Fiber Optics Illustrated Dictionary - Part 105 ppt

Warn-ings may even be associated with a specific segment of a network e.g., fiber optic transmission link.. Data values are used to indicate a no alarm condition or that an incoming yell

Fiber Optics Illustrated Dictionary

1032

V-dimension of recorded spot In facsimile transmis-sions, the X-dimension of recorded spot is a means

of describing variation density in terms of the mini-mum density The largest center-to-center space be-tween recorded spots is measured in the direction of the recorded line When it is assessed perpendicular

to the recorded line, it is the V-dimension ofrecorded spot The same principles can be applied to assess the scanning spot

YIeA color image information encoding scheme in which the chroma (color) signals (C) are separated from the luminance (brightness) signals(Y).AY/C

splitter cable enables the two signals to be handled separately

Yablonovitch, Eli (ca 1947- ) A Bell research sci-entist and physics professor at Harvard and UCLA who pioneered concepts in photonic crystals, struc-tures that have significant potential for selectively controlling the behavior and wavelength filtering of light which, inturn,is valuable in the development

of dense wavelength fiber-based transmission sys-tems and superfast computer syssys-tems Yablonovitch described the structures in "Inhibited spontaneous emission in solid-state physics and electronics," in

1987, and by the early 1990s, had succeeded in pro-ducing a photonic crystal in a material with a rela-tively high refractive index (now called Yablonovite)

In the mid-1990s, he collaborated with Sievenpiper

et a1 in devising means to adapt the technology to longer wave lengths using 3D circuit arrangements Yablonovitch has been awarded numerous honors for his work with photonic crystals, including the Wood Prize of the Optical Society of America See Kawakami, Sujiro; photonic crystal

YAG See yttrium-aluminum-garnet

Vagi, Hidetsugu (1886-1976) AJapanese researcher, lab director, and educator who worked with his lab engineer, Shintaro Uda, to develop and describe a new, more sensitive directional antenna structure See Yagi-Uda antenna

Yagi-Uda antenna A narrow bandwidth, linear, di-rectional antenna array that resembles a driven dipole antenna with branches (passive directors),- usually along one plane The Yagi-Uda antenna improves gain with reflectors and directors (branches extend-ing out from the main rods) and works in high fre-quency ranges (radar, television, etc.) Rooftop tele-vision aerials commonly use Yagi-Uda antennas This important antenna was designed and built ca 1924-1926 by Shintaro Uda and possibly also by Hidetsugu Vagi, Uda's lab director at Tohoku Uni-versity The relative contributions of the two engi-neers are not clear It was fIrst described in a paper

by Vagi and Uda in 1926, but did not come to inter-national attention untilitwas described again by Vagi

in an English language Institute of Radio Engineers (IRE) paper in 1928 Following this wider dissemi-nation ofinformation, many called it the Vagi antenna and, ironically, it came to be more widely used in Ja-pan than abroad Uda continued to refine the design and adapted it for television reception in the mid-1950s.Anoriginal Yagi-Uda antenna is housed in the

© 2003 by CRC Press LLC

seum In 1995, the antenna was awarded an IEEE

Electrical Engineering Milestone

Yahoo A significant, high-profile, extensive search

and information site originally developed at Stanford

Univershy and established on the World Wide Web

in the mid-1990s Yahoo provides general search

ca-pabilities as well as a large database ofsites organized

according to popular categories and topics Yahoo

also sponsors Yahoo Groups (formerly E-Groups),

discussion lists http://www.yahoo.com/

Year 2000, Y2K A designation for the electronic

changeover to the new century, a circumstance that

was not anticipated and accounted for by all

program-mers when designing hardware, operating systems,

spreadsheets, databases, backup software,

schedul-ers, and the like Many software programs and

hard-ware clocks accommodated only up to the year 1999

and were not capable of rolling over to 2000 A

sig-nificant number took into consideration only the last

two or three digits of the year, and thus were unable

to resolve a "00" that followed a "99," for example,

causing potential file and data problems for backup

systems as well as various application programs

yellow alarm See yellow signal

Yellow Book CD-ROM A CD-ROM authored and

written according to Yellow Book standards in ISO

9660 format, a format very common in computer

mul-timedia applications

Yellow Book 1 Standard for the physical format of

a CD-ROM or audio CD disk (as opposed to the

logi-cal format) DVD drives are able to read CD-ROMs

created according to Yellow Book standards The

Yellow Book followed from the original Red Book

digital audio (CD-DA) standards Yellow Book made

it possible to store computer data in addition to

au-dio data and supported up to about 650 MBytes of

data There are two subcategories, Mode 1and Mode

2, for data with and without logical error correction

(LECC) Mode 2 can support both Mode 2 and Mode

1 on a disc See CD-ROM, ISO 9660 2 Standards

for audits of U.S government organizations,

pro-grams, and functions, and of government assistance

paid to nonprofit organizations, and contractors

Yellow Book, Jargon This is a common name for the

illustrated printed publication The New Hackers

Dic-tionary,which is descended from the infamous

Jar-gon File See JarJar-gon File

Yellow Box An Apple Computer Inc designation for

an object-oriented, OS-independent developer

plat-form that was initiated after NeXT was folded into

Apple Computer See Blue Box, Red Box, Rhapsody

yellow pages 1 colloq A common name for a

num-ber ofbusiness/advertising sections in various phone

directories printed on yellow paper to distinguish the

section from residential and government listings

Many online electronic business directories are

col-loquially called the yellow pages, although British

Telecom has a trademark on the name 2 A Sun

Mi-crosystems client/server protocol for system

configu-ration data distribution now known as Network

In-formation Service (NIS) See Network InIn-formation

Yellow Pages A trademark of British Telecommuni-cations

yellow signal In telecommunications, an alarm con-dition, warning, or failure signal, usually in anetwork

