Wavelength routers for optical networks on chip using optimized photonic crystal ring resonators

In this paper, we propose an optical 1 x 2 passive wavelength router (lambda-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 x 4 lambda-router configuration obtained by assembling eight 1 x 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 x 4 lambda-router has a footprint of 30 mu m x 30 mu m, and it is capable of connecting four transmitters with four receivers with a maximum crosstalk between the ports equal to -13.9 dB.