In the April 1996 issue of Fiber Optic Product news, there is an article on a Lucent Technologies (formerly Bell Labs...no relation...sigh...) product which wavelength-multiplexes quantity 8, 2.5 Gb/second signals on a single fiber, for a total of 20 Gb/sec. This is a real, purchaseable system. On the same page is a somewhat more experimental system, done by Corning and Siemens, in which eight channels at 10 Gb/sec each were transmitted on a single Corning fiber. "Wow", I said. Far faster than the 2.5 Gb/sec transmission that is currently fairly standard for long-haul fiber trunks. I wasn't prepared, however, for page 38, in an article titled "Research Teams Achieve 1 Trillion bits a Second." In fact, three separate groups did this. I copy the article below. CP relevance? Well, the justification the government uses to regulate the airwaves, via the FCC, is that the available bandwidth is limited, which it is. But that argument has never been true with fiber, at least in theory, and is becoming even less true in practice. For example, that recent flap over Internet-based long-distance telephone interconnects (LD companies don't want competition) is based on the fact that the normal providers of these services want to get their dime a minute rates come hell or high water. Sure, that's a might cheaper than it was a decade ago. But with fiber transmission probably less than 1/100th the cost of older coaxial transmission systems, per connection, it is unclear why they're even continuing to meter LD phone calls. Even if we only consider that 20 Gb/second fiber from Lucent, that is equivalent to about 300,000 simultaneous voice calls. With a standard, 36-fiber cable, that represents 18x300,000 two-way calls, or about 4.8 million calls. This is probably far greater than the maximum number of people on LD in the US at any given time, and that's just a single cable trunk. If we assume that the fiber cable costs $1/meter per fiber, and the cost of trenching, burial, and interconnects raise this to $10/meter/fiber, and if we generously assume that the average LD call goes 3000 miles (5,000,000m), that call occupies 1/150,000th of a $50 million fiber for a few minutes. If we suppose that the fiber has to gross $100,000,000 per year to pay for itself, and even if it's only operating at an average 10% load level(both assumptions are pessimistic, that only works out to a cost of 1.3 cents per minute per call. That's why these LD phone companies are so scared: If we can transmit Internet on fiber, that fiber can accept this extra traffic at very low marginal cost. Part of article follows: "Research teams Achieve 1 Trillion bits a second" Debra Norman, Editor in Chief. Three research teams achieved their ultimate goal by sending the most information possible over optical fiber. The scientists, including a 12-member group from AT&T Research, Bell Laboratories, Lucent Technologies, reported in post-deadline papers at the Optical Fiber Conference held recently in San Jose, Calif., that they had sent one terabit of information over non-zero-dispersion fiber in a second's time. In short, it is similar to transmitting the contents of 1,000 copies of a 30-volume encyclopedia in one second. The researchers had not expected to send that much data until at least the year 2000. In the paper, the group described a 1 Tb/s transmission experiment that utilized WDM [wavelength division multiplexing] and polarization multiplexing. The outputs of 25 lasers were multiplexed using star couplers and waveguide grating routers. The wavelengths ranged from 1542 nm (channel 1) to 1561.2 nm (channel 25) with 100 GHz channel spacing. All lasers were external-cavity lasers except for channel 16, which used a DFB laser. Four of the laser outputs (channels 10,11,17, and 25) were amplified and filtered before multiplexing. The multiplexed wavelengths were then amplified and propagatedthrough an polarization beamsplitter to align al the polarizations. Polarization controllers at the output of each laser allowed independent polarization control for each source. The 25 co-polarized wavelengths were split by a 3-dB coupler, separatedly modulated by LiNbO3 Mach-Zehnder modulators, and then recombined with orthogonal polarizations in a PBS. The modulators have a small-signal bandwidth of 18 GHz and built-in polarizers. The 20 Gb/s NRZ drive signals were produced by electronically multiplexing two 10-Gb/s 215-1 pseudorandom bit streams using a commercial GaAs multiplexer. Two other groups from Japan, Fujitsu and Nippon Telephone and Telegraph Co., also submitted papers reporting that they reached the terabit mark. All three groups achieved the record with different experiments. Scientists from NTT demonstrated 100 Gb/s x 10 channel (1 Tb/s), error-free transmission of all the 10 channels over a 40 km dispersion-shifted fiber using a low-noise single supercontinuum WDM source fitted with a newly developed arrayed-waveguide grating demultiplexer/multiplexer. By fully utilizing the super-broad bandwidth of the SC spectra over 200 nm, up to 5 Tb/s would be possible. Fujitsu researchers achieved 1.1 Tb/s (55 wavelengths x 20 Gb/s) WDM transmission over 150 km of 1.3 mm [?] zero-dispersion singlemode fiber using preemphasis and dispersion compensating fiber with a negative dispersion slope. BER [bit error rate] degradation was not observed in any channel, even without channel-by-channel dispersion adjustment. [end of quoted portion] Jim Bell jimbell@pacifier.com