| Multimode fibers have wide applications in optical network and the optical power splitter is one of the key passive components in Multimode communications. Optical power splitter is used to distribute the power of signals, which makes it indispensible in optical communication system, Optical Subscriber Network, CATV, PON and local network. MMI devices based on self-imaging are considered one of the important planar light wave circuit components. This is mainly because their advantages such as ease of fabrication, low sensitivity to fabrication parameters, compact size and wide bandwidth. They have been utilized as optical power splitters, combiners, optical hybrid couplers, multiplexers and demultiplexers.The traditional multimode power splitters are designed using the Y-junction, which makes it large in size and impossible to realize the N×M structure. What's more, there will be severe propergation loss if the number of the outputs grows large. Thus, the study on MMI structure is significant both theoretically and practically.Here in this paper, research is made in fabrication and application of multimode waveguides using the Ag+-Na+ ion-exchange technique in glass. First, Ag+-Na+ ion exchange was run in nitrate melt.Then an electric field was applied. By using this method it is possible to control independently the width and depth of the waveguide. Three-dimensional beam propagation method (3D-BPM) was utilized to simulate and design power splitters with Multimode Interference (MMI) structure and Y-junction.The results showed that the measured loss of multimode straight waveguide can be lower than 0.28dB/cm,and the insertion loss and uniformity of the 1×2 splitters can be 3.6dB and 0.21dB.It is proved that the fabrication process has adjustable parameters and reliably repeatability, which makes it suitable for optical power splitters with high performance.In conclusion, passive glass waveguides made by silver ion-exchange technique is a potential candidate for IO applications. |
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