Large N x N waveguide grating routers

We show how the grating diffraction properties of a N x N waveguide grating router (WGR) can limit the size of N when the device operates with a uniqu e set of N wavelengths as a strict-sense nonblocking N x N cross connect. W e motivate why, for large N, the N optical channels should be chosen equall y spaced in wavelength and not in frequency, Two different approaches to in crease N are presented. We report on results obtained in a 40 x 40 and a 80 x 80 WGR.