geas ece board exam reviewer module 06

MODULE 6

QUESTION

Sound to electrical.

Mircophone

QUESTION

Infrasonic.

Less than 20Hz

QUESTION

Ultrasonic.

Greater than 20000Hz

QUESTION

Min. deviation, longest wavelength.

red

QUESTION

Why the sky is blue.

Scattering

QUESTION

Why tip of needle is blurred when viewed from screen.

Diffusion of light

QUESTION

Min. distance to see an object.

25cm

QUESTION

Wavelength sensitive to eyes.

555nm

QUESTION

Blackbody emits ___.

No radiation

QUESTION

Black body.

Absorb emit

QUESTION

Tuning fork placed on a table top.

Loudness inc.

QUESTION

Gay Lussac.

Constant volume

QUESTION

Axis of ___.

Radius of gyration

QUESTION

3rd most conductive.

Yold

QUESTION

Diopter.

4th power

QUESTION

Linear momentum is doubled.

4 times KE

QUESTION

Reflection of sound.

Echo

QUESTION

Classification of compound.

Acid and base

QUESTION

Atomic number of Boron.

5

QUESTION

Normal body temperature of human.

37ᵒ

QUESTION

Proposed that protons and neutrons are concentrated in a nucleus.

Ernest Rutherford

QUESTION

Liquid non-metal at normal temperature.

Bromine

QUESTION

The branch of optical technology concerned with the transmission of radiant power (light energy) through fibers.

Fiber optics

QUESTION

The basic functions of a fiber optic data link.

Convert an electrical input signal to an optical signal, send the optical signal over an optical fiber, and convert the optical signal back to an

electric signal.

QUESTION

The three parts of a fiber optic data link.

Transmitter, optical fiber, and receiver

QUESTION

The decrease in the amount of light reaching the end of the fiber.

Loss

QUESTION

In fiber optic systems, designers consider what trade-offs?

Trade-offs in fiber properties, types of connections, optical sources, and detector types in military and subscriber-loop applications.

QUESTION

Seven advantages of fiber optics over electrical systems.

Improved system performance, immunity to electrical noise, signal security, electrical isolation, reduced size and weight, environmental

protection, and overall system economy

QUESTION

The advent of quantum physics successfully explained the photoelectric effect in terms of fundamental particles of energy called.

Quanta

QUESTION

What are the fundamental particles of energy (quanta) known as when referring to light energy?

Photons

QUESTION

What type of wave motion is represented by the motion of water?

Transverse-wave motion

QUESTION

Illustrated as straight lines, showing the direction in which light is travelling at any point.

Light rays

QUESTION

Those substances that transmit almost all the light waves falling upon them are said to be.

Transparent

QUESTION

Substances through which some light rays can pass, but through which objects cannot be seen clearly because the rays are diffused, are called.

Translucent

QUESTION

Those substances that are unable to transmit any light rays are called.

Opaque

QUESTION

Typical optical detector materials used for receiver operation in the 850-nm wavelength region.

Silicon(Si), gallium arsenide(GaAs), and gallium aluminum arsenide(GaAlAs)

QUESTION

Examples of optical detector materials used for receiver operation in the 1300-nm and 1550-nm wavelength regions.

Germanium(Ge), indium phosphide(InP), and indium gallium arsenide(InGaAs)

QUESTION

Output saturation, occurs at input optical power levels typically.

Greater than 1 milliwatt(mW)

QUESTION

Typical reverse-bias voltage applied across the active region of an avalanche photodiode(APD).

Over 100 volts

QUESTION

Typical semiconductor materials used in the construction of low-noise APDs include.

Silicon(Si), indium gallium arsenide(InGaAs), and germanium(Ge)

QUESTION

Typically, semiconductor lasers emit light spread out over an angle of.

10 to 15 degrees

QUESTION

The two most common semiconductor materials used in electronic and electro-optic devices.

Silicon(Si) and gallium arsenide(GaAs)

QUESTION

Typically LEDs for the 850-nm region are fabricated using.

GaAs and AlGaAs

QUESTION

LEDs for the 1300-nm and 1550-nm regions are fabricated using.

InGaAsP and InP

QUESTION

Basic LED types used for fiber optic communication systems.

Surface-emitting LED(SLED), edge-emitting LED(ELED), and super luminescent diode(SLD)

QUESTION

Preferred optical source for short-distance(0 to 3km), low data-rate fiber optic systems.

SLEDs, and ELEDs

QUESTION

Typically, SLEDs operate efficiently for bit rates.

Up to 250 megabits per second(Mb/s)

QUESTION

ELEDs may be modulated at rates.

Up to 400 Mb/s

QUESTION

SLDs may be modulated at bit rates of.

Over 400 Mb/s

QUESTION

In SLEDs, the size of the primary active region is limited to a small circular area of.

20µm to 50µm in diameter.

QUESTION

LDs typically can be modulated at frequencies up to.

Over 2 gigahertz(GHz)

QUESTION

Electronic coolers used to cool LDs in system applications.

Thermo-electric(TE) coolers

QUESTION

For the lowest data rates (0 to 20 megabits per second), sources tend to operate in the.

850-nm window

QUESTION

For moderate data rates (50 to 200Mbps), sources tend to operate in the.

1300-nm window

QUESTION

Are usually only used in the extremely long distance high-data-rate applications(undersea links, etc).

1550-nm transmitters

QUESTION

Typical low-frequency applications are.

Analog audio and single channel video systems

QUESTION

Types of systems for moderate frequency applications.

Multi-channel analog audio and video systems as well as frequency modulated(FM) systems

QUESTION

Typical high frequency applications are.

Cable television trunk line and raw radar remoting applications

QUESTION

Are typically used in cable television trunk line applications.

1550-nm transmitters

QUESTION

Electronics industries association / telecommunications industries association.

EIA / TIA

QUESTION

For most fiber optic measurements, these standard procedures are documented by the.

EIA / TIA

QUESTION

Each component measurement procedure is assigned a unique number given by.

