We show how the grating diffraction properties of a N N waveguide grating router (WGR) can limit the size of N when the device operates with a unique set of N wavelengths as a strict-sense nonblocking N N cross connect. We motivate why, for large N, the N optical channels should be chosen equally spaced in wavelength and not in frequency. Two different approaches to increase N are presented. We report on results obtained in a 4040 and a 8080 WGR.
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