A CROW/MZI-based switch for silicon photonics applications

In this work, the authors propose the design of an electro-optical silicon-photonics hitless switch that follows wavelength-division multiplexing (WDM) conditions in terms of channel bandwidth, shape factor, and free spectral range. Through a careful step-by-step design, the authors study a switch device composed of a coupled-resonator optical waveguide (CROW) structure merged with a Mach-Zehnder interferometer (MZI) modulator. The MZI modulator controls the coupling to the CROW and hence turns the switch on and off. The traditional matrix analysis of the CROW structure is modified to accommodate the MZI modulator section. The proposed switch requires a chip area of less than 0.01225 mm2. The switch transmission satisfies WDM requirements with a channel-free spectral range of 100 GHz, channel flat-top response with a passband for the through/drop ports of 64.6 GHz/33 GHz, and a shape factor of 0.76/0.6. Besides, the switch transmission features an insertion loss for the through/drop ports of 0.23/1 dB, a switching speed of 100 GHz, and a competitive switch-on/off ratio of 33 dB.