Numerical simulations of 2-D vertical cavity surface emitting laser arrays

Modal behavior of a 2-D (square lattice geometry) antiguided vertical cavity surface emitting laser (VCSEL) array was studied by 3-D bidirectional beam propagation method. The VCSEL array is made by periodical transverse variation of resonance frequency of a local cavity formed by Bragg reflectors and active layer. Using a method based on functions of Krylov´s subspace, a number of array optical modes were found for different spacing lengths between elements and a size of the array. In calculations, both Fourier and space variable descriptions of beam propagation were combined. The FFT technique was used for calculations of the Fourier image and the original. Array optical modes having different symmetry properties were found. They include in-phase mode with constant phase over the array, out-of-phase mode with alternating phase between elements and modes with mixed symmetry. 4×4 and 10×10 laser arrays were studied numerically. Conditions are found for favorable lasing of the in-phase mode providing high laser beam quality.