Chapter 3 - Theory

Question 1

Fiber with a ______ numerical aperture have a _________ bandwidth capability due to greater pulse spreading. Called modal dispersion.

Answer 1

Large; smaller

Question 2

The bending of a beam of light in transmission between two dissimilar lights.

Answer 2

Refraction

Question 3

Index of refraction

Answer 3

1.471 (miles and kilometers per second)

Question 4

When a light beam changes direction at an interface, between two dissimilar media and reflects back into the medium from which it originated.

Answer 4

Fresnel Reflection

Question 5

The sum of all reflections in a fiber span, including all component reflections and the Rayleigh backscatter of the optical fiber.

Answer 5

Optical Return Loss

Question 6

Reflectance and ORL are expressed in

Answer 6

dB

Question 7

Fiber optics typically uses wavelengths that are transmitted from which wavelength range?

Answer 7

770 nm to 1675 nm wavelength

Question 8

Nanometers most commonly used in fiber optics?

Answer 8

850, 1300, 1310, 1550, 1625

Question 9

Are infrared regions visible to the human eye?

Answer 9

Yes

Question 10

The _____________ is different at each wavelength.

Answer 10

Speed of light

Question 11

Loss of signal power

Answer 11

Attenuation

Question 12

Core and cladding ovality is ____________

Answer 12

Fiber Geometry

Question 13

When transmission loss increases because the fiber radius has decreased to the point that light rays begin to pass through the cladding boundary.

Answer 13

Macrobending

Question 14

Manufactured using existing G.652 fiber specifications and are ideal for fiber to the building.

Answer 14

Bend-insensitive single-mode fibers

Question 15

Lowest losses and reflections are created by having the fibers in contact or near contact.

Answer 15

End Separation

Question 16

What does VCSEL Source stand for?

Answer 16

Vertical-cavity surface - emitting laser as source

Question 17

What fiber is constructed with a core that has hundreds of concentric layers of glass between the center of the core and the cladding?

Answer 17

Graded-index Lightwave Propagation Multimode Fiber

Question 18

What is Chromatic dispersion?

Answer 18

Different wavelengths travel at different speeds, leading to unequal amounts of bending.

Question 19

What is a multimode issue that limits bandwidth?

Answer 19

Modal dispersion

Question 20

What does the number of modes in a fiber do as the wavelengths decrease?

Answer 20

The number of modes increases

Question 21

The _________ the fiber’s numerical aperture, the greater the effect of DMD.

Answer 21

Larger

Question 22

Which wavelength has the lowest attenuation?

Answer 22

1550nm

Question 23

What part of the electromagnetic spectrum is used by fiber optic systems?

Answer 23

Infrared Light Region

Question 24

What is the bending of light called?

Answer 24

Refraction

Question 25

What type of reflection is caused by an air gap in the connector pair?

Answer 25

Fresnel

Question 26

What are three ways to reduce modal dispersion in a multimode system?

Answer 26

LED, VCSEL, Graded-index fiber

Question 27

True or False: All wavelengths travel at the same speed through the fiber.

Answer 27

False

Question 28

What type of dispersion effects multimode fiber and is a direct relation to the larger core size?

Answer 28

Modal dispersion