The field of fiber optics is rife with specialized terms and acronyms, each crucial to understanding the technology, its functionality, and its various applications. This article will explain the top 100 most commonly used fiber optic terms and acronyms, offering a foundational understanding of the subject.
1. Optical Fiber: An optical fiber is a thin, flexible medium capable of transmitting light between the two ends of the fiber. Made from high-quality glass, silica, or plastic, it serves as the backbone of the internet and telecommunication infrastructure.
2. Fiber Optics: This term refers to the technology and the medium involved in transmitting information as pulses of light through optical fibers.
3. Bandwidth: The capacity of a network to transmit data, usually measured in bits per second (bps). Higher bandwidths allow more data to be sent in a given amount of time.
4. Cladding: The layer of material that surrounds the core of an optical fiber. Its purpose is to trap light within the core, enabling data to travel long distances.
5. Core: The inner part of the optical fiber where light travels. The diameter of the core determines the fiber’s capability – single mode or multimode.
6. Single Mode Fiber (SMF): A type of fiber optic cable with a small core (usually 9 micrometers in diameter) that allows only one mode (path) of light to travel. This type of fiber is typically used for long-distance transmissions.
7. Multimode Fiber (MMF): A type of fiber optic cable with a larger core (50 or 62.5 micrometers) that allows multiple modes of light to travel. It’s used for short-distance transmissions, such as within a building.
8. Attenuation: The reduction in power density (attenuation) of a light signal as it travels through the fiber, often measured in decibels per kilometer (dB/km).
9. Decibel (dB): A unit of measurement for the intensity of sound or power level of an electrical signal by comparing it with a given level on a logarithmic scale.
10. Refractive Index: A measure of how much light slows down (and thus is bent) when entering a material.
11. Total Internal Reflection (TIR): A phenomenon occurring when a propagated wave strikes a medium boundary at an angle larger than the critical angle with respect to the normal to the surface. In fiber optics, it is the principle that allows light signals to be transmitted through fiber cables.
12. Numerical Aperture (NA): A measure of the light gathering ability of optical fiber. It depends on the refractive index of both core and cladding.
13. Wavelength: The distance between successive crests of a wave, especially points in a sound wave or electromagnetic wave. Fiber optic systems typically use light in the infrared region, which has longer wavelengths than visible light.
14. Chromatic Dispersion: A phenomenon in which different colors (wavelengths) of light travel at different speeds through an optical fiber, causing the light pulse to spread over distance and potentially limiting the distance and speed at which data can be transmitted.
15. Polarization Mode Dispersion (PMD): A type of signal distortion that occurs in single-mode fibers, causing different polarization modes of light to travel at different speeds.
16. Scattering: A general physical process where some forms of radiation, such as light, are forced to deviate from a straight trajectory by one or more localized non-uniformities in the medium through which they pass.
17. Rayleigh Scattering: The scattering of light or other electromagnetic radiation by particles much smaller than the wavelength of the radiation. In fiber optics, this scattering can cause signal loss.
18. Optical Time Domain Reflectometer (OTDR): A device used to measure the characteristics of an optical fiber, including length, loss characteristics, and fault detection.
19. Optical Network Terminal (ONT): A device that converts optical signals transmitted via fiber to electrical signals that can be used by devices in a home or business.
20. Fiber to the Home (FTTH): A broadband network architecture that uses optical fiber to provide all or part of the last mile telecommunications connectivity to the home.
21. Fiber to the Premises (FTTP): This is similar to FTTH but is a term that can include both homes and businesses.
22. Dense Wavelength Division Multiplexing (DWDM): A technology that puts multiple signals on different wavelengths, all onto one fiber. This increases the total capacity that a single fiber can carry.
23. Passive Optical Network (PON): A telecommunications network that uses point-to-multipoint fiber to the premises, in which unpowered fiber optic splitters are used to enable a single optical fiber to serve multiple premises.
24. Synchronous Optical Networking (SONET) / Synchronous Digital Hierarchy (SDH): Standards for transferring digital information over fiber optic cables that can transport large amounts of data over long distances.
25. Ethernet: A standard communications protocol embedded in software and hardware devices, intended for building a local area network (LAN).
26. Dark Fiber: Optical fiber infrastructure (cabling and repeaters) that is currently in place but is not being used.
27. Fiber Optic Connector: A detachable, flexible device for connecting fiber optic cables. Examples include LC, SC, ST, FC connectors.
28. Splice: A permanent joint between two fibers. Splicing can be done by fusion (melting together) or using mechanical splices.
29. Optical Amplifier: A device used to amplify an optical signal directly, without the need to convert it to an electrical signal first.
