Mixing of a laser beam and a spectrum of light in a birefringent optical fiber

Abstract

Four-wave mixing (FWM) in optical fibers has been widely investigated as a technique of realizing wavelength tunable light sources,1–3 and, at the same time, as a source of noise that must be eliminated in wavelength-division-multiplexed transmission systems.4–6 FWM has also been demonstrated as a means of measuring fiber properties, such as the third-order nonlinearity in a fiber,7 the intermodal dispersion in a two-mode fiber,8 and the refractive-index profile of a graded-index fiber.9 Recently, we observed a new FWM process in a birefringent fiber, where a distinct frequency-shifted beam was produced as a result of mixing a laser beam with a spectrum of superfluorescent light.10 In this paper, we outline a theory to explain why this process is possible, and present experimental results to compare with the theory.