Optical systems and networks

1. Maximum attenuation range of a Gigabit PON is:

		a)	3 dB
		b)	13 dB
		c)	32 dB
		d)	130 dB

Evaluate your answer

2. The physical reach of a PON is typically:

		a)	200 km
		b)	>1000 km
		c)	20 km
		d)	few meters

Evaluate your answer

3. Gigabit PON by ITU-T (2010) can offer the following bit rates for the downstream / upstream:

		a)	1 Gbps symmetric
		b)	10 Gbps / 2.5 Gbps asymmetric
		c)	10 Gbps symmetric
		d)	10 Gbps / 1.25 Gbps asymmetric

Evaluate your answer

4. DWDM allows for:

		a)	channel spacing at least 20 nm
		b)	channel spacing 0.8 nm and even less
		c)	the use of Fabry-Perot lasers
		d)	the use of LED

Evaluate your answer

5. CWDM allows for:

		a)	channel spacing 20 nm or more
		b)	channel spacing 0.8 nm and even less
		c)	the reach of about 1000 km
		d)	fibre capacity up to 1 Tbps

Evaluate your answer

6. FTTH is:

		a)	an active optical network without any passive network components
		b)	access network, where fibres are terminated at the end user's home
		c)	an access network, where fibres are combined with metallic infrastructure
		d)	an access network, where fibres are combined with Wi-Fi connection

Evaluate your answer

7. Basic transport module in Optical Transport Hierarchy (OTM -0.1, without multiplexing) can transmit:

		a)	STM-16 at 2.5 Gbps
		b)	STM-16 at 10 Gbps
		c)	STM-64 at 2.5 Gbps
		d)	STM-64 at 40 Gbps

Evaluate your answer

8. Optical splices:

		a)	have greater attenuation than optical connectors
		b)	exhibit no back reflections, which affect connectors
		c)	typically, have attenuation of about 1-2 dB
		d)	cannot be detected by optical reflectometers

Evaluate your answer

9. OTDR:

		a)	uses the mechanism of Stimulated Raman Scattering
		b)	uses the mechanism of Rayleigh back-scattered light
		c)	requires access to both ends of a fibre
		d)	can measure at the distance of 1000 km (undersea connections)

Evaluate your answer

10. OTDR

		a)	displays optical splices as peaks (local maximum of intensity)
		b)	displays optical connectors as peaks
		c)	cannot display splices because of no back reflections
		d)	cannot display connectors because of large back reflections

Evaluate your answer

11. The typical range of EDFA's gain is:

		a)	5 to 10 dB
		b)	30 to 50 dBm
		c)	20 to 50 dB
		d)	10 to 15 dBm

Evaluate your answer

12. Booster is an optical amplifier, which is located:

		a)	at the beginning of the network close to the source of optical radiation
		b)	at the termination of the network, right before the receiver of optical radiation
		c)	in the middle of the network, together with dispersion compensator
		d)	at the end of the network, but its pump is located in the middle of the network

Evaluate your answer

13. EDFA's principle of operation is associated with

		a)	Stimulated Raman Scattering
		b)	back scattering
		c)	stimulated emission of radiation
		d)	spontaneous emission of radiation

Evaluate your answer

14. Raman amplifier can generate radiation at the wavelength that is:

		a)	identical to the wavelength of the pump module
		b)	dependant on the length of the fibre
		c)	shifted by about 100 nm towards longer wavelengths
		d)	shifted by about 100 nm towards shorter wavelengths

Evaluate your answer

15. Raman amplifier can operate as:

		a)	RLA
		b)	RDA
		c)	NRD
		d)	DRA

Evaluate your answer

16. One of the disadvantages of doped fibre amplifiers is:

		a)	low gain
		b)	narrow spectrum of emitted wavelengths
		c)	significant ASE noise
		d)	flat gain

Evaluate your answer

17. EDFA's pump can operate at the wavelength of:

		a)	630 nm
		b)	980 nm
		c)	630 nm
		d)	1550 nm

Evaluate your answer

18. Chromatic dispersion:

		a)	is expressed in [ps/km]
		b)	is composed of material and modal dispersion
		c)	is composed of material and polarization mode dispersion
		d)	means that each frequency component propagates at different speed

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19. Modal dispersion

		a)	means that each frequency propagates along different optical path (trajectory)
		b)	means that each frequency component propagates at different speed
		c)	means that each mode propagates along different optical path (trajectory)
		d)	is always a negative value

Evaluate your answer

20. Dispersion Compensating Fibres:

		a)	can be designed as Photonic Crystal Fibres
		b)	exhibits positive values of dispersion parameter
		c)	can have dispersion of even 1000 ps/ns/km
		d)	can compensate positive material dispersion by negative modal dispersion

Evaluate your answer

21. PMD refers to:

		a)	different speed for both axes of a fibre
		b)	interference of selected polarizations
		c)	different values of refractive index at different fibre lengths
		d)	each wavelengths propagating at different speed

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22. Running DWDM system over CWDM system:

		a)	has as its goal to increase the information capacity and the transmission rate
		b)	is required because CWDM technology is no longer supported
		c)	requires different modulation format for CWDM and DWDM
		d)	is impossible because of Four Wave Mixing

Evaluate your answer