Crosstalk-, loss-, and length-reduced digital optical Y-branch switches using a double-etch waveguide structure

We demonstrate a novel Y-branch digital switch with a double-etch waveguide structure to greatly enhance the loss and crosstalk performance. The double-etch design increases the coupling between the two tapered Y-branch waveguides, which allows for efficient switching while decreasing the radiation loss that arises from the branching angle. This combined advantage also allows us to reduce the switch length, which in turn results in an efficient high-speed design. The measured crosstalk and loss are -19 and 3 dB, respectively, for a 3-mm-long switch. Further crosstalk reduction is expected from the simulation of a more optimized design.