Subcarrier multiplexing with dispersion reduction and direct detection

Patent · Tue Jan 21 04:00:00 EST 1997

OSTI ID:426634

Sargis, P D; Haigh, R E; McCammon, K G

An SCM system is disclosed 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. 2 figs.

• Research Organization: University of California
• DOE Contract Number: W-7405-ENG-48
• Assignee: Univ. of California, Oakland, CA (United States)
• Patent Number(s): US 5,596,436/A/
• Application Number: PAN: 8-502,732
• OSTI ID: 426634
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
DATA TRANSMISSION
DESIGN
MICROWAVE EQUIPMENT
MULTIPLEXERS
OPTICAL FIBERS