Optical fibers provide the means for transmitting large amounts of data from one place to another and are used in high precision sensors. It is important to have a good understanding of the fundamental properties of these devices to continue to improve their applications. A specially type of optical fiber known as a W-fiber has some desirable properties and unique characteristics not found in matched-cladding fibers. A properly designed W- fiber supports a fundamental mode with a finite cutoff wavelength. At discrete wavelengths longer than cutoff, the fundamental mode experiences large amounts of loss. The mechanism for loss can be described in terms of interaction between the fiber's supermodes and the lossy interface at the fiber's surface. Experiments and computer simulations support this model of W-fibers. The property of a finite cutoff wavelength can be used to develop various fiber devices. Under consideration here is the fiber polarizer. The fiber polarizer produces an output that is linearly polarized along one of the fiber's principal axes. Some of the polarizer properties can be understood from the study of W-fibers. / Master of Science