Description : LEDs operating at 850 nm provide sufficient optical power for short-distance, low-bandwidth multimode systems. List three conditions that prevent the use of LEDs in longer distance, higher bandwidth multimode systems.
Last Answer : Multimode fiber dispersion, the relatively high fiber attenuation, and the LED's relatively low optical output power.
Description : List the two principal optical detectors used in fiber optic systems.
Last Answer : The semiconductor positive-intrinsic-negative (PIN) photodiode and avalanche photodiode (APD).
Description : Why can multimode graded-index fiber 1300-nm systems using LEDs operate over longer distances and at higher bandwidths than 850-nm systems?
Last Answer : Longer distances and higher bandwidths are possible because fiber material losses and dispersion are significantly reduced at the 1300-nm region.
Description : Why are LEDs preferred over laser diodes for low- and moderate-frequency analog applications?
Last Answer : LEDs require less complex circuitry than lasers.
Description : Which type of fiber optic connector (butt-jointed or expanded beam) brings the prepared ends of two optical fibers into close contact?
Last Answer : Butt-jointed connectors.
Description : Which part of a fiber optic transmitter converts the processed electrical signal to an optical signal?
Last Answer : The optical source.
Description : Why are visible-light LEDs not used for fiber optics? ∙ a. It has high losses ∙ b. It has short wave ∙ c. It has low attenuation ∙ d. It has weak signal
Last Answer : ∙ a. It has high losses
Description : Why is detector saturation not generally a problem in fiber optic communications systems?
Last Answer : Because fiber optic communications systems operate at low optical power levels.
Description : List five precautions to take when installing fiber optic systems on board naval ships.
Last Answer : a. Never bend an optical fiber or cable at a radius of curvature less than the minimum bend radius. b. Never pull fiber optic cables tight or fasten them over or through sharp corners or ... the hardware. e. Allow only trained, authorized personnel to install or repair fiber optic systems.
Description : What type of modulation do most analog fiber optic communications systems use?
Last Answer : Intensity modulation.
Description : In fiber optic systems, designers consider what trade-offs?
Last Answer : Trade-offs in fiber properties, types of connections, optical sources, and detector types in military and subscriber-loop applications.
Description : Which light emitter is preferred for high-speed data in a fiber-optic system? ∙ A. incandescent ∙ B. LED ∙ C. neon ∙ D. laser
Last Answer : D. laser
Description : Which light emitter is preferred for high speed data in a fiber-optic system ∙ a. Incandescent ∙ b. LED ∙ c. Neon ∙ d. Laser
Last Answer : ∙ d. Laser
Description : Which of the following is not a common application of fiber-optic cable? a. Computer networks b. Long-distance telephone systems c. Closed circuit TV d. Consumer TV
Last Answer : d. Consumer TV
Description : Which of the following is not a common application of fiber-optic cable? ∙ a. Computer networks ∙ b. Long-distance telephone systems ∙ c. Closed circuit TV ∙ d. Consumer TV
Description : Why is it generally only necessary to refer to point-to-point data links when discussing the process of fiber optic system design?
Last Answer : Because fiber optic systems that incorporate complex architectures can be simplified into a collection of point-to-point data links before beginning the design process.
Description : List the three parts of a fiber optic data link
Last Answer : Transmitter, optical fiber, and receiver.
Description : Describe the basic functions of a fiber optic data link
Last Answer : The basic functions of a fiber optic data link are to 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 electrical signal.
Description : Fiber optic connectors can reduce system performance by increasing what two types of noise?
Last Answer : Modal and reflection.
Description : What are the two types of output interfaces for fiber optic transmitters?
Last Answer : Optical connectors and optical fiber pigtails.
Description : What are the two basic types of preamplifiers used in fiber optic receivers?
Last Answer : The high-impedance amplifier and the transimpedance amplifier.
Description : List the types of fiber optic components considered part of a fiber optic cable plant.
Last Answer : Optical fiber cables, connectors, splices, mounting panels, jumper cables, and other passive components.
Description : Give two reasons why optical fiber manufacturers depart from the traditional circular core and cladding, low-loss glass fiber design?
Last Answer : To increase performance and reduce cost
Description : Does underfilling a multimode optical fiber excite mainly high-order or low-order modes?
Last Answer : Low-order modes.
Description : Low-order and high-order modes propagate along an optical fiber. How are modes determined to be low-order or high order modes?
