A NEW APPROACH FOR OPTIMIZATION OF WAVELENGTH MULTIPLEXERS WITH PHASED WAVE-GUIDE ARRAYS BY USE OF THE BEAM-PROPAGATION METHOD

An approach to the optimization of wavelength multiplexers with phased waveguide arrays is presented. It is based on a simulation of the str ucture by the beam propagation method. The approach takes into account not only the symmetry of the structure but also the perturbations due to. both emitted radiation and coupling between the waveguides at the ends of the phased waveguide array. Low-loss cosine-shaped bends are used. Both the design principles and the optimization of real waveleng th multiplexers are described. The optimized multiplexers, based on si lica waveguides on a silicon substrate, have sizes of about 50 mm X 30 mm, fibre-to-fibre losses of 1-2 dB and cross-talk values between - 4 0 and - 29 dB.