A cascadable polarization-based 1-to-9 multimode optical fiberswitch using a PMMA fiber array holder

We have constructed an optical fiber switch, which allows to route an information carrying laser beam to nine multimode optical fibers. The fibers are accurately positioned in a polymethylmethacrylate (PMMA) fiber array holder, fabricated with deep proton lithography. To switch light from one fiber to another, we use active control of the polarization of light by means of nematic liquid crystal retarders or ferroelectric polarization rotators. The system shows insertion losses as low as 3 dB and crosstalk ratios below -30 dB. These figures are still susceptible to considerable improvements. The switching speed is on the order of 10 Hz using nematic liquid crystals and was extended to 10 kHz with ferroelectric liquid crystals. Potential applications of the fiber switch are discussed. As an illustration we have demonstrated the multiplexing of optical fiber proximity sensors. We also describe scale reduction and cascadability issues     

应用于空间光通信的锥形光纤阵列

空间光到光纤的耦合是自由空间光通信的关键技 术,针对光纤纤芯直径很小,给耦合 带来很大困难这一问题,文章先分析了空间光到单光纤的耦合模型,然后提出了采用锥形光 纤阵列提高耦合效率的接收方法,之后,在实验室试制了锥形光纤阵列样品,并在微振动环 境下采用两种方法测量接收光功率,第一种方法是采用一个大靶面雪崩光电二极管(APD) 同时接收九根光纤光功率,第二种方法是采用熔融拉锥型光分路器将9根光纤中的光合并进 入一根光纤,然后用光功率计进行测量,测量结果表明,采用第一种方法比第二种方法得到 的光功率稍高,这是因为熔融拉锥后的光纤会有能量泄露。从总体上看,两种接收方法均说 明锥形光纤阵列样品达到了预期的接收效果。     

A surface-emitting laser array with backside guiding holes for passive alignment to parallel optical fibers

A simple method of coupling parallel fibers to a surface-emitting laser (SEL) array is proposed and demonstrated. The SEL chip has guiding holes on the backside which are aligned precisely to the SEL mesas on the front side. Optical coupling can be achieved by simply inserting fibers to the guiding holes. A 4/spl times/3 array of common-anode SELs with guiding holes is fabricated and assembled in a face-down manner. Three fiber tapes each of which includes four fibers are coupled to the array. The average of measured coupling efficiencies to multimode fibers is 35.0% and further improvement can be expected.     

Low-loss plastic molded optical multifiber connector for ribbon-to-single fiber fan-out

This paper describes a newly developed low-loss demountable multifiber connector for ribbon-to-single optical fiber fan-out. The connector plugs contain special gathering parts that make a high-density arrangement for monocoated optical fibers. Using a multi-V-grooved mold, the optical fibers are accurately positioned and then a plastic formation process is adopted to form the plug. Plugs are precisely aligned by using two pins. An average connecting loss of 0.07 dB has been achieved in the stationary mode distribution with index matching. The change in connecting loss did not exceed ± 0.03 dB when the connector was subjected to heat cycles in a temperature range of-30-+60degC.     

Versatile Multifiber Optical Connectivity Solution: From Concept to Realization

Multifiber interconnection technology is one of the important keys to increase package density in optical networks. We present a novel releasable multifiber optical connectivity solution from the initial concept to the functional prototypes. This connectivity solution relies on a V-groove alignment platform and a microlens array. It can, e.g., provide reliable connections between a fiber array and an active optoelectronic component array or between a fiber array and an optical waveguide device. Moreover, within a free-space propagation region, it provides access to collimated optical beams, thus enabling various light manipulation options. The microlens V-groove fabrication process makes use of a dedicated assembly station that has been designed for automation. The microlens array is positioned on the platform, aligned relative to the V-grooves, and fixed with a low-cost adhesive bonding technology. Uniform and stable low losses for fiber-to-fiber coupling via two lenses have been achieved for single-mode and multimode fibers at wavelengths of 850, 1300, and 1550 nm. This connectivity solution represents, therefore, a versatile cost-effective technology for releasable connections of fiber arrays to any other optical multiport device     

2/spl times/4 optical add-drop module with no difference in propagation length

We developed a micromachined X-type 2/spl times/4 optical add-drop module (OADM) featuring no difference in propagation length. Four pairs of lensed fibers are aligned in "X" position, and four micromirrors are located between the pairs of optical fibers. The OADM was fabricated utilizing a silicon-on-insulator process. Electrostatic comb actuators can be driven up to 90 /spl mu/m to change the light path within 1 ms. The insertion loss and the on-off ratio were less than 3 and 70 dB, respectively. The loss uniformity in every channel was 1.5 dB.     

