CTE CTE Fiber Optics & Transmission Systems

Question 1

What is the maximum attenuation typically specified for single-mode fiber at 1550 nm in modern DWDM systems?

Accepted Answer

0.2 dB/km

Answer

10 dB/km

Answer

3.5 dB/km

Answer

1.0 dB/km

Question 2

What distinguishes single-mode fiber (SMF) from multimode fiber (MMF) in terms of core diameter?

Accepted Answer

SMF has a ~9 µm core; MMF has a 50–62.5 µm core

Answer

SMF has a 50 µm core; MMF has a 9 µm core

Answer

Both have identical core diameters but differ in cladding material

Answer

SMF has a 100 µm core; MMF has a 62.5 µm core

Question 3

What type of dispersion in single-mode fiber causes different wavelength components of a pulse to travel at different speeds?

Accepted Answer

Chromatic dispersion

Answer

Modal dispersion

Answer

Polarization mode dispersion

Answer

Intermodal dispersion

Question 4

In an OTDR trace, a sharp spike followed by a loss step typically indicates what type of event?

Accepted Answer

A mechanical connector or reflective splice

Answer

A fiber bend exceeding the minimum bend radius

Answer

A fusion splice with loss

Answer

Fiber end-face damage

Question 5

Which ITU-T recommendation defines Dense Wavelength Division Multiplexing (DWDM) channel spacing and frequency grid?

Accepted Answer

ITU-T G.694.1

Answer

ITU-T G.691

Answer

ITU-T G.652

Answer

ITU-T G.984

Question 6

What is the primary function of an Erbium-Doped Fiber Amplifier (EDFA) in a long-haul DWDM link?

Accepted Answer

Amplify multiple WDM channels simultaneously in the optical domain without O-E-O conversion

Answer

Regenerate the optical signal by converting it to electrical and back to optical

Answer

Compensate chromatic dispersion across the fiber span

Answer

Monitor per-channel optical power for network management