispersion and the polarization-splitting coupler has been realized. An optical isolator consisting of fiber polarizers and a spherical YIG with a lens function and an optical circulator consisting of polarizing-splitting couplers and spherical YIGs have been achieved.     

一种改进的2×2 SOI Mach-Zehnder热光开关

本文设计并制作了基于强限制多模干涉耦合器的2×2 SOI马赫-曾德热光开关.这种光开关采用了深刻蚀结构的多模干涉耦合器和输入/输出波导,较大地提高了干涉耦合器的性能并减少了连接耦合损耗.同时,在调制臂区域采用浅刻蚀结构,保持其单模调制状态.深刻蚀多模干涉耦合器具有优越的特性,在实验中测得不均衡度只有0.03 dB,插入损耗－0.6 dB.基于这种耦合器的新型热光开关,其插入损耗为－6.8 dB,其中包括光纤-波导耦合损耗－4.3 dB,开关时间为6.8 μs.     

Design and Evaluation of an N:N Optical Coupler Using an Integrated Waveguide Mirror

We proposed and fabricated an N:N optical coupler using an integrated waveguide mirror. Optical circuits can be miniaturized with small bending by reflecting mirrors. The parabolic curve was applied to the mirror shape because it was necessary to collimate the reflected beam so as to distribute the input light to the output waveguides. We fabricated the 8:8 optical coupler using silica waveguide. The chip size was about 7mm x 15mm. The excess loss of the device was about 8 dB larger than simulation results calculated using beam propagation method. The dependence on the wavelength and polarization was about 0.4 and 0.15 dB, respectively. The excess loss was mainly attributed to the mirror tilt and will be reduced by optimizing the etching conditions to decrease the mirror tilt angle.     

Power Analysis and Experimental Study of the Fiber Null Coupler with an Acousto-optic Device

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L波段小型化同轴-共面波导定向耦合器

设计了一种适用于L波段高功率微波辐射场测量的同轴型定向耦合器。分别选择同轴线和金属底板共面波导（CBCPW）作为主副传输线,减小定向耦合器横截面积;利用小孔耦合理论和微元法对耦合结构进行理论分析,选择连续渐变的菱形耦合缝隙,缩短定向耦合器长度;采用数值模拟的方法对耦合器结构进行优化,并对其性能参数进行实验测试,结果表明, 在1~2 GHz频带范围内耦合度约为47 dB,方向性大于17 dB。     

Compact wavelength-insensitive fabrication-tolerant silicon-on-insulator beam splitter

A star coupler-based beam splitter for rib waveguides is reported. A design method is presented and applied in the case of silicon-on-insulator rib waveguides. Experimental results are in good agreement with simulations. Excess loss lower than 1 dB is experimentally obtained for star coupler lengths from 0.5 to 1 μm. Output balance is better than 1 dB, which is the measurement accuracy, and broadband transmission is obtained over 90 nm.     

A dual-channel wavelength multiplexer / demultiplexer based on the restricted-resonance self-imaging effect

The authors propose a high-performance 980 / 1550-nm wavelength multiplexer / demultiplexer based on the restricted-resonance self-imaging effect in a buried-type waveguide system. The device functions either as a multiplexer or a demultiplexer, depending upon the direction of light propagation. Using the modal propagation analysis (MPA), characteristics of the device are investigated. We carried out the design of the device and showed that the device performance can be optimized by appreciate selection of the coupler width. A demultiplexer with an insertion loss of 0.4 dB and contrast of 25.5 dB at wavelength 1550 nm and 32 dB at 980 nm is demonstrated.     

A novel compact wavelength-division multiplexer using highly dispersive waveguide-to-waveguide coupling

A novel compact wavelength-division multiplexer using highly dispersive waveguide-to-waveguide coupling is designed, simulated and analyzed. The device consists of two very close single-moded waveguides that are periodically connected to form a mode-dependent dispersive grating. It is demonstrated that the wavelengths over the edges of the photonic band gap contributed by the grating can be separated in a very short propagation distance. Using the finite-difference time-domain method, the result shows that the wavelengths of 1570 and 1530 nm are separated by the grating in a coupler length of 57 μm which is much shorter than the required length of about 340 μm without grating assistance. The channel contrast of 20 dB and the insertion loss about 2 dB are achieved.     

SOI通道转换型多模干涉耦合器的研究

设计和制作了基于SOI的通道转换型多模干涉耦合器。用二维BPM方法分析了耦合器的性能与多模波导宽度和长度的依赖关系.制作出的耦合器能实现良好的通道转换,器件的功率转换比为73,附加损耗为2.2 dB.提高器件制作的精度将能进一步改善耦合器的性能.