DESIGN OF A HOLOGRAPHIC CONCAVE GRATING USED AS A MULTIPLEXER DEMULTIPLEXER IN DENSE WAVELENGTH-ROUTED OPTICAL NETWORKS WITH SUBNANOMETER CHANNEL SPACING

The performance parameters of a free-space concave grating multiplexer /demultiplexer have been evaluated for applications in wavelength rout ed optical networks. The conditions for the stationarity of astigmatis m with wavelength were rigorously derived and a novel design method wa s adopted to minimize the optical aberrations. The performance of this system is close to diffraction-limited over the wavelength ranges 148 0-1520 nm or 1530-1570 nm. The optical isolation is better than - 30dB for a channel spacing of 0 . 5 nm and the losses due to aberrations a re estimated to be less than 4 dB. The results can be used to design a spectrograph suitable for wavelength cross-connection in all-optical networks.