Study On Multimode Interference Couplers

Along with the development of optical communication systems toward high-speed and large-capacity, the development of high-performance integrated optical components has already become people's urgent demand. The multimode interference optical coupler has obtained more and more widespread application for its compact structure, wide band and polarization insensitive characteristics.Traditional multimode interference theory is based on high-contrast waveguide structure, and there is relative large amount of error when it is used to analyze the low-contrast components. Firstly, this article introduces dielectric waveguide theory and numerical simulation method of optical waveguide: the beam propagation method (BPM). Then, taking the low-contrast 1×4 multimode interference coupler as an example, on the basis of the traditional theory and considering different equivalent widths of guided modes, we propose three different optimal design methods and employ BPM to carry on the simulation of couplers'performance. Results indicate that the proposed optimization methods have enhanced the loss, uniform and comprehensive performance of the couplers greatly. Finally, taking light switch and phase array wavelength division multiplexing/de-multiplexing as examples, we make further introduction of the applications of multimode optical couplers.