EIA / TIA-526-X

QUESTION

The cutback method for measuring multimode fiber attenuation is.

EIA / TIA-455-46

QUESTION

The cutback method for measuring single mode fiber attenuation is.

EIA / TIA-455-78

QUESTION

Describes how to properly prepare fiber ends for measurement purposes.

EIA / TIA-455-57

QUESTION

A 20-mm diameter mandrel is typically used for.

62.5µm fiber

QUESTION

Another common mode filter for single mode fibers is.

30-mm diameter circular free-form loop

QUESTION

Additional information on multimode and single mode filters(and launch conditions) is available in.

EIA / TIA-455-50 and EIA / TIA-455-57, respectively

QUESTION

The test method for uncabled single mode fiber cutoff wavelength is.

EIA / TIA-455-80

QUESTION

The test method for cabled single mode fiber cutoff wavelength is.

EIA / TIA-455-170

QUESTION

The test method for measuring the bandwidth of multimode fibers in the frequency domain is.

EIA / TIA-455-30

QUESTION

Chromatic dispersion is measured in the frequency domain using.

EIA / TIA-455-169 and EIA / TIA-455-175

QUESTION

The procedure for measuring multimode and single mode fiber geometry is detailed in.

EIA / TIA-455-176

QUESTION

The fiber-geometrical parameters measured include.

Cladding diameter, cladding noncircularity, core-cladding concentricity error, and core noncircularity

QUESTION

Core diameter is measured using.

EIA / TIA-455-58

QUESTION

Describes the procedure for measuring the near-field power distribution of optical waveguides.

EIA / TIA-455-43

QUESTION

Output near-field radiation pattern can be obtained by using.

EIA / TIA-455-43

QUESTION

The numerical aperture(NA) of a multimode fiber having a near-parabolic refractive index profile is measured using.

EIA / TIA-455-177

QUESTION

Describes various procedures, or methods, for measuring the far-field power distribution of optical waveguides.

EIA / TIA-455-47

QUESTION

The mode field diameter of a single mode fiber can be measured using.

EIA / TIA-455-167

QUESTION

Provides information on the mathematics behind the transformation procedure between the far-field and near-field.

EIA / TIA-455-167

QUESTION

Insertion loss of both multimode and single mode interconnection devices is measured using.

EIA / TIA-455-34

QUESTION

The mandrel wrap method of measuring the insertion loss of an interconnecting device is included in.

EIA / TIA-455-34

QUESTION

Return loss and reflectance are measured using.

EIA / TIA-455-107

QUESTION

The fiber optic test method for measuring the attenuation of an installed optical fiber using an optical time-domain reflectometer(OTDR).

EIA / TIA-455-61

QUESTION

The group index(N) is provided by fiber manufacturers or is found using.

EIA / TIA-455-60

QUESTION

Point defects are located and measured using.

EIA / TIA-455-59

QUESTION

The transmission loss of fiber optic cable plants is measured using.

EIA / TIA-526-14 method B (multimode fiber) or EIA / TIA-526-7 (single mode fiber)

QUESTION

Fiber inspection is done visually by the use of a standard microscope at.

200 to 400 times magnification

QUESTION

Ferrule-type ST® connectors are becoming the commercial connector of choice for local area network(LAN) and data transfer links and are the standard connector for navy light duty applications. This connector is described in specification sheets 16,17, and 18 of.

MIL-C-83522

QUESTION

One type of heavy-duty connector designed for use in harsh navy environments is described by the military specification.

MIL-C-28876

QUESTION

Standard core sizes for multimode step-index fibers are.

50µm and 100µm

QUESTION

Standard core sizes for multimode graded-index fibers are.

50µm, 62.5µm, 85µm, and 100µm

QUESTION

Standard core sizes for single mode fibers are.

Between 8µm, and 10µm

QUESTION

Standard multimode graded-index fiber core and cladding sizes are.

50/125µm, 62.5/125µm, 85/125µm, and 100/140µm

QUESTION

Typical values of relative refractive index difference(Δ) are around.

0.01 to 0.02

QUESTION

An OFCC cable consists of individual single fiber cables, called.

Optical fiber cable components(OFCC)

QUESTION

The OFCC outer diameter is typically.

2millimeters(mm)

QUESTION

The fiber is typically buffered with a polyester elastomer to a total diameter of.

900µm

QUESTION

An OFCC cable of 0.5inch cable outer diameter can accommodate about.

12 fibers

QUESTION

OFCC type cable is also being evaluated for use in navy applications with fiber counts up to.

36 fibers(OFCC)

QUESTION

Involves calculating the rise times of the link transmitter and the optical fiber.

Risetime budget

QUESTION

The composite optical transmitter/fiber risetime is referred to as the.

Fiber exit risetime

QUESTION

Consists of all the fiber optic cables and the fiber optic interconnection equipment within the shop, including connectors, splices, and interconnection boxes.

Fiber optic cable plant

QUESTION

Optical fibers or cables should never be bent at a radius of curvature less than a certain value, called the.

Minimum bend radius

QUESTION

A hybrid device that converts electrical signals into optical signals and launches the optical signals into an optical fiber.

Fiber optic transmitter

QUESTION

Two basic types of amplifiers used in fiber optic receivers.

High-impedance amplifiers and transimpedance amplifier

QUESTION

Fiber optic receivers can be classified into two categories.

Digital and analog

QUESTION

Consists of an optical transmitter, optical fiber, and an optical receiver.

Point to point fiber optic data link

QUESTION

A common fiber optic application is the.

Full duplex link

QUESTION

Consists of a single transmission line that is shared by a number of equipments.

Linear bus topology

QUESTION

Consists of equipments attached to one another in a closed loop or ring.

Ring topology

QUESTION

Configuration wherein each equipment is connected a common center hub.

Star topology

QUESTION

Consists of a transmission line that branches, or splits.

