Neodymium:glass fiber optic sources and amplifiers for the fiber optic gyroscope

Lasers and amplifiers made from single-mode fibers doped with rare-earth ions have been the subject of much attention in the past few years because of their high efficiency and excellent compatibility with fiber systems. While most of previous work on rare-earth doped fibers has been motivated by applications to communications, devices made from these solid-state materials are also of great interest for use in interferometric fiber sensors whose performance requirements are quite different. This dissertation describes the needs of one fiber interferometric sensor, the fiber optic gyroscope, and presents experimental demonstration of optical sources and amplifiers which are especially suitable to meet these needs.; The accuracy of interferometric sensors is degraded by source frequency changes caused by environmental temperature drift. The gyroscope also requires that sources be sufficiently broad in spectrum to minimize coherent errors, yet spatially coherent enough to couple efficiently into single-mode fiber. Sources made from rare-earth ions may enable orders of magnitude better stability than the semiconductor sources currently used; sources made in single-mode fiber have excellent spatial coherence and efficiencies enhanced by optical guiding. Two broadband optical sources both made from neodymium-doped fiber are characterized. The first is a nonresonant structure which emits amplified spontaneous emission; the second is a laser with an unusually large bandwidth. Both devices show adequate spectral width ({dollar}>{dollar}15 nm at full-width half-maximum), high output power ({dollar}>{dollar}1-10 mW) and good frequency stability ({dollar}sim{dollar}10 ppm/{dollar}spcirc{dollar}C). Some interesting physical phenomena were observed in these novel devices: emission wavelength dependence on pump wavelength, and laser spectral modulation caused by fiber bends.; The use of a doped fiber amplifier to increase storage time in a pulsed fiber recirculating delay line memory is also described. The delay line is of general use for signal processing, but has particular application to the re-entrant loop approach to the gyroscope. Experimental demonstration of pulse storage for hundreds of recirculations confirms expectations that doped fiber amplifiers have important advantages--much lower pump power and much less pump polarization--over stimulated Raman scattering which is the gain mechanism in previous work on such circuits.