The signal is often a yellow-colored light, though it may be an auditory or textual signal or a specific data value or sequence On gauges, there may be a yel-low band indicating a warning level, with a red band for more serious problems, such as danger levels or stop indicators

Color-coded signals are industry and even product specific but, in general, red signals are used for more serious conditions and yellow signals for localized failures or less serious warnings (conventions simi-lar to those used in railroad and traffic signals) Warn-ings may even be associated with a specific segment

of a network (e.g., fiber optic transmission link)

In ATM networks alarm interfaces indicate whether alarm conditions are present Data values are used to indicate a no alarm condition or that an incoming yellow signal, for example, has been received Loss

of frame failures are commonly signaled by alarms

Detection of a yellow or red signal alarm in a data

network may trigger other signals, such as unavail-able signal states, and timers to log the duration of

an unavailable signal event

In SONET networks, a yellow signal may remotely signal a failure or help intrunkconditioning A far end receive failure is a more specific instance of a failure detection signal in the downstream direction

In DS3 network interfaces, a yellow signal may trig-ger a yellow alarm, described in ANSI Tl.107-1989

A loss of signal, loss of frame, or alarm indication signal (AIS) may trigger a red alarm, which is cleared ifthere are no severely errored seconds (SESs) Com-monly, in data networks, alarms are declared after a certain number of consecutive seconds have elapsed (e.g., 2 seconds) and cleared after a certain number

of seconds have elapsed (e.g., 10 seconds)

yellow wire 1 A color designation used by ffiM to indicate wires used to re-establish a broken connec-tion in traces or flat cables (ribbon cables) See blue wire, purple wire, red wire 2 A color commonly used

for ring on the second phone in four-wire phone

in-stallations (two wires for each phone) The corre-E~~:SI~~~~~~~~~~a~~i~~ certification pro- I. Yes, yes key A pushbutton shortcut key on some

ap-pliances or keyboards (e.g., teletype-style) to Rrovide

an affirmative response without typing ''yes '

YIGSee yttrium-iron-garnet

YIG filter A wide bandwidth filter in which a YIG crystal is positioned within the field of a permanent magnet associated with a solenoid and tuned to the center of the frequency band

YIQA color model originating from hardware characteristics that is used in color television transmis-sion and for some computer monitors Yis luminosity;

I andQprovide chroma signals separate from the lu-minosity in order to provide backward compatibility

Fiber Optics Illustrated Dictionary

with black and white standards On black and white

(grayscale) televisions, only the Y component of the

signal is displayed See Y signal

YModemA data transfer protocol commonly used

with modems developed by Chuck Forsberg as a

suc-cessor to XModem Typically faster than XModem

or Kermit, though not as well supported on BBSs and

at services bureaus as XModem and ZModem

YMo-dem comes in two flavors, batch and nonstop

(YMo-dem-G) The batch version allows multiple files to

be sent in a transmission session and wildcard

char-acters for filenames are supported When errors in

transmission are frequent, YModem is able to fall

back automatically to smaller packets, thus

accom-modating a poor line connection, but is not

compat-ible with the error correction ofXModem See

XMo-dem, ZModem

YModem-GA nonstop streaming variation of the

batch-oriented YModem network communications

software developed by Chuck Forsberg

YModem-G does not wait for receiver acknowledgments and

does not have built-in error correction, instead it

re-lies on an error-correcting modem to supply the

er-ror logic It's appropriate in situations where a good

clean connection is available and speed is desired If

a problem with a bad block is encountered, the

en-tire transfer is aborted Unlike ZModem, it cannot

resume a new transmission at the point at which

er-rors and termination of the initial session occurred

See YModem, ZModem

yocto-y A prefix for an SI unit quantity of 10-24,or

.000 000 000 000 000 000 000 001 It's a

mind-bogglingly small quantity See yotta-,

zepto-yoke 1 A clamp or frame that unites or holds two

parts or assemblies firmly together 2 A coil

assem-bly installed over the neck of a cathode-ray tube

(CRT) to deflect the electron beam as currents pass

through it 3 A ferromagnetic assembly, without

windings, that forms apermanent connection between

two magnetic cores

yotta-Y A prefix for an SI unit quantity of 1024,or

1,000,000,000,000,000,000,000,000 or 10008

•It's a mind-bogglingly large quantity See yocto-, zetta-

Young, Thomas(1773-1829) Aprecocious English

scientist and physician who was accepted into the

Royal Society when just barely in his 20s Young

be-came the foreign secretary to the Society in 1802 and

retained the position for the rest of his life In 1800,

he publishedExperiments on Sound and Light and

described his influential research into the theory of

optical interference Young lived in a period of

his-tory when the wave and particle nature of light were

only barely understood and still hotly debated

Fresnel was the first to really make use of the many

important discoveries of Young See interference,

Newton's rings

YSZyttrium-stabilized zirconia A material that is

usually distributed in powder fonn for manufacture

into a range of products that are corrosion-resistant

and readily shaped with molds It sells for about $400

- $700 per 100 grams of powder or suspension The

material is used in the production of oxygen sensors

1034

and oxygen generation systems See yttrium, zirconia yttriumA metallic element similar to the rare-earth metals with which it is typically found Yttrium ox-ide is used with Europium to make red phosphors for cathode-ray tubes See erbium, europium, gadolinium yttrium aluminateA substance with a low dielec-tric constant that is suitable for high-frequency ap-plications

