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p-p


Abbreviation for peak-to-peak. The algebraic difference between extreme values of a varying quantity.

 


pA


Abbreviation for picoamp. One trillionth of an Amp or 10-12 Amps.

 


PABX


Abbreviation for private automatic branch exchange. See PBX.

 


Packet


In data communications, a sequence of binary digits, including data and control signals, that is transmitted and switched as a composite whole. The packet contains data, control signals, and possibly error control information, arranged in a specific format.

 




Packet Switching


The process of routing and transferring data by means of addressed packets so that a channel is occupied during the transmission of the packet only, and upon completion of the transmission the channel is made available for the transfer of other traffic.

 


PAL


Abbreviation for phase alternation by line. A composite color standard used in many parts of the world for TV broadcast. The phase alternation makes the signal relatively immune to certain distortions (compared to NTSC). Delivers 625 lines at 50 frames per second. PAL-plus is an enhanced-definition version.

 


Parity


A term used in binary communication systems to indicate whether a number of 1’s in a transmission is even or odd. If the number of 1’s is even, the parity is said to be even; if the number of 1’s is odd, the parity is said to be odd.

Parity
 


Passband


The region of usable frequency in electronics or wavelength in optics.

 


Passive Branching Device


A device which divides an optical input into two or more optical outputs.

Passive Branching Device
 


Passive Device


Any device that does not require a source of energy for its operation. Examples include electrical resistors or capacitors, diodes, optical fiber (photo), cable, wires, glass, lenses, and filters.

Passive Device
 


Pathological Test Code


A special test pattern used with DTV and HDTV signals to create the longest strings of zeros and ones over the serial link. This requires the serial transport link to handle much lower frequency components than is typical in a normal data link.

 


Pay-Per-View (PPV)


An event that has an associated viewing cost, and which may be purchased separately from any package or subscription. The ordered events could include movies, special events, such as sporting, or adult programming. The event could be purchased by either impulse PPV by using a television remote (this application requires a continuous land line phone based connection), or over the phone PPV (this application may have additional costs for processing).

 


PBX


Abbreviation for private branch exchange. A subscriber-owned telecommunications exchange that usually includes access to public switched networks.

 


PC


Abbreviation for physical contact. Refers to an optical connector that allows the fiber ends to physically touch. Used to minimize backreflection and insertion loss.

 


PCB


Abbreviation for printed circuit board. Also referred to as PWB (printed writing board).

 


 


Peak Power Output


The output power averaged over that cycle of an electromagnetic wave having the maximum peak value that can occur under any combination of signals transmitted.

 


Peak Wavelength


In optical emitters, the spectral line having the greatest output power. Also called peak emission wavelength.

 


PFM


Abbreviation for pulse-frequency modulation. Also referred to as square wave FM.

 


Phase Constant


The imaginary part of the axial propagation constant for a particular mode, usually expressed in radians per unit length. See also attenuation.

 


Phase Noise


Rapid, short-term, random fluctuations in the phase of a wave caused by time-domain instabilities in an oscillator.

 


Phase-shift Keying (PSK)


1) In digital transmission, angle modulation in which the phase of the carrier discretely varies in relation, either to a reference phase or to the phase of the immediately preceding signal element, in accordance with data being transmitted. 2) In a communications system, the representation of characters, such as bits or quaternary digits, by a shift in the phase of an electromagnetic carrier wave with respect to a reference, by an amount corresponding to the symbol being encoded. Also called biphase modulation, phase-shift signaling.

 


Photoconductive


Losing an electrical charge on exposure to light.

 




Photodetector


An optoelectronic transducer such as a PIN photodiode (illustrated) or avalanche photodiode. In the case of the PIN diode, it is so named because it is constructed from materials layered by their positive, intrinsic, and negative electron regions.

Photodetector
 


Photodiode (PD)


A semiconductor device that converts light to electrical current.

 


Photon


A quantum of electromagnetic energy. A particle of light.

 


Photonic


A term coined for devices that work using photons, analogous to the electronic for devices working with electrons.