Tree topology

QUESTION

The process of varying one or more characteristics of an optical signal to encode and convey information.

modulation

QUESTION

A discontinuous signal that changes from one state to another in discrete steps.

Digital signal

QUESTION

A popular form of digital modulation.

Binary modulation

QUESTION

The process of arranging symbols that represent binary data in a particular pattern for transmission.

Line coding

QUESTION

A continuous signal whose amplitude, phase, or some other property varies in a direct proportion to the instantaneous value of a physical variable.

Analog signal

QUESTION

Modulation wherein the intensity of a optical source’s output signal is directly modulated by the incoming electrical analog base band signal.

Intensity modulation

QUESTION

A signal that is in its original form and has not been changed by a modulation technique.

Base band signal

QUESTION

Involves identifying all of the sources of loss in the fiber optic link.

Power budget

QUESTION

The difference between the transmitter output power and the receiver sensitivity is referred to as the.

Available power

QUESTION

The ratio of the optical detector’s output photocurrent in amperes to the incident optical power in watts

responsivity

QUESTION

A semiconductor positive-negative(p-n) structure with an intrinsic region sandwiched between the other two regions.

PIN photodiode

QUESTION

When no light is incident on the photodiode, a current is still produced called.

Dark current

QUESTION

The detector thickness is related to the amount of time required for the electrons generated to flow out of the detector active area. This time is referred to as the electron.

Transmit time

QUESTION

It is given by tRC=RC

RC time constant

QUESTION

Means that the output electrical current(photocurrent) of the photodiode is linearly proportional to the input optical power.

Detector linearity

QUESTION

A photodiode that internally amplifies the photocurrent by an avalanche process.

Avalanche photodiode(APD)

QUESTION

Occurs when accelerated electrons collide with other electrons in the semiconductor material, causing a fraction of them to become part of the photocurrent.

Avalanche multiplication

QUESTION

Defined as the first stage of amplification following the optical detector.

Pre amplifier

QUESTION

Defined as the remaining stages of amplification required to raise the detector’s electrical signal to a level suitable for further signal processing.

Post amplifier

QUESTION

It includes thermal noise, dark noise, and quantum noise.

Receiver noise

QUESTION

The noise resulting from the random motion of electrons in a conducting medium.

Thermal noise

QUESTION

Noise caused by current fluctuations because of the discrete nature of charge carriers.

Shot noise

QUESTION

Results from dark current that continues to flow in the photodiode when there is no incident light.

Dark current noise

QUESTION

Results from the random generation of electrons by the incident optical radiation.

Quantum noise

QUESTION

Involves wrapping the test fiber around a mandrel.

Mandrel wrap mode filter

QUESTION

The wavelength of a single mode fiber above which the fiber propagates only the fundamental mode.

Cut off wavelength

QUESTION

A technique of measuring the cutoff wavelength wherein the same fiber with small bends is used as the reference fiber.

Bend-reference technique

QUESTION

A technique of measuring the cut-off wavelength wherein a piece of the multimode fiber is used as the reference fiber.

Multimode-reference technique

QUESTION

Causes the spreading of the light pulse as it travels along the fiber.

Dispersion

QUESTION

Defined as the average diameter of the cladding.

Cladding diameter

QUESTION

Defined as the average diameter of the core.

Core diameter

QUESTION

The difference between the smallest radius of the fiber (Rmin) and the largest radius (Rmax) divided by the average cladding radius(R).

Cladding noncircularity, or ellipticity

QUESTION

For multimode fibers, it is the distance between, the core and cladding centers divided by the core diameter.

Core-cladding concentricity error

QUESTION

The difference between the smallest core radius(Rmin) and the largest core radius(Rmax) divided by the core radius(Rc).

Core noncircularity

QUESTION

An electro-optic device that accepts optical signals from an optical fiber and converts them into electrical signals.

Fiber optic receiver

QUESTION

The minimum amount of optical power required to achieve a specific receiver performance.

Receiver sensitivity

QUESTION

Refers to the range of optical power levels over which the receiver operates within the specified values.

Dynamic range

QUESTION

A device that converts input energy of one form into output energy of another.

transducer

QUESTION

A transducer that converts an optical signal into an electrical signal.

Optical detector

QUESTION

Semiconductor detectors are designed so that optical energy(photons) incident on the detector active area produces a current called.

photocurrent

QUESTION

A passive device that distributes optical power from more than two input parts among several output parts.

Star coupler

QUESTION

A passive device that splits the optical power from one input fiber to more than two output fibers.

Tree coupler

QUESTION

Fiber optic couplers that prevent the transfer of power between input fibers.

Directional couplers

QUESTION

Transmits the same amount of power through the coupler when the input and output fibers are reversed.

Symmetrical coupler

QUESTION

The loss of optical power as light travels along the fiber.

attenuation

QUESTION

Measured by End users at the operating wavelength(λ) of a fiber.

Total attenuation(A)

QUESTION

Also known as attenuation rate.

Attenuation coefficient(α)

QUESTION

The area of the fiber face illuminated by the light beam from the optical source.

Launch spot size

QUESTION

The angular extent of the light beam from the optical source incident on the fiber end face.

Angular distribution

QUESTION

Results when the launch spot size and angular distribution are smaller than that of the fiber core.

Underfilled launch

QUESTION

Occurs when the launch spot size and angular distribution are larger than that of the fiber core.

Overfilled launch condition

QUESTION

A device that removes any cladding mode power from the fiber.

Cladding-mode stripper

QUESTION

A device that attenuates specific modes propagating in the core of an optical fiber.

Mode filter

QUESTION

One of the most popular splicing techniques in commercial applications.

Electric arc fusion(arc fusion)

QUESTION

A short discharge of electric current that prepares the fiber ends for fusion.

prefusion

QUESTION

Two basic types of fiber optic connectors.

Butt-joined connectors and expanded-beam connectors

QUESTION

Use two lenses to first expanded and then refocus the light from the transmitting fiber into the receiving fiber.