yttrium-aluminum-garnetYAG Acrystalline sub-stance used in laser electronics, YAG may be doped

or undoped YAG can be shaped into fibers, rods, single crystals and polycrystalline forms It is useful

in precision lasers, filter and bandgap components, and for reinforcing fiber in composite materials When YAG is doped with cerium, it can be used to produce scintillation AYAG scintillating crystal has

a long lifespan and is useful in electron microscopy See scintillator

yttrium-aluminum-perovskiteYAP A crystalline substance used as a scintillating material in electron microscopy, YAP has high light-emitting properties and good resistance to high temperatures and radia-tion damage YAP has a faster decay time than yt-trium-aluminum-garnet (YAG) YAP is versatilein terms of emitted spectrum (may not require replace-ment ofan existing photomultiplier) and long-lived, capable ofoutliving the lifespan ofthe instrument for which it is producing a scintillation material (e.g., electron microscope)

yttrium-iron-garnetYIG A crystal used in the manufacture of amplifiers, filters, multiplexors, etc that is used with a variable magnetic field to tune wideband microwave circuits See YIG filter Yukawa, Hideki(1907-1981) A Japanese physicist who proposed a new nuclear force-field theory and a massive nuclear particle, the meson The existence

of the meson was verified by Cecil Powell a couple

of decades later Yukawa furthered the nuclear pro-cess ofK capture, the absorption ofan innermost

en-circling electron This theory, too, was subsequently confirmed Yukawa received the Nobel Prizein Phys-ics in 1949 for his significant contributions to the un-derstanding of quantum mechanics

yuppieyoung urban/upwardly mobile professional

A takeoff on the term hippie from the sixties, a yup-pie was generally someone born into a home with good financial resources or who was ambitious and was likely to enjoy a prosperous living

yurtA sturdy, circular, temporary, mobile shelter of Asian origin Yurts are used on work sites where shel-ter for equipment and workers is needed during con-struction or installation work.Inthe author's town, little yurts have been popping up around the various road construction sites under which new fiber optic cables are being installed

YUV A color encoding scheme to accommodate hu-man visual systems which are less sensitive to color variations than to intensity variations (particularly in individuals who are color blind) Thus, YUV uses full bandwidth to encode luminance (Y) and half band-width to encode chroma (UV) See YIC.

yVV-matrix of a vacuum tube

© 2003 by CRC Press LLC

Zulu time See Zulu time 3.abbrev Zebra time See

Zebra time 4.symb zetta- See zetta 5 The name

ofa formal specification language for describing and

modeling computing systems, based on axiomatic set

theory and predicate calculus Z was developed at

Ox-ford University in the early 1980s

Z axis A reference baseline or vector within a

coor-dinate system, most often associated by convention

with rectangular or Cartesian coordinates The Z axis

is oriented perpendicular to the X and Y axes in a

three-dimensional system See Cartesian coordinates,

X axis, Y axis

Z axis modulation The varying of the intensity of

an electron stream in a cathode-ray tube (CRT) by

manipulating the cathode or control grid

Z code In telegraphy, a system of shortcut codes

re-lated to short phrases to save transmissions time Z

codes were those prefixed with "Z," a rarely used

let-ter, to reduce the chance of confusing them with the

content ofa message For example, ZFB meant "Your

signal is Failing Badly."

Z Fiber A commercial pure silica core optical fiber

developed by Sumitomo Electric Industries, Ltd

(SEI) which held the record for low loss at

attenua-tion of0.154 dBlkm from 1986 to 2002, when it was

succeeded by a new fiber by the same company Z

Fiber is suitable for repeaterless submarine dense

wavelength division multiplex (DWDM)

transmis-sions applications See Sumitomo Electric Industries,

Z-PLUS Fiber

Z force The pressure sensitivity of touch-activated

devices, such as touchscreen monitors or

touch-sen-sitive pads, as are often used in kiosks

Z Series Recommendations A series of ITU-T

rec-ommended guidelines for programming languages

and general software aspects of telecommunications

systems These guidelines are available for purchase

from the ITU-T Since ITU-T specifications and

rec-ommendations are widely followed by vendors in the

telecommunications industry, those wanting to

maxi-mize interoperability with other systems, or conform

to software conventions widely used, need to be

aware ofthe information disseminated by the ITU-T

A full list ofgeneral categories is listed in Appendix

C and specific series topics are listed under

indi-ommendations See Z Series Recommendations chart

Z-80 The Zilog Z-80 8-bit computer microprocessor was released in 1976 by the Zilog Corporation and was quickly incorporated into many control and ro-botics applications, and into a number of popular microcomputers such as the Tandy Radio Shack Model I and LNW-80 computers While it was ca-pable ofclock rates up to 2.5 MHz, implementations

of 1.4 to 2.4 were common

The Z-80 evolved from the Intel 8080 with which it was more or less compatible; it was faster, with more instructions, not all of which were used to ensure compatibility with 8080 systems The Z-80 has a simple register structure, including index registers and an accumulator, and is capable of 16-bit address-ing through 8-bit double register pairs, somethaddress-ing not found on most ofthe other microprocessing chips that were incorporated into 8-bit microcomputers at the time

