This paper examines the use of optical lattice filters as wavelength a
dd/drop devices in WDM ring or bus networks. Various filter design met
hodologies are investigated, including methods to produce passband-fla
ttened low sidelobe filters. The effects of cascading such devices are
examined from the viewpoint of net transmission bandwidth and coheren
t or ''in-band'' crosstalk and are compared with the use of pairs of 1
:n wavelength multiplexer/demultiplexers to perform the add/drop funct
ion. We find that the use of optical lattice-type add/drop filters res
ults in a much broader net transmission bandwidth than even the use of
pairs of passband-flattened 1:n wavelength multiplexer/demultiplexers
. The use of passband-flattened optical lattice filters with correspon
dingly broad stopbands helps to significantly broaden the coherent cro
sstalk-limited bandwidth. The characteristics of a four-channel add/dr
op filter fabricated using silica waveguide technology and the perform
ance of a three-node 3 x 2.5 Gbps WDM ring network built using a numbe
r of these devices are reported. (C) 1998 Academic Press.