Fiber optic expanded-beam connectors

QUESTION

Use two cylindrical plugs(referred to as ferrules), an alignment sleeve, and sometimes axial springs to perform fiber alignment.

Ferrule connectors

QUESTION

Two ways that the navy classifies fiber optic connectors.

Light-duty connectors and heavy-duty connectors

QUESTION

Redistributes the optical signal without optical-to-electrical conversion.

Passive coupler

QUESTION

Electronic devices that split or combine the signal electrically and use fiber optic detectors and sources for input and output.

Active couplers

QUESTION

A passive device that splits the optical power carried by a single input fiber into two output fibers.

Optical splitter

QUESTION

Normally splits the input optical power evenly between the two output fibers.

Y-coupler

QUESTION

A passive device that combines the optical power carried by two input fibers into a single output fiber.

Optical combiner

QUESTION

Combines the functions of the optical splitter and combiner.

X-coupler

QUESTION

Multiport couplers that have more than two input or two output ports.

Star and tree couplers

QUESTION

Caused by a step change in the refractive index that occurs at the fiber joint.

Fresnel reflection

QUESTION

Reduces the step change in the refractive index at the fiber interface, reducing Fresnel reflection.

Index matching gel

QUESTION

Occurs when a small gap remains between fiber-end faces after completing the fiber connection.

Fiber separation(longitudinal misalignment)

QUESTION

Occurs when the axes of the two fibers are off set in a perpendicular direction.

Lateral, or axial misalignment

QUESTION

Occurs when the axes of two connected fibers are no longer parallel.

Angular misalignment

QUESTION

Some common examples of poor fiber ends.

Fiber-end face tilt, lip, and hackle

QUESTION

The basic fiber cleaving technique for preparing optical fibers are coupling.

Score-and-break method

QUESTION

Removes most surface imperfections introduced by the fiber cleaving process.

Polishing the fiber ends

QUESTION

Occurs when the fiber, mounted to the polishing tool, moves over a 5µ to 15µ grit abrasive paper.

Rough-polishing

QUESTION

Occurs when the mounted fiber moves over a 0.3µ to 1µ grit abrasive paper in the same figure-eight motion.

Fine-polishing

QUESTION

A source of intrinsic coupling loss.

Fiber mismatches

QUESTION

A permanent fiber joint whose purpose is to establish an optical connection between two individual optical fiber.

Fiber optic splice

QUESTION

A fiber splice where mechanical fixtures and materials perform fiber alignment and connection.

Mechanical splice

QUESTION

A fiber splice where localized heat fuses or melts the ends of two optical fibers together.

Fusion splice

QUESTION

Epoxy resins that seal mechanical splices and provide index matching between the connected fibers.

Transparent adhesives

QUESTION

It means that the fiber cladding consists of a single homogeneous layer of dielectric material.

Matched cladding

QUESTION

It means that the fiber cladding consists of two regions: the inner and outer cladding regions.

Depressed cladding

QUESTION

The smallest operating wavelength when single mode fibers propagate only the fundamental mode.

Single mode fiber cutoff wavelength

QUESTION

Fibers having a silica glass core and a plastic cladding.

Plastic clad silica (PCS) fibers

QUESTION

Method wherein gaseous metal halide compounds, dopant material, and oxygen are oxidized(burned) to form a white silica powder (SiO2).

Vapor phase oxidation

QUESTION

Manufacturers call SiO2 the.

soot

QUESTION

Method wherein multicomponent glass rods form the fiber structure.

Direct-melt process

QUESTION

A tight-buffered fiber surrounded by arimid yarn and a low-halogen outer jacket.

Optical fiber cable components(OFCCs)

QUESTION

Makes a permanent joint between two fibers or two groups of fibers.

Fiber optic splice

QUESTION

Permit easy coupling and uncoupling of optical fibers.

Fiber optic connectors

QUESTION

Distribute or combine optical signals between fibers.

Fiber optic couplers

QUESTION

What are the main causes of coupling loss?

Poor fiber end preparation and poor fiber alignment

QUESTION

A measure of an optical source’s power launching capability.

Radiance

QUESTION

Caused by inherent fiber characteristics.

Intrinsic coupling losses

QUESTION

Caused by jointing techniques.

Extrinsic coupling losses

QUESTION

A short length of optical fiber (usually 1 meter or less) permanently fixed to the optical source or detector.

Fiber pigtail

QUESTION

Waves that are neither transmitted nor absorbed, but are reflected from the surface of the medium they encounter.

Reflected waves

QUESTION

When a wave approaches a reflecting surface, the wave that strikes the surface is called.

The incident wave

QUESTION

When a wave approaches a reflecting surface, the wave that bounces back is called.

The reflected wave

QUESTION

An imaginary line perpendicular to the point at which the incident wave strikes the reflecting surface is called.

The normal

QUESTION

The angle between the incident wave and the normal.

Angle of incidence

QUESTION

The angle between the reflected wave and the normal.

Angle of reflection

QUESTION

The angle of incidence is equal to the angle of reflection.

Law of reflection

QUESTION

Attenuation is mainly a result of what three properties?

Light absorption, scattering, and bending losses

QUESTION

The loss of optical power as light travels along the fiber.

attenuation

QUESTION

The portion of attenuation resulting from the conversion of optical power into another energy form, such as heat.

absorption

QUESTION

Caused by the electronic transition of metal ions, such as iron, nickel and chromium, from one energy level to another.

Extrinsic absorption

QUESTION

Describes the value of refractive index as a function of radial distance at any fiber diameter.

Refractive index profile

QUESTION

The refractive index of the core is uniform and undergoes an abrupt change at the core-cladding boundary.

Step-index profile

QUESTION

The refractive index at the core varies gradually as a function of radial distance from the fiber center.

Graded-index fiber

QUESTION

Determines the shape of the core’s profile.

Profile parameter (α)

QUESTION

The NA of a multimode graded-index fiber is at its maximum value at the fiber axis. This NA is the.

