Fibre Channel SAN Extension over Optical Networks
DWDM Concepts
DWDM Components
OADM
Optical
Amplifier
Other DWDM components that might be required are:
Erbium-Doped Fibre Amplifier (EDFA) optical amplifiers are optical
repeaters that can be used to boost the signal on longer spans, or to
preamplify the signal before it leaves the local site. An optical fibre is
doped with the rare earth element erbium, which allows the fibre to
absorb light at one frequency and emit light at another frequency. A
second laser couples light into the fibre at infrared wavelengths, which
excites the erbium atoms. When the DWDM optical signal enters the
fibre, it stimulates the already-excited erbium atoms to emit photons at
the same wavelength as the incoming DWDM signal. This action
amplifies a weak optical signal to a higher power at the same
wavelength.
Optical Add/Drop Multiplexers (OADMs) can de-multiplex (drop) and/or
re-multiplex (add) specific wavelengths while allowing all other
wavelengths to pass through unaffected.