DESIGN AND PERFORMANCE OF CONCAVE HOLOGRAPHIC GRATINGS FOR APPLICATIONS AS MULTIPLEXERS DEMULTIPLEXERS FOR WAVELENGTH ROUTED OPTICAL NETWORKS/

The design method and the performance of two types of concave gratings for operation as multiplexers/demultiplexers, with 10 nm/mm reciproca l linear dispersion, required to multiplex/demultiplex channels separa ted by 0.5 nm in wavelength, are presented. The first type of grating is designed in such a way that the principal ray of the central wavele ngth in the spectrum is diffracted at normal angles to the image field . The second type of grating is a Rowland circle mount. In each case, two recording configurations are obtained. The performances of the mou nts are almost identical. In the first configuration, the coupling los s is less than -2.7 dB and the optical isolation is better than -37 dB . In the second configuration, the losses are less than -1.8 dB and th e optical isolation is better than -43 dB. Finally, a Rowland circle g rating with 4 nm/mm reciprocal linear dispersion, which can multiplex/ demultiplex at least 175 channels with loss less than -2.6 dB and cros stalk better than -28 dB, is presented. These spectrographs can be use d for wavelength routing applications in wavelength division multiplex ing (WDM) networks. (C) 1996 Society of Photo-Optical Instrumentation Engineers.