Axial numerical aperture,NA(O)

QUESTION

Sound to electrical.

Mircophone

QUESTION

Infrasonic.

Less than 20Hz

QUESTION

Ultrasonic.

Greater than 20000Hz

QUESTION

Min. deviation, longest wavelength.

red

QUESTION

Why the sky is blue.

Scattering

QUESTION

Why tip of needle is blurred when viewed from screen.

Diffusion of light

QUESTION

Min. distance to see an object.

25cm

QUESTION

Wavelength sensitive to eyes.

555nm

QUESTION

Blackbody emits ___.

No radiation

QUESTION

Black body.

Absorb emit

QUESTION

Tuning fork placed on a table top.

Loudness inc.

QUESTION

Gay Lussac.

Constant volume

QUESTION

Axis of ___.

Radius of gyration

QUESTION

3rd most conductive.

Yold

QUESTION

Diopter.

4th power

QUESTION

Linear momentum is doubled.

4 times KE

QUESTION

Reflection of sound.

Echo

QUESTION

Classification of compound.

Acid and base

QUESTION

Atomic number of Boron.

5

QUESTION

Normal body temperature of human.

37ᵒ

QUESTION

Proposed that protons and neutrons are concentrated in a nucleus.

Ernest Rutherford

QUESTION

Liquid non-metal at normal temperature.

Bromine

QUESTION

The branch of optical technology concerned with the transmission of radiant power (light energy) through fibers.

Fiber optics

QUESTION

The basic functions of a fiber optic data link.

Convert an electrical input signal to an optical signal, send the optical signal over an optical fiber, and convert the optical signal back to an

electric signal.

QUESTION

The three parts of a fiber optic data link.

Transmitter, optical fiber, and receiver

QUESTION

The decrease in the amount of light reaching the end of the fiber.

Loss

QUESTION

In fiber optic systems, designers consider what trade-offs?

Trade-offs in fiber properties, types of connections, optical sources, and detector types in military and subscriber-loop applications.

QUESTION

Seven advantages of fiber optics over electrical systems.

Improved system performance, immunity to electrical noise, signal security, electrical isolation, reduced size and weight, environmental

protection, and overall system economy

QUESTION

The advent of quantum physics successfully explained the photoelectric effect in terms of fundamental particles of energy called.

Quanta

QUESTION

What are the fundamental particles of energy (quanta) known as when referring to light energy?

Photons

QUESTION

What type of wave motion is represented by the motion of water?

Transverse-wave motion

QUESTION

Illustrated as straight lines, showing the direction in which light is travelling at any point.

Light rays

QUESTION

Those substances that transmit almost all the light waves falling upon them are said to be.

Transparent

QUESTION

Substances through which some light rays can pass, but through which objects cannot be seen clearly because the rays are diffused, are called.

Translucent

QUESTION

Those substances that are unable to transmit any light rays are called.

Opaque

QUESTION

Typical optical detector materials used for receiver operation in the 850-nm wavelength region.

Silicon(Si), gallium arsenide(GaAs), and gallium aluminum arsenide(GaAlAs)

QUESTION

Examples of optical detector materials used for receiver operation in the 1300-nm and 1550-nm wavelength regions.

Germanium(Ge), indium phosphide(InP), and indium gallium arsenide(InGaAs)

QUESTION

Output saturation, occurs at input optical power levels typically.

Greater than 1 milliwatt(mW)

QUESTION

Typical reverse-bias voltage applied across the active region of an avalanche photodiode(APD).

Over 100 volts

QUESTION

Typical semiconductor materials used in the construction of low-noise APDs include.

Silicon(Si), indium gallium arsenide(InGaAs), and germanium(Ge)

QUESTION

Typically, semiconductor lasers emit light spread out over an angle of.

10 to 15 degrees

QUESTION

The two most common semiconductor materials used in electronic and electro-optic devices.

Silicon(Si) and gallium arsenide(GaAs)

QUESTION

Typically LEDs for the 850-nm region are fabricated using.

GaAs and AlGaAs

QUESTION

LEDs for the 1300-nm and 1550-nm regions are fabricated using.

InGaAsP and InP

QUESTION

Basic LED types used for fiber optic communication systems.

Surface-emitting LED(SLED), edge-emitting LED(ELED), and super luminescent diode(SLD)

QUESTION

Preferred optical source for short-distance(0 to 3km), low data-rate fiber optic systems.

SLEDs, and ELEDs

QUESTION

Typically, SLEDs operate efficiently for bit rates.

Up to 250 megabits per second(Mb/s)

QUESTION

ELEDs may be modulated at rates.

Up to 400 Mb/s

QUESTION

SLDs may be modulated at bit rates of.

Over 400 Mb/s

QUESTION

In SLEDs, the size of the primary active region is limited to a small circular area of.

20µm to 50µm in diameter.

QUESTION

LDs typically can be modulated at frequencies up to.

Over 2 gigahertz(GHz)

QUESTION

Electronic coolers used to cool LDs in system applications.

Thermo-electric(TE) coolers

QUESTION

For the lowest data rates (0 to 20 megabits per second), sources tend to operate in the.

850-nm window

QUESTION

For moderate data rates (50 to 200Mbps), sources tend to operate in the.

1300-nm window

QUESTION

Are usually only used in the extremely long distance high-data-rate applications(undersea links, etc).

1550-nm transmitters

QUESTION

Typical low-frequency applications are.

Analog audio and single channel video systems

QUESTION

Types of systems for moderate frequency applications.

Multi-channel analog audio and video systems as well as frequency modulated(FM) systems

QUESTION

Typical high frequency applications are.

Cable television trunk line and raw radar remoting applications

QUESTION

Are typically used in cable television trunk line applications.

1550-nm transmitters

QUESTION

Electronics industries association / telecommunications industries association.

EIA / TIA

QUESTION

For most fiber optic measurements, these standard procedures are documented by the.

EIA / TIA

QUESTION

Each component measurement procedure is assigned a unique number given by.

