Fiber Switch Research Articles

A miniature low cost and high reliability 1 × 2 mechanical optical switch

This paper presents the design, fabrication and tests of a miniature 1 × 2 mechanical type optical switch, whose components are fabricated by precision machining and MEMS technologies. The packaging and alignment are integral processes utilizing the CCD image processing technique and PZT-stages controlled technique in association with the optimization software enabling the fiber-to-fiber alignment to low optical loss requirement. Optical fibers in use have the following specifications: single-mode fiber (SMF) outer diameter 125 µm, core diameter 9 µm, zero degree of the fiber tip angle and non-anti-reflection coating. The initial gap of the input and output fibers is 10 µm. First, we produced a fiber holder and a V-groove by MEMS technology and used a relay as the input fiber switching actuator. Through proper mechanism design, the fiber positioning error can be reduced to below 0.1 µm. After the optimized alignment process, the results presented that the insertion loss could be controlled to ch1: 0.8 dB, ch2: 1.4 dB at a switching time of 5 ms. The reliability tests demonstrated that the variation of the insertion losses are ch1: 0.04 dB, ch2: 0.02 dB after 10 000 cycle times, and ch1: 0.024 dB, ch2: 0.006 dB throughout 100 switch times after 1 000 000 cycle times. The developed 1 × 2 optical switch largely reduces the physical size to 1/2–1/3 in comparison with traditional mechanical optical switches, and the cost is only about 1/10–1/20 of the MEMS type optical switches. The advantages of this innovative optical switch are: small size (only about 20 × 16 × 7.5 mm3), low cost (only about US$10), high reliability, cross-talk ≦ −80 dB and automatic alignment.

Eyestalk Ablation Has Little Effect on Actin and Myosin Heavy Chain Gene Expression in Adult Lobster Skeletal Muscles

The organization of skeletal muscles in decapod crustaceans is significantly altered during molting and development. Prior to molting, the claw muscles atrophy dramatically, facilitating their removal from the base of the claw. During development, lobster claw muscles exhibit fiber switching over several molt cycles. Such processes may be influenced by the secretion of steroid molting hormones, known collectively as ecdysteroids. To assay the effects of these hormones, we used eyestalk ablation to trigger an elevation of circulating ecdysteroids and then quantified myofibrillar mRNA levels with real-time PCR and myofibrillar protein levels by SDS-PAGE. Levels of myosin heavy chain (MHC) and actin proteins and the mRNA encoding them were largely unaffected by eyestalk ablation, but in muscles from intact animals, myofibrillar gene expression was modestly elevated in premolt and postmolt animals. In contrast, polyubiquitin mRNA was significantly elevated (about 2-fold) in claw muscles from eyestalk-ablated animals with elevated circulating ecdysteroids. Moreover, patterns of MHC and actin gene expression are significantly different among slow and fast claw muscles. Consistent with these patterns, the three muscle types differed in the relative amounts of myosin heavy chain and actin proteins. All three muscles also co-expressed fast and slow myosin isoforms, even in fibers that are generally regarded as exclusively fast or slow. These results are consistent with other recent data demonstrating co-expression of myosin isoforms in lobster muscles.

Design and characteristics of large displacement optical fiber switch

Plastic optical fiber (POF) is suitable for indoor local area network (LAN), for example, in-home or office networks, because of its flexibility and its ease of connection due to its relatively large core diameter. A 1/spl times/2 optical switch for indoor LAN using POF and a shape memory alloy (SMA) coil actuator with magnetic latches was successfully fabricated and tested. In this paper, the design concept and the characteristics of this switch are described. To achieve switching by the movement of a POF, large displacement is necessary because the core diameter is large (e.g., 0.486 mm). A SMA coil actuator is used for large displacement and a magnetic latching system is employed for fixing the position of the shifted POF. For this design, the insertion loss is 0.40 to 0.50 dB and crosstalk is more than -50 dB without index-matching oil. Switching speed is less than 0.5 s at a driving current of 80 mA. A cycling test was performed 1.4 million times at room temperature. Another optical fiber switch was fabricated and successfully actuated using plastic clad fiber (PCF). PCF also has a large core diameter (e.g., 0.20 mm) and optical switches using PCF will be useful for short distance networks between buildings.

