Pair Of Fibers Research Articles

High‐dynamic‐range C+L band variable optical attenuator using a titled angle shutter

AbstractA high‐dynamic‐range variable optical attenuator (VOA) using a movable shutter, which moves in a tilted‐angle direction to the collimate fiber pair, is proposed. The VOA operates in the C+L band with the advantages low cost, high dynamic range of more than 50 dB, low insertion loss of 0.8 dB, low wavelength‐dependent loss (WDL), and low polarization‐dependent loss of ±0.4 dB and 0.4 dB, respectively, with attenuation of 50 dB. A compact size of 5.0 × 1.5 × 1.5 cm is obtained. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1000–1002, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21547

Fabrication of alignment structures for a fiber resonator by use of deep-ultraviolet lithography

We present a novel method to mount and align an optical-fiber-based resonator on the flat surface of an atom chip with ultrahigh precision. The structures for mounting a pair of fibers, which constitute the fiber resonator, are produced by a spin-coated SU-8 photoresist technique by use of deep-UV lithography. The design and production of the SU-8 structures are discussed. From the measured finesses we calculate the coupling loss of the SU-8 structures acting as a kind of fiber splice to be smaller than 0.013 dB.

Effective elastic moduli and stress concentrator factors in random structure aligned fiber composites

We consider a linearly elastic composite medium, which consists of a homogeneous matrix containing a statistically uniform random set of aligned fibers. Effective elastic moduli as well as the stress concentrator factors in the components are estimated. The micromechanical approach is based on the Green’s function technique as well as on the generalization of the “multiparticle effective field method” (MEFM, see for references, Buryachenko [1]). The refined version of the MEFM takes into account the variation of the effective fields acting on each pair of fibers. The dependence of effective elastic moduli and stress concentrator factors on the radial distribution function of the fiber locations is analyzed.

A Multi-Range Fiber-Optical Non-Contact Displacement Micrometer

A multi-fiber reflection displacement micrometer is developed. The device consists of a light source and a receiving fiber-array of identical fibers and photo detectors that detect the light reflected from the surface being measured. The differential output of each neighboring fiber pair is proportional to the surface displacement in a section of the total range. The light intensity variation of the source and the reflectance change of the surface are compensated when the differential output is divided by the summation output. A scale voltage is given to each output of neighboring fibers in order to shift each output to correspond to the actual displacement within the total range, which can be varied by selecting the number of fibers in the receiving fiber array. The micrometer offers the advantages of wide range, non-contact, no electrical interference, simplicity, and low cost. It can be used in medical experiments and laboratory instruments.

Multi‐Functional Particle Detection with Embedded Optical Fibers in a Poly(dimethylsiloxane) Chip

This paper describes a polydimethylsiloxane microfluidic chip with embedded optical fibers for particle detection. It consists of a microchannel for sample delivery, two pairs of fibers for multi‐functional particle detection, and electrodes for high voltage supply to generate electrokinetic particle motion. A small size semiconductor laser and a Si‐PIN detector are used for optical detection. The detection system allows easy switch between two‐fiber detection mode and one‐fiber detection mode, and is capable of counting particles, measuring particle velocity, and identifying particle sizes in a single polydimethylsiloxane chip. The technique described here is potentially applicable to a range of particulate diagnostic systems.

Reverse dispersion fiber with depressed core-index profile for dispersion-managed fiber pairs

A reverse dispersion fiber (RDF) with depressed core-index profile has been developed successfully by using plasma chemical vapor deposition (PCVD) process. The fabricated RDF has a core-effective-area of 45μm2, a dispersion of −19.65ps/nm/km and a dispersion slope of −0.132ps/nm2/km while maintaining the low bending induced attenuation and low PMD value. The dispersion-managed pairs, which consisted of RDF and non-zero dispersion shifted fiber with ultra large effective core-area (ULAF), have the ultra low dispersion slope of less than 0.006ps/nm2/km at the wavelength range of 1530–1625nm, and the largest dispersion value is lower than 0.2ps/nm/km. Moreover, the attenuation characteristic also shows a remarkable flatness over the broadband wavelength, the attenuation at 1550nm is only 0.224dB/km. The dispersion-managed pairs are suitable for large capacity, high bit-rate long-haul wavelength division multiplexing (WDM) transmission system without using dispersion compensation mode.

Novel Tweezers for Biological Cells Using Piezoelectric Polylactic Acid Fibers

We fabricated poly-L-lactic acid (PLLA) fiber samples using high-speed spinning in order to improve their piezoelectricity. If an electric field is applied to the PLLA fiber in the direction perpendicular to its fiber axis, the PLLA fiber must be driven by the piezoelectric effect. We developed an effective method of applying an electric field to the PLLA fiber. As a result, we could drive the PLLA fiber by the shear piezoelectric effect under the application of ac voltage, and observed the bending motion of the entire PLLA fiber. Next, we have designed tweezers using a pair of PLLA fibers controlled by applied ac voltage, and have pursued the realization of PLLA fiber tweezers; finally, this was achived. On the basis of our experimental results, we believe that there is a high possibility of realizing the PLLA fiber tweezers for the manipulation of soft and minute samples such as biological cells.