EIA / TIA-526-X

QUESTION

The cutback method for measuring multimode fiber attenuation is.

EIA / TIA-455-46

QUESTION

The cutback method for measuring single mode fiber attenuation is.

EIA / TIA-455-78

QUESTION

Describes how to properly prepare fiber ends for measurement purposes.

EIA / TIA-455-57

QUESTION

A 20-mm diameter mandrel is typically used for.

62.5µm fiber

QUESTION

Another common mode filter for single mode fibers is.

30-mm diameter circular free-form loop

QUESTION

Additional information on multimode and single mode filters(and launch conditions) is available in.

EIA / TIA-455-50 and EIA / TIA-455-57, respectively

QUESTION

The test method for uncabled single mode fiber cutoff wavelength is.

EIA / TIA-455-80

QUESTION

The test method for cabled single mode fiber cutoff wavelength is.

EIA / TIA-455-170

QUESTION

The test method for measuring the bandwidth of multimode fibers in the frequency domain is.

EIA / TIA-455-30

QUESTION

Chromatic dispersion is measured in the frequency domain using.

EIA / TIA-455-169 and EIA / TIA-455-175

QUESTION

The procedure for measuring multimode and single mode fiber geometry is detailed in.

EIA / TIA-455-176

QUESTION

The fiber-geometrical parameters measured include.

Cladding diameter, cladding noncircularity, core-cladding concentricity error, and core noncircularity

QUESTION

Core diameter is measured using.

EIA / TIA-455-58

QUESTION

Describes the procedure for measuring the near-field power distribution of optical waveguides.

EIA / TIA-455-43

QUESTION

Output near-field radiation pattern can be obtained by using.

EIA / TIA-455-43

QUESTION

The numerical aperture(NA) of a multimode fiber having a near-parabolic refractive index profile is measured using.

EIA / TIA-455-177

QUESTION

Describes various procedures, or methods, for measuring the far-field power distribution of optical waveguides.

EIA / TIA-455-47

QUESTION

The mode field diameter of a single mode fiber can be measured using.

EIA / TIA-455-167

QUESTION

Provides information on the mathematics behind the transformation procedure between the far-field and near-field.

EIA / TIA-455-167

QUESTION

Insertion loss of both multimode and single mode interconnection devices is measured using.

EIA / TIA-455-34

QUESTION

The mandrel wrap method of measuring the insertion loss of an interconnecting device is included in.

EIA / TIA-455-34

QUESTION

Return loss and reflectance are measured using.

EIA / TIA-455-107

QUESTION

The fiber optic test method for measuring the attenuation of an installed optical fiber using an optical time-domain reflectometer(OTDR).

EIA / TIA-455-61

QUESTION

The group index(N) is provided by fiber manufacturers or is found using.

EIA / TIA-455-60

QUESTION

Point defects are located and measured using.

EIA / TIA-455-59

QUESTION

The transmission loss of fiber optic cable plants is measured using.

EIA / TIA-526-14 method B (multimode fiber) or EIA / TIA-526-7 (single mode fiber)

QUESTION

Fiber inspection is done visually by the use of a standard microscope at.

200 to 400 times magnification

QUESTION

Ferrule-type ST® connectors are becoming the commercial connector of choice for local area network(LAN) and data transfer links and are the standard connector for navy light duty applications. This connector is described in specification sheets 16,17, and 18 of.

MIL-C-83522

QUESTION

One type of heavy-duty connector designed for use in harsh navy environments is described by the military specification.

MIL-C-28876

QUESTION

Standard core sizes for multimode step-index fibers are.

50µm and 100µm

QUESTION

Standard core sizes for multimode graded-index fibers are.

50µm, 62.5µm, 85µm, and 100µm

QUESTION

Standard core sizes for single mode fibers are.

Between 8µm, and 10µm

QUESTION

Standard multimode graded-index fiber core and cladding sizes are.

50/125µm, 62.5/125µm, 85/125µm, and 100/140µm

QUESTION

Typical values of relative refractive index difference(Δ) are around.

0.01 to 0.02

QUESTION

An OFCC cable consists of individual single fiber cables, called.

Optical fiber cable components(OFCC)

QUESTION

The OFCC outer diameter is typically.

2millimeters(mm)

QUESTION

The fiber is typically buffered with a polyester elastomer to a total diameter of.

900µm

QUESTION

An OFCC cable of 0.5inch cable outer diameter can accommodate about.

12 fibers

QUESTION

OFCC type cable is also being evaluated for use in navy applications with fiber counts up to.

36 fibers(OFCC)

QUESTION

Involves calculating the rise times of the link transmitter and the optical fiber.

Risetime budget

QUESTION

The composite optical transmitter/fiber risetime is referred to as the.

Fiber exit risetime

QUESTION

Consists of all the fiber optic cables and the fiber optic interconnection equipment within the shop, including connectors, splices, and interconnection boxes.

Fiber optic cable plant

QUESTION

Optical fibers or cables should never be bent at a radius of curvature less than a certain value, called the.

Minimum bend radius

QUESTION

A hybrid device that converts electrical signals into optical signals and launches the optical signals into an optical fiber.

Fiber optic transmitter

QUESTION

Two basic types of amplifiers used in fiber optic receivers.

High-impedance amplifiers and transimpedance amplifier

QUESTION

Fiber optic receivers can be classified into two categories.

Digital and analog

QUESTION

Consists of an optical transmitter, optical fiber, and an optical receiver.

Point to point fiber optic data link

QUESTION

A common fiber optic application is the.

Full duplex link

QUESTION

Consists of a single transmission line that is shared by a number of equipments.

Linear bus topology

QUESTION

Consists of equipments attached to one another in a closed loop or ring.

Ring topology

QUESTION

Configuration wherein each equipment is connected a common center hub.

Star topology

QUESTION

Consists of a transmission line that branches, or splits.