Many hobbyists acquired their first machine lan-guage and assembly lanlan-guage programming skills on

the Z-80 chip The original Z-80 was followed by faster versions, such as the Z-80A, Z-80B, and oth-ers, and has been used for over two decades in many control applications such as robotics and satellite te-lemetry, due to its simple efficiency, low cost, and practical instruction set See TRS-80

z-fold, zigzag fold, fanfold Aterm for a type of fold often usedincontinuous-feed forms and other com-puter printouts The name is derived from the shape ofthree sheets ofpaper that alternately fold one way

or the other along the perforations

Z-marker See zone marker

Z·PLUSFiber Acommercial pure silica core opti-cal fiber with fluorine-doped silica cladding, devel-oped by Sumitomo Electric Industries, Ltd (SEI) which held the record for low loss at attenuation of 0.154 dB/km from 1986 to 2002, when it was suc-ceeded by a new fiber by the same company The Z-fibers are widely used in repeaterless submarine cable installations See Sumitomo Electric Industries, Ltd.,

Z Fiber

Z++Just ase++is seen as a more recent, object-ori-ented derivative ofthe C programming language, Z++

Fiber Optics Illustrated Dictionary

isan object-oriented extension of Z, a formal

speci-fication language for describing computing systems

SeeZ

ZlA historically important pioneer home-brewed

binary relay computer developed in Germany in the

mid-1930s by Konrad Zuse While this was a

signifi-cant pioneering computer construction, it was largely

unknown outside of Germany due to the second

World War and, as such, did not significantly

influ-lTU-T Z Series Reeommendations

Recom

Z.I00 S~<;i~c~tioll~lIid description

lan~e{$PL)

Z.lOS SDLcom.biriedwith ASN.lmodules

(SDLlASN.l)

ZJ 06 '.GOmtnol1itl~rchangefonnatfqr"

SDL

Z.107 SDl.,withembeddedASN.l

Z.l09 SDLcoml)ilJedwith UML

Z.l10 Criteriaforuseofformal description

techniquesl.lYITU-T

Z.120 Messagesequencechart(MSC)

Z.130 ITI!0bject<ietinitio~ language

Z.140 Jlu:~r~tll1tj,t~bttlaJ' combmed:,

notation'V'e~i9q3·(TTCN 3);(1ore

language

Z.141 Jberre~~dTabular ColIlbitled

NotationversiotJ 3 (TTCN"3):

'[abul8fpr~entation fonnat

Z.200···: CHII.L::1'11e[fU.T Progranlmitlg

Language

Z.30t Introduction to the

CCITIman-machine language

Z.302 Themeta-ltltlguage for describing

MMLsyntQ.and dialogue

proced~~::.;: '

Z.311 Iptrpd1.lpp~~~Q:syntax.•and,9j~lQgue·

Z.312 BfiSic f01'lJlatlay()ut

Z.314 The character.set andbasic elements

Z.315 Input{cotnp1~pd}languagesyr1taJt.

Z.3t6· Ol1tputJ81i~gf:sYntaxspecification

Z.317 Man-macb.i!l.edialogue procedures

Z.321 Introductionto the extendedMML

for visualdisplayterminals

Z.322 Capabilities of visual display

terminals

Z.323 'Man-~cl:!W~igteraction

Z.331 >Introductioltto:thespecification of

the.man-macnineinterface

Z.332 Methodologyfortbe specification of

theman-machineinterface -General

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ence the industry abroad It is noteworthy that it was built in an apartment, rather thaninauniversity re-search facility as were other pioneer computing plat-forms See Zuse, Konrad

Z3 Ahistoric programmable, general purpose com-puter, developed by Konrad Zuse The Z3 was re-leased in 1941 See ZI, Zuse, Konrad

zapslangTo eradicate data, to bum out a circuit, or

to apply charge to an object or environment It may

or may not be intentional, and can result from power fluctuations such as those caused by lightning (which

is probably where the term originated) You can zap

a file to kill specific data (or the whole file), you can zap food in a microwave, and you can zap or"fry"a circuit by accidentally shorting it The tenn is occa-sionally used to indicate a quick change, such as the changing of a TV station with a remote, but this di-lutes the meaning of the term and is better avoided (unless perhaps it's a lightning fast change) as zap is intended to describe an action or event that is poten-tially dangerous, lethal, or destructive, especially where electricity is involved See kill

zapper1 A device for applying a sudden stimulus such as electricity or heat that affects an immediate change such as a burn or incision Examples include shock devices such as a stungunor a laser torch or scalpel 2 A software utility that causes something

to be instantly altered or removed, such as a file zapper that may be designed to seek out and perma-nently eradicate the entries of customers who have not purchased anything for more than a year ZBLAN Aheavy metal fluoride glass used in the fab-rication offibers, ZBLAN is fluorine with zirconium, barium, lanthanum, aluminum, and sodium (Zr, Ba, La,Al, Na), sometimes called fluorozirconate Fibers manufactured with ZBLAN have low attenuation and good transmission properties Compared to silica-based glass, ZBLAN supports a broader spectrum of wavelengths, from ultraviolet to infrared It is also possible to dope ZBLAN fibers for use as fiber am-plifiers

