Function Of Fiber Length Research Articles

Unipolar diffusional charging of fibrous aerosols—Theory and experiment

Models for the unipolar charging of fibers were developed. The theoretical models using idealized geometries—either prolate spheroids or cylinders—and considering both the free-molecular and continuum cases served as a basis for numerical simulations. Simulation results showed that the fibers can carry more charges than equal surface area spheres. In the experimental component of this study, a prototype charger was designed and constructed. The rate of charging was measured as a function of fiber length and charger parameters. It was found that the fiber collection efficiency depends both on charge numbers and the aerodynamic drag of the fiber. The fiber length classification can be achieved by electrostatic precipitation.

High power Q-switched erbium doped fiber laser

The design rules and experiments with the Q-switched Er/sup 3+/ fiber laser are presented. The optimization of the fiber parameters resulted in 230 W/8 ns pulses for 250 mW of green pumping power, the highest peak power combined with such short pulses ever demonstrated for this type of laser. Self-mode-locked operation is also reported. The performance of the Q-switched laser is analyzed as a function of fiber length, pulse repetition rate, and pumping conditions. >

Short Fiber Reinforced Thermoplastics: Prediction of Stiffness in Injection Molded PS-PPO Blends

The prediction of stiffness in short fiber reinforced thermoplastics is stud ied as a function of fiber length using injection molded blends of PS and PPO. The theoret ical models for predicting composite stiffness are reviewed. The results are first compared with the theoretical models advanced for uniaxially aligned composites. These models predict higher than experimental values. However, agreement between the predictions and experimental values improves when the effect of fiber orientation distribution in the injec tion molded samples is taken into account and as the ductility (or the PPO content) of the matrix increases. Cox's model when used with the "laminate analogy" gives the closest prediction to the experimental stiffness. Reinforcement efficiency factor for stiffness is a strong function of retained fiber lengths. The dependence of composite stiffness on the matrix ductility and the effects of compatibility on the mechanical properties of PS-PPO blend system are also discussed.

The diffusion coefficients for ultrathin chrysotile fibers

The diffusion coefficient for chrysotile fibers was determined from measurements of the total penetration and the size distributions before and after a diffusion battery. A protocol was developed in which the fibers were produced by nebulizing a methanol suspension of chrysotile fibers. The fibers were collected on carbon-coated nucleopore filters. After dissolving the filter substrata, the fibers were verified as chrysotile and sized. Experimental variables were flow rate and total pressure. The fiber diffusion coefficients as a function of fiber length and diameter were obtained by first obtaining the size dependent penetrations, then calculating the diffusion coefficient from the Gormley-Kennedy equation. Four experiments were analyzed in depth. Although two of the experiments were at reduced pressure, the corrections due to increased Knudsen number were less than the variation among the experiments. p] The most significant experimental results were that the measured diffusion coefficients were larger than calculations from existing theory. Also, thicker fibers had surprisingly large diffusion coefficients. Theoretical calculations indicated that models based on hypothetical spherical particles gave similar results when either the hybrid, Asgharian-Yu-Gradon, or equivalent volume diameters were used.

Output saturation characteristics of erbium-doped fiber amplifiers pumped at 975 nm

We report the signal saturation behavior of an erbium-doped fiber amplifier pumped at 975 nm. We have characterized the output saturation powers as a function of fiber length and observed that the output saturation powers peak at an optimum length close to the optimum length for small signal gain. The output saturation power is found to be higher at a signal wavelength of 1.555 μm than at 1.532 μm.

Er/sup 3+/-Yb/sup 3+/ and Er/sup 3+/ doped fiber lasers

Single-mode fiber lasers operating at approximately 1.57 mu m are described. Output powers of >2 mW are reported for laser diode pumped operation. Direct comparison is made between fiber lasers using sensitized erbium (Er/sup 3+/ and Yb/sup 3+/) and erbium on its own. The performance of Er/sup 3+/-Yb/sup 3+/ fiber lasers is analyzed in more detail as a function of fiber length. Both CW and Q-switched operations are studied and the results obtained demonstrate that practical sources at 1.5 mu m are available from diode pumped Er/sup 3+/-Yb/sup 3+/ systems.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Fracture Studies of Discontinuous Fiber Reinforced Thermoplastic Composites

The strength and toughness of discontinuous fiber reinforced composites were evaluated as a function of fiber length, fiber type, fiber volume and resin-fiber adhesion. Glass, car bon and aramid fiber reinforced nylon 6/6 composites, prepared by both extrusion com pounding and long fiber pultrusion techniques, were injection molded and characterized in tensile, Izod impact, and instrumented falling dart impact testing.