High-precision absolute distance and vibration measurement with frequency scanned interferometry

We report high-precision absolute distance and vibration measurements performed with frequency scanned interferometry using a pair of single-mode optical fibers. Absolute distance was determined by counting the interference fringes produced while scanning the laser frequency. A high-finesse Fabry-Perot interferometer was used to determine frequency changes during scanning. Two multiple-distance-measurement analysis techniques were developed to improve distance precision and to extract the amplitude and frequency of vibrations. Under laboratory conditions, measurement precision of approximately 50 nm was achieved for absolute distances ranging from 0.1 to 0.7 m by use of the first multiple-distance-measurement technique. The second analysis technique has the capability to measure vibration frequencies ranging from 0.1 to 100 Hz with an amplitude as small as a few nanometers without a priori knowledge.

Inhibition of neutral endopeptidase (NEP) facilitates neurogenic inflammation

Neutral endopeptidase (NEP) and angiotensin-converting enzyme (ACE) are involved in neuropeptide degradation and may modulate neurogenic inflammation. We therefore explored the effect of specific blockers of NEP and ACE on the intensity of neurogenic inflammation. We investigated eight subjects on three occasions. Two pairs of microdialysis fibers equipped with intraluminal wires were inserted intracutaneously into the volar forearms and electrical stimuli were delivered via the intraluminal electrodes. The microdialysis fibers were perfused either with normal saline, phosphoramidon (NEP inhibitor), or captopril (ACE inhibitor). CGRP release was assessed in the microdialysis eluate via a specific EIA and by evaluating the extent and intensity of the neurogenic flare via a laser Doppler imager. The area of hyperalgesia and allodynia was assessed during electrical stimulation. Inhibition of NEP with phosphoramidon increased flare intensity ( P < 0.002) and size ( P < 0.01), while blocking ACE had no effect on neurogenic vasodilation. CGRP release could be measured in microdialysis samples after phosphoramidon perfusion only ( P < 0.03), not in samples with captopril or saline perfusion. No effect on the areas of hyperalgesia and allodynia could be detected. Our findings suggest that NEP but not ACE is most important for CGRP degradation in human skin. This may be of particular importance for the understanding of pain disorders like migraine or complex regional pain syndrome.

Reconfigurable Information-Sharing Network System Based on a Cyclic-Frequency AWG and Wavelength-Tunable Lasers

We propose an information-sharing network system, capable of forming and dynamically reconfiguring multiple information-sharing groups on the same network platform by using wavelength routing and distributed shared memory technologies. The network system comprises information-sharing terminal nodes equipped with a shared memory and a wavelength-tunable transmitter, network management terminal and an arrayed-waveguide grating (AWG). The information-sharing terminal nodes are connected to an AWG by a pair of optical fibers, forming a star-shaped topology. Information is shared among the information-sharing terminal nodes through the establishment of a logical information-sharing ring. This is accomplished by adjusting the output of the wavelength-tunable transmitter at each terminal node to an appropriate wavelength according to the wavelength-routing characteristics of the AWG wavelength router. We developed a prototype information-sharing network system, in which, as preliminary experiments, HDTV and SDTV videos were used for real-time information sharing. The dynamic reconfiguration of information-sharing groups and a simple automatic restoration technique have been successfully demonstrated. The system is applicable to distributed computer processing systems and high-capacity information-sharing applications such as high-quality videoconferences.

Contractile dysfunction of cardiomyopathic hamster myocytes is pronounced under high load conditions

To understand the pathophysiology of hereditary cardiomyopathy, the contractile function of cardiomyopathic hamsters has been studied at the cellular level. However, most of the studies to date have described the cell shortening under the unloaded condition. Using a novel force–length measurement system for single cardiomyocytes, we studied the contractile function of cardiomyopathic hamster myocytes over a wide range of loading conditions. Cardiomyocytes were isolated from the ventricles of eight- to 10-week-old cardiomyopathic (CMP) hamsters (Bio TO-2 strain), as well as control (CTRL) Syrian hamsters. A pair of carbon fibers was attached to both ends of single cardiomyocytes and their contractile characteristics were recorded while changing the after-load by controlling the fiber motion. Under the unloaded condition, the shortening fraction (CMP 9.2 ± 0.5% vs. CTRL 10.7 ± 0.8%, P = 0.06) and maximum shortening velocity (CMP 98.2 ± 7.3 μm/s vs. CTRL 147.2 ± 6.5 μm/s, P < 0.05) were decreased in CMP hamster myocytes. The peak force under the isometric condition (CMP 35.8 ± 2.2 mN/mm 2 vs. CTRL 69.0 ± 8.4 mN/mm 2, P < 0.05) and external work (CMP 898 ± 130 J/m 3 vs. CTRL 3058 ± 576 J/m 3, P < 0.05) under physiologically loaded conditions were also decreased, but the differences were more pronounced under the loaded conditions. Calcium transients measured by Indo-1 revealed elevated diastolic level, decreased peak level, and slower diastolic decay in CMP myocytes thus being consistent with the observed contractile dysfunction. These results clearly indicate the importance of the loading conditions in evaluating the contractile function of CMP hamster myocytes, and may provide insights into the mechanism of contractile dysfunction in this disease.