By 1998, D Tucker at the NASA/Marshall Space Flight Center had reported that ZBLAN does not crystalize as readily, and is clearer, if constructed in

a near-weightless environment away from Earth's gravity This leads to a remarkably pure, clear fiber and ZBLAN's transmission properties approach that which is considered theoretically best ZBLAN sig-nificantly outperfonns silica glasses in the regions above which they "top off' at wavelengths of about 2.3fl.ZBLANis capable oftransmitting wavelengths

of up to 4.5 fland higher.Inactual use, ZBLAN is currently limited to short distances, but with im-proved fabrication processes to prevent or reduce crystallization, the potential ofZBLAN for fiber com-munications in a broad spectrum of wavelengths is excellent

Scientists point out that the whole process doesn't have to take place at zero "g" to take advantage of space-based ZBLAN optical fiber The fiberpreforms

could be created in space, with the filaments pulled back on Earth See prefonn, vapor deposition process

© 2003 by CRC Press LLC

4.0 1.5 io 2.5 3.0 15 w.v.length (1ft1cs'aM)

0.5 100.00

Comparison of ZBLAN fibers pulled at 0 G (left) and1 G(right) aboard a low-gravity experiment con-ducted by the NASA/Marshall Space Flight Center Bubbles and other defects in the example on the right will scatter optical signals and interfere with traansmission The pure, uncrystallized optical fiber

on the left has the potential to transmitt 100 times more data than traditional silica-based optical fibers [NASA/Marshall photos.J

ZBLAN - Silica Comparison

Opticalfibers madefrom ZBLAN rather than silica exhibit aprofile ofefficiencyfar closer to the theoreti-cal best NASA has been conducting research intopull-ing ZBLAN fibers in space where conditions can be createdfor reducing crystallization [NASA/Marshall Space Flight Center, 1998.J

10,000.00

I

I

A miniature furnace designed to study ZBLAN

op-ticalfiber pulling under low gravity conditions aboard

a KC-135 aircraft It is operated here by Guy Smith

of the University ofAlabama in collaboration with

Dr Dennis Tucker ofthe Marshall Space Flight

Cen-ter, in experiments conducted in 1999.

Fiber Optics Illustrated Dictionary

ZBTSISee zero byte time slot interchange

Zebra time, Z timeThe same as Greenwich Mean

Time See Greenwich Mean Time, Z

Zeeman effectAneffect observed in 1896 on the

structure ofgas spectrum lines when subjected to the

influence of a moderately strong magnetic field It

was observed by Pieter Zeeman that sharp spectral

lines split into multiple closely spaced lines This

early puzzle gave rise to a number oflines ofresearch

in quantum physics The number of lines is

gener-ally three, although anomalous effects have been

ob-served and even stronger magnetic fields can cause

some spectral lines to emerge

The Zeeman effect is a useful tool in a number of

ar-eas of science including the study of laser light.It

intrigues quantum physicists and is used by

astro-physicists to map the magnetic field strengths of

so-lar effects and to study other galactic magnetic fields

The Zeeman effect is often described along with the

Stark effect (the influence of strong electrical fields

on spectral lines) See Stark effect

ZenAnAsian Buddhist system ofbeliefthat

encour-ages meditation and self-discipline, and the

attain-ment ofenlightenattain-ment through direct intuitive

expe-rience See Zen mail

Zen mailA tongue-in-cheek descriptive phrase for

computer communications that erroneously (or

de-liberately) arrive with no content in the body of the

message See Zen

zener currentInan intense electric field, a current

through an insulator sufficient to excite an electron

from the valence band to the conduction band

zener diodeAnelectronic component that behaves

like a rectifier below a certain voltage, but exhibits a

sudden increase in current-carrying capacity above

a specific voltage level (zener value) and a

corre-sponding decrease in dynamic resistance resulting in

a reverse breakdown The dual nature (di-) makes it

possible to represent conducting and nonconducting

(or very low conducting) states as a binary system

and the breakdown under reverse bias (functioning

as an open circuit) is particularly useful as a

refer-ence circuit or as a shutoffcircuit to respond to power

surges above a certain voltage threshold

Doping is amanufacturing process in which elements

such as rare earth elements are introduced into a

sub-stance (e.g., fiber optic cable) to improve its

quali-ties for a particular purpose such as the transmission

of laser light Doping is also used in semiconductors

to influence their conducting qualities Heavy

dop-ing in p-n junctions, for example, results in very thin

depletion layers that hinder impact ionization but

fa-cilitate quantum tunneling and the flow of current

This, inturn, leads to zener breakdown which is

somewhat related to avalanche breakdown from

im-pact ionization, as may occur in lightly doped p-n

junctions

Zener diodes are used in voltage regulators and power

supplies and help prevent electrostatic discharge in a

wide variety ofsemiconductor technologies They are

becoming especially important in the mobile

commu-nications industry because small portable devices

1038

become vulnerable to voltage surges/static electric-ity when they are connected to other devices such as network cables, docks Tiny zener diodes capable of absorbing static surges are thus being incorporated into mobile phones, pagers, etc

zener effectAreverse-current breakdown effect that occurs at a semiconductor or insulatorjunction in the presence of a high electric field See zener current, zener diode

