Multicore Multimode Fiber-A New Type of Fiber Using Coupled-Core Structures

A new type of multimode fiber, multicore multimode fiber (MCMMF), which uses coupled multicore structure is proposed. The fiber has a large number of single mode cores with optimized coupling to achieve high bandwidth. A theoretical model for analyzing the MCMMF is developed. The effect of fiber parameters, such as index contrast, core radius, and core spacing on the bandwidth is systematically studied. Numerical simulations show that the bandwidth of a MCMMF can be optimized by choosing correct ratio of core spacing to core radius for a given profile design. In addition, mode coupling among the super-modes can further increase the bandwidth due to the small spacing in effective indices in coupled core structures. A MCMMF with 165 cores is fabricated. High bandwidth of 8.4 GHz·km in the 850 nm window is achieved. Using this fiber and a VCSEL-based 25 Gb/s SR transceiver, error free transmission though 150 m fiber is demonstrated.