A Low-Loss Fused Biconical Taper Type Few-Mode Multiplexer/Demultiplexer

A low-loss all-fiber mode converter is fabricated, and it forms a mode multiplexer/demultiplexer by cascading 4-mode (LP01, LP11, LP21, LP02) multiplexer. Then, it is prepared by the fused tapering method. The cascade experiment evaluates the insertion loss and crosstalk. Insertion loss is less than −5.5dB, and crosstalk is less than −15 dB. Moreover, the wavelength flatness of insertion loss in the C-band is less than 1.137 dB. Fifty-time repeated experiments have proven the stability of the process. As a result, it verifies the possibility of mode division multiplexing transmission in commercial applications.