Zenith CorporationOne ofthe early entrants to the radio industry, Zenith was founded in 1931 by a ra-dio amateur and soon became a major manufacturer Zenith now promotes consumer flat-screen, large-size television/media screens Too bad the commercials aren't as classy as the products

ZEONEXA commercial tradename for ZION Technology's implementation of cyclic olefin poly-mer See cyclic olefin polypoly-mer

zeppelin antennaA horizontally oriented antenna, which is a multiple ofa halfwavelength in length with

a two-wire transmission coming into one end, which

is also a multiple of a halfwavelength

zepto-A standard metric prefix of the Systeme In-temationale (SI) The zepto unit is used in scientific measurement requiring very small numbers and rep-resents1000- 7in decimal See zetta-

zero balancingAtelephone service accounting tech-nique in which a specific dollar quantity is distrib-uted over a large category ofcalls The total base price

of all the calls within the category is used to calcu-late an adjustment percentage so the full dollar amount produces a zero balance (rounding errors are not permitted)

zero beatIn electronics and acoustics, a condition during which two combined frequencies match, and

consequently do not create a beat.

zero beat reception, homodyne receptionIn radio transmission reception, a system that uses locally generated voltage at the receiving end of the trans-mission, which is the same frequency as the original carrier and combines it with the incoming signal See beat reception, heterodyne

zero bias1.Ina cathode-ray tube (CRT), the absence ofany difference in potential between the cathode and its control grid 2.In teletypewriter transmission cir-cuits, zero bias is a state in which the length of the received signal matches the length of the transmit-ted signal

zero bit insertion, bit stuffingIn data communica-tions, the process of inserting a zero bit after a series

of one bits in order to specify a distinct break or change Thus, the beginning or ending of a frame is not misconstrued This is sometimes used in place of control signals

zero compressionA data compression technique in which nonsignificant leading zeros are removed

zerofIllA data manipulation technique in which ze-ros are inserted into a file or transmission without affecting the meaning of the data See zero bit in-sertion

zero dispersionIn an optical waveguide,physical characteristics that result in the propagating

© 2003 by CRC Press LLC

one end of the link to another (without dispersing).

This situation is actually somewhat difficult to

achieve, especially in long haul fiber optic links

car-rying multiple wavelengths

Due to the different reflective lines of travel of

dif-ferent light beams, they tend to arrive at the endpoint

at different times Different frequencies in the same

lightguide (e.g., in multimode fiber) also will have

different travel speeds due to their different energy

levels and characteristics In addition, the

wave-lengths of the lightwaves are not usually coincident

with acoustical vibrations that occur in the cable

ex-cept at certain specific frequencies Thus, various

types of dispersion almost invariably occur and, in

fact, tend to be detrimental to the composition of the

signal at the endpoint (it's usually advantageous for

related signals to arrive at the same time)

Thus, zero dispersion often a design goal in the

en-gineering and construction of fiber optic

communi-cations systems However, there are situations where

radiant energy in a cable will travel without

disper-sion and may beinphase with energy that could cause

noise In very short cable lengths, there may not be

sufficient distance/time for the different parts ofa

sig-nal to shift from one another, especially if the

lightguide is very straight and little internal

reflec-tion is necessary to channel the light In a carefully

engineered cable where graded index fiber is used to

compensate for differences in reflectivity and travel

time in different wavelengths, dispersion may be

minimized and approach zero Thus, there is a

bal-ance between trying to achieve zero dispersion and

interference factors that may impinge upon the

sig-nal when it reaches that level See dispersion,

zero-dispersion wavelength

zero-dispersion slopeIn a single-mode optical fiber,

for example, the rate of change of dispersion at the

zero-dispersion wavelength relative to the light

beam's wavelength

zero-dispersion wavelength(symb - Ao)In an

op-tical waveguide, the wavelength(s) at which material

disperson and waveguide dispersion cancel one

an-other, in the sense that they are in phase When

un-wanted wavelengths move in step with operational

wavelengths, significant interference can occur The

Aois sometimes called the "dispersion window."

Indispersion-unshifted silica-based optical fibers, the

Aooccurs at about 1.3 Jlm, in dispersion-shifted fibers

at about 1.55 Jlm Dispersion-shifting may be

accom-plished by doping the fiber It is important to

under-stand the disperion wavelength phenomenon so as to

avoid undesired nonlinear interference and

modula-tion instability It is also possible to achieve high data

transmission rates near this frequency, so it helps to

know just where that point lies

Dispersion-shiftedfiber (DSF) shifts the

zero-disper-sion point from 1310 to 1550 nm to move it out of

the phase range However, four-wave mixing may

occur in these fibers, so they are more suitable for

single-channel systems than others To gain the

ad-vantages of dispersion-shifted fiber while avoiding

persion-shifted fiber was developed (e.g., OFS's TrueWave RS fiber)

Dispersion-compensatingfiber (DCF) is another

spe-cialized type of fiber useful for endlink connections because it has a high negative dispersion value that reverses chromatic dispersion

