ode a semiconductor device that emits incoherent optical radiation in the form of electromagnetic waves when biased in the forward direction. lighted fiber fiber illuminated and in use. lit fiber a fiber strand in use. material dispersion the non-linear relationship between frequency and the index of refraction in the core of a fiber that broadens an optical pulse. media interface connector a connector used to connect multimode fiber to an FDDI station. microwaves waves shorter than radio waves but longer than infrared. modal dispersion the spreading of light pulses. mode field diameter a measure of the intensity of light traveling within a fiber. modified chemical vapor deposit the deposit of chemical vapor or gas during the fabrication of an optical fiber. Glossary multimode fiber fiber with a relatively large core, which allows mul- tiple rays of light to simultaneously propagate through the fiber. Newton's prism a prism used by Isaac Newton to analyze the colors of light. non-return-to-zero a transmission scheme by which 0 is coded as a 0 signal level and 1 as a plus pulse numerical aperture the square root of the difference between the square of the core of a fiber and the square of its cladding. Nyquist relationship the relationship between bandwidth (W) and the signaling rate (B) such that B =2W. optical mode converter a converter that converts single-mode fiber to optical mode fiber and vice versa. optical window a wavelength or group of wavelengths. peering point location where two or more Internet Service Providers interconnect. period the time required for a signal to be transmitted over a distance of one wavelength. photodetector a device that detects light and generates an electric current. photoelectric effect the transfer of light energy to an electron when a metal placed in a vacuum has light focused. photon a Greek word meaning light. photophone a device invented by Alexander Graham Bell that used a membrane to modulate an optical signal. plastic-clad silica an optical cable manufactured using a 