Analysis of Fiber Dyes By Liquid Chromatography Mass Spectrometry (LC-MS) with Electrospray Ionization: Discriminating Between Dyes with Indistinguishable UV-Visible Absorption Spectra

Abstract Liquid chromatography mass spectrometry (LC-MS) is shown to provide high discriminating power for the identification of textile dyes that can not be reliably distinguished on the basis of their UV/visible absorption profile. Seven pairs of commercial dyes having nearly identical UV/visible absorption profiles and absorption maxima within 5 nm, were identified successfully by LC-MS. Two pairs of cotton fibers, which were indistinguishable by microspectrophotometry, were differentiated by LC-MS. A single wavelength UV/visible detector was used to monitoring dye elution from the column. The utility of the method for comparing questioned and known fibers is discussed.

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.

Automation of multi-degree-of-freedom fiber-optic alignment using a modified simplex method

Automation of fiber-to-optic alignment is the key to reduce the cost of the packaging process for the manufacturing of fiber-optic devices. Due to its fast convergence and easy of implementation, the King's modified simplex method (MSM) seems suitable for the fiber-optic alignment automation. This paper presents the use of this method on automatic three-dimensional (3D) fiber-to-optic alignment. A series of experiments have been conducted for the 3D alignment of a single mode fiber coupled with laser diode (LD) on an active automated alignment machine. The performance of this method is investigated and relevant problems are discussed. It is found that the simplex method is difficult in handling the problem in which the optimum point of the system is spatial dependent on the 3D space. A strategy is proposed to deal with this problem. The experimental results showed that the proposed idea successfully captures the global peak in all the 50 alignment trials for 10 different LD–fiber pairs, regardless of the position and size of the initial simplex.

A microfabricated capillary electrophoresis chip with multiple buried optical fibers and microfocusing lens for multiwavelength detection

We present a new microfluidic device utilizing multiwavelength detection for high-throughput capillary electrophoresis (CE). In general, different fluorescent dyes are only excited by light sources with appropriate wavelengths. When excited by an appropriate light source, a fluorescent dye emits specific fluorescence signals of a longer wavelength. This study designs and fabricates plastic micro-CE chips capable of performing multiple-wavelength fluorescence detection by means of multimode optic fiber pairs embedded downstream of the separation channel. For detection purposes, the fluorescence signals are enhanced by positioning microfocusing lens structures at the outlets of the excitation fibers and the inlets of the detection fibers, respectively. The proposed device is capable of detecting multiple samples labeled with different kinds of fluorescent dyes in the same channel in a single run. The experimental results demonstrate that various proteins, including bovine serum albumin and beta-casein, can be successfully injected and detected by coupling two light sources of different wavelengths to the two excitation optic fibers. Furthermore, the proposed device also provides the ability to measure the speed of the samples traveling in the microchannel. The developed multiwavelength micro-CE chip could have significant potential for the analysis of DNA and protein samples.