Tree topology

QUESTION

The process of varying one or more characteristics of an optical signal to encode and convey information.

modulation

QUESTION

A discontinuous signal that changes from one state to another in discrete steps.

Digital signal

QUESTION

A popular form of digital modulation.

Binary modulation

QUESTION

The process of arranging symbols that represent binary data in a particular pattern for transmission.

Line coding

QUESTION

A continuous signal whose amplitude, phase, or some other property varies in a direct proportion to the instantaneous value of a physical variable.

Analog signal

QUESTION

Modulation wherein the intensity of a optical source’s output signal is directly modulated by the incoming electrical analog base band signal.

Intensity modulation

QUESTION

A signal that is in its original form and has not been changed by a modulation technique.

Base band signal

QUESTION

Involves identifying all of the sources of loss in the fiber optic link.

Power budget

QUESTION

The difference between the transmitter output power and the receiver sensitivity is referred to as the.

Available power

QUESTION

The ratio of the optical detector’s output photocurrent in amperes to the incident optical power in watts

responsivity

QUESTION

A semiconductor positive-negative(p-n) structure with an intrinsic region sandwiched between the other two regions.

PIN photodiode

QUESTION

When no light is incident on the photodiode, a current is still produced called.

Dark current

QUESTION

The detector thickness is related to the amount of time required for the electrons generated to flow out of the detector active area. This time is referred to as the electron.

Transmit time

QUESTION

It is given by tRC=RC

RC time constant

QUESTION

Means that the output electrical current(photocurrent) of the photodiode is linearly proportional to the input optical power.

Detector linearity

QUESTION

A photodiode that internally amplifies the photocurrent by an avalanche process.

Avalanche photodiode(APD)

QUESTION

Occurs when accelerated electrons collide with other electrons in the semiconductor material, causing a fraction of them to become part of the photocurrent.

Avalanche multiplication

QUESTION

Defined as the first stage of amplification following the optical detector.

Pre amplifier

QUESTION

Defined as the remaining stages of amplification required to raise the detector’s electrical signal to a level suitable for further signal processing.

Post amplifier

QUESTION

It includes thermal noise, dark noise, and quantum noise.

Receiver noise

QUESTION

The noise resulting from the random motion of electrons in a conducting medium.

Thermal noise

QUESTION

Noise caused by current fluctuations because of the discrete nature of charge carriers.

Shot noise

QUESTION

Results from dark current that continues to flow in the photodiode when there is no incident light.

Dark current noise

QUESTION

Results from the random generation of electrons by the incident optical radiation.

Quantum noise

QUESTION

Involves wrapping the test fiber around a mandrel.

Mandrel wrap mode filter

QUESTION

The wavelength of a single mode fiber above which the fiber propagates only the fundamental mode.

Cut off wavelength

QUESTION

A technique of measuring the cutoff wavelength wherein the same fiber with small bends is used as the reference fiber.

Bend-reference technique

QUESTION

A technique of measuring the cut-off wavelength wherein a piece of the multimode fiber is used as the reference fiber.

Multimode-reference technique

QUESTION

Causes the spreading of the light pulse as it travels along the fiber.

Dispersion

QUESTION

Defined as the average diameter of the cladding.

Cladding diameter

QUESTION

Defined as the average diameter of the core.

Core diameter

QUESTION

The difference between the smallest radius of the fiber (Rmin) and the largest radius (Rmax) divided by the average cladding radius(R).

Cladding noncircularity, or ellipticity

QUESTION

For multimode fibers, it is the distance between, the core and cladding centers divided by the core diameter.

Core-cladding concentricity error

QUESTION

The difference between the smallest core radius(Rmin) and the largest core radius(Rmax) divided by the core radius(Rc).

Core noncircularity

QUESTION

An electro-optic device that accepts optical signals from an optical fiber and converts them into electrical signals.

Fiber optic receiver

QUESTION

The minimum amount of optical power required to achieve a specific receiver performance.

Receiver sensitivity

QUESTION

Refers to the range of optical power levels over which the receiver operates within the specified values.

Dynamic range

QUESTION

A device that converts input energy of one form into output energy of another.

transducer

QUESTION

A transducer that converts an optical signal into an electrical signal.

Optical detector

QUESTION

Semiconductor detectors are designed so that optical energy(photons) incident on the detector active area produces a current called.

photocurrent

QUESTION

A passive device that distributes optical power from more than two input parts among several output parts.

Star coupler

QUESTION

A passive device that splits the optical power from one input fiber to more than two output fibers.

Tree coupler

QUESTION

Fiber optic couplers that prevent the transfer of power between input fibers.

Directional couplers

QUESTION

Transmits the same amount of power through the coupler when the input and output fibers are reversed.

Symmetrical coupler

QUESTION

The loss of optical power as light travels along the fiber.

attenuation

QUESTION

Measured by End users at the operating wavelength(λ) of a fiber.

Total attenuation(A)

QUESTION

Also known as attenuation rate.

Attenuation coefficient(α)

QUESTION

The area of the fiber face illuminated by the light beam from the optical source.

Launch spot size

QUESTION

The angular extent of the light beam from the optical source incident on the fiber end face.

Angular distribution

QUESTION

Results when the launch spot size and angular distribution are smaller than that of the fiber core.

Underfilled launch

QUESTION

Occurs when the launch spot size and angular distribution are larger than that of the fiber core.

Overfilled launch condition

QUESTION

A device that removes any cladding mode power from the fiber.

Cladding-mode stripper

QUESTION

A device that attenuates specific modes propagating in the core of an optical fiber.

Mode filter

QUESTION

One of the most popular splicing techniques in commercial applications.

Electric arc fusion(arc fusion)

QUESTION

A short discharge of electric current that prepares the fiber ends for fusion.

prefusion

QUESTION

Two basic types of fiber optic connectors.

Butt-joined connectors and expanded-beam connectors

QUESTION

Use two lenses to first expanded and then refocus the light from the transmitting fiber into the receiving fiber.

