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Fiber Optic Cable: Sending Data on a Beam of Light

From Moon cameras to ‘bend insensitive,’ fiber optics light the way

The National Aeronautics and Space Administration used fiber optics in the television cameras it sent to the Moon. The technology was considered so groundbreaking that it was classified “confidential,” so only those who had the correct security clearance were permitted to handle the cameras.

Communications Specialties Fiberlink Matrix. Photo courtesy of Communications Specialties by Art Kingdom

Now hundreds of millions of miles of fiber optic cable and thousands of pieces of equipment later, fiber optic cable is used around the world in an ever-growing list of applications. The reason being, light has an information carrying capacity 10,000 times that of the highest radio frequency being used, which means that one fiber not only carries more information than thousands of wires, it carries data further.


Guiding light by refraction is a fairly simple and old technology, and was first demonstrated in Paris during the 1840s. By 1880 Alexander Graham Bell invented the “Photophone” to transmit voice signals over an optical beam. Bell patented the process, but it never left the laboratory because he could not find a way to protect the beam from being disrupted.

In the early 1950s, research was conducted that led to the invention of optical fiber, and in 1963, a Japanese scientist proposed that optical fibers could be used for communications. However, the quality of the fiber was such that the loss of light over a relatively short distance was hindering further advances in communications. In 1970, Corning developed the purest glass ever made, and by 1981 General Electric fused quartz ingots and produced fiber optic strands 25 miles long. Fiber optic telecommunications was on its way.

An optical fiber is thin, flexible, and transparent and acts as a waveguide or “light pipe,” and typically consists of a transparent core surrounded by a transparent cladding material with a lower index of refraction, so the signal stays in the core.


MultiDyne DVI-6000. Photo courtesy of MultiDyne In addition, optic fiber is completely immune to interference, including lightning, and it does not conduct electricity; which means it can come in direct contact with high-voltage electrical equipment or power lines. In addition, because it is made of glass, fiber optic will not corrode and is unaffected by most chemicals. Therefore, it can be buried directly in most types of soil, or exposed to most corrosive atmospheres in chemical plants.

Since it transmits light, there is no spark from a broken fiber, so there is no fire hazard and no danger of electrical shock to personnel repairing those cables. Fiber optics can also be lashed to telephone poles or existing electrical cables without concern for signal pickup.

DOW-KEY 7001

The Dow-Key model 7001 is based on “micro electro-mechanical systems” (MEMS) technology. That type of switch has an optical input, an optical cross-point and an optical output, and MEMS employs electronically-controlled mirrors to route the optical signals. The silicon mirrors are positioned and controlled with electrostatic charges.

The 7001 switches signals in the pure optical domain with an operating wavelength of 1530-1565 nm in C-band and a data rate of 4 Gbps. The system is configured partially as crossbar and partially as fan-out, with 8×14 I/O ports using LC connectors. On the control side, the unit is equipped locally with a windows based touch screen and with a modern “graphical user interface” (GUI) on the front panel that allows the user to graphically set the desired paths.


Communications Specialties’ Fiberlink Matrix signal router is a fully configurable and Society of Motion Picture & Television Engineers (SMPTE) compliant 32×32 optical router. The inputs and outputs can be ordered in quantities of one and they do not have to match, providing the ability to build a matrix that is ideal for specific applications and budgets.

Available with “Lucent connectors” or “straight tip” connectors, the Fiberlink matrix is compliant with SMPTE standard 297-2006, and supports up to 3G-serial digital interface (SDI) data rates, and works with both single mode and multimode fiber. It features redundant power supplies for operational dependability. The entire enclosure is only three rack units (RU) high.


MultiDyne offers its DVI-6000 to government system planners looking for an optical router to replace copper routing switches. Single wavelength and single-fiber operation make it attractive for working with optical routers. Its ability to handle any combination of multimode and single-mode fibers is an important feature.

The DVI-6000 handles DVI, RGB-HV (UXGA), and component video with resolutions up to 1920 x 1200. It converts RGB-HV IN to DVI signals out of the receiver or into it. It also handles audio and HD-SDI. The unit utilizes full bandwidth signal processing (no compression or dropped data), which is considered critical for “secure content,” and the DVI-6000 is expandable.


In a first for the audio/video industry, Extron is offering fiber optic cable that is “bendinsensitive” which will make difficult installations easier. The fiber is offered in OM4 single and multimode versions. It is part of Extron’s recently introduced line of pre-terminated or bulk fibers, cable termination tools, field installable connectors and test equipment.

The fiber optic field is mature and dynamic. Many who installed fiber optic cables early on are updating their systems, while on the other end of the spectrum there are those still contemplating a transition from copper to fiber.