A new form of optical transmission system using 1 × 6 optical switch

Optical switches are useful for various optical systems. This paper describes a new form of optical transmission system, using 1 × 6 optical switch with built-in optical multiplexer. The insertion loss of the optical switch was 3.1 dB (including filter loss of 1.4 dB). This switch is useful for a traffic monitoring system, and its transmission characteristics were measured. The measured signal-to-noise ratio is 44 dB when the switch is applied to a 2-km video transmission line.     

Multimode optical fiber demultiplexer-star coupler using a single gradient-index-rod lens and a multi-facet grating

An optical fiber multi-function device consisting of a single gradient-index-rod lens and a multi-facet blazed reflection grating is proposed to simultaneously realize functions of wavelength demultiplexing and optical signal distribution in a multimode optical fiber transmission system. We analyzed the demultiplexing characteristics and the tolerance of optical components using the ray trace method. This device can realize not only low loss optical signal distribution but also offers improved demultiplexing characteristics in comparison with the previously proposed demultiplexer-multiposition switch. The following characteristics are expected from the design using commercially available optical components: a working band of 0.64–0.88 μm, channel separation of 34–36 nm, 3 dB bandwidth of 27–28 nm, channel cross-talk of less than - 40 dB and minimum excess insertion loss of 0.9–2.1 dB.     

Broadband 2 × 2 free-space optical switch using electronically controlled liquid lenses

To the best of our knowledge, proposed is the first liquid lens technology-based 2 × 2 free-space optical switch using a pair of Electronically Controlled Variable Focus Lenses (ECVFLs). By independently controlling the focal lengths of two cascaded liquid ECVFLs, the two input optical beams are spatially adjusted to couple to their respective output beam ports. At 633-nm, the experimental switch demonstrates 26.3 dB crosstalk, 23.0 dB within-channel isolation, 1.1 dB optical loss, and 0.2 dB Polarization Dependent Loss (PDL). A 0.2 dB Wavelength Dependent Loss (WDL) is measured over 633-nm and 514-nm wavelengths. A 1 × 2 optical-fiber coupled switch version is also tested. The proposed switch can be useful in free-space laser systems as well as fiber-based modules.     

Flexible integration of optical switch with optical power splitting and attenuating functions for optical fiber-based networking applications

A flexible integration of optical switch with optical power splitting and attenuating functions has been proposed to optimally serve optical fiber-based networking applications. In this switch, an etched binary-slope sidewall reflector is electrostatically actuated in and out of the plane to manipulate optical signals between input and output optical fibers. The fabrication process is a simple combination of a bulk-silicon micromachining process and silicon-to-glass anodic bonding where fiber alignment grooves, reflectors and actuators are fabricated on the same silicon substrate. Ball-lensed fibers are assembled with the device to achieve high coupling efficiency. Performances of the fabricated devices are measured and discussed. The switching time is less than 9 ms at 31 V. The excess loss of the device is less than 3 dB and the controllable attenuation range is up to 38 dB at 139 V, respectively. Moreover, polarization-dependent loss is less than 0.7 dB in the whole attenuation and splitting range.     

基于磁光开关的高精度光实时延时线

 给出了基于高速磁光开关的光实时延时技术的方案。研究了拓扑结构和磁光开关对光延时性能的影响。研制了5 bit,32位的光实时延时系统,并建立了光延时的测试平台,经测试,延时线延时精度优于3 ps。对光延时单元插损进行测试,结果显示:32态单元插损为0.12~0.88 dB,各态变化呈随机性。     

光梯度力驱动的纳米硅基光开关

通过一道光改变另一道光的传输路线是光子集成网络中重要而长远的目标, 然而, 由于硅材料的光学非线性较弱, 在硅材料上实现开关的全光控制难以实现. 因此本文提出了一种由光梯度力驱动的纳米硅基光开关, 实现了硅基光开关的全光控制. 该光开关由一个部分悬空的微环谐振器和一个交叉波导结构构成, 当通入一道控制光时, 悬空的微环谐振器在光梯度力的作用下发生弯曲, 微环谐振器的谐振波长随之发生变化, 从而实现光信号的传输路线发生改变. 该光开关利用纳米光子制造技术在标准绝缘体上硅晶圆上制造, 实验数据得出其最小消光比为10.67 dB, 最大串扰为 -11.01 dB, 开关时间分别为180 ns和170 ns. 该光开关具有尺寸小, 响应速度快, 低损耗和可拓展等优点, 在片上集成光路、高速信号处理以及下一代光纤通信网络中具有潜在应用.     

