Terabit/second-transmission demonstrations make a splash at OFC 96

Terabit/second-transmission demonstrations make a splash at OFC `96

Two groups of researchers reported terabit-per-second data transmission at the recent Optical Fiber Communication conference (San Jose, CA). In a wavelength-division multiplexing experiment, H. Onaka and colleagues at Fujitsu Laboratories Ltd. (Kawasaki, Japan) used 46 distributed-feedback diode lasers and nine external-cavity tunable diode lasers to send data through 150 km of single-mode fiber over 55 channels with wavelengths ranging from 1531.70 to 1564.07 nm. External signal modulation by a lithium niobate (LiNbO3) Mach-Zehnder modulator at 20 Gbit/s yielded a total transmission rate of 1.1 Tbit/s. Erbium-doped fiber amplifiers were used for the transmitter postamplifier, for the receiver preampli fier, and for in-line repeaters spaced every 50 km along the single-mode fiber. Dispersion- compensating fiber incorporated in the in-line repeaters and the preamplifier yielded dispersion-flat fiber without four-wave mixing.

A system combining polarization multiplexing with wavelength-division multiplexing transmitted data through 55 km of nonzero-dispersion fiber at 1 Tbit/s. AT&T Research (Holmdel, NJ) scientist Alan Gnauck and collaborators at Lucent Technologies (Holmdel, NJ) multiplexed the outputs of 25 lasers using star couplers and waveguide-grating routers; wavelengths ranged from 1542 to 1561.2 nm. Polarization controllers and a polarizing beamsplitter (PBS) aligned the polarizations of the 25 lasers. The combined output on each of the 25 channels was split by a 3-dB coupler, and each branch was separately modulated at 20 Gbit/s by a LiNbO3 Mach-Zehnder device. The two orthogonal polarizations for each channel were then recombined by a PBS for a total of 50 independent data channels. After transmission, the signals were polarization demultiplexed prior to wavelength demultiplexing.