Systems measurements of 2/spl times/2 poled fiber switch

The performance of a 2/spl times/2 all-fiber electrooptical switch is characterized in a system at up to 40 Gb/s. Error-free transmission is demonstrated. The device was also employed as a protection switch at 10 Gb/s in an installed fiber link.

Customer-oriented GMPLS service management and resilience differentiation

Generalized Multi-Protocol Label Switching (GMPLS) is currently under standardization at the Internet Engineering Task Force (IETF). It basically reuses the MPLS control plane (IP routing and signaling) for various technologies such as fiber switching, DWDM, SONET, and packet MPLS. In this article, we propose a management architecture, which allows a service provider to offer customers various services based on a GMPLS infrastructure. The business model behind the architecture is comparable to the online flight ticket sales systems known.

A Lagrangean Relaxation-Based Approach for Routing and Wavelength Assignment in Multigranularity Optical WDM Networks

Optical wavelength-division multiplexed (WDM) networks often include optical cross-connects with multigranularity switching capability, such as switching on a single lambda, a waveband, or an entire fiber basis. In addition, it has been shown that routing and wavelength assignment (RWA) in an arbitrary mesh WDM network is an NP-complete problem. In this paper, we propose an efficient approximation approach, called Lagrangean relaxation with heuristics (LRH), aimed to resolve RWA in multigranularity WDM networks particularly with lambda and fiber switches. The task is first formulated as a combinatorial optimization problem in which the bottleneck link utilization is to be minimized. The LRH approach performs constraint relaxation and derives a lower-bound solution index according to a set of Lagrangean multipliers generated through subgradient-based iterations. In parallel, using the generated Lagrangean multipliers, the LRH approach employs a new heuristic algorithm to arrive at a near-optimal upper-bound solution. With lower and upper bounds, we conduct a performance study on LRH with respect to accuracy and convergence speed under different parameter settings. We further draw comparisons between LRH and an existing practical approach via experiments over randomly generated and several well-known large sized networks. Numerical results demonstrate that LRH outperforms the existing approach in both accuracy and computational time complexity, particularly for larger sized networks.

Advances in Efficiency, Speed Reported at OFC 2004

Researchers unveiled impressive results in component design and system performance at OFC 2004. Highlights included record low loss in a hollow photonic bandgap fiber and all-optical packet switching at a staggering rate of 160 Gbit/s.

Simulation and realization of a novel micromechanical bi-stable switch

A new concept for a micro mechanical bi-stable switch is presented. The bi-stability is achieved by a mechanically pre-stressed toggle-lever. As bi-stability occurs only in a certain range of geometries for the given mechanical device, extensive FEM analysis (ANSYS) has been used to get a proper design of the switch and to optimise the layout for symmetrical switching behaviour, large stroke and low mechanical stress in the mechanical elements. An analytical model of the bi-stable switch has been developed which gives similar results as the FEM calculations. Switching between the bi-stable states is done electro-statically. The bi-stable switch has been realized using silicon-on-insulator (SOI)-technology. First experimental results show that such bi-stable toggle-lever switches can be utilized for direct multimode fibre switching where a stroke of about 100 μm is needed.

Micro-optical 1 x 4 fiber switch for multimode fibers with 600-microm core diameters.

The design, manufacture, and test of a 1 x 4 micro-optical fiber switch for multimode fibers with 600-microm core diameters are described. Microlens array telescopes allow for variable and fast beam deflection when the positions of the cylindrical microlens arrays relative to each another are altered by specially designed piezomechanical actuators. Standard achromats are used for collimation of light emitted by the input multimode fiber and for focusing of the deflected light onto a linear array of output multimode fibers. Design and assembly of micro-optical as well as of optomechanical components are discussed. Insertion loss and cross talk are measured, and the results are compared with those of numerical optical simulations. Measurements of switching time and long-term stability, as well as of thermal behavior, are also presented.

