DWDM Questions

DWDM QUESTIONS

1. How are optical fiber amplifiers classified? Where are they placed with reference to a laser source? A. They are classified in power amplifier’s, placed at the output of a laser source, preamplifier’s placed before the receiver and line amplifier’s placed somewhere between the source and the receiver. 2. What are the factors affecting optical technology A. a. Next Generation Fibers b. Optical cross-connect c. All Optical regenerators d. Broadband Amplifiers e. Grating Technologies f. End-to-End Network Management g. Circulators h. Optical ADM i. Wavelength Routing j. Translators k. All optical Signal Processing and Optical PM l. Tunable Lasers m. Fixes Lasers/ Receivers on ITU Grid 3. Modal Dispersion applies to both Single mode and Multimode fibers True/False A. False – Only to MMF 4. Why wavelength conversion? A. For Scalability, Performance, to reduce wavelength contention, transparent, interoperability, increase network capacity. 5. List all the optical network elements A. Optical fibers, optical amplifiers, wavelength division mux/demux, transponders, optical add/drop mux (OADM) and optical cross-connect (OCCS or OXC) 6. What are the performance parameters of a optical amplifier A. Gain, Noise figure, and saturated output.

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DWDM QUESTIONS

7. What is the linear and nonlinear effect? A. In linear effect the transmission problem increases as the length of the cable increases. Example – Attenuation. In Non Linear effect the transmission problem increases as the signal power increases and it is independent of the length of the cable. Example – Scattering. 8. Four wave mixing (FWM) in fiber transmission system is a phenomenon that can be eliminated – True / False A. False – Cannot be eliminated. 9. What are the pros and cons of optical ring? A. Pros     

Sectionalize network by geography Fast (50) Restoration, high reliability Simplified OSS, each ring is a complete system uses mature SONET concepts for OSS control. Simple Switching mechanisms Incremental builds as you need capacity, less up-front outlay

Cons    

Cost/complexity increase if demands must transit multiple rings from O-D Does not support restoration COS – All protected and non protected (except for preemptable service) As network scales, must ‘stack’ rings to service demands Limited flexibility to handle demand churn without manual intervention

10. Why fibers carry so much data? A. A single laser can be turned on and off up to a billion times per second and a single strand of glass fiber can carry multiple wavelengths (different colors) of light simultaneously.

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DWDM QUESTIONS

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