Wavelength-selective coupling of two-core optical fiber: application and design

Abstract

Wavelength-selective coupling characteristics of evanescent fields between nonidentical single-mode fibers are investigated theoretically. We study the application of two-core fiber, which has two adjacent cores embedded in a cladding, especially for fiber-optical amplifiers, using three-wave mixing or stimulated Raman scattering. The theory shows how to minimize the power-transfer efficiency between two cores either at the signal or at the pump wavelength, while maintaining 100% power transfer at the other wavelength. As a result, owing to the wavelength-selective coupling, a periodic interaction of the signal and pump lights is expected only in one of the two cores. This permits an efficient amplification of signal light. The attractive feature of the use of the two-core fiber is that various optics, such as lenses, beam splitters, and grating filters, can be eliminated from the setup.