Air-clad photonic lanterns: fabrication and applications

The fabrication steps for an air-clad photonic lantern that can excite the first two LP mode groups in a multimode fiber are presented in this paper. A multiplexing crosstalk below -16.8 dB is measured on the fabricated lantern using S² imaging technique over a wavelength of 1525 nm to 1575 nm. The de-multiplexing crosstalk is measured for both LP₀₁ and LP₁₁ mode groups as -16.8 dB and -9.4 dB respectively using loss measurements. 2 × 40 Gb/s MIMO-less MDM transmission through 7 m of two mode step index fiber is demonstrated using the fabricated photonic lanterns. 2×10 Gb/s MIMO-less MDM transmission through 1.6 km standard 50/125 µm multimode fiber is also demonstrated and a Q value higher than 3.7 is obtained for both spatial channels over all input polarizations. Simple intensity modulation and direct detection schemes are used for these MDM transmissions.