Design of wavelength multiplexers/demultiplexers for WDM optical networks

Wavelength multi/demultiplexers are essential components in wavelength routed networks. The design requirements for a free-space diffraction grating with subnanometer channel spacing are presented. The analytic conditions for stationarity of second order aberration coefficient with respect to wavelength are derived for a spherical concave grating. The introduction of these conditions to the derived analytic expression for the means squared geometric transverse ray deviation and the wavefront variance allows to obtain a performance near to diffraction-limited. The experimental results confirm the accuracy of the theoretical predictions. Design considerations for an integrated optic concave grating are presented.