Multichannel fiber ferrule for a stable laser-diode array module

We developed a multichannel fiber ferrule for a stable laser-diode array module. To apply YAG laser welding to parallel butt couple between the laser-diode and the single-mode fiber arrays, hermetically sealed and precisely aligned equi-interval fibers are required. We describe a V-grooved ceramic ferrule for embedding fibers. Fibers are fixed by soldering, using a flat ceramic lid and aligned with a 250 μm pitch. Our ferrule allowed a metallic, stem mounting laser-diode, to be fixed by YAG laser welding. All 30 samples tested have a leak rate of less than 1×10^-10 atm·cc/s. Optical coupling of fabricated modules was 9.7±0.2 dB and coupling loss change from 25°C to 115°C was within 0.5 dB     

All-silicon integrated optical modulator

The authors describe the operating principle, design, and performance of an all-silicon light modulator at 1.3 μm wavelength. The modulator is based on the plasma effect in silicon and the mode selectivity of single-mode optical fibers, resulting in low polarization dependence and the capability of handling high light intensities. Standard silicon IC technology is used in the fabrication process and the modulator has a vertical structure that takes up a small surface area (the active area matches the single-mode fiber core of 9 μm diameter), simplifying integration with other circuitry on the same chip. The modulator can be directly coupled to a single-mode optical fiber, without using lenses or other bulk optical components. Typical performance of the fabricated modulators is 6 dB insertion loss, 24% modulation depth, and 60 MHz bandwidth with a current drive of 22 mA rms     

Parallel optical transmitter module using angled fibers and a V-grooved silicon optical bench for VCSEL array

We propose an advanced structure of optical subassembly (OSA) for packaging of the vertical-cavity surface-emitting laser (VCSEL) array, using (111) facet mirror of the V-groove ends formed in a silicon optical bench (SiOB) and angled fiber apertures. The feature of our OSA can provide a low optical crosstalk between neighboring channels, a low feedback reflection, and a large misalignment tolerance along the V-groove. We describe the optimized design of fiber angle, VCSEL position, and fiber position. The fabricated OSA structure consists of 12 channels of angled fiber array, 54.7/spl deg/ V-grooves, Au-coated mirrors on (111) end facet of the V-grooves, and flip-chip-bonded VCSEL array on a SiOB. In this structure, the beam emitted from the VCSEL is deflected at the 54.7/spl deg/ mirror of (111) end facet and propagated into the angled fiber. The angled fiber array was polished by 57/spl deg/. Fabricated OSAs showed a coupling efficiency of 30%-50% that is 25 times larger than that obtained from an OSA with a vertically flat fiber array. Our OSA showed large misalignment tolerance of about 90 /spl mu/m along the longitudinal direction in the V-groove. We fabricated a parallel optical transmitter module using the OSA and demonstrated 12 channels /spl times/2.5 Gb/s data transmission with a clear eye diagram.     

Fabrication of 7×6 multimode optical fiber gratingdemultiplexer-star coupler using a single GRIN-rod lens

A multimode optical fiber grating demultiplexer-star coupler having seven demultiplexing channels and six fan-out channels is demonstrated. This device consists of an input-output fiber array, in which 42 output fibers are aligned radially around an input fiber, a single gradient-index (GRIN)-rod lens and a multifacet blazed reflection grating. In this device, the incident light beam is split into six beams, each of which is diffracted at the multifacet grating and couples to the output fibers. The device has a working band from 0.62 to 0.88 μm, channel separation from 36 to 45 nm and 3 dB bandwidth from 13 to 24 nm. We also evaluate the unevenness in the center wavelength and the minimum excess loss among the fan-out channels and discuss the relationship between the unevenness and the fabrication accuracy of the optical components in detail     

High Power Fiber Bundle Array Coupled LDA Module

1 Introduction High power laser diode arrays (LDA) have many advan- tages such as small volume, long working life, high slope efficiency and high optical density, so they have many applications in medical treatment, material pro- cessing, and for the pumping source of solid laser and etc. But unfortunately, the LDA can not be easy to use directly in these fields because of their poor beam quality and extremely asymmetric divergent beams (!x≈ 5°～10°and !y≈20°～35°, for example), so it …     

Optical and optoelectronic devices for optical fiber transmissionsystems

The present status and research trends in light sources, detectors, and various optical components are described, focusing mainly on those for single-mode fiber systems. Laser-diode and light-emitting-diode sources are described, and their problems and advantages are examined. The features of optical detectors, namely, avalanche and p-i-n photodiodes are discussed. A method of comparing the performance of optical receivers with different detectors, by examining the minimum detectable power at a specified error probability for the received pulses, is presented. Optical components such as optical filters, couplers, dividers, isolators, connectors, and switches are considered briefly. The potential of optoelectronic integrated circuits is discussed     

塑料光纤在裂缝监测中应用的可行性研究

针对普通石英光纤断裂应变较小在实际工程应 用中易发生断裂的问题,本文提出在结构裂缝监测 工作中运用塑料光纤(POF)代替普通石英光纤,设计了由光源、POF及光功率计组成 的塑料光纤裂 缝传感装置,并通过裂缝模拟装置对纤芯直径分别为0.25mm及0.5mm的POF在裂缝 监测中应用的可 行性进行了验证。实验结果表明,裂缝开度为0到6mm范围内,两种型号POF内部光 的强度随裂缝扩 展呈现逐渐减弱的变化,裂缝开展初期光强度变化明显,当裂缝宽度趋近于6mm时变化逐渐 减弱,符合理 论规律,且光纤直径较大时光强度变化更明显。因此POF可以有效感知裂缝的扩展 ,且光纤直径较大时对裂缝感知更敏感,将其应用在结构裂缝监测工作中是可行性的。     

