All-fiber mode division multiplexer optimized for C-band

We demonstrate the excitation of all of the higher-order modes in a few-mode fiber using mode-selective couplers made by taper-polish method. Each mode selective coupler provides exclusive mode coupling between the LP₀₁ mode of a single-mode fiber and each of the LP₁₁, the LP₂₁, and the LP₀₂ modes of a few-mode fiber, respectively. We also demonstrate the C-band optimized mode division multiplexer using cascaded mode selective couplers.