EXACT MODAL-ANALYSIS AND OPTIMIZATION OF NXNX1 CASCADED WAVE-GUIDE STRUCTURES WITH MULTIMODE GUIDING SECTIONS

Cascaded multimode interference waveguide devices are analyzed to pred ict their switching properties, The results obtained using an exact mo dal analysis of an infinite slab model of these structures are compare d to those found using simple approximations, Using this model, design parameters for both 2 x 2 x 1 and 8 x 8 x 1 switching structures are optimized; robustness of the numerical optimization algorithm is discu ssed, Sensitivity of device transmission performance to lengths and wi dths of each of the multimode regions, phase shifts in the interconnec t regions, and wavelength are presented for the optimized devices. The deviations of the multimode region lengths found using simple approxi mations from those found by optimizing the model are also presented.