Thomas Boehm
NT1310 Physical Networking
Gary L
Week 9 Activity
Light Sources and Components – Definitions

1. Forward Biased LED- When the LED is forward biased (a positive voltage is applied to the p region and a negative voltage to the n region), current flows through the LED. 2. Incoherent Light- Photons emitted from the junction where the p and n regions meet are not in phase, nor are they launched in the same direction. These are out of phase photons 3. Laser- Acronym for light amplification by stimulated emission of radiation. It produces a coherent source of light with a narrow beam and a narrow spectral bandwidth. Used to provide the high-powered, tightly controlled light wavelengths necessary for high-speed, long-distance optical fiber transmissions. 4. Output Pattern- The output pattern or NA of the light source directly relates to the energy coupled into the core of the optical fiber. The output pattern of a laser light source is very narrow, allowing a majority of the light energy to be coupled into the core of a single-mode or multimode optical fiber. 5. Output Power- Optical output power levels are normally expressed as the amount of light coupled into a one meter optical fiber. Laser output power varies depending on the application. 6. Modulation Speed- Light Emitting Transistors are responsible for the modulation speed. Modulation speed of 4.3 gigahertz was reached in 2009. 7. Core Diameter Mismatch- When 2 different cores are 2 different circumferences. 8. Current- The flow of electrons in a conductor. 9. PIN Photodiode- works like a PN photodiode; however, it is manufactured to offer better performance. The better performance comes in the form of improved efficiency and greater speed. 10. Avalanche Photodiode- With the APD, a small bundle of photons can trigger an avalanche of electrons. The APD accomplishes this through a process called photo multiplication. Is constructed with one more P region. 11. Responsivity- The responsivity of the photodiode describes how well the photodiode converts a wavelength or a range of wavelengths of optical energy into electrical current. It’s the ratio of the photodiode electrical output current to its optical input power. 12. Optical Subassembly- A typical LED transmitter contains an electrical subassembly, optical subassembly, and receptacle, The electrical subassembly amplifies the electrical input signal with the driver integrated circuit (IC). The driver IC provides the current to drive the LED in the optical subassembly. The optical subassembly mates with the receptacle to direct light into the optical fiber. 13. Dynamic Range- Is measured in decibels. It is the difference between the maximum and minimum optical input power that the receiver can accept. 14. Operating Wavelength- Fiber-optic receivers are designed to operate within a range of wavelengths. This is because the transmitters operate within a certain wavelength. If these 2 do not line up it may not perform well or at all. 15. Fiber-Optic Coupler- A device that combines or splits optical signals. 16. Opto-mechanical Switch- An optical switch with one or more input ports and two or more output ports. 17. Optical Attenuator- Is a passive device that is used to reduce the power level of an optical signal. Hence the word attenuator. 18. Optical Isolator- Reduces the effects of interference. 19. Wavelength Division Multiplexing- Wavelength division multiplexing (WDM) is the combining of different optical wavelengths from two or more optical fibers into just one optical fiber. 20. Passive Optical Network- A telecommunications technology that implements a point-to-multipoint architecture, in which unpowered Fiber Optic Splitters are used to enable a single optical fiber to serve multiple end-points such as customers, without having to provision individual fibers between the hub and customer. 21. FTTH- Fiber to the Home 22. FTTB- Fiber to the Building- central office to the building. 23. FTTC- Fiber to the Curb- central office to the curb. 24. FTTN- Fiber to the Node - central office to the node. 25. Feeder Cable- Cable running from a central office to a remote terminal, hub, head end, or node. 26. Distribution Cable- An optical fiber cable used “behind-the-shelf” of optical fiber patch panels; typically composed of 900 micron tight buffered optical fibers supported by aramid and/or glass-reinforced plastic (GRP). 27. Drop Point- Point where you drop the cables 28. Local Convergence Point- The access point where the feeder cables are broken out into multiple distribution cables. 29. Network Access Point- The network access point (NAP) is located close to the homes or buildings it services. This is the point where a distribution cable is broken out into multiple drop cables. 30. Network Interface Device- The NID is typically mounted to the outside of the house or building. It is an all-plastic enclosure designed to house the electronics that support the network.

References
Oliviero, A., & Woodward, B. (2009). Cabling: The complete guide to copper and fiber-optic networking. Indianapolis, IN: Wiley Pub.
https://en.wikipedia.org/