A study on the development of transmission-type extrinsicFabry-Perot interferometric optical fiber sensor

The conventional reflection-type extrinsic Fabry-Perot interferometric (EFPI) optical fiber sensor has good sensitivity and resolution compared with other types of optical fiber sensors. However, they have the disadvantage that the distinction of strain direction of EFPI is difficult because of measurement method by only fringe counting. This paper presents the newly developed transmission-type EFPI (TEFPI) optical fiber sensor, which has been improved by additional functions, and whose measuring system differs from that of the reflection-type EFPI optical fiber sensors using a single-mode fiber (SMF) and multimode (MMF) fibers as light guides and reflectors, respectively. The output signal of the TEFPI optical fiber sensor was analyzed with the uniform plane wave-based model, the SMF power distribution-based model and the splice loss-based model; the analyzed signals were then verified experimentally. Based on the results of analysis, the TEFPI optical fiber sensor was fabricated using two single-mode fibers connected to the light source and optical receiver; this was then used in strain measurement. The strain measured by the TEFPI optical fiber sensor was compared with that measured by the electric strain gauge     

辐照光纤的主动恢复效应

在辐照环境下,光纤的光传输特性因辐照引起的缺陷及色心的形成而恶化,光纤的抗辐照性能直接影响其在辐照环境下的应用。而光纤本身在形成色心的同时,存在着光、热等褪色恢复效应,且光褪色与光纤中传输光有关,光功率越强,波长越短,褪色效果越明显。利用该特点,人为的向光纤中注入短波长强光,可增强光褪色效果,减少光纤因辐照产生的损耗量,实现光纤辐照损耗的主动恢复,保偏光纤在辐照下的光褪色实验给出了有力的证明。据此提出了主动恢复效应和基于该效应利用两个光源主动增强光纤抗辐照性能的设计方法,并对其实际应用价值进行了探讨。     

Glass fibers for optical communications

Glass optical waveguides with attenuations below 20 dB/km have made possible a new approach to optical communications. These glass fibers satisfy requirements for transmission over kilometer lengths with experimental systems utilizing existing devices for sources and detectors. The realization of material and fabrication advances necessary for this accomplishment are the topic of this paper. Basic theoretical principles are introduced in a review fashion. The application of these principles in choice of materials and fabrication is described. Results in fiber performance following this framework are given in a section on evaluation, which includes information capacity, attenuation, and some environmental requirements. Preliminary experiments in bundling and cabling are discussed, followed by concluding remarks.     

Reproducible optical fiber tips for photon scanning tunnelingmicroscopy with very small (<5°) cone angle

Sharp optical fiber tips for photon scanning tunneling microscopes (PSTMs) have been fabricated by employing a new alternative technique for etching multimode optical fibers. The tip diameter is less than 30 mm, while the cone full-angle can be as sharp as 3°. To the knowledge of the authors, such tips are the sharpest reported up to now. Measurements, with 19 tips, of the evanescent wave decay distance produced by frustrated reflection of light on a same sample, show good reproducibility. Furthermore, the PSTM images, taken with the new tips, are very sharp and fit with images of the same sample obtained with an atomic force microscope (AFM)     

Fused taper infrared optical fiber couplers in chalcogenide glass

We have fabricated low loss, high coupling ratio bidirectional optical couplers for infrared light using multimode step-index chalcogenide fiber. Using a fusion technique similar to that commonly employed with silica fibers, we have found a temperature regime where fusion can occur while interdiffusion of the core and cladding materials will not. The resultant device has a roughly 3:1 coupling ratio, less than 0.3 dB of excess insertion loss, and preserves the guided modes of the fiber intact     

光纤型光可变衰减器的探索

通过熔融拉锥工艺制备熔锥光纤,将两熔锥光纤以一定的方式装配在二维精密微调架 上,制备光纤型光可变衰减器。利用光信号在光纤锥形区特有的传输和耦合特性,实现了光纤间的耦合,耦合效率决定了光能量的衰减程度,从而决定了光纤型光可变衰减器的性能。用耦合模理论分析了锥形光纤间的传输和耦合性质,并从实验上给出了两锥形光纤间的耦合与两锥形光纤间的距离的关系,为制备光纤型光可变衰减器提供了理论和实验依据。     

Fabrication of multiple parallel suspended-core optical fibers by sheet-stacking

We demonstrate the fabrication of a novel type of optical fibers with multiple parallel air-suspended cores by the sheet-stacking method. Using this technique we have constructed optical fibers with up to 10 parallel micron-size suspended cores. No extra scattering loss from the fabrication process was observed in a fabricated dual air-suspended core fiber. The sheet-stacking method opens the way towards using a wide range of optical glasses for manufacturing multiple parallel suspended-core specialty optical fibers with novel optical functionalities such as dispersion tunability. Fusion splicing has also been successfully used to connect such a multiple core fiber with a conventional silica fiber.