Active and Passive Components

Question 1

Explain the difference between an Active and Passive component?

Answer 1

An Active Component is one that requires external power to perform its function.

A Passive Component is one that requires No External power to perform its function.

Question 2

State four examples of an Active Component?

Answer 2

• Transmitters/Light Sources
• Receivers/Detectors
• Media and Mode Convertors
• Optical Switches
• Optical Amplifiers
• Routers

Question 3

What are the two different types of transmitters/light sources used in fibre optic systems?

Answer 3

Light Emitting Diodes (LED’s)

Laser Diodes

Question 4

State the four basic requirements of a Transmitter/Light Source?

Answer 4

Launch Power
Wavelength
Linewidth
Price

Question 5

State the advantage of a Laser over LED?

Answer 5

With a Laser, the intensity of the transmitted power is over a very short wavelength and over distance this allows a signal to be less affected by modal dispersion.

Question 6

State the drawback of using Laser over LED?

Answer 6

More Expensive than LED’s

Higher demand on drive circuits

Temperature-sensitive

Question 7

State the four basic requirements of a Receiver?

Answer 7

• Responsively
• Operating wavelength
• Sensitivity
• Dynamic range (dB).

Question 8

Explain the difference between a Switch and a Router?

Answer 8

A switch is designed to connect computers within a network, while a router is designed to connect multiple networks together.

Question 9

State two different types of Passive Components?

Answer 9

• Couplers and Splitters
• Wave Division Multiplexers
• Optical Isolators

Question 10

Explain how a Wavelength Division Multiplexer works?

Answer 10

It enables huge increases in network capacity by allowing many wavelengths to be transmitted simultaneously on each fibre in the network.

Question 11

Explain how Power Budgets are calculated?

Answer 11

Power budgets are calculated from the difference between the transmitter launch power level and the receiver minimum sensitivity level

For example, if the transmitter launch level was 13dBm and the receiver level was 42dBm (42 – 13 = 29) the power budget would be 29db.

Question 12

Explain how Loss Budgets are calculated?

Answer 12

Loss budgets are calculated by adding up the losses of the fibre cabling, splices and connectors.

A typical example of a loss budget for a multimode installation might be;

1km of 62.5/125 fibre at 850nm = 3.5dB
2 fusion splices = 0.6 dB
2 fibre connections = 1.5dB

		Total Loss Budget	=		5.6dB

Question 13

Calculate the Loss Budget for 10km of 8/125 OS2 cable operating at 1310nm and terminated with a FOPP using FC/PC pigtails?

Answer 13

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Question 14

Calculate the Loss Budget for 2km of 50/125 operating within the First Window of Operation, and terminated with Hot Melt ST connectors?

Answer 14

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