30. Erbium Doped Fiber Amplifier (EDFA): A type of optical amplifier that uses a short length of optical fiber doped with erbium ions to boost a signal.
31. Return Loss: The loss of signal power resulting from the reflection caused at a splice, connector, or a discontinuity in the fiber.
32. Fusion Splicer: A device that uses heat to fuse or weld two fiber ends together to form a single long fiber. The aim is to fuse the fibers together in such a way that light passing through the fibers is not scattered or reflected back by the splice.
33. Wavelength-division multiplexing (WDM): A technology which multiplexes a number of optical carrier signals onto a single optical fiber by using different wavelengths (i.e., colors) of laser light.
34. Course Wavelength Division Multiplexing (CWDM): A type of WDM that uses wider channel spacing to allow less precise and thus cheaper transceiver designs.
35. Optical Add-Drop Multiplexer (OADM): A device used in WDM systems for multiplexing and routing different channels of light into or out of a single mode fiber (SMF).
36. Light Amplification by Stimulated Emission of Radiation (LASER): A device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. Lasers can produce coherent light, useful in various applications, including fiber optic communications.
37. Light Emitting Diode (LED): A semiconductor light source that emits light when current flows through it. LEDs are used in short to medium-range fiber optic transmission systems.
38. Optical Power Meter (OPM): A device used to measure the power level of an optical signal.
39. Optical Spectrum Analyzer (OSA): An instrument used to measure the power and wavelength of optical signals.
40. Bit Error Rate (BER): The number of bit errors divided by the total number of transferred bits during a studied time interval. BER is a key parameter that quantifies the quality of a digital transmission system.
41. Transmitter: An electronic device that produces radio waves with an antenna. In the context of fiber optics, the term is used to refer to the device converting electrical signal to optical signal.
42. Receiver: A device that converts incoming optical signals back to electrical signals.
43. Optical Isolator: An optical component which allows the transmission of light in only one direction.
44. Patch Panel: An array of ports on a fiber optic equipment rack where the cable connections are made.
45. Network Interface Device (NID): A device serving as the demarcation point between the carrier’s local loop and the customer’s on-premises wiring.
46. Optical Splitter: A device that splits the light signal into two or more outputs.
47. Fiber Optic Adapter: A device used to connect two fiber optic connectors.
48. Fiber Distributed Data Interface (FDDI): A standard for transmitting data on optical fiber cables at a rate of around 100,000,000 bit/s (100 Mbps).
49. Gigabit Ethernet (GbE): A term referring to various technologies for transmitting Ethernet frames at a rate of a gigabit per second, as defined by the IEEE 802.3-2008 standard.
50. 10 Gigabit Ethernet (10 GbE): A version of Ethernet with a nominal data rate of 10 Gbit/s, ten times as fast as Gigabit Ethernet.
51. Fiber to the Curb (FTTC): A telecommunications system based on fiber-optic cables run to a platform that serves several customers. Each of these customers has a connection to this platform via coaxial cable or twisted pair.
52. Fiber to the Node (FTTN): A telecommunication infrastructure in which the last mile of fiber optic cable is replaced by coaxial cable or twisted pair to reduce the costs of having an entirely optical network.
53. Bi-Directional (BiDi) Transceiver: A type of transceiver that uses WDM to transmit and receive data over a single fiber.
54. Optical Return Loss (ORL): The total sum of power reflections seen looking into a fiber from a reference point.
55. Polarization Maintaining Fiber (PMF): A type of single-mode fiber that maintains the polarization of light launched into it.
56. Field-Programmable Gate Array (FPGA): An integrated circuit that can be customized for a particular task by a designer after manufacturing.
57. Avalanche Photodiode (APD): A highly sensitive semiconductor electronic device that exploits the photoelectric effect to convert light into electricity.
58. Vertical-Cavity Surface-Emitting Laser (VCSEL): A type of semiconductor laser diode with laser beam emission perpendicular to the top surface, contrary to conventional edge-emitting semiconductor lasers (also in-plane lasers) which emit from surfaces formed by cleaving the individual chip out of a wafer.
59. Photodetector: A device that converts light into an electrical signal.
60. Raman Amplifier: A type of optical amplifier that uses Raman scattering to amplify an optical signal.
61. Integrated Services Digital Network (ISDN): A set of communication standards for digital telephone connection and the transmission of voice and data over a digital line.
62. Mode Field Diameter (MFD): The distribution of the intensity across the mode field in a fiber, typically defined as the diameter at the point where the field has dropped to/e^-2 (about 13.5%) of its maximum value.
