CTA Fiber Optics & Physical Layer Technologies

Question 1

What is the primary difference between single-mode fiber (SMF) and multimode fiber (MMF)?

Accepted Answer

SMF has a smaller core that supports one light path, enabling longer distances; MMF has a larger core supporting multiple light paths over shorter distances

Answer

SMF carries only analog signals; MMF carries digital signals

Answer

SMF is always faster than MMF regardless of distance

Answer

MMF is used for all long-haul backbone applications

Question 2

What phenomenon in fiber optic transmission causes different wavelengths of light to travel at slightly different speeds, limiting bandwidth over distance?

Accepted Answer

Chromatic dispersion

Answer

Attenuation

Answer

Modal noise

Answer

Fresnel reflection

Question 3

In DWDM (Dense Wavelength Division Multiplexing), what is the standard channel spacing defined by the ITU-T grid?

Accepted Answer

100 GHz (approximately 0.8 nm)

Answer

10 nm

Answer

1 nm

Answer

50 MHz

Question 4

What type of fiber connector is most commonly used in US data centers and enterprise networks for high-density single-mode applications?

Accepted Answer

LC (Lucent Connector)

Answer

ST (Straight Tip)

Answer

FC (Fiber Channel)

Answer

MTRJ

Question 5

What does an OTDR (Optical Time-Domain Reflectometer) measure in a fiber optic link?

Accepted Answer

The distance to faults, splices, and connectors by analyzing backscattered light pulses

Answer

The total fiber bandwidth capacity

Answer

The chromatic dispersion coefficient

Answer

The number of wavelengths on a DWDM system

Question 6

What is the typical operating wavelength window for long-haul single-mode fiber transmission in DWDM systems?

Accepted Answer

1550 nm C-band (approximately 1530–1565 nm)

Answer

850 nm window

Answer

1310 nm O-band only

Answer

1625 nm L-band exclusively