Damia Wood
NT 1310 August 11, 2014
048 Cordova
Unit 9: Ex. 1: Light Sources and Components- Definitions

1. Forward Biased LED: A voltage applied to a circuit or device, esp a semiconductor device, in the direction that produces the larger current. 2. Incoherent Light: Electromagnetic radiant energy not all of the same phase, and possibly also consisting of various wavelengths. 3. Laser: A device that generates an intense beam of coherent monochromatic light (or other electromagnetic radiation) by stimulated emission of photons from excited atoms or molecules. Lasers are used in drilling and cutting, alignment and guidance, and in surgery; the optical properties are exploited in holography, reading bar codes, and in recording and playing compact discs. 4. Output Pattern: aka NA of light source directly relates to the energy coupled into the core of the optical fiber. 5. Output Power: Amount of power a component, circuit or system can deliver to a load. 6. Modulation Speed: In fiber optics, modulation is associated with the telecommunications and data transport of digital information signals and analog audio/video signals, in which the digital/analog signal(s) are transmitted within another sine wave form known as a "passband". Common references for analog include pulse-code modulation (PCM), amplitude modulation (AM) and frequency modulation (FM). Digital modulation technologies are accomplished by "keying" methods: Phase-shift keying (PSK), Frequency-shift keying (FSK), Amplitude-shift keying (ASK) and Quadrature-amplitude modulation (QAM). 7. Core Diameter Mismatch: The central part of an optical fiber that provides the transmission region for an optical signal. The core is manufactured of an optically pure glass of a high refractive index surrounded by a lower refractive index cladding. Optical cores can range in size from 4.5 micron (single-mode) to 1000 micron (multimode) with common sizes ranging from 9 micron single-mode to 50 and 62.5 micron multimode fibers. 8. Current: The time rate of flow of electric charge, in the direction that a positive moving charge would take and having magnitude equal to the quantity of charge per unit time: measured in amperes. 9. PIN Photodiode: A photodiode that contains a widely spaced near-intrinsic (I) semiconductor region, sandwiched in between a positively-doped (P) and negatively-doped (N) semiconductor regions. The intrinsic region develops electron energy, when the diode is forward biased, through "high-level injection" flooding its region with charge carriers from the P and N portions of the diode. 10. Avalanche Photodiode: 11. Responsivity: is the measurement with respect to ratio of the input to output gain within a detector. Responsivity in respect to a photodetector is usually linear as a function of incident power and is expressed in units of amperes or volts per watt. 12. Optical Subassembly: a structural assembly, as of electronic parts, forming part of a larger assembly. 13. Dynamic Range: the ratio of the largest to the smallest intensity of sound that can be reliably transmitted or reproduced by a particular sound system, measured in decibels. 14. Operating Wavelength: In a waveguide, such as closed waveguide, an optical fiber, or a slab dielectric waveguide in an optical integrated circuit, the wavelength that (a) the guide is capable of transmitting, i.e., is capable of supporting over useful distances. 15. Fiber-Optic Coupler: is a device used in optical fiber systems with one or more input fibers and one or several output fibers. Light entering an input fiber can appear at one or more outputs and its power distribution potentially depending on the wavelength and polarization. 16. Optomechanical Switch: produces different optical paths from two optical path sections out of a plurality of optical path sections that are oriented in different spatial directions. 17. Optical Attenuator: is a device used to reduce the power level of an optical signal, either in free space or in an optical fiber. The basic types of optical attenuators are fixed, step-wise variable, and continuously variable. 18. Optical Isolator: A passive optical component that is used block out or "isolate" reflected or unwanted light, such as noise between wavelengths. 19. Wavelength Division Multiplexing (WDM): The multiplexing (and de-multiplexing) of different wavelengths (channels) within a specific wavelength or wavelength windows, for the purpose of carrying many different signals over a single optical fiber. 20. Passive Optical Network: A synonymous term used for the original FTTx installations, consisting of no powered optical components between the central office and the customer. An all-optical network (AON) in the outside plant supplying broadband services from a Central Office (CO) or a cable TV head-end, using minimal distribution fiber feeding into splitters and supporting a wide customer base. 21. FTTH: The end-result of optical fiber being continuously installed to the individuals home. Fiber to the Home or FTTH as it became known, was the ultimate goal for many telephone company's bid for providing multiple services (voice, video and data) to the individual subscriber over optical fiber installed from the Central Office (CO) to the individual's home. Utilizing what the cable TV industry had for years in the form of optical splitters, the major telephone companies updated their fiber optic networks with a new type of Corning licensed SMF-28 (SMF-28E � the "E" stood for "extended") optical fiber that had eliminated the hydroxyl ion loss at the 1490 nanometer wavelength window, common to the older SMF 28 optical fiber that the telephone companies had been installing for years prior. In this way, the major phone companies could begin to offer three, "all-digital" services to the customer, and bring fiber all of the way to the outside of the individual's home. 22. FFTB: During the initial build-up of the "Fiber-to-the-"x" installations, Fiber to the Building was the name and acronym applied to the Fiber-to-the-whatever designator was designated meaning the "vertical" installation of optical fiber for the urban scenario. FTTB was used in urban "high-density" installations for both high-rise businesses and living scenarios, with a centrally located cabinet structure either in a vault under the street or in an equipment room located within the building. Splitters were installed in either and fiber was run to the individual customers in the building. The meaning of the term eventually evolved to include the campus area network scheme. 23. FTTC: Optical fiber installation to the individual customer. Included in the "Fiber to the x" build-ups in the early 2000s, Fiber to the Curb or FTTC was a common installation practice for analog-type installations such as the early forms of fiber to the home and the first multi-serviced cable TV installations, still distributing analog-type services. Fiber optic cable would be brought into a central portion of high density neighborhood and then terminated into a curbside cabinet, either on the ground, in the ground or on a pole and then converted back to coax or wire cable to the home. Sometimes these installations included optical splitters to further diversify the optical portion of the network before terminating the fiber in an individual neighborhood cabinet. 24. FTTN: The installation of optical fiber to a junction box (node) in a neighborhood that serves a few hundred customers within a radius of about a mile. The connections from the node to the customer premises often uses DSL over existing telephone wires or coaxial cable (DOCSIS) from the cable company. 25. Feeder Cable: A set of electric cables, usually individually insulated conductors with a high ampacity, used to remotely connect portable dimmer racks, power distribution racks, and the like, to the electrical supply. 26. Distribution Cable: in a CATV system, the transmission cable from the distribution amplifier to the drop cable. 27. Drop Point: The final leg of "distribution" in the physical plant of an installed communications network, consisting of trunk, feeder and "drop" cables. The drop cable is the final cable that physically connects the customer to the network. This cable usually contains a minimal number of transmission components (wire and/or fiber) to support a single customer or multiple customers (in a multiple housing/apartment/business) environment. 28. Local Convergence Point: serves as a point of flexibility and where splitters would be located in PON systems. 29. Network Access Point: was a public network exchange facility where Internet service providers (ISPs) connected with one another in peering arrangements. 30. Network Interface Device: is a device that serves as the demarcation point between the carrier's local loop and the customer's premises wiring.