Power flow in multimode step-index plastic photonic crystal fibers

Calculation of Bandwidth of Multimode Step-Index Polymer Photonic Crystal Fibers

“…For the multimode SI PPCF with RI of the core , core diameter , and optical fiber diameter , we solved the time-dependent power flow Equation (1) using a finite-difference method, assuming and [ 35 , 36 ]. We looked at impact of the diameters of air holes in the cladding of d = 1, 1.5, and 2 µm (i.e., the influence of NA of the fiber) and width of the launch beam distribution with (FWHM) z=0 = 1°, 5°, and 10° on the bandwidth.…”

“…For (FWHM) z=0 = 5° this length is L c ≃ 4.5 m for = 1.4844, L c ≃ 11 m for = 1.4757 and L c ≃ 39 m for = 1.4458. For (FWHM) z=0 = 10° this length is L c ≃ 2.5 m for = 1.4844, L c ≃ 9 m for = 1.4757 and L c ≃ 33 m for = 1.4458 [ 36 ]. One can see that the shorter the length L c results in the faster bandwidth improvement.…”

Treatment of Mode Coupling in Step-Index Multimode Microstructured Polymer Optical Fibers by the Langevin Equation

“…Mode coupling is the process of energy transfer between neighboring modes during their propagation along the optical fiber. Mode coupling is mostly induced by intrinsic random perturbations of the fiber, such as refractive index variations, microbends, and stresses [ 19 , 20 , 21 ].…”

“…The angular input optical power distribution that results from a specific launch gets modified gradually with distance from the input fiber end by the effect of mode coupling. The expected beam properties, including the far-field radiation pattern, are altered as a consequence [ 19 , 20 ]. Thus, for example, if we arrange a centrally symmetric launch (along a cone) at a fixed angle θ = θ 0 to the fiber axis, a ring can be imaged behind the output end of a short fiber—the ring diameter is related to that initial launch angle .…”

“…This is a steady-state distribution (SSD) that is independent of the launch conditions except for the overall brightness: normalized to its peak value, the SSD is one and the same whatever the launch angle(s). By employing the power flow equation [ 19 ], these patterns have been predicted as a function of the launch conditions and fiber length in SI mPOF. In this paper, we report for the first time on the application of the Langevin equation in the treatment of mode coupling in SI mPOF.…”