oc assignment questions

                                                OFC ASSIGNMENT-1                     date: 01-9-2011

1              Bring out a brief historical development of optical fiber communication

2   Draw the electromagnetic spectrum, Explain different ranges and their              wavelengths. Clearly show the range of wavelengths used for optical fiber   communication.

3          What are the advantages of optical fibers over conventional transmission lines?

4          What are the various elements of an optical communication system? Explain each element in brief.

5          a). Describe the quantum nature of light. Explain basic optical laws in detail with   

                 Relevant mathematical expressions.

            b). Define and explain V-number

6          Define an optical fiber. Explain in detail different types of optical fibers giving neat sketches.

7          A silica optical fiber with a core diameter large enough to be considered by ray   

           theory analysis has a core refractive index of 1.5 and a cladding refractive index of   

           1.47. Determine

i)                    Critical angle at the core cladding interface

