Birefringent fibers have attracted considerable attention in recent years for their potential applications in communication and sensing. In this thesis we selectively infiltrate high-index liquids or liquid crystals (LCs) into specified air holes of the photonic crystal fibers (PCFs) by using a selective blocking technique and the vacuum filling method to form half-filled birefringent PCFs and central-filled liquid crystal PCF (LCPCF). We first measure the bending loss of the half-filled PCF. Smaller bending loss was obtained as the PCF was bent in 0¢X due to the dominat index-guiding. Compared with the full-filled PCF, the half-filled PCF possesses a smaller bending loss for the reduction of liquid-filled air holes. The birefringent properties of the half-filled PCF and the LCPCF were then measured in cooperation with the Sagnac fiber loop. We can obtain the birefringence of the half-filled PCF of 2.39¡Ñ10^-4 at £f = 1411 nm, and the sensitivity to temperature, strain, and torsion can be obtained as -0.614 nm/¢XC, 0.466 pm/£g£`, and -0.316 nm/deg. These large sensitivities make the half-filled PCF useful in sensing applications. We also measured the birefringence of the central-filled LCPCF with variant laser irradiation and temperature. The optical and thermal birefringence variations from 2.8¡Ñ10^-3 to 4.12¡Ñ10^-3 and from 2.3¡Ñ10^-3 to 3.3¡Ñ10^-3 can be oberserved, respectively. The optically and thermally tunable birefringence of the central-filled LCPCF was experimentally demonstrated.

Pulling bulk crystal into fiber is suitable for laser, amplified spontaneous emission (ASE), and optical amplifier applications in optical communications because of its structural similarity to silica fiber. Moreover, fiber configuration can confine pump light in a small cross-sectional area with a high energy density for a long distance. Among crystal fiber growth techniques, the laser-heated pedestal growth method (LHPG) was adopted. It is crucible free and can therefore produce high-purity, low-defect-density single crystals. However, interface loss of the crystal fiber is one of the main causes of optical loss. In order to reduce the optical loss, a proper method to clad the fiber is important for high device performance. For laser application, high-efficient Nd:YAG lasers were demonstrated using gradient-index crystal fibers. We used controlled profile of the active ion resulted in index difference of 0.0284 between the center and the edge of the fiber to confine the laser beam in the center region and thus reduced the interface loss. A laser output power of 80 mW was achieved with a slope efficiency of 28.9%, which, to our knowledge, is the highest ever achieved for diode-laser-pumped Nd:YAG fiber laser. For ASE and optical amplifier applications, Cr4+:YAG crystal fiber was studied due to its fluorescent spectrum just covering the low loss window of silica optical fiber. To reduce the fiber diameter and propagation loss, a novel cladding technique, codrawing LHPG (CDLHPG), was developed. Although fused-silica-clad fiber can be made with a 29-micron-diameter core and a propagation loss of less than 0.1 dB/cm, which is a factor of 7 smaller than that of an unclad fiber, it has almost no Cr4+ fluorescence in the core area due to the entering of SiO2 in YAG. With proper controlled growth parameters of the CDLHPG method, a double-clad fiber with a core diameter of 25 micron was successfully grown. Up to 2.36 mW of ASE with a bandwidth of 265 nm was demonstrated. After splicing the double-clad fiber with conventional single mode fiber, we successfully demonstrated the first transition metal-doped fiber amplifier in the optical fiber communication band. Up to 16-dB of gross gain at 1.47 micron was achieved.