A polymeric optical switch array based on arrayed waveguide grating structure

A novel 1 × N optical switch array based on arrayed waveguide grating (AWG) structure is presented in this paper. The device is designed for polymeric materials with a large negative thermooptic (TO) coefficient, which is employed to change the imaging effect and to realize optical switching. When input wavelength is located in a special waveband, the optical signal will image at different output channel as temperature changes. The two-dimensional finite difference beam propagation method (FD-BPM) has been used to simulate a 1 × 9 optical switch array. The insertion loss of this switch array is below 1.37 dB and the extinction ratio is better than 31 dB at 1550 nm, when the coupling and propagation loss is neglected. The optimum design and the simulation results show that this structure could be a multiple wavelengths switching at the same time.     

Polycarbonate hollow-core microstructured optical fiber

A hollow-core microstructured polymer optical fiber is fabricated from polycarbonate material and guidance by inhibited coupling in a two-layer structure is demonstrated in two strong transmission bands with minimum losses of 9.0 dB/m at 800 nm and 3.1 dB/m at 1550 nm. The latter corresponds to a loss well below the polycarbonate material loss at this wavelength, and to our knowledge it is the lowest loss hollow-core polymer fiber reported to date. The short-term operational temperature limit of the fiber is shown to be 135 degrees C, significantly higher than that of conventional polymer optical fibers made of other polymers.     

Rigid reed-type routing switch for multimode optical fibers

A mechanical switch developed earlier for routing light in multimode optical fibers has been improved by reducing its cubic volume, insertion loss, switching time, and required switching power. Using an immersion fluid, an insertion loss below 0.5 dB was realized. The switching time is shorter than 13 msec, and the required switching power less than 16 mW.     

Fabrication of low OH loss holey fibers with varying air hole sizes and their optical properties

We experimentally investigate a flexible fabrication technique for low OH and transmission losses holey fibers with a Ge-doped core and air holes in a silica cladding region. Versatile holey fibers of different size, pitch, and shape of air holes were achieved by controlling the temperature and heating time of the holey fiber preform. In addition, we suppress the OH loss of less than ∼0.323 dB/km at 1383 nm. After fabricating holey fibers, we measure their optical properties including cut-off wavelength, mode field diameter, splicing loss, dispersion, bending loss, and polarization dependent loss based on the size of air holes. The total transmission loss was measured to be ∼0.226 dB/km at 1550 nm by improving the fabrication process. After fabricating optical patch cord based on holey fibers, we measured the long-term stability of the fabricated holey fiber by using the temperature cycling technique for 24 and obtained low power fluctuation of 0.2 dB. We achieve the high quality holey fiber with a low bending loss of ∼0.04 dB/turn under a bending radius of 2.5 mm at 1550 nm. We also obtain a tunable band rejection filter with a number of bending turns.     

Charge state switching of deep levels for low-power optical modulation in silicon waveguides

We demonstrate a method for the efficient modulation of optical wavelengths around 1550 nm in silicon waveguides. The amplitude of a propagating signal is mediated via control of the charge state of indium centers, rather than using free-carriers alone as in the plasma-dispersion effect. A 1×1 switch formed of an integrated p-i-n junction in an indium-doped silicon on insulator (SOI) waveguide provides 'normally-off' silicon absorption of greater than 7 dB at zero bias. This loss is decreased to 2.8 dB with application of a 6 V applied reverse bias, with a power consumption of less than 1 μW.     

宽带磁共振T/R开关的设计与实现

磁共振系统中的发射/接收（transmit/receive,T/R）开关用于收发通路的切换,要求在隔离大功率信号的同时具有较小的插入损耗;另外,在宽带磁共振谱仪中,一般的窄带T/R开关也不再适用.本文基于PIN（positive-intrinsic-negative）二极管设计了工作频率为10~100 MHz的宽带磁共振T/R开关.通过减小电平跳变、优化开关过冲和解决二极管被动导通等问题,获得了插入损耗小于1 dB、大功率信号隔离度大于75 dB、开关时间1 μs的整体性能.用本文设计的宽带T/R开关替代一般探头中的窄带T/R开关,在0.5 T核磁共振（NMR）波谱仪上测得了氢核和氟核两个不同频率的磁共振信号,验证了宽带T/R开关的宽带性能.     

