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Today the world of fiber optics is bigger than ever. What is available to the engineer and the technician is now only apparent to the well informed. Not all engineers and technicians have a background or an education in the field of fiber optics. This report is intended to be an informative preliminary guide to those readers whose interest lies in the field of fiber optics. The advantages of fiber optic systems are discussed and compared to conventional systems. Although a fiber optic system includes transmitters and receivers, this report concentrates primarily on fiber optic connectors and cables. It also includes a look at the characteristics of the fibers themselves. The basis for this report is information obtained from a survey taken from a select number of manufacturers of fiber optic connectors and fiber optic cables. Available fiber optic connectors range from reusable to permanently installed, cheap to expensive, plastic to stainless steel. Some require special tools and preparation including the use of epoxy, whereas others can be used in the field quickly without any special tools or epoxy. Since many connectors, however, require epoxy, this report introduces six different types of epoxies, showing their characteristics and listing their applications. The fiber cable has become a widely appreciated medium for data and information transmission systems. The consumer has many choices from one or two fibers per cable to a bundle fiber cable. The cables have many designs which lead to various applications. These cable designs and their characteristics are summarized and discussed. There are many other optical devices that are available and on the market. Among these devices were not covered in this report, the coupling from one fiber to another (attached side by side) was investigated theoretically. The case where internal reflection in the fiber’s core created an evanescent field in the cladding (this is when the angle of incidence is greater than the critical angle) was emphasized. This shows that the power in the evanescent field is imaginary (reactive), and the angle of refraction is also imaginary. However, when the evanescent field extends on out to the second fiber’s cladding, and continues until it reaches and enters the second fiber’s core, power then exists; thus, optical power was transferred by way of an evanescent field.

This thesis discusses the dispersion of optical pulses in fiber waveguides. Procedures for determining the transfer function of an optical fiber using either time domain measurements or frequency domain measurements are given. A test set is described which uses time domain measurements for dispersion characterization. Complex transfer function data are presented for various fiber lengths as well as optical connectors. Prediction of bandwidths of long fibers from bandwidth/measurements taken on shorter length fibers is discussed. A relation between the bandwidth of cascaded connectors in terms of the bandwidth of a single connector is obtained.

Coupling efficiency an alignment sensitivity models for the coupling of light from a fundamental mode Gaussian light beam into a single mode optical fiber are given. Experimental results are presented which verify the coupling and misalignment predictions of the models. Data were taken at two wavelengths: 0.6328 and 0.8460 micrometers. The light sources were a HeNe laser and a GaAlAs laser respectively. Coupling efficiencies were measured versus beam spot size; and lateral, axial and angular misalignments of the beam and fiber axes.

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A gender difference in absolute muscle strength is well documented. The extent to which quantitative (fiber area and number) and qualitative (specific tension) differences in muscle contribute to this is not well understood. The purpose of this study was to examine a variety of muscle characteristics in the biceps brachii and vastus lateralis in a sample of males (n=8) and females (n=8) with a wide range of training histories. Measurements included motor unit number, size and activation, and voluntary strength of the elbow flexors and knee extensors. Fiber characteristics were determined from needle biopsies and muscle areas by computerized tomographical scanning. Females were approximately 52% and 66% as strong as the males in the upper and lower body respectively. A significant (p ≤ .05) correlation was found between strength and muscle cross-sectional area. Females had 45, 41, 30 and 25% smaller muscle cross-sectional areas for the biceps brachii, total elbow flexors, vastus lateralis and total knee extensors respectively (p ≤ .01). No significant gender difference was found in the strength to cross-sectional area ratio for elbow flexion and knee extension. Males had significantly larger type I fiber areas (4597 vs. 3483 um² ) and mean fiber areas (6632 vs. 3963 um² ) than females in biceps brachii (p ≤ .05) and significantly larger type II fiber areas (7700 vs. 4040 um²) and mean fiber areas (7070 vs. 4290 um²) in the vastus lateralis (p ≤ .05). The difference in type II fiber area in the biceps brachii was not statistically significant despite the fact that these fibers were almost twice as large in the males as in the females (8207 vs. 4306 um²). No significant gender difference was found in biceps fiber number (180,620 vs. 156,872) or muscle area to fiber area ratio in the vastus lateralis (451,468 vs. 465,007). No significant gender differences were found in any of the motor unit characteristics. The results indicate that the primary determinant of the greater muscle strength of males is their larger mean fiber areas which results in greater muscle cross-sectional areas. / Thesis / Master of Science (MSc)