Structural born vibration is the most concern issue for industry. Traditionally, the accelerometer is usually used as the major monitoring device for vibration. As the mechanism getting more and more complexity, more compact, tinier and more lighting, the traditional accelerometers are suffered from the loading effect. Its accuracy of measurement is suspected and cannot match the modern measurement requirement. Hence, the studies of fiber optic vibration sensors become an urgent issue in this era. The reflection wavelength of a fiber Bragg grating¡]FBG¡^is sensitive to the variation of the strain and temperature. Our sensor configuration is made of an interferometer and fiber Bragg grating. The vibration induces a strain of the fiber Bragg grating, and it makes a phase difference between those two light beams in the interferometer. A demodulation circuit is needed to detect the phase difference caused by the vibration. In this project, the aim is focused on the vibration measurement for some complicated rotational machines or structures. A fiber optic accelerometer will be designed and studied as a vibration monitor for the other subprojects. In this the thesis, two kinds of vibration sensor head are designed and studied, the first is a bending loss sensor head and the other is an optic fiber Bragg grating sensor head. The results are narrated as follows¡G¡]1¡^ The dynamic range of the bending loss sensing head is about 50 dB.¡]2¡^The dynamic range of the optic fiber Bragg grating sensing head is 38 dB with test frequency range between 100 ~ 400 Hz, the noise level is around 1.95 ¡Ñ 10-2 rad.

Abstract The electrical microphone has came to maturity, which has some restrictions on high electromagnetic and wet environments¡CFiber-Optic sensor can improve the problems, because it has better characters in electromagnetic interference and wet environment than the traditional microphone. The structure of Sagnac interferometer is circulator, so the design of head to a sensor has to wind fiber around. Because the minimum radius of winded fiber has a threshold, we can not miniaturize the sensor-head. A typical Mach-Zehnder interferometer has to use high-coherence light source and the length of two arms in equality without any interference, so it is difficult in fabrication. If we make a microphone by FBG and Mach-Zehnder interferometer, and the advantage is that we can use low-coherence light source, and shorten the length of two arms in interferometer. By using the structure, the minimum measured pressure of sound is 0.6 Pa, and the dynamic range is 30dB.

In this paper, the fesibility of using a Fiber Bragg Grating (FBG) as a sensing scheme to detect the underwater acoustic signals is analyzed. When a FBG is disturbed by an underwater sound, the wavelength of the FBG is changed. Therefore, the central spectrum of the reflected light is shifted according to the wavelength change of the FBG. This spectrum can be detected by an imbalanced two-arm interferometer. Its transfer function will be studied. Also, the polarization induced signal fading of those two-arm interferometers will be studied.

Thesis (Ph. D.)--Drexel University, 2004. / Includes abstract and vita. Includes bibliographical references (leaves 546-560).

Thesis (M.S.) in Civil Engineering--University of Maine, 2002. / Includes vita. Bibliography: leaves 134-141.

Thesis (M.S.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains xvi, 273 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 211-215).

Cotton fiber development is a fundamental biological phenomenon. In spite of its economical importance, a large proportion of cotton fiber initiation is unknown. A naked seed mutant (N1N1) was compared with its isogenic lines of cotton (Gossypium hirsutum, TM-1) using a 70-mer oligonucleotide microarray that contained 1,536 features designed from a subset of cotton fiber ESTs. Statistical analysis and quantitative RT-PCR identified 23 "fiber-associated" genes. The annotation suggested that the temporal regulation of genes involved in transcriptional and translational regulation, signal transduction, and cell differentiation during early stages of fiber development. To get a large view of fiber initiation, a new cotton oligonucleotide microarray was developed containing sequences from an ovule EST library from Gossypium hirsutum L. T̲M̲-1 immature o̲vules (GH_TMO), a set from Jonathan Wendel's lab at Iowa State University, and the pilot set of oligos used for previous study. Global gene expression studies were performed with microdissected fiber initials (or epidermis) and inner ovules to investigate fiber preferentially expressed genes. Laser capture microdissection and antisense RNA (aRNA) amplification allowed us to collect fiber initials (0 DPA and 2 DPA) or epidermal layers (-2 DPA) from whole ovule tissues. The gene expression profiles of fiber initials showed up-regulation of fiber proteins, myb transcription factors, and hormonal regulators as well as trichome related factors during fiber initiation. In each developmental stage, different sets of gene categories in molecular function or biological processes were over- or under-represented, suggesting temporal regulation of genes during fiber development. One of the possible "fiber associated genes" found in microarray analyses, RD22 like gene (GhRDL), was highly enriched in the epidermis of cotton ovules during fiber initiation. The function of GhRDL was studied with the Arabidopsis trichome system which shares many similarities with fiber development. Overexpression of 35S::GhRDL into Arabidopsis thaliana Columia-0 induced seed hairs (or seed trichomes) and pRDL:GUS was localized in Arabidopsis seeds. This suggests that GhRDL plays an important role in the seed trichome development and can be a key player in cell differentiation and fiber development. / text

