ACCURATE NUMERICAL-ANALYSIS OF MULTIMODE-INTERFERENCE-BASED 3-DB COUPLERS

The power coupling characteristics of a multimode-interference-based 3 -dB coupler have been analyzed by using the vector finite-element and least-squares boundary residual methods. The numerical results obtaine d have been compared with published experimental data to show the accu racy and the versatility of these numerical schemes. The results predi ct that a full treatment of the two-dimensional cross section is of pa rticular importance for the design and the simulation of effective wav eguide devices to enable a study of their important optical properties such as polarization and fabrication tolerances. (C) 1998 Optical Soc iety of America.