 


Photovoltaic


Providing an electric current under the influence of light or similar radiation.

 


Pigtail


A short optical fiber permanently attached to a source, detector, or other fiber optic device at one end and an optical connector at the other.

Pigtail
 


Planar Waveguide


A waveguide fabricated in a flat material such as thin film.

 


Plastic Clad Silica (PCS):


Also called hard clad silica (HCS). A step-index fiber with a glass core and plastic or polymer cladding instead of glass.

 


Plastic Fiber


An optical fiber having a plastic core and plastic cladding.

 


PLC


Abbreviation for planar lightwave circuit. A device which incorporates a planar waveguide.

 


Plenum


The air handling space between walls, under structural floors, and above drop ceilings, which can be used to route intrabuilding cabling.

 


Plenum Cable


A cable whose flammability and smoke characteristics allow it to be routed in a plenum area without being enclosed in a conduit.

 


Point-to-Point Transmission


Transmission between two designated stations.

Point-to-Point Transmission
 


Polarization


The direction of the electric field in the lightwave. If the electric field of the lightwave is in the Y Axis, the light is said to be vertically polarized. If the electric field of the lightwave is in the X axis, the light is said to be horizontally polarized.

Polarization
 


Polarization Maintaining Fiber


Fiber designed to propagate only one polarization of light that enters it.

Polarization Maintaining Fiber
 


Polarization Mode Dispersion (PMD):


Polarization mode dispersion is an inherent property of all optical media. It is caused by the difference in the propagation velocities of light in the orthogonal principal polarization states of the transmission medium. The net effect is that if an optical pulse contains both polarization components, then the different polarization components will travel at different speeds and arrive at different times, smearing the received optical signal

Polarization Mode Dispersion (PMD):
 


PON


Abbreviation for passive optical network. A broadband fiber optic access network that uses a means of sharing fiber to the home without running individual fiber optic lines from an exchange point, telco CO, or a CATV headend and the subscriber’s home.

PON
 


Port


Hardware entity at each end of the link.

 


POTS


Abbreviation for plain old telephone system. A call that requires nothing more than basic call handling without additional features.

 


PPM


Abbreviation for pulse-position modulation. A method of encoding data.

 


Preform


The glass rod from which optical fiber is drawn.

Preform
 


Profile Dispersion


Dispersion attributed to the variation of refractive index contrast with wavelength.

 


ps


Abbreviation for picosecond. One trillionth of a second or 10-12 seconds.

 


PSTN


Abbreviation for public switched telephone network. A domestic telecommunications network usually accessed by telephones, key telephone systems, private branch exchange trunks, and data arrangements.

 


Public Switched Networks (PSN)


1. Any common carrier network that provides circuit switching among public users. 2. A switched network accessible to the public for originating and terminating telecommunications messages. 3. Any common carrier switched network, whether by wire or radio, including local exchange carriers, interexchange carriers, and mobile service providers, that use the North American Numbering Plan in common with provision of switched services.

 


Pulse


A current or voltage which changes abruptly from one value to another and back to the original value in a finite length of time. Used to describe one particular variation in a series of wave motions. The parts of the pulse include the rise time, fall time, and pulse width, pulse amplitude. The period of a pulse refers to the amount of time between pulses.

Pulse
 


Pulse Dispersion


The dispersion of an optical signal as it propagates through an optical fiber. Also called pulse spreading.

 


Pulse-code Modulation (PCM):


A technique in which an analog signal, such as a voice, is converted into a digital signal by sampling the signal’s amplitude and expressing the different amplitudes as a binary number. The sampling rate must be at least twice the highest frequency in the signal.

 


Pump Laser


A power source for signal amplification, typically a 980 nm or 1480 nm laser, used in EDFA applications.

 


Push


1) In electronic marketing, to send data to another computer without a direct request from that computer. 2) In networking, to send data from a server to a client in compliance with a previous request from the client, as soon as the data becomes available.

 


pW


Abbreviation for picowatt. One trillionth of a Watt or 10-12 Watts.