Zero-dispersion wavelength parameters have tradi-tionally been difficult to measure precisely, hinder-ing the development ofa reference standard Mechels

et al have described the development ofa frequency-domain phase-shift system intended to reduce sys-tematic Aomeasurement errors See dispersion zero insertion forceZIF A type of socket used in integrated circuits that allows a chip to be inserted without undue pressure A lever or screw is then pushed or turned to secure the component so that it

is not dislodged due to bumping or transit

This type of socket costs more than standard pres-sure sockets and tends to be used in specialized sys-tems such as test syssys-tems or with specific chips that are larger or more expensive

zero level Alevel established in order to have a ref-erence from which to judge further states or activi-ties of sounds and signals for observation, calibra-tion, or testing The definition of zero level is tech-nology specific

zero potentialThe potential of the Earth, used as a reference measure

zero power peripheral Adevice that requires very little power and consequently can draw that power from the primary device to which it is attached, or from the circuit with which it is associated Some mo-dems and most telephones take their power from the phone line, unless they have extra features (e.g., speakerphone) requiring additional power

Zero power peripherals are favored in constrained spaces and mobile communications as they are often less bulky than standard peripherals with power sup-plies, and easier to attach, since extra electrical out-lets are not required

zero punch Apunch located specifically in the third row from the top ofa punch card See Hollerith card, punch card

zero shift, zero drift Adescriptive measure of the amount of shift or drift that has occurred from the original setting or calibration point, at a subsequent point in time See zero stability

zero stabilityThe ability of an instrument to retain its original state or settings over time, that is, to with-stand zero shift Zero stability is generally considered

a desirable characteristic See zero shift

zero stuffingSee zero bit insertion

zero suppressionThe elimination of zeros that are not meaningful Zero suppression is often used to in-crease the readability of information with leading zeros, for formatting or transmission purposes, which would otherwise be distracting or confusing to a hu-man reader In these cases, the zeros are often re-placed with a blank (a space character on printouts) Tables and columnar data (like financial statements) are usually printed with zero suppression

Fiber Optics Illustrated Dictionary

zero transmission level reference pointFor an

ar-bitrarily selected point in a circuit, a level reading that

is subsequently used against which to measure

trans-mission levels in other points of the circuit or at the

same point at another time In telephone

transmis-sions, the reference point is frequently selected at the

location of the source of the transmission

zero usage customerAlisted subscriber who has not

used the network to which he or she has access

zero water peak fiber A type of optical

communi-cations fiber first commercially released by OFS in

2002.This fiber pennanently eliminates a water peak

that typically occurs at1400nm while preserving the

1300nm wavelength band, thus substantially

increas-ing capacity over traditional sincreas-ingle-mode fibers

car-rying E-band coarse wavelength division (CWDM)

multiplexed transmissions

zerofI1I, zeroize To insert the zero character into

un-used storage locations This is done for a variety of

reasons: for fonnatting, for creating space savers, and

sometimes as a delay mechanism to match up

trans-mission speeds with output speeds of slower output

devices (printers, facsimile machines, etc.)

zetta- Z Astandard metric prefix ofthe Systeme

In-ternationale (SI) The zetta unit is used in scientific

measurement requiring very large numbers and

rep-resents 1021 or1,000,000,000,000,000,000,000or

10007in decimal See yotta-, zepto-

ZIFSee zero insertion force

Zimmermann, Philip R A software engineer and

cryptography specialist, best known for developing

the Pretty Good Privacy (PGP) encryption scheme

based upon the Blowfish technology, Zimmennann

is the founder ofPGP, Inc He is a software engineer

with a long history of experience in cryptography,

data security, data communications, and realtime

em-bedded systems development

Zimmennann has been honored with numerous

hu-manitarian awards due to his contribution to the

safe-guarding of personal privacy, including the 1996

Norbert WienerAward, the 1995 Pioneer Award from

the Electronic Frontier Foundation, and many more

Zimmennann is a member of the International

Asso-ciation of Cryptologic Research, the AssoAsso-ciation for

Computing Machinery (ACM), and others See

Blow-fish, PGP Inc., Pretty Good Privacy

zinc(symb - Zn) A malleable, light-bluish, active,

metallic element (AN - 30)with a relatively high

electropotential, useful in plating, dipping, and

gal-vanizing, to prevent corrosion in other metals.Ittends

to be brittle and difficult to work with above and

be-low 100 - 1500

C Combined with copper, it fonns

brass It is used for piping, construction accessories,

and household items

zinc-fluoride(symb - ZnF , F2Zn1) A white,

crys-talline zinc compound Zinc-fluoride is one ofa

num-ber of zinc compounds suitable for use in

ZBLAN-type high-quality optical glass applications See

ZBLAN

zinc-oxide(symb - ZnO, 0IZn1) A white,

crystal-line zinc compound (familiar in commercial sun

screens and antiseptive ointments) that is widely used

1040

in optics Historically, zinc was used in early voltaic cells (the forerunners to modem batteries) such as the Daniell cell See Daniell battery

At some wavelengths, ZnO is transparent It is used

in deposition processes, photocopier photoconductive surfaces, light-emitting diode components, and blue lasers The material behaves differently when it in-teracts with gas molecules, making it suitable for the detection of flammable gases It may be used to im-prove the physical properties of rubber When zinc-oxide is combined with aluminum (AI), fluoride (F),

or indium(In),it can function as an electrically-con-ducting oxide in optoelectronic applications New fabrication applications for ZnO are being de-vised In January2002,Eagle-Picher Technologies announced the successful development ofp-type thin film layers created from ZnO by a molecular beam epitaxy (MBE) process This has potential for detec-tors and light-emitting diode and laser illuminadetec-tors

in the ultraviolet(UV)range The addition of Mag-nesium (Mg) brings the spectral range even deeper into the UV spectrum

zinc-selenide(symb - ZnSe, Se1Zn1)An amber-to-reddish-colored crystalline zinc compound that has good unifonnity and transmission properties, as well

as low bulk absorption ratings, though it is more brittle and subject to cracking than glass In commer-cial applications, it transmits in the ca.0.5 - 15J.lm range and is popular for laser optics in the infrared spectrum

