Tag Archives: Optical Fiber

Super Fast: Teams Develop Optical Fiber Cables That Carry Data Faster Than 100 Terabits A Second

Now that’s fast. Two independent groups have developed fiber optic cables capable to transferring data at an incredible rate of 100 Terabits per second. This unbelievable speed is far greater than anything available today.

Just to give an idea of what 100 Terabits (or about 12 Terabytes) per second means, take this example. An HD movie with a running time of about 2 hours has a size of about (or less than) 4 Gigabytes (GB). 1 Terabyte (or TB) equals roughly 1000 GB. Thus, you could download 250 HD movies, each running for 2 hours, in one second!! That’s a running time of 500 hours, there being 720 hours in one month! Even if you watched 5 of these movies a day (an unrealistic rate, by any estimate), you could go on like that for 50 days after just 1 second of download.

Even the busiest optical line in the world, that between Washington D.C. and New York, experiences a maximum speed of a few Terabits per second.

Optical cable


How they did it

The first team, from Japan’s NIICT, led by Jun Sakaguchi, adopted a simple strategy. They developed an optical fiber having seven optical cores, completely insulated from one another. Each of these could carry 15.6 TBits/s. The information would then be read and processed at the end of the communication line. The total speed thus achieved was 109.2 TBits/s.

The second team, from NEC Global’s R&D, led by Dayou Quan, took a more complicated route. They fed in packets of information from 370 lasers (as light pulses) into a single optical fiber core. The lasers each had different positions in the Infrared Spectrum, as well as different polarizations, amplitudes and, importantly, phases. This ensures that the signals don’t interfere with each other. Using this technique, the team transferred data across 165 kilometers (!) at a speed of 101.7 Tbits/s.

New World?

The path is being paved for a world which craves for more data and information. Even then, 100 Tbits/s is more than anyone asked for or needs. Is this the beginning of a world where all forms of entertainment come in 3-D?

Quantum Breakthrough: Matter Guided through Optical Guides, Just Like Light Through Optical Fibers

It’s atoms now, and not only light. Researchers at ARC Center of Excellence for Quantum Atom Optics, Research School of Physics, ANU, have successfully guided supercooled Helium atoms through an optical guide made of a laser beam. This is the first ever successful at guiding matter waves.

Speckles, Modes and the Rest of the Basics:

When light is guided in an optical fiber, there can be many modes of transmission. These modes interfere and produce a speckle pattern’ on the screen after emerging from the fiber. The light can be adjusted so as to eliminate the speckle, which indicates that the light is in a single mode, or technically, coherent’. Scientists say that the light has the same phase factor’ throughout, which doesn’t vary with time.

Laser Speckle
Laser Speckle, the indication of multiple modes

There are many other coherent substances that can be made. One of them is known as the Bose-Einstein Condensate (BEC). During the 1920’s, Satyendranath Bose and Albert Einstein worked out the statistics of bosons and showed that, if cooled enough, they can be made to fall into a single giant ground state. In this state, any addition to the number density of the particles makes more particles fall into the ground state. This is, thus, called a Condensate’, appropriately named, Bose-Einstein Condensate’.

Bose Einstein Condensate
Bose-Einstein Condensate (The peaks indicate the number density of atoms in the ground state. Note how it rises with fall in temperature) (nK=nanoKelvin) (Courtesy: Colorado University)

BEC is a remarkable state of matter. Thousands of bosons (for example, Helium atoms) can condense and behave like a single super-atom. BEC physics is one of the richest and the present interest is primarily because BEC physics mimics that of superconductors.

The guiding of matter waves

What the team of researchers has achieved is this: They took a bunch of atoms and trapped them. Then,  they irradiated this with laser light pointing downwards towards gravity. This produced a speckled pattern.

As Ken Baldwin, one of the team members, reports

We have shown that when atoms in a vacuum chamber are guided inside a laser light beam, they too can create a speckle pattern – an image of which we have captured for the first time.

The BEC guide
The schematic for the BEC guide used by the researchers. (Courtesy: Nature)

The atoms were cooled to lower and lower temperatures, until the atoms formed the BEC. Since the BEC is a coherent state, with the lowering of the intensity of the laser light, the speckled pattern suddenly disappeared.

Team leader, Dr. Andrew Truscott, reported that:

The atoms … behaved more like waves than particles, forming a Bose-Einstein condensate (BEC).   When the BEC was loaded into the guide, the speckle pattern disappeared, showing that just one mode was being transmitted the single quantum wave.

Looking at the images and by measuring the arrival times of the atoms on the Multi-Channel Plate (MCP), the researchers could differentiate between a speckled, multi-mode transmission and a smooth, single-mode transmission.


Earlier it was only light that could be guided in a wave guide (here, the optical fiber). No longer is that true. This breakthrough demonstrates that it is possible to guide atoms in a BEC state in an optical guide (not glass). This will allow higher precision atom-interferometers.