Investigation of bandwidth in multimode W-type microstructured plastic optical fibers

By employing the time-dependent power flow equation (TD PFE), we examine the bandwidth in multimode W-type (double clad) microstructured plastic optical fibers (mPOFs) with a PMMA (polymethyl methacrylate) solid core for parametrically varying depth and width of the intermediate layer (IL) (inner cladding). The investigated W-type mPOF's bandwidth was calculated for various configurations of the air-holes in the inner cladding and varied launch excitations. We obtained that results for smaller inner cladding air-holes at longer fiber lengths exhibit greater bandwidth. On the other hand, for shorter fibers, the launch beam which only excites guided modes, has no effect on the bandwidth due to the air-hole size. The W-type mPOF with a narrower inner cladding has a greater bandwidth. The bandwidth is also larger for a narrow launch that only excites guided modes as opposed to a wider launch that excites both guided and leaky modes. Therefore, the bandwidth increases as the width of the IL is reduced, or by decreasing the diameter of air-holes in the IL, or by exciting only guided modes. W-type mPOFs can be more easily tailored for a specific use in optical fiber sensors and communications because to their programmable properties.