OPTIMIZATION OF ROWLAND CIRCLE MOUNTS FOR GRATING DEMULTIPLEXERS AND NARROW-BAND SPECTROGRAPHS

A simple equation for the parameters of the Rowland circle grating mou nt is derived that ensures that the astigmatism and the meridional sph erical aberration are stationary at the wavelength of correction. This is important in optimizing the design of grating multiplexers-demulti plexers and cross connects in wavelength-division multiplexed networks and high-resolution narrow-band spectrographs. An analysis of aberrat ions in three-dimensional and planar two-dimensional optical schemes i s presented, and it is shown that in the wavelength range of 1530-1570 nm diffraction-limited performance can be achieved for 160 channels i n a three-dimensional multiplexer-demultiplexer and for more than 800 channels for a planar free-space scheme. (C) 1996 Optical Society of A merica