Telecommunications Fiber Optics

Question 1

What physical phenomenon allows fiber optic cables to transmit light?

Accepted Answer

Total internal reflection

Answer

Total internal reflection causes light to bounce within the fiber core when it strikes the cladding at an angle below the critical angle.

Question 2

What is the difference between single-mode and multimode fiber?

Accepted Answer

Single-mode has a smaller core and supports longer distances; multimode has a larger core for shorter distances

Answer

Single-mode fiber's smaller core (8-10 µm) allows only one light path, reducing dispersion and enabling longer transmission distances than multimode.

Question 3

What does OTDR stand for and what is it used for?

Accepted Answer

Optical Time Domain Reflectometer; used to test fiber for faults and measure length

Answer

An OTDR (Optical Time Domain Reflectometer) sends light pulses into fiber and analyzes reflections to locate faults, splices, and measure cable length.

Question 4

What wavelength does standard single-mode fiber primarily use for long-haul transmission?

Accepted Answer

1550 nm

Answer

1550 nm (C-band) is the preferred wavelength for long-haul single-mode transmission because optical fiber has minimum attenuation at this wavelength.

Question 5

What does WDM stand for in fiber optics?

Accepted Answer

Wavelength Division Multiplexing

Answer

WDM (Wavelength Division Multiplexing) combines multiple optical signals at different wavelengths on a single fiber, multiplying capacity.

Telecommunications Practice Test

Telecommunications Practice Test

Telecommunications Fiber Optics