Experimental demonstration of adaptive VFF-RLS-FDE for long-distance mode-division multiplexed transmission.We experimentally demonstrate adaptive variable-forgetting-factor (VFF) recursive-least-square frequency-domain equalization (RLS-FDE) for mode-division multiplexing.  The VFF-RLS-FDE algorithm improves convergence speed as transmission distance increases. 
VFF-RLS-FDE
For MDM transmission over a 1,000-km few-mode fiber, the convergence speed was increased by 18.7 times in comparison with LMS-FDE. 
LMS-FDE
Experimental demonstration of adaptive VFF-RLS-FDE for long-distance mode-division multiplexed transmission.We experimentally demonstrate adaptive variable-forgetting-factor (VFF) recursive-least-square frequency-domain equalization (RLS-FDE) for mode-division multiplexing.  The VFF-RLS-FDE algorithm improves convergence speed as transmission distance increases. 
VFF-RLS-FDE
For MDM transmission over a 1,000-km few-mode fiber, the convergence speed was increased by 18.7 times in comparison with LMS-FDE.  In the meantime, the convergence error performance of VFF-RLS is also much superior to LMS while fixed-forgetting-factor RLS has a 0.2 dB penalty compared with LMS. 
LMS
Experimental demonstration of adaptive VFF-RLS-FDE for long-distance mode-division multiplexed transmission.We experimentally demonstrate adaptive variable-forgetting-factor (VFF) recursive-least-square frequency-domain equalization (RLS-FDE) for mode-division multiplexing.  The VFF-RLS-FDE algorithm improves convergence speed as transmission distance increases.  In the meantime, the convergence error performance of VFF-RLS is also much superior to LMS while fixed-forgetting-factor RLS has a 0.2 dB penalty compared with LMS.  The proposed VFF-RLS algorithm achieves better performances than conventional RLS in terms of convergence speed and convergence error.
RLS