Nokia Optical Networking Fundamentals

Here you have the best Nokia 4A0-205 practice exam questions

You have 48 total questions to study from
Each page has 5 questions, making a total of 10 pages
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This questions were last updated on May 10, 2025
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Question 1 of 48

What is the definition of OSNR?

The OSNR is defined as the ratio between the transmitted optical power and the received optical power over 1 km of fiber, including both signal and optical noise.

The OSNR is the ratio between the optical output signal power and the optical input signal power of the device being analyzed.

The OSNR is defined as the ratio between the average optical signal power and the average optical noise power over a specific spectral bandwidth.

The OSNR is defined as the ratio between the optical signal power (including noise) and the optical noise power over a specific spectral bandwidth.

Correct Answer: C

The Optical Signal-to-Noise Ratio (OSNR) is defined as the ratio between the average optical signal power and the average optical noise power over a specific spectral bandwidth. This definition accurately identifies OSNR as a measure of the quality of an optical signal by comparing its strength to the noise level within a given bandwidth.

Question 2 of 48

Which of the following are the main reasons for fiber attenuation?

Refraction and reflection

Scattering and absorption

Chromatic dispersion (CD) and polarization mode dispersion (PMD)

Small channel spacing

Correct Answer: B

The main reasons for fiber attenuation are scattering and absorption. Scattering occurs when light is scattered in different directions due to microscopic variations in the fiber material, while absorption happens when impurities in the fiber absorb some of the light energy, converting it to heat. Both these factors contribute to the loss of signal strength as light travels through an optical fiber.

Question 3 of 48

What is the meaning of first, second, and third window in the optical fiber propagation context?

These windows correspond to three different minimum and maximum optical power levels used for optical transmission.

These windows are three different wavelength intervals where the WDM optical transmission occurs.

These three windows are three different angles of incidence of the light injected by the laser into the fiber.

Different optical transmission windows correspond to different safety requirements and rules for the related lasers operating with these windows.

Correct Answer: B

In the context of optical fiber propagation, the first, second, and third windows refer to specific wavelength intervals where optical transmission is most efficient. These windows are typically associated with fiber optic communication and Wavelength Division Multiplexing (WDM) systems, where different wavelength ranges are used to transmit multiple signals simultaneously over a single fiber. The first window is usually around 850 nm, the second window around 1300 nm, and the third window around 1550 nm. These ranges are chosen due to their low attenuation and minimal signal loss properties.

Question 4 of 48

In which window(s) does the attenuation reach its minimum peak?

First window (850 nm)

Second window (1300 nm)

Third window (1550 nm)

Both first and second windows

Correct Answer: C

The correct answer is the third window (1550 nm). Attenuation in optical fibers is lowest in the third window, around 1550 nm, where the signal loss is minimized, making it ideal for long-distance communication.

Question 5 of 48

Which of the following statements is true about chromatic dispersion (CD)?

Different channels have different bandwidth and this causes different CD performances.

The fiber attenuation changes along the fiber, and when the light crosses these differences the CD takes place.

Different wavelengths propagate at different speeds within the same media and therefore different colors travel in the fiber with different speed.

The fiber attenuation introduces inter-channel interference.

Correct Answer: C