The capacity of single-mode fiber optical transmission systems is limited. Spatial Division Multiplexing (SDM) is an attractive option for expanding the channel capacity, in addition to Wavelength Division Multiplexing (WDM) and Polarization Division Multiplexing (PDM). Few-mode fibers (FMFs) as one of the SDM approaches have been investigated in past few years due to their large information transport capacity [1,2].
Synopsys RSoft mode solution tools, a BPM-based mode solver and an FEM-based mode-solver, combined with RSoft’s powerful scanning and post processing capabilities, are excellent tools to study the critical parameters of FMFs, such as effective index, normalized frequency, normalized propagation constant, mode profile, mode area, dispersion parameters, bending loss and so on. In addition, the challenging task of designing FMFs with low differential mode group delays (DMGDs) can be accomplished with small post-processing tasks. This includes designing FMFs so that all modes can be simultaneously used in multiple input, multiple output (MIMO) technologies and processed with as low s complexity as possible.
This tip demonstrates an example to calculate the critical parameters mentioned above for FMF. Figure 1 shows a trench-assist graded LP6 FMF. This structure receives a good deal of interest because it can reduce the bending sensitivity which become a source of difficulty when the number of LP modes increases. The user profile defined in Equation 1 was used to create the graded trench-assisted fiber. The design strategy is to choose the highest possible normalized frequency value