Wavelength Routers for Optical Networks-on-Chip Using Optimized Photonic Crystal Ring Resonators

In this paper, we propose an optical 1 × 2 passive wavelength router (λ-router), based on photonic crystal ring resonators. The router, as basic building block to be assembled into higher order routing matrices, exploits a broadband crossing between two photonic crystal waveguides and a photonic crystal ring resonator. Moreover, we analyze the behavior of a 4 × 4 λ-router configuration obtained by assembling eight 1 × 2 routers. The design criteria are pointed out, and the numerical results, obtained by the finite-difference time-domain and the plane-wave expansion methods, are reported. The 4 × 4 λ-router has a footprint of 30 μm × 30 μm, and it is capable of connecting four transmitters with four receivers with a maximum crosstalk between the ports equal to -13.9 dB.