Measurement of Rayleigh backscatter-induced linewidth reduction

We present measurements of the linewidth reduction for a semiconductor laser exposed to the Rayleigh backscatter from a single-mode fibre. The linewidth is measured as a function of fibre length and laser to fibre coupling efficiency and shows good agreement with the estimate from a simple statistical model.

Evaluation of polarization mode coupling coefficient from measurement of polarization mode dispersion

Polarization mode coupling coefficient is evaluated from the measurement of polarization mode dispersion as a function of fiber length in a single-mode fiber having an elliptical-core with 10-percent ellipticity. The modal dispersion measurement are carried out by the improved spatial technique based on an optical heterodyne detection at the wavelengths of 0.85 and 1.3 μm. The coupling coefficients are evaluated from the measurements to be <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3.4 \times 10^{-3}</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4.6 \times 10^{-3}</tex> m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> for modal-birefringence magnitudes of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8 \times 10^{-6}</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3 \times 10^{-6}</tex> , respectively. The coupling coefficients obtained from the dispersion measurement are coincident with those evaluated from the extinction-ratio measurements. In addition, dependence of the coupling coefficient on propagation constant difference between the two orthogonally polarized HE <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</inf> modes is investigated based on Lorentzian power spectrum model.

Compression of optical pulses chirped by self-phase modulation in fibers

The use of self-phase modulation in a single-mode fiber to chirp an optical pulse, which is then compressed with a grating-pair compressor, has been shown to be a practical technique for the production of optical pulses at least as short as 30 fsec. We report the results of a theoretical analysis of this process. Numerical results are presented for the achievable compression and compressed pulse quality as functions of fiber length and input pulse intensity. These results are given in normalized units such that they can be scaled to describe a wide variety of experimental situations and can be used to determine the optimum fiber length and compressor parameters for any given input pulse. Specific numerical examples are presented that suggest that the technique will generally be useful for input pulses shorter than about 100 psec. For energies of a few nanojoules per pulse, the compressed pulse widths will typically be in the femtosecond regime.

Length dependence of the effective cutoff wavelength in single-mode fibers

The effective cutoff wavelength of a depressed cladding single-mode fiber in either a cabled or a loose state depends upon the length of the fiber. This dependence can be accurately represented by a linear function of the logarithm of the fiber length for lengths between 1 m and 1 km. Cutoff will shift 55-66 nm per decade length for slightly and moderately depressed cladding designs, respectively. Neglecting all sources of differential mode attenuation except leaky-mode loss, the computed behavior of cutoff as a function of fiber length agrees reasonably well with the observed behavior for a moderately depressed cladding design. On the other hand, agreement is poor for a slightly depressed cladding design. A knowledge of the length dependence of cutoff is essential for establishing a production requirement for cutoff based upon the needs of the system.

DEPOSITION OF INHALED MAN-MADE MINERAL FIBRES IN THE LUNGS OF RATS

The lung retention of man-made mineral fibres by rats, sacrificed 5 days after the end of a 6 day period of exposure to the airborne fibre, has been examined as a function of fibre length, diameter and aerodynamic equivalent diameter. The retention of fibres < 0.5 μm dia. showed a peak of about 7.6% at 21 μm fibre length and was significantly higher than the retention (< 1%) of fibres in the diameter categories 0.5-0.7 μm and 0.7-1.0 %mUm. In terms of aerodynamic equivalent diameter, retention was a maximum, ca. 7%, at de = 1 μm, but decreased rapidly to about 0.5 % at de between 1.5 and 2.5 μm amd 0.01% at ca. 4 μm. When fibre length only was considered, irrespective of diameter, retention fell sharply as length increased from 2 to 10 μm, then more slowly to < 0.05% at ca. 40 μm.

Polarization holding in birefringent single-mode fibers

Perturbations in highly birefringent single-mode fibers couple the two polarization modes and degrade the polarization-holding ability. With a broadband source we demonstrate wavelength averaging of the power in either mode, permitting a simple measurement of the power transfer to the cross-polarized mode as a function of fiber length. Using this technique, we confirm experimentally the theory of random mode coupling between the polarization modes.

Inorganic ion‐doped glass fibres as microspectrofluorimetric standards

SUMMARYUranyl and europium ion‐doped fibres of 5–45 μm diameter were prepared which emit in the green and red spectral regions, respectively. Measurements were made of fluorescence flux as a function of fibre length, dopant concentration, slit shape and fibre diameter. The flux was found to be proportional to fibre length and fluorophor concentration and proportional to the square of the fibre radius. In addition, the fluorescence flux as a function of aperture size and shape and fibre position has been measured experimentally and compared to computer generated fluorescence flux envelopes. It is suggested that inorganic ion‐doped fibres are suitable for use as microspectrofluorimetric standards.

Fiber Strength as a Function of Fiber Length and Gauge Length

Fiber Strength as a Function of Fiber Length and Gauge Length