Six dietary fiber sources, wheat bran, corn bran, soy bran, oat hulls, rice bran, and cellulose were examined with regard to their abilities to bind copper, zinc, and iron. Their chemical composition, some of their physical properties, and their in vivo action on mineral status in tissues of chicks were investigated. Also, a comparison of the physicochemical properties of neutral detergent treated (NDF) and pepsin-pancreatin treated (EIR) residues was made. The release of endogenous copper, zinc, and iron from the fiber sources was pH dependent. Greater amounts of minerals were released into solution at pH 0.65 than into solution at pH 6.8. After a sequential treatment of pH 0.65 solution, neutralization, then pH 6.8 buffer, the mineral levels in the residues were similar to those remaining in the residues after the near neutral treatment. This indicated that the minerals were rebound after the pH of the solution was raised from acidic to near neutral. The amount of zinc in the residues from the sequential treatment correlated positively to protein and phytic acid contents and negatively to NDF and EIR contents. Neither copper nor iron showed any significant correlations. Hydrogen ion buffering capacities were determined for three preparations of the six fiber sources: (1) untreated, original material; (2) NDF-treated; and (3) EIR-treated materials. The buffering capacities were expressed as functions of the slopes of titration curves, where the smaller the slope, the greater the buffering capacity. The treated preparations had lower buffering capacities than did the untreated preparation. The treatments reduced the amounts of digestible/soluble components, especially protein in the fiber sources. Protein content was strongly correlated to buffering capacity for the untreated and the EIR-treated preparations but not for the NDF-treated preparation. Wheat bran, soy bran, oat hulls, and cellulose were subjected to NDF and EIR treatments, and the residues were used as column material for cation exchange experiments. A factorial experiment was performed using fibers by treatments by three solutions. The solutions were copper alone, zinc alone, and copper-zinc in combination. Cation exchange capacities (CEC) and protein contents were also determined. The CEC values for the residues from the two treatments for wheat bran and cellulose were similar but were very different for the soy bran (EIR-treated CEC was higher than NDF-treated) and oat hulls (NDF much greater than EIR). More mmoles of copper were bound than zinc whether presented alone or in equimolar combination. Protein content correlated to mmoles mineral bound for only the NDF-treated residues and only when the minerals were presented singly. These in vitro experiments demonstrated the intrinsic differences of the fiber sources. One fiber source may be beneficial to nutritional status while another may be detrimental. The fiber isolation technique produced residues with different compositions and different physical properties. Future biochemical investigations of dietary fiber must acknowledge the possible divergence from physiological reality which results from the isolation methodology. The chick feeding study used diets which had the fiber sources added to be equivalent to the addition of 6% dietary fiber (as NDF). At this level, all the fiber sources, except rice bran, resulted in adequate growth and adequate deposition of tissue minerals. The chicks on the rice bran diet had lowered feed intakes, significantly reduced growth and significantly lower tibia zinc, iron, and manganese levels. One factor in the rice bran diet, which may have influenced the status of the chicks, was its phytic acid content which was the highest of the fiber sources. This in vivo experiment again indicates the dissimilarity in effects of the dietary fiber sources.