The two-lambda method can provide a strategic approach to implement all-opt
ical devices for communication wavelength division multiplexing (WDM) signa
l processing based on volume holography, By writing holograms at 488 nm in
LiNbO3:Fe and reading them in the third window of optical communication sys
tems (1550 nm), the feasibility of WDM demultiplexers and holographic memor
ies for digital bytes is here demonstrated.