Integrated non-blocking optical router harnessing wavelength- and mode-selective property for photonic networks-on-chip.

In this paper, we propose and demonstrate a 4×4 non-blocking optical router utilizing 8 mode (de)multiplexers and a 4×4 microring-based grid network, which can passively assign signals carried by optical wavelength and mode channels from an arbitrary input port to corresponding output ports without additional switch time, realizing the non-blocking property. The proposed device is fabricated on a silicon-on-insulator platform using the standard Complementary Metal-Oxide-Semiconductor (CMOS) fabrication processes. The insertion loss is lower than 5.7 dB including the loss of the auxiliary mode (de)multiplexers (AMUXs), while the crosstalk is lower than -15.6 dB for all routing states. Moreover, the transmission spectra from the input ports to the next cascading device are also measured to demonstrate the feasibility of further expanding via cascading multiple blocks, with the insertion loss and crosstalk lower than 7.1 dB (including the mode coupling loss of AMUXs) and -16.4 dB, respectively. The 12 Gbps dynamic transmission experiment is demonstrated with clear and open eye diagrams, illustrating the utility of the device. The device has high geometrical symmetry and good scalability, we exhibit all solutions to expand the 4×4 optical router to 8×8 and 16×16 optical routers with the advantages and deficiencies of each solution discussed.