Fiber optic expanded-beam connectors

QUESTION

Use two cylindrical plugs(referred to as ferrules), an alignment sleeve, and sometimes axial springs to perform fiber alignment.

Ferrule connectors

QUESTION

Two ways that the navy classifies fiber optic connectors.

Light-duty connectors and heavy-duty connectors

QUESTION

Redistributes the optical signal without optical-to-electrical conversion.

Passive coupler

QUESTION

Electronic devices that split or combine the signal electrically and use fiber optic detectors and sources for input and output.

Active couplers

QUESTION

A passive device that splits the optical power carried by a single input fiber into two output fibers.

Optical splitter

QUESTION

Normally splits the input optical power evenly between the two output fibers.

Y-coupler

QUESTION

A passive device that combines the optical power carried by two input fibers into a single output fiber.

Optical combiner

QUESTION

Combines the functions of the optical splitter and combiner.

X-coupler

QUESTION

Multiport couplers that have more than two input or two output ports.

Star and tree couplers

QUESTION

Caused by a step change in the refractive index that occurs at the fiber joint.

Fresnel reflection

QUESTION

Reduces the step change in the refractive index at the fiber interface, reducing Fresnel reflection.

Index matching gel

QUESTION

Occurs when a small gap remains between fiber-end faces after completing the fiber connection.

Fiber separation(longitudinal misalignment)

QUESTION

Occurs when the axes of the two fibers are off set in a perpendicular direction.

Lateral, or axial misalignment

QUESTION

Occurs when the axes of two connected fibers are no longer parallel.

Angular misalignment

QUESTION

Some common examples of poor fiber ends.

Fiber-end face tilt, lip, and hackle

QUESTION

The basic fiber cleaving technique for preparing optical fibers are coupling.

Score-and-break method

QUESTION

Removes most surface imperfections introduced by the fiber cleaving process.

Polishing the fiber ends

QUESTION

Occurs when the fiber, mounted to the polishing tool, moves over a 5µ to 15µ grit abrasive paper.

Rough-polishing

QUESTION

Occurs when the mounted fiber moves over a 0.3µ to 1µ grit abrasive paper in the same figure-eight motion.

Fine-polishing

QUESTION

A source of intrinsic coupling loss.

Fiber mismatches

QUESTION

A permanent fiber joint whose purpose is to establish an optical connection between two individual optical fiber.

Fiber optic splice

QUESTION

A fiber splice where mechanical fixtures and materials perform fiber alignment and connection.

Mechanical splice

QUESTION

A fiber splice where localized heat fuses or melts the ends of two optical fibers together.

Fusion splice

QUESTION

Epoxy resins that seal mechanical splices and provide index matching between the connected fibers.

Transparent adhesives

QUESTION

It means that the fiber cladding consists of a single homogeneous layer of dielectric material.

Matched cladding

QUESTION

It means that the fiber cladding consists of two regions: the inner and outer cladding regions.

Depressed cladding

QUESTION

The smallest operating wavelength when single mode fibers propagate only the fundamental mode.

Single mode fiber cutoff wavelength

QUESTION

Fibers having a silica glass core and a plastic cladding.

Plastic clad silica (PCS) fibers

QUESTION

Method wherein gaseous metal halide compounds, dopant material, and oxygen are oxidized(burned) to form a white silica powder (SiO2).

Vapor phase oxidation

QUESTION

Manufacturers call SiO2 the.

soot

QUESTION

Method wherein multicomponent glass rods form the fiber structure.

Direct-melt process

QUESTION

A tight-buffered fiber surrounded by arimid yarn and a low-halogen outer jacket.

Optical fiber cable components(OFCCs)

QUESTION

Makes a permanent joint between two fibers or two groups of fibers.

Fiber optic splice

QUESTION

Permit easy coupling and uncoupling of optical fibers.

Fiber optic connectors

QUESTION

Distribute or combine optical signals between fibers.

Fiber optic couplers

QUESTION

What are the main causes of coupling loss?

Poor fiber end preparation and poor fiber alignment

QUESTION

A measure of an optical source’s power launching capability.

Radiance

QUESTION

Caused by inherent fiber characteristics.

Intrinsic coupling losses

QUESTION

Caused by jointing techniques.

Extrinsic coupling losses

QUESTION

A short length of optical fiber (usually 1 meter or less) permanently fixed to the optical source or detector.

Fiber pigtail

QUESTION

Waves that are neither transmitted nor absorbed, but are reflected from the surface of the medium they encounter.

Reflected waves

QUESTION

When a wave approaches a reflecting surface, the wave that strikes the surface is called.

The incident wave

QUESTION

When a wave approaches a reflecting surface, the wave that bounces back is called.

The reflected wave

QUESTION

An imaginary line perpendicular to the point at which the incident wave strikes the reflecting surface is called.

The normal

QUESTION

The angle between the incident wave and the normal.

Angle of incidence

QUESTION

The angle between the reflected wave and the normal.

Angle of reflection

QUESTION

The angle of incidence is equal to the angle of reflection.

Law of reflection

QUESTION

Attenuation is mainly a result of what three properties?

Light absorption, scattering, and bending losses

QUESTION

The loss of optical power as light travels along the fiber.

attenuation

QUESTION

The portion of attenuation resulting from the conversion of optical power into another energy form, such as heat.

absorption

QUESTION

Caused by the electronic transition of metal ions, such as iron, nickel and chromium, from one energy level to another.

Extrinsic absorption

QUESTION

Describes the value of refractive index as a function of radial distance at any fiber diameter.

Refractive index profile

QUESTION

The refractive index of the core is uniform and undergoes an abrupt change at the core-cladding boundary.

Step-index profile

QUESTION

The refractive index at the core varies gradually as a function of radial distance from the fiber center.

Graded-index fiber

QUESTION

Determines the shape of the core’s profile.

Profile parameter (α)

QUESTION

The NA of a multimode graded-index fiber is at its maximum value at the fiber axis. This NA is the.

Axial numerical aperture,NA(O)