Optical Communications, the Industry

HISTORICAL DEVELOPMENT

The use of light for transmission of information is far from novel. Paul Revere transmitted light signals to alert his troops from British invasion and Alexander Graham Bell was the first to transmit speech several hundred meters over a beam of light shortly after he invented the telephone in 1880. Very little came of it due to the lack of practical applications to support the concept. Further developments advancing the concept of transmission of visible light for telecommunication purposes were made in the 1940s by Bell Laboratories.

The term 'Fiber Optics' was coined in 1956 by N.S. Kapany. A.L. Schawlow and C.H. Townes of Bell Labs proposed plans for the first working Laser (an acronym for light amplification by the stimulated emission of radiation) in 1958.

The first experimental demonstration of Laser technology occurred in 1960. However, the potential for low-cost optical communication was not fully realized until 1962 with the demonstration of Laser operations in semiconductor devices.

Shortly after the Laser demonstration, Bell Labs initiated research on Laser wave guides and atmospheric Laser transmission. In the atmospheric transmission tests, severe losses resulted from fog and snow. Consequently, atmospheric optical transmission applications only seemed feasible in fair weather location and with links of 100-300 meters.

Beam wave guides were initially developed using lenses or mirror pairs spaced about 100 meters apart. The lens guides were enclosed in underground conduit (15 Cm in diameter) providing the first operations independent of the weather.

A gas lens was developed providing the capability to guide the Laser beams around curves a few hundred meters in radius, thus deviating from the straight line-of-sight installation requirements of glass-lens guides. All the transmission methods initially studied involved expensive installations that greatly limited their inclusion in real-life applications.

About this time, laboratories in several countries were researching alternative Laser-wave guiding techniques. A significant development in 1966 was the transmission of light through glass fiber (similar to the composition of today's fiber cables) at the Standard Telecommunications Laboratories in England by K.C. Kao and G.A. Hockham. Previously, fibers generally had losses in excess of 1000 dB/Km. Kao and Hockham estimated that by carefully controlling the purity of the glass, losses could be reduced to 20 dB/Km, a level considered attainable and quite suitable for communications.

Corning Glass produced the first 20dB/Km single mode fiber in 1970 and by 1972, losses were down to 4dB/Km in laboratory samples. Throughout the 1970s, research continued in many area of fiber optic communications. Semiconductor devices were developed specifically for fiber optics systems, the first being the Burrus LED, a high-radiance, small-area diode.

PRACTICAL APPLICATION

The initial impetus toward the commercial application of optical communication came from the telephone industry and the military. Both saw a highly efficient transmission medium in fiber optics. For the telephone companies, fiber optics offered longer distance and high-capacity transmission, particularly suited to digital transmission of data, video, and voice. The dielectric properties of fibers reduced electromagnetic-induced problems and the small size made efficient use of crowded conduits. As for the military, the fiber's light weight and security offered additional reasons for adopting fiber optics.

In 1976, a 2.5Km trunk carrying voice, data and video at 44.7Mb/s, was introduced by Western Electric Atlanta.

In 1977, a 2Km link operating at 20Mb/s was installed to connect a satellite ground station to a data processing center.

In 1980, Bell Systems announced its long haul fiber optic project, a link from Cambridge, Massachusetts to Washington D.C.

Since its successful implementation of the early 1980s, fiber optic communication has gained wide acceptance, as evidenced by the estimated millions of miles of fiber optic cable now in place.

The advantages of a fiber optic system over coaxial and twisted pair counterparts are numerous: high bandwidth in Terra Hz, RFI/EMI noise immunity, total electrical isolation, high transmission security, low cross talk, decrease in spark/fire hazard and lighting damage, lightweight, small in size, low budget attenuation transmission loss, no short circuit, wide temperature range, fewer amplifier repeaters, stable performance, low bit error rate, topology compatibility, decreasing cost and wide open, advanced and up-to-date technology.

The many advantages and continued advancement in sampling experience with fiber optics reveals that optical communication is anticipated to be the primary media of choice in the future.

Fiber optic site applications in the CCTV industry, including security surveillance networks, are infinite. A few examples are: airports, university and high school campuses, hospitals, municipal and metropolitan facilities, factory assembly product lines, chemical and nuclear power plants, hazard field plants, under water transmission, transatlantic voice communication, military night vision, ballistic missiles, desert navigation, robotic unman operations, and many high graphic workstations.

Optical technology has also proven itself as an essential partner to the CATV industry, with hundreds of TV channels being transmitted over one SM single fiber. And now with advanced multiplexing technology, more and more channels can be multiplexed over one single fiber, providing for separate channels for a variety of purposes including finance, banking, insurance, brokerage, medical, text file, consumer selling products by department store replacing catalogs, E-commerce data bases and video imaging.

The latest advancement in optical communication technology is digital video transmission. Opticomm's extensive product line offers new techniques to utilize digital transmission for a wide variety of video/audio/data protocols at very high bandwidth rate. For example, Opticomm's DigiBand^® line of products provide for the uncompressed digital transport of high-bandwidth digital video such as SDI and HDTV.