Effect of lateral error on the coupling efficiency and beam quality of gaussian beam launched into large-core fiber

We study the effect of lateral error on the coupling efficiency and beam quality of a Gaussian beam coupled into a large-core multimode fiber. The formula for the effect of lateral error on coupling efficiency is derived in detail and verified with both simulations and experiments. The effect of lateral error on beam quality is also analyzed with the use of ZEMAX and verified with our experimental setup. The results show that lateral error can change the path of the light coupled into the fiber to such a large extent that it influences the power distribution of the Gaussian beam.