Maximum channel density in multimode optical waveguides for parallel interconnections

The maximum channel alignment density of multimode optical waveguides is presented for the first time from the viewpoint of inter-channel crosstalk. The inter-channel crosstalk is theoretically estimated by taking into account the two possible origins (mode coupling and mode conversion) of crosstalk we have focused. Then, we show the advantage of GI cores for reducing the “crosstalk due to mode coupling” by numerically solving the coupling length of each mode. From the viewpoint of mode coupling, we can say the minimum inter-core space should be 10 μm for GI-core waveguides, while more space is required for SI cores in order to maintain the crosstalk less than -20 dB.