Microstructured Optical Fiber Fabrication:An Intergrated Parametric Approach

Rosalind Mary Wynne
Boston University

A process for synthesizing microstructured optical fibers or “holey fibers” has been developed. We present a practical fabrication procedure combined with a parametric model that is designed to control and predict the lattice dynamics of a holey fiber during the fiber manufacturing process. This work provides a straight-forward technique to produce high quality novel microstructured optical fibers. The results of this investigation can serve as a “road map” to future research in the area of micro- and nano- structured fiber technology development.

The precision parametric model we have developed allows for the identification of appropriate draw parameters and predicts the final lattice behavior (i.e. degree of hole-collapse or expansion). The parameters from this model successfully identified the fiber-drawing domain and baseline parameters that control the glass dynamics of the lattice structure. A single-draw over-collapse technique was employed to draw a microstructured fiber housing four holes in a square lattice. After the fibers samples were drawn the cross-sections were examined with an optical microscope. The theoretical predictions of the modified fluid mechanical model were validated. The fiber samples successfully maintained the lattice structure.

The fabrication steps of the single-draw over-collapse technique were refined to improve the quality and lattice complexity of the holey fiber samples. A functional fiber sample based on the square lattice geometry with a high index core region was fabricated. This sample was optically characterized to determine the fiber’s suitability for transmission or sensor applications. Measurements provided information on the nonlinear properties (affective area, Aeff and non-linear coefficient, ?), transmission loss, and numerical aperture (NA) of the fibers. The performance evaluation of this fiber sample was comparable and in some cases, an improvement on previously reported fibers with a similar lattice arrangement. The square lattice fiber supported wavelengths from 1022nm-1700nm. Attenuation measurements indicated losses of 10dB/m at 1300nm and 5.7dB/m at 1550nm. The fiber demonstrated a NA = 0.139, an Aeff =39µm2 and ?=2.5 W-1km-1. Fiber samples fabricated in this thesis have a number of potential applications and are currently being used as a phantom in the Keck microscope for a CenSSIS research project at Northeastern University.

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