e, ultrathin filaments of glass, we could use them as a revolutionary new communications pipeline. Thus began the move toward researching and developing optical technology. In 1970 came the developments that have allowed us to deploy large amounts of fiber. Corning Glassworks introduced the first development, broomsticking, a procedure for manufacturing ultrapure filaments of glass. Glass that has an inner core etched into it is melted at extremely high temperatures, and as the glass melts and drops down the tube, it begins to cool and form a strand. By the time it gets to the bottom of the tube, it is a fiber-optic thread. Being able to create the fiber cable itself solved half the equation. Because the fiber's diameter is minuscule (measured in micrometers, or microns, abbreviated u), the light source that pulses energy on this tiny fiber also has to be minuscule. In 1970, Bell Labs completed the equation by introducing the first laser diode small enough to fit through the eye of a needle. Characteristics of Fiber Optics Fiber optics operates in the visible light spectrum, in the range from 101 Hz to 1015 Hz. Wavelength is a measure of the width of the waves being transmitted. Dif- ferent fiber-optic materials are optimized for different wavelengths. The EIA/TIA standards currently support three wavelengths for fiber-optic transmission: 850, 1,300, and 1,550 nanometers (nm). Each of these bands is about 200 nm wide and offers about 25THz of capacity, which means there is a total of some 75THz of capacity on a fiber cable. The bandwidth of fiber is also determined by the number of wavelengths it can carry, as well as by the number of bits per second that each wavelength supports. (As discussed in Chapter 1, each year, wavelength division multiplexers are enabling us to derive twice as many wavelengths as the year before, and hence they enable us to exploit the underlying capacity of the fiber cables.) With fiber, today we can space repeaters about 500 miles (800 km) apart, but new developments continue to increa