Zinc-selenide is used in lenses for carbon-dioxide lasers and certain guidance systems and spectro-scopes It has also been used in experimental photo-conductive semiconductor switching circuits Com-pounds similar to zinc-selenide are sometimes used

in vertical-cavity surface-emitting lasers (VCSELs) zip v To bundle up or compress a file or set of files, usually for transferring or archiving The tenn is now commonly used for any such processing (zipping) of files, regardless of the archive utility used, but origi-nally referred to programs called gzip and PKZIP See arc, compress, gzip, PKZIP

ZIPZone Infonnation Protocol

zipped See zip, gzip, PKZIP

zirconia A substance exhibiting different molecular structures at different temperature ranges Oxides may be combined with zirconia to reduce structural changes that occur at different production tempera-tures Once stabilized, the material becomes highly resistant to temperature-induced phase transitions Zirconia is customarily made by injecting zirconium-dioxide powder into molds and grinding the molded components to industry standards

Zirconia is a versatile material that is made into a ce-ramic for use in many industries, including the fabri-cation of joint prosthesis for surgical implantation The material is favored for ferrules for fiber optic joint support due to its strength, resistance to environmen-tal erosion, and low insertion loss qualities; though some companies are now creating plastic ferrules with good optical performance See ferrule, zirco-nium oxide See YSZ

© 2003 by CRC Press LLC

with high refractory properties, low thermal

conduc-tivity, low friction coefficents, and high heat

toler-ance Zirconium oxide is strong, versatile, and

chemi-cal and corrosion-resistant It is created by

stabiliz-ing zirconia crystals to resist structural changes at

different temperatures The material is suitable for the

production ofceramic ferrules for fiber optic

connec-tors and, when combined with metal leads, can

pro-vide illumination for spectrometers.Itis also used in

oxygen-sensing components See zirconia

ZivSee Lempel-Ziv

ZModemA fast, flexible, error-correcting,

full-du-plex file transfer data transmission protocol similar

to XModem and YModem, but with updates and

en-hancements YModem and ZModem were written by

Chuck Forsberg

ZModem is well supported by various

telecommu-nications programs, and many BBSs and service

bu-reaus use it

ZModem includes fallback and dynamic adjustment

of packet size, which is important if the connection

is a line with fluctuating characteristics One of

ZModem's most valuable features is its ability to

re-sume a file transfer that has been aborted With

al-most all earlier desktop serial file transfer programs,

if the line was interrupted or the file transfer aborted

99% of the way through, the program would start

again from the beginning when reconnected, rather

than resuming from where it left off ZModem can

detect a partial file, establish a new starting point at

the end of the partial file, and continue transmitting

until the transfer is completed or interrupted If

you've ever spent a couple of hours transferring a

very large file on a slow link and lost it when the

trans-mission was almost complete, you will appreciate

ZModem's "resume" feature See XModem,

YMo-demo

ZOG A high-performance frame- and link-based

hypertext system designed for local area networks

(LANs) developed at Carnegie Mellon University.It

has evolved into a commercial product called

Knowl-edge Management System (KMS)

zone 1 Anarea, usually contiguous, which mayor

may not be self-contained; or has some common

char-acteristics within itself; or which is distinguished as

different, in some way, from the surrounding area;

or which is assigned on the basis of size, population,

or some other economic or practical characteristic (as

in shipping zones) 2 A section of computer storage

allocated for a particular purpose 3 In telephone

communications, a specified area outside the local

ex-change.4.Incellular phone communications, a zone

consisting of adjacent cells is called a cluster 5 A

region in which communications are banned or

im-peded, called a blackout zone 6 A physical or

vir-tual region ofaccess within a network, sometimes

de-lineated by physical structures such as a workstation

or router See firewall

zone, optical recognition Aregion manually

speci-fied by the user, or automatically detected and

en-closed by the optical recognition software, that

cor-ample, some optical document recognition systems, and some of the better optical character recognition systems, can distinguish columns and page numbers, images and formulas, and scan each separately from the others Some software facilitates the preconfiguration ofzones in a template Order prior-ity for the zones may be assigned In this way a long document, such as a book in which most ofthe pages are identical in format, can be scanned without re-setting the zones each time

Zones in Optical Recognition

Many optical recognition programs will automati-cally determine zones or allow them to be manually configured This allows the flow oftext, and separa-tion ofgraphics and text to be handled more efficiently

by the software, as in this Caere Omnipage example.

zone, punch cardOne of three specific positions on the top ofa punch card See punch card, zone punch zone blankingTurning offa cathode-ray tube (CRT)

at a point in the sweep of an antenna

zone cabling Acabling architecture designed for open office systems in which various physical zones are designated and cabled so that office desks and equipment can be moved around without ever being too far from the various necessary outlets and con-nectors

zone marker, Z-markerA vertically radiating bea-con of light that signals a zone above a radio station transceiver

zone method Awire installation ceiling distribution system in which the space above rooms is organized