Rigid reed-type routing switch for multimode optical fibers

Abstract

A mechanical switch developed earlier for routing light in multimode optical fibers has been improved by reducing its cubic volume, insertion loss, switching time, and required switching power. Using an immersion fluid, an insertion loss below 0.5 dB was realized. The switching time is shorter than 13 msec, and the required switching power less than 16 mW.     

基于Norland紫外固化胶的热光开关器件

采用新型聚合物材料Norland紫外固化胶（NOA）制备了聚合物M-Z型热光开关器件。对NOA薄膜材料的光学性质进行了表征,采用感应耦合等离子体（ICP）方法制备出形貌良好的波导器件。测得在1 550 nm波长下,长2.2 cm的直波导插入损耗为8.3 dB。在电极上施加直流信号,测得热光开关的消光比为11 dB,驱动功率为85 mW。引入直流偏置网络,获得了器件的开关特性曲线,测得开关器件的上升时间为1.085 ms,下降时间为489.5μs。实验结果表明：NOA材料在热光开关及其它聚合物光波导集成器件的制备中具有很大的应用潜力。     

Microwave signal delay line based on multicore optical fiber

A fiber-optic delay line based on the successive transmission of a modulated optical signal through all seven cores of an optical fiber has been fabricated. The total loss of the signal after the transmission through all cores is less than 12 dB. The group delay in the range of modulation frequencies of 6 to 12GHz is found to be 5.62 μs for a fiber as short as 160 m.     

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.     

Technical study of visible light wavelength division multiplexing using polymer optical fiber

Visible light wavelength division multiplexing (VWDM) experiment was performed using polymer optical fiber (POF). Lights of two different wavelengths (650 and 530 nm) were sent to a single POF. Red light (650 nm) was used for 100-Mb/s full duplex IP data transmission and green light (530 nm) was used for voice signal transmission. Light sources are light-emitting diodes (LEDs). A POF coupler (splitter) and the prisms were employed as multiplexer and demultiplexer, respectively. The channel isolation and insert loss were measured, which are 20.5 and 17.65 dB for 650-nm channel respectively, and 19.16 and 20.55 dB for 530 nm one respectively.     

Improved planar optical branching elements for multimode fibre transmission systems

The optical tapping and fan-out elements which we had previously fabricated for multimode fibre transmission systems all suffered from the serious drawback that the aging of the light-sensitive foil used in our simple planar technology resulted in a deterioration in the performance of structures using such foil as a planar waveguide. This paper introduces improved optical structures in which this drawback has been avoided while stil retaining the simple technique by which high fibre positioning accuracy is assured. In addition the overall insertion loss of the structures has been reduced to about 2 dB for the fan-out structure and 1.2 dB–1.5 dB for the access coupler.     

单端面透射模式长周期光栅的设计和测试

本文设计了一种单端面长周期光栅透射模式折射率传感器。首先,将2×2单模光纤耦合器输入端的一个光纤接头与光源相连接、输出端的两个光纤接头分别与光谱分析仪和长周期光栅的一个光纤接头相连接。然后,在包含长周期光栅的光纤另一个端面溅射反射银膜。最后,以一系列不同折射率的甘油水溶液为待测液体介质研究了直接透射模式与单端面镀银膜模式下长周期光栅的响应光谱的异同。实验结果表明:单端面镀银膜的长周期光栅的响应光谱仍然以透射谱的形式出现。对于同一种液体,单端面镀银膜的长周期光栅与直接透射模式的长周期光栅的响应光谱有着近乎相同的谐振波长值,但它们的光损耗存在一定的差异。在0~80%的甘油溶液中,直接透射模式下的光损耗从-12.92 dB变为-16.28 dB,再逐渐变到-13.22 dB;单端面镀银膜模式下的光损耗从-13.13 dB变为-13.74 dB,再逐渐变到-11.45dB。与直接透射模式相比,单端面镀银膜的长周期光栅的相对光损耗与甘油浓度的线性关系更加良好。本研究设计的长周期光栅测量系统采用单端面探头的方式检测环境介质,因而在测量中操作更加灵活方便,非常适合于远距离、恶劣环境或深层液体环境中的折射率测量。