Fig. 1. Schematic diagram of proposed WSS employing an N-fold set of wavelength-dedicated 1×M equi-path switching trees.

Fig. 2. Implementation of Fig. 1 utilizing inplane 1×3 and 3×1 arrayed-waveguide grating devices for the demux and mux sections.

Fig. 3. Waveguide diagram of 1×4 tree utilizing dual-nanobeam MZIs as the 1×2 constituent switches.

Fig. 4. Waveguide diagram of 1×4 tree utilizing MZI constituent 1×2 switches composed of a pair of three-waveguide couplers, each containing a central nanobeam.

Fig. 5. Waveguide diagram of 1×4 tree using asymmetric contra-couplers as 1×2 elemental switches, each switch containing an offset dual-grating coupling region.

Fig. 6. Overall spectral response of the switches in Figs. 3, 4, and 5 in the zero bias state (unshifted spectrum) and in the full-bias state (shifted spectrum).

Fig. 7. Passive demultiplexing of a multiwavelength input stream using a sequence of dedicated-resonance 2×2 devices (the example of the Fig. 3 structure).

Fig. 8. Proposed design of three-wavelength, four-output WSS utilizing Fig. 3 devices.