Low-crosstalk and low-loss waveguide crossings on InP with small dimensions

With the increasing scale of integration, resulting in a higher on-chip complexity, waveguide crossings with good performance are becoming increasingly important. Worst-case paths contain a high number of crossings, depending on the number of channels being processed, in switching matrices, multiwavelength add drop filters (up to 15), and optical cross-connects. Crossings with very low crosstalk and loss can be realized in fiber-matched waveguide structures as used in lithium niobate or silica-based technology. In highly integrated semiconductor devices, crossings may contribute significantly to the loss and crosstalk performance. In this paper we present the results of a series of experiments for the design of high-performance semiconductor waveguide crossings