Subcarrier multiplexing with dispersion reduction and direct detection

Patent · Wed Jan 01 04:00:00 EST 1997

OSTI ID:870797

Sargis, Paul D ^[1]; Haigh, Ronald E ^[2]; McCammon, Kent G ^[3]

---

1. Modesto, CA
2. Tracy, CA
3. Livermore, CA

An SCM system for simultaneously reducing the concomitant problems of receiver complexity and dispersion penalty and without requiring the use of an expensive, high-bandwidth optical detector. The system provides both a dispersion reduction and a direct detection to the receiver, with microwave mixers and lithium niobate external modulators that produce sidebands that are only separated by a few gigahertz from a principal laser optical carrier. Digital data streams are independently impressed upon these sidebands for transmission over an ordinary single-mode fiber. Independent high-speed data streams are upconverted to microwave frequencies. These subcarriers are then combined with a microwave power combiner and amplified with a microwave amplifier. A solid-state 1550-nm laser carrier is modulated by the microwave subcarriers. An erbium-doped fiber amplifier (EDFA) is used just prior to long-distance transmission over ordinary single-mode fiber. The transmitted optical signal may then traverse multiple EDFAs to compensate for long-haul optical fiber losses prior to detection. At a receiving end, the optical signal is split into multiple paths. The subcarrier channels are optically pre-selected using a narrowband optical filter, such as a fiber Fabry-Perot (FFP) filter. An optical detector converts the selected optical signal into a baseband electrical data stream.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA
• DOE Contract Number: W-7405-ENG-48
• Assignee: Regents of University of California (Oakland, CA)
• Patent Number(s): US 5596436
• OSTI ID: 870797
• Country of Publication: United States
• Language: English

Related Subjects

/359/
1550-nm
amplified
amplifier
band optical
bandwidth optical
baseband
carrier
channels
combined
combiner
compensate
complexity
concomitant
converts
data
data stream
detection
detector
digital
digital data
direct
direct detection
dispersion
edfa
edfas
electrical
electrical data
erbium-doped
expensive
external
fabry-perot
ffp
fiber
filter
frequencies
gigahertz
high-bandwidth
high-speed
high-speed data
impressed
independent
independently
laser
laser optical
lithium
lithium niobate
long-distance
long-haul
losses
microwave
microwave amplifier
microwave frequencies
microwave power
mixers
mode fiber
modulated
modulators
multiple
multiplexing
narrowband
narrowband optical
niobate
nm laser
optical
optical carrier
optical detector
optical fiber
optical filter
optical signal
optically
ordinary
paths
penalty
power
power combiner
pre-selected
principal
prior
produce
provides
receiver
receiving
reducing
reduction
requiring
scm
selected
separated
sidebands
signal
simultaneously
single-mode
single-mode fiber
solid-state
speed data
split
stream
streams
subcarrier
subcarriers
transmission
transmitted
transmitted optical
traverse
upconverted
wave frequencies