PNNI-based control plane for automatically switched optical networks

Much effort has been spent on the definition of control plane protocols for automatically switched optical networks (ASON). Most of the proposals brought into the standardization for an International Telecommunications Union-Telecommunication Sector, Internet Engineering Task Force, and Optical Internetworking Forum are based on Internet protocol concepts. One such proposal is the generalized multi-protocol label switching (GMPLS), an extension of the MPLS traffic engineering control plane model that includes nonpacket switched technologies (time, wavelength, and fiber switching). Recently, the potential use of private network-network interface (PNNI) in ASONs has been discussed as an alternative proposal by the standardization bodies. The goal of this paper is to appropriately adapt asynchronous transfer mode into an optical PNNI (O-PNNI) protocol that can be used as the control plane of ASONs. The paper also provides a critical viewpoint on the potential usage of either O-PNNI or GMPLS control plane and analyzes the pros and cons of each. The methodology adopted toward devising O-PNNI hinges on reviewing PNNI along with ASON recommendations in order to determine the set of PNNI features that require adaptation. Having identified these features we engineer and present appropriate solutions relating to routing, signaling and addressing aspects.

Stolas: switching technologies for optically labeled signals

GMPLS-based labeled optical burst switching (LOBS) networks are being considered as the next-generation optical Internet. GMPLS includes wavelength switching next to label and fiber (space) switching. We present a new concept of optically labeling bursts of packets suitable for LOBS networks supported by GMPLS. It is based on angle modulation, which enables control information to modulate the phase or frequency of the optical carrier, while payload data are transmitted via intensity modulation (IM). In particular, the optical label is orthogonally modulated, with respect to the payload, using either frequency shift keying or differential phase shift keying. We present a performance analysis of the modulation schemes by means of simulations where the influence of the payload IM extinction ratio and laser linewidth are investigated. In addition, the transmission performance of an IM/FSK combined modulated signal is experimentally validated at 10 Gb/s, demonstrating at the same time an FSK label swapping operation. Finally, a suitable optical label-controlled switch design is proposed that takes advantage of these novel labeling techniques, and efficiently combines widely tunable, fast switching lasers and SOA-MZI wavelength converters with an arrayed waveguide grating router.

Silicon-based coupling platform for optical fiber switching in free space

This paper presents the novel concept of a silicon-based coupling platform integrated with an electrostatic-driven out-of-plane optical switch, a self-parking framework, a flat-topped mesa, a v-groove and a microball lens array. The electrostatic-driven out-of-plane optical switch consists of a vertical mirror on a suspension polyimide diaphragm. It can reduce the large motion space required in in-plane optical switches. The method of corner compensation with the help of IntelliCAD software was applied to design the self-parking framework and flat-topped mesa. These were fabricated at the same time by the anisotropic wet etching technique. The microball lens array was batch-fabricated with the microelectromechanical systems technique and batch-assembled onto the coupling platform. The design of the optical platform is able to control the distance between the fiber, the microball lens and the vertical mirror. Therefore, it can enhance the coupling efficiency. Furthermore, not only does it provide an accurate coupling distance, but also it reduces the cost of the micro-assemblage.

Optical devices based on liquid crystal photonic bandgap fibres

Photonic Crystal Fibers (PCFs) have appeared as a new class of optical waveguides, which have attracted large scientific and commercial interest during the last years. PCFs are microstructured waveguides, usually in silica, with a large number of air holes located in the cladding region of the fiber. The size and location of these air holes opens up for a large degree of design freedom within optical waveguide design. Further, the existence of air holes in the PCF gives access close to the fiber core and by introducing new materials into the air holes, a high interaction between light and hole material can be obtained, while maintaining the microstructure of the waveguide. In this paper, we describe what we call Liquid Crystal Photonic Bandgap Fibers, which are PCFs infiltrated with Liquid Crystals (LCs) in order to obtain increased fiber functionality. We describe a thermo-optic fiber switch with an extinction ratio of 60dB and tunable PBGs using thermo-optic tuning of the LC. These devices operate by the PBG effect and are therefore highly sensitive to the refractive index distributions in the holes.

Thermo-optic switching in liquid crystal infiltrated photonic bandgap fibres

A new type of hybrid photonic crystal fibres, which are infiltrated with liquid crystals, are demonstrated. Thermo-optic fibre switching, which utilises the phase transitions of a thermochromic liquid crystal inside a photonic crystal fibre, is demonstrated.