A multichannel single fiber EMG recording system has been developed and tested. This system is based on a multichannel needle electrode which has the ability to record EMG signals from multiple sites within the muscle under study without reinsertion. Therefore, not only is the recording volume of the electrode. increased but also enhancement of the single channel electrodes is possible through spatial filtering. The recording system, currently implemented on a PDP-11/34 computer, amplifies, filters and digitally stores the multichannel EMG signals for further signal processing. Signal processing techniques were developed to detect and extract motor unit action potentials from the EMG signal. Due to the large amount of data recorded by the multichannel electrode, slower sampling rates for digitizing the action potentials were required. Even with near Nyquist sampled signals the accuracy of this technique was shown to be nearly equivalent to conventional extraction of action potential features samples at four times the Nyquist rate. Finally, the problem of superpositioning of action potentials was addressed. By modifying the interpolation routine an algorithm for resolving superpositions was developed. / Thesis / Master of Engineering (ME)

This thesis is centered on the study of spontaneous droplet migration along conical fibers. One of the key motivations for this project was to better understand the water-harvesting mechanism used by natural organisms like cacti. These desert plants exploit the conical shape of their spines to make fog condense into small droplets at the tip of theses spines. Then, droplets will spontaneously move towards the thickest end of the spines, bringing water to the main body of the plant. The key force behind drop migration on a conical fiber has been identified as the fluid surface tension by Lorenceau an Quéré in 2004. These authors also suggested and tested a model predicting the speed of drops on conical fibers. Here, we explore a larger range of relative sizes of drops compared to the fiber radius. The present document describes how an experimental set-up was designed in order to study droplet migration with conical glass fibers and silicone oil droplets. Using optical microscopy and data analysis, the droplet speed was measured as well as the other experimental parameters. Finally, a simple theoretical model has been developed to predict the droplet speed as a function of geometrical parameters and fluid characteristics. / Thesis / Master of Science (MSc)

In recent years, nanoprobe-based devices have attracted significant attention and found a wide range of applications, including nanostructure imaging, single molecular detection, and physical, chemical, and biological sensing applications. However, since the scale of nanodevices is substantially less than the optical diffraction limit, their fabrication remains a difficult challenge. Despite significant efforts, most of the fabrication techniques developed so far require expensive equipment and complicated processing procedures, which has hindered their applications. In this thesis, we developed a new class of fluorescent nanoprobes consist of a silica fiber taper, a single carbon nanotube, and nanoscale fluorescent elements (such as semiconductor quantum dots). This nanoprobe provides a natural interface between the nanoscale structures (i.e., the fluorescent elements) and the microscale structure (i.e., the fiber taper), which can significantly simplify their fabrication. Furthermore, since the nanoscale fluorescent elements are produced through bottom-up processes such as chemical synthesis, we can easily tailor the functionalities of such fluorescent nanoprobes to many different applications in nanophotonics, including near field imaging, nonlinear optics mapping, and quantum electrodynamics. We have custom designed an optical system for this nanoprobe fabrication. We have characterized the nanoprobes using transmission electron microscope (TEM) and scanning electron microscope (SEM) and performed preliminary experiments on near field scanning. Our current fabrication/imaging systems can be readily upgraded to achieve more advanced applications in nonlinear optics and quantum optics. / Master of Science

An index grating is a periodic perturbation of the refractive index in a waveguide's axial direction. Gratings have important roles in optical communication as spectral filters and dispersion compensators. The spectral response characteristics of gratings can be controlled by shaping the profile of the index modulation, a process called apodization. Apodizing different layers of the grating using different apodizing functions is proposed for adding more degrees of freedom to the design. An approach to designing a two-layer separately apodized grating that yields virtually the same reflectivity and dispersion responses as an arbitrary zero-"dc", apodized, un-chirped grating is proposed. A design example is presented, and coupled-mode theory is employed to compute the reflectivity responses of the original zero-"dc" design and the nearly equivalent separately-apodized design proposed in this thesis. An approach to designing a four-layer separately apodized grating that yields virtually the same reflectivity and dispersion responses as an arbitrary chirped grating is proposed. The largest bandwidth a four-layer separately-apodized grating designed using this approach can yield is as large as the largest bandwidth a variable-period conventional design can yield. Also, a similar, less-capable design approach is proposed for two-layer separately apodized gratings that are equivalent to conventional, chirped gratings. Design examples are presented. For all of the separately apodized gratings designed, the layers have a varying "dc" index change that is proportional to the varying "ac" index change. Furthermore, the period, which is the same in every layer, is constant, i.e. independent of the position. Both considerations enhance the prospects of fabricating the separately-apodized designs using a simple, reproducible technique. One such technique is proposed that separately-apodizes halves of the waveguide, instead of layers, but the design approaches are easily adjusted to this case. / Master of Science