Last Answer : Depends on the bending caused by the velocity difference of the wave traveling through different mediums
Description : . The product of the bit rate and distance of a fiber-optic system is 2 Gbits-km/s. What is the maximum rate at 5 km? ∙ A. 100 Mbits/s ∙ B. 200 Mbits/s ∙ C. 400 Mbits/s ∙ D. 1000 Gbits/s
Last Answer : C. 400 Mbits/s
Description : The product of the bit rate and distance of a fiber-optic system is 2 Gbits km/s. What is the maximum rate at 5 km? ∙ a. 100 Mbits/s ∙ b. 200 Mbits/s ∙ c. 400 Mbits/s ∙ d. 1000 Gbits/s
Last Answer : c. 400 Mbits/s
Description : SONET stands for ∙ a. System Optical Network ∙ b. Synchronous Optical Network ∙ c. Silica Optic Network ∙ d. System Optical Fiber Net
Last Answer : ∙ b. Synchronous Optical Network
Description : Most fiber optic light sources emit light in which spectrum? ∙ A. visible ∙ B. infrared ∙ C. ultraviolet ∙ D. X-ray
Last Answer : B. infrared
Description : Most fiber-optic light sources emit light in which spectrum? ∙ a. Visible ∙ b. Infrared ∙ c. Ultraviolet ∙ d. X-ray
Last Answer : ∙ b. Infrared
Description : Which performance parameter is the minimum amount of optical power required to achieve a specific bit-error rate (BER) in digital systems or a given signal-to-noise ratio (SNR) in analog systems?
Last Answer : Receiver sensitivity.
Description : What is the difference between passive and active fiber optic couplers?
Last Answer : Passive couplers redistribute optical signals without optical-to electrical conversion.
Description : The Navy classifies fiber optic connectors in what two ways?
Last Answer : Light-duty and heavy-duty connectors.
Description : What connection properties result in fiber optic connector coupling loss?
Last Answer : Poor fiber alignment and end preparation, fiber mismatches, and Fresnel reflection.
Description : Define a fiber optic splice.
Last Answer : A permanent fiber joint whose purpose is to establish an optical connection between two individual optical fibers.
Description : Which fiber optic component (splice, connector, or coupler) makes a permanent connection in a distributed system?
Last Answer : Splice.
Description : List five common fiber optic transmitter packages.
Last Answer : TO can, DIP, butterfly lead microcircuits, circuit cards, and stand-alone optical fiber converters.
Description : What are the three parts of a fiber optic transmitter?
Last Answer : Interface circuit, source drive circuit, and an optical source.
Description : What is a fiber optic receiver?
Last Answer : An electro-optic device that accepts optical signals from an optical fiber and converts them into electrical signals
Description : List four system topologies that can be constructed using point-to-point fiber optic links.
Last Answer : Linear bus, ring, star, and tree topologies.
Description : What is the main disadvantage of using fiber-optic cables?
Last Answer : High attenuation.
Description : What effect does noise have on the fiber optic signal?
Last Answer : Noise obscures or reduces the quality of the signal.
Description : Explain with neat sketch block diagram of optical fiber communication system and list out sources and detectors suitable for it.
Last Answer : OR 1. The light source is normally an infrared LED or LASER device which is driven by the current value from the V to I convertor. It emits light which is proportional ... optical energy electrical signal. The light detectors which are used as PIN photodiode and avalanche photo diode.
Description : Which semiconductor sources (LD or LED) emit more focused light and are capable of launching sufficient optical power into both single mode and multimode fibers?
Last Answer : LDs.
Description : Are the effects of temperature changes on LDs more or less significant than for LEDs?
Last Answer : More.
Description : Semiconductor LEDs emit incoherent light. Define incoherent light
Last Answer : Light waves that lack a fixed-phase relationship
Description : Which type of optical splitter (Y-coupler or T-coupler) splits only a small amount of power from the input fiber to one of the output fibers?
Last Answer : T-coupler
Description : What is the basic fiber cleaving technique for preparing optical fibers for coupling?
Last Answer : Score-and-break.
Description : Quality fiber-end preparation is essential for proper system operation. What properties must an optical fiber-end face have to ensure proper fiber connection?
Last Answer : Be flat, smooth, and perpendicular to the fiber axis.
Description : The amount of optical power coupled into an optical fiber depends on what four factors?
Last Answer : (1) The angles over which the light is emitted. (2) The size of the source's light-emitting area relative to the fiber core size. (3) The alignment of the source and fiber. (4) The coupling characteristics of the fiber (such as the NA and the refractive index profile)