Periodic dielectric waveguide-based cross- and T-connections with a resonant cavity at the junctions

► Ultrasmall cross- and T-connections in periodic dielectric waveguides. ► A crosstalk of less than 1.6% in the sideway waveguides for the cross-connection. ► A transmission of larger than 93% at the desired output port for the cross-connection. ► A total transmission up to 95% at two output ports for the T-connection. ► Different power splitting ratios achieved for the T-connection.