Supermode analysis of the 18-core photonic crystal fiber laser

The modal of 18-core photonic crystal fiber laser is discussed and calculated. And corresponding far-field distribution of the supermodes is given by Fresnel diffraction integral. For improving beam quality, the mode selection method based on the Talbot effect is introduced. The reflection coefficients are calculated, and the result shows that an in-phase supermode can be locked better at a large propagation distance.