Optical Fiber Switch Based on Carbon Nanotube Actuation

AbstractCarbon nanotubes represent an attractive material option for many applications, including electromechanical actuators. Though single wall carbon nanotubes exhibit advantageous actuator properties, such as large force generation and low operating voltage, functional devices based on carbon nanotube actuation have not yet been reported. Here we describe the fabrication and performance evaluation of a 1×2 electromechanical optical fiber switch based on a carbon nanotube actuator. The side-to-side movement of the input fiber of the device between two output fibers is a result of the actuation of an assembly of carbon nanotubes that have been attached to the fiber. The intensities of optical signals exiting the two outputs are monitored, and switching times down to 30 ms are demonstrated. Initial results indicate that mechanical optical switches using carbon nanotube actuators may be preferable to switches using alternative technologies due to the inexpensive assembly, low operating power, potentially high switching speeds, and potentially low insertion loss of the carbon nanotube based devices.

Fixed and fluid: stability and change in the geography of the Internet

The geography of today's Internet infrastructure is grounded in the fiber installations, routers, switches and central offices that guide electronic messages around the world. While the location of hardware is relatively fixed, the task of identifying the locations where data and information are stored is a far more difficult task. Advances in technology have created a very fluid definition of the location of information that has become increasingly distributed and ethereal. This paper examines the current structure and location patterns of Internet infrastructure hardware in the USA and how content distribution networks and peer-to-peer networks have disrupted traditional information location. The comparison of the two provides insight into how the geography of infrastructure hardware is influencing Internet technology and business.

Multistage optical switching networks

The backbone networks evolution to high-speed DWDM networks generates new problems for switching. This function element must be also based on optical technology. For large capacity this cannot be realized by a single matrix, but by multistage switching networks. In the paper three types of optical matrices have been described: fiber switch FX, wavelength fiber switch WSX and wavelength interchanging fiber switch WIX. Based on these matrices, four switching network constructions were considered. The connection properties of these switching networks were evaluated, determining the electronic equivalent switching network for which these properties are well known.

Alterations in gene expression in hamster diaphragm after emphysema and lung volume reduction surgery.

The authors have demonstrated previously that emphysema and lung volume reduction surgery (LVRS) resulted in a significant shift of type IIx/b to type IIa fibres in the diaphragm of hamsters with elastase-induced emphysema. To explore the mechanisms leading to this fibre switching, the mRNA expression of the myogenic regulatory factors, the inhibitors of DNA binding proteins (Id-proteins) and insulin-like growth factor-I were examined. Ribonucleic acid was extracted from the diaphragm of control, emphysematous, emphysematous and sham operated and LVRS hamsters and subjected to reverse transcriptase polymerase chain reaction. Compared to control, the ratio MyoD to myogenin declined with emphysema, sham and even more after LVRS, due to a decrease in MyoD mRNA and an increase in myogenin mRNA. Similarly, compared to control, Id-1 protein mRNA levels decreased significantly in sham and even more in LVRS. Id-2 protein mRNA levels decreased in all groups, but reached statistical significance in LVRS only, compared to control. 1) the reduced MyoD/myogenin ratio may be the mechanism of the shift to a slower fibre type, 2) the decreased MyoD/myogenin ratio in lung volume reduction surgery animals suggests that lung volume reduction surgery enhances rather than decreases the load placed on the diaphragm and 3) the observed down-regulation of the inhibiting factors may facilitate the diaphragm adaptation to overload.

Micro-optical fiber switch for a large number of interconnects using a deformable mirror

In this letter, we demonstrate the limitations for 1 /spl times/ N free space optical switch with a moving macro-lens. We use a deformable mirror to overcome these limitations. The adaptive mirror corrects for the aberrations. Power coupling efficiencies between 6 and 3 dB (including losses due to the optical elements) are feasible for an optical switch allowing up to 3019 receiver fibers.

All-optical modulation and demultiplexing systems with significant timing jitter tolerance through incorporation of pulse-shaping fiber Bragg gratings

In this letter, we demonstrate the use of a superstructured fiber Bragg grating to preshape optical pulses to obtain optimal operation of nonlinear all-optical switches. Specifically, we demonstrate the conversion of 2.5-ps soliton pulses into 20-ps rectangular pulses at the input to both fiber and semiconductor optical amplifier-based switches, and show that rectangular switching windows can be achieved thereby providing a 5-10-fold reduction in timing jitter sensitivity. Error free penalty free optical time-division-multiplexing switching was readily achieved over a /spl plusmn/7-ps timing mismatch range for the square pulse driven fiber nonlinear optical loop mirror switch versus a /spl plusmn/1-ps range for the switch driven directly with 2.5-ps laser pulses.