Multimode VCSEL(Vertical Cavity Surface Emitting Laser) coupling into MMF (Multimode Optical Fiber) and its
influence on MMF link has been numerically studied. Considering the transverse misalignment between VCSEL and
MMF, coupling efficiency between VCSEL higher-order modes and modes of MMF is calculated and the Mode Power
Distribution in the MMF is obtained. Simulation of MMF link with multimode VCSEL indicates that the higher-order
VCSEL modes lead to decreasing of the eye opening of received signal. The transverse misalignment of VCSEL between
MMF greatly deteriorates the eye opening. With 300m OM3-MMF link , the EOP (eye-opening-penalty) is greater than
14dB when the misalignment between VCSEL and MMF is lager than 5μm.