OSP Links

Question 1

True/False

Fiber optic links generally use two fibers for full duplex (bidirectional) links.

Answer 1

ANSWER: True

The easiest way to transmit signals over fiber is to use one fiber for transmission in each direction. FTTH is an exception that used each fiber bidirectionally.

Question 2

True/False

LEDs have higher output power and bandwidth than lasers.

Answer 2

ANSWER: False

No, LEDs have lower output power and less bandwidth than lasers.

Question 3

Singlemode fiber systems covering long distances and using DWDM use \_\_\_\_\_\_\_\_\_\_ sources.
A. F-P laser
B. DFB laser
C. VCSEL
D. LED

Answer 3

ANSWER: B. DFB laser

DFB lasers (distributed feedback lasers) have more power, narrower spectral width and greater stability which makes them prefereable for DWDM.

Question 4

Wavelength division multiplexing uses __________ to transmit multiple signals on a single fiber.
A. The ability of fiber to transmit multiple wavelengths without mixing
B. F-P Lasers
C. The wide spectral width of lasers
D. The high fiber bandwidth

Answer 4

ANSWER: A. The ability of fiber to transmit multiple wavelengths without mixing

WDM works because different wavelengths (colors) of light can be transmitted simultaneously without interference.

Question 5

Coarse wavelength division multiplexing (CWDM) systems require __________ to allow transmitting in the E-Band (1260-1360 nm).
A. Low water peak fiber
B. DFB lasers
C. 1490 nm pump lasers

Answer 5

ANSWER: A. Low water peak fiber

Coarse wavelength division multiplexing (CWDM) uses the entire range of wavelengths from 1260 to 1675 nm, including the wavelengths previously unavailable due to the water peak at 1383 nm.

Question 6

Long wavelength singlemode links at wavelengths in the range of 1300-1650 nm links must use __________ detectors in the receiver for the best sensitivity performance.
A. Silicon
B. Germanium
C. InGaAs

Answer 6

ANSWER: C. InGaAs

InGaAs detectors are the ones which have the necessary sensitivity at the longer wavelengths and low enough noise to make good receivers.

Question 7

Fiber amplifiers used in DWDM systems work in the \_\_\_\_\_\_\_\_\_\_ wavelength range.
A. 650-850
B. 850-1300
C. 1300-1550
D. 1480-1650

Answer 7

ANSWER: D. 1480-1650

Erbium-doped fiber amplifiers work in the 1480-1650 nm range.

Question 8

Multiple Response: Identify one or more choices that best complete the statement or answer the question.

Singlemode transceivers use \_\_\_\_\_\_\_\_\_\_ sources for their higher coupled power and bandwidth.
 A. LED
 B. VCSEL
 C. F-P lasers
 D. DFB lasers

Answer 8

ANSWER: C,D

F-P and DFB lasers have the right characteristics for SM transmission.

Question 9

Multiple Response: Identify one or more choices that best complete the statement or answer the question.

Multimode transceivers use \_\_\_\_\_\_\_\_\_\_ sources depending on their requirements for coupled power and bandwidth.
 A. LED
 B. VCSEL
 C. F-P lasers
 D. DFB lasers

Answer 9

ANSWER: A,B

LEDs are used for slower MM links, VCSELs for faster ones.