63. Cleanroom: A facility used for the production and research in which the concentration of airborne particles is controlled to specified limits.
64. Erbium: A chemical element (symbol Er) used in creating optical amplifiers.
65. Insertion Loss (IL): The loss of signal power resulting from the insertion of a device in a transmission line or optical fiber.
66. Optical-to-Electrical Converter (O/E): A device (also called a photoreceiver) that converts an optical signal into an electrical signal.
67. Optical Switch: A device that selectively switches optical signals from one channel to another.
68. Laser Diode (LD): A laser where the active medium is a semiconductor similar to that found in a light-emitting diode.
69. Fiber Bragg Grating (FBG): A type of reflector constructed in a short segment of optical fiber that reflects particular wavelengths of light and transmits all others.
70. Mechanical Splice: A junction of two or more optical fibers that are aligned and held in place by a self-contained assembly.
71. Optical Line Terminal (OLT): A device which serves as the service provider endpoint of a passive optical network.
72. Optical Network Unit (ONU): A device that transforms optical signals transmitted via fiber to electrical signals that can be used by devices in a home or business.
73. Mode-Field Diameter (MFD): A measurement of the distribution of the intensity across the mode field in a fiber.
74. Electro-Optic Modulator (EOM): An optical device in which a signal-controlled element exhibiting an electro-optic effect is used to modulate a beam of light.
75. Power Over Ethernet (PoE): A technology for wired Ethernet LANs (local area networks) that allows the electrical current, necessary for the operation of each device, to be carried by the data cables rather than by power cords.
76. Power Budget: The amount of power supplied to the system, minus the amount of power required by the system.
77. Time Division Multiplexing (TDM): A method of transmitting and receiving independent signals over a common signal path by means of synchronized switches at each end of the transmission line so that each signal appears on the line only a fraction of time in an alternating pattern.
78. Trans-impedance Amplifier (TIA): An amplifier that converts input current into output voltage.
79. Photo Diode (PD): A semiconductor device that converts light into an electrical current.
80. Optical Coupler: A device that connects three or more fiber ends, dividing one input between two or more outputs, or combining two or more inputs into one output.
81. Fiber Optic Modem (FOM): A modem that uses fiber optic cables to send and receive data.
82. Opto-isolator: A component that transfers electrical signals between two isolated circuits by using light.
83. Pulse Code Modulation (PCM): A method used to digitally represent analog signals.
84. Laser Safety Class: A system that classifies lasers into safety categories according to their potential to cause harm.
85. Wavelength Blocker (WB): A device that can block certain wavelengths while allowing others to pass.
86. Optical Add Drop Multiplexer (OADM): A device used in wavelength-division multiplexing systems for multiplexing and routing different channels of light into or out of a single mode fiber.
87. Reconfigurable Optical Add-Drop Multiplexer (ROADM): A type of optical add-drop multiplexer that adds the ability to remotely switch traffic from a wavelength-division multiplexing system at the wavelength layer.
88. Tunable Laser: A type of laser whose wavelength of operation can be altered and selected by the user.
89. Tunable Filter: An optical filter whose wavelength can be tuned (adjusted), typically by means of a control voltage.
90. Receiver Sensitivity: The minimum magnitude of input signal required to produce a specified output signal having a specified signal-to-noise ratio, or other specified criteria.
91. Fault Locator: A system or device used to locate faults (defects) in a network or cable.
92. Optical Modulator: A device which is used to modulate a beam of light. The beam may be carried over free space, or propagated through an optical waveguide.
93. Propagation Delay: The length of time taken for the quantity of interest to reach its destination.
94. Non-return to Zero (NRZ): A form of binary level digital signal modulation where the signal drops (returns) to zero between each bit.
95. Return to Zero (RZ): A line code used in telecommunications signals in which the signal drops (returns) to zero between each bit.
96. Pulse-Amplitude Modulation (PAM): A modulation technique in which the amplitude of the pulse varies in proportional to the instantaneous amplitude of the message signal.
97. Digital Subscriber Line (DSL): A technology for transmitting digital data over telephone lines.
98. Forward Error Correction (FEC): A system of error control for data transmission, where the sender adds redundant data to its messages, which allows the receiver to detect and correct errors.
99. Fabry-Perot (FP) Laser: A simple form of laser diode that uses direct feedback to generate the laser waveform.
100. Optical Circulator: A special fiber-optic component that can be used to separate optical power traveling in opposite directions in one single fiber.
With this knowledge, understanding, and navigating fiber optic communication and technology becomes more achievable. As the technology continues to advance, more terms will undoubtedly join this list, further expanding the fiber optics vocabulary.