Strictly Nonblocking WDM Cross-connects

Using (WDM) technology, an optical network can route multiple signals simultaneously along a single optical fiber by encoding each signal on its own wavelength. If the network contains places where multiple fibers connect together and signals are allowed to be moved from any of the incoming fibers to any of the outgoing fibers, then the network is said to contain cross-connects. More precisely, a $k_1\,\times\,k_2$ WDM cross-connect has k1 input fibers and k2 output fibers. Each of the k1 input fibers supports the same n1 input wavelengths and each of the k2 output fibers supports the same n2 output wavelengths. Since a signal on input wavelength $\lambda$ can be routed from its input fiber to an output fiber such that it arrives on the output fiber using wavelength $\gamma$, where $\lambda \neq \gamma$, the cross-connect must be capable of performing wavelength conversion. Along any fiber in the cross-connect a device called a wavelength interchanger can be inserted to perform wavelength conversion. In other words if the path of a signal from an input fiber to an output fiber passes through a \wins, then the wavelength of the signal can be changed to any wavelength that is not already in use along the fiber leaving the wavelength interchanger. Given the high cost of \wisns, the overall cost of a \CC{k_1}{k_2} is minimized by reducing the number of \wis in the cross-connect. However, a desirable property for a cross-connect C is for C to always be able to provide a route (and wavelength conversion) for any valid demand from any pair of input and output fibers regardless of the routes of other demands currently routed in C. If C has this capability then it is said to be strictly nonblocking. For most of this paper we consider a demand to be a request for a connection from an input fiber to an output fiber such that the connection starts on a specified input wavelength and leaves the c on a second specified wavelength. Using this demand model, we consider cross-connects for which $k_1$ is not necessarily equal to $k_2$ and the number $n_1$ of supported input wavelengths can differ from the number $n_2$ of supported output wavelengths. Without loss of generality we assume that $k_1 \leq k_2$ and present a family of \snob \CCns{k_1}{k_2}s that use \Opt \wisns. For the case when $k_1 = k_2=k$ and $n_1 = n_2$, we prove that this is optimal. For cs where $n_1$ is not necessarily equal to $n_2$, we show that if there is at most one wavelength interchanger on any path from an input fiber to an output fiber, \Opt \wis are optimal. Finally, we consider a more flexible demand model where $k_1 = k_2$ but the input and output wavelengths are not specified as part of the demand. We show that $2k-1$ \wis are still necessary for any \snob \CC{k}{k}.

Broad-band tunable all-fiber bandpass filter based on hollow optical fiber and long-period grating pair

We report a tunable all-fiber bandpass filter based on a short hollow optical fiber serially concatenated between a pair of long-period fiber gratings. With novel core mode blocking in the hollow core fiber and its optimal design, the device showed a low insertion loss of 1.5 dB and broad-band passband tuning range of 84.3 nm covering both S- and C-band.

Single cell mechanics of rat cardiomyocytes under isometric, unloaded, and physiologically loaded conditions.

One of the most salient characteristics of the heart is its ability to adjust work output to external load. To examine whether a single cardiomyocyte preparation retains this property, we measured the contractile function of a single rat cardiomyocyte under a wide range of loading conditions using a force-length measurement system implemented with adaptive control. A pair of carbon fibers was used to clamp the cardiomyocyte, attached to each end under a microscope. One fiber was stiff, serving as a mechanical anchor, while the bending motion of the compliant fiber was monitored for force-length measurement. Furthermore, by controlling the position of the compliant fiber using a piezoelectric translator based on adaptive control, we could change load dynamically during contractions. Under unloaded conditions, maximal shortening velocity was 106 +/- 8.9 microm/s (n = 13 cells), and, under isometric conditions, peak developed force reached 5,720 nN (41.6 +/- 5.6 mN/mm(2); n = 17 cells). When we simulated physiological working conditions consisting of an isometric contraction, followed by shortening and relaxation, the average work output was 828 +/- 123 J/m(3) (n = 20 cells). The top left corners of tension-length loops obtained under all of these conditions approximate a line, analogous to the end-systolic pressure-volume relation of the ventricle. All of the functional characteristics described were analogous to those established by studies using papillary muscle or trabeculae preparations. In conclusion, the present results confirmed the fact that each myocyte forms the functional basis for ventricular function and that single cell mechanics can be a link between subcellular events and ventricular mechanics.

Use of space and movement patterns in monogamous adult Eurasian beavers (Castor fiber)

AbstractMonogamy in mammals is characterized by reduced sexual dimorphism in morphology and behaviour. Ten pairs of Eurasian beaver Castor fiber were radio‐tracked to test how far this concept can be applied to movement behaviour by focusing on sex‐related effects on territory sizes and movement patterns. Within monogamous pairs, males and females occupied territories of almost equal size during the whole radio‐tracking period and more specifically after parturition. The territories of pair members overlapped on average by 81.6±14.0%sd while the territory overlap between residents and their neighbours was small to non‐existent (on average between 0.5% and 2.2%). Males had larger 95% utility distributions than did females during the whole tracking period and after parturition. There was no significant difference between the 50% utility distributions for both sexes. Furthermore, males and females spent equal proportions of their time in territory border zones. There was a non‐significant trend for males to move greater distances at night than females. Nightly distance moved correlated positively with territory size in females but not in males. Nightly distance moved correlated with neither body weight nor colony size. These results suggest that beavers show reduced sexual dimorphism in space use and movement patterns within adult monogamous pairs.

Nonlinearity management in fiber transmission systems with hybrid amplification

Nonlinearity management in transmission lines with periodic dispersion compensation and hybrid Raman-Erbium doped fiber amplification is studied both analytically and numerically. Different transmission/compensating fiber pairs are considered, with particular focus on the SMF/DCF case.