I’m afraid OptiFiber will not help with this simulation. OptiFiber uses modal analysis, but this method won’t work well for this sample. Your sample fibre has a radius of 980 µm, wavelength .65 µm, core and cladding refractive index 1.49 and .13725. The V number is therefore 5,494. The number of modes for high V number is estimated from 0.5*V^2, which is more than 15 million. I’m afraid that is too many modes! OptiFiber can perform multimode analysis. It will work reliably even if there are dozens of modes, but 15 million is just too many!
You can probably get meaningful results from a propagation kind of simulation, like BPM, but modal analysis is simply the wrong method for this problem.