Dispersion compensation based on dual-mode optical fiber with inhomogeneous profile core

It is well known that the first higher order mode of optical fibers exhibits large negative waveguide dispersion by operating close to its cutoff wavelength. By using this dispersion, the positive dispersion in conventional 1.3 μm zero dispersion optical fibers for 1.55 μm signal light can be compensated. In this paper, we focus on the dispersion compensation technique using the first higher order mode in a dual-mode optical fiber, which supports both the fundamental LP₀₁ and first higher order LP₁₁ modes. Numerical calculations show that the waveguide dispersion of the first higher order mode is very sensitive to the refractive-index profile of optical fibers. In addition, it is demonstrated that a directional coupler composed of a single-mode fiber and a dual-mode fiber operates as a mode converter, which converts the signal light from the LP₀₁ mode to the LP₁₁ mode