The upper limits on fiber capacity haven't been reached just yet. Two announcements made around an optical-fiber conference and trade show in San Diego recently indicate continued progress in squeezing more data into fiber.\nIn the first announcement, researchers say they\u2019ve obtained 26.2 terabits per second over the roughly 4,000 mile-long trans-Atlantic MAREA cable, in an experiment; and in the second, networking company Ciena says it will start deliveries of an 800 gigabit-per-second, single wavelength light throughput system in Q3 2019.\nHigh-speed laser\nMAREA, translated as \u201ctide\u201d in Spanish, is the Telef\u00f3nica-operated cable running between Virginia Beach, Va., and Bilbao in Spain. The fiber cable, initiated a year ago, is designed to handle 160 terabits of data per second through its eight 20-terabit pairs. Each one of those pairs is thus big enough to carry 4 million high-definition videos at the same time, network-provider Infinera explains in an Optical Fiber Conference and Exhibition published press release.\nInfinera researchers claim, though, that using, for the first time on a cable like this, an own-built variant of high-speed laser modulation, called PM-16QAM, it has squeezed 26.2 terabits through a pair over the length of the cable. That\u2019s a 20% gain over the design specification.\n\u201cThe method could increase network capacity without requiring new cables, which can cost hundreds of millions of dollars to build,\u201d Infinera says.\nMore than half of the world\u2019s population is now online, and that number is still dramatically growing in some regions such as Africa. There\u2019s been a tenfold increase in 13 years there, according to the UN\u2019s ITU. Data centers, too, are requiring increasing bandwidth. Microsoft and Facebook are MAREA owners.\nAny capacity gain now in fiber is good, explains Dr. Pierre Mertz, one of the engineers. That\u2019s because fiber capacity (data per second) might be reaching its limits. \u201cIn simple terms, if you try to push the limits of fiber capacity, you will reduce the reach,\u201d he says.\nThat\u2019s because noise contamination, and consequently efficiency, deteriorates the longer the pipe. It\u2019s an effect called Shannon\u2019s Limit (Wikipedia), named after the scientist who discovered the scattering communications theorem in 1948.\nCoherent optics\nIn the second San Diego announcement, a faster system is being introduced. \u201cWaveLogic 5 solutions will begin to become available in the second half of 2019,\u201d says Ciena in a press release announcing an 800-gigabit fiber solution geared, in part, toward data center connects that can now be using 100 or 200 gigabits or less. It uses the latest coherent optical transmission \u2014 an attempt to ramp up fiber for more capacity.\nCoherent optics translate traditional digital signals in fiber through modulation. \u201cIt takes the typical ones and zeroes in a digital signal \u2014 the blinking on and off of the light in the fiber \u2014 and uses sophisticated technology to modulate the amplitude and phase of that light, and send the signal across each of two polarizations,\u201d explains Ciena on its website. That encodes more data into the light waves.\nThe race is on to try beat Shannon\u2019s noise law. I wrote recently about an attempt to use even the noise itself to carry information. And last year I wrote about experiments elaborately twisting light in cables in order to carry more information.\n\u201cNetwork capacities are increasing by 25% to 50% every year, and systems running at 10 gigabits per second just cannot keep up with this kind of rapid scalability,\u201d Ciena says.\n\u201cEvery gain we make becomes harder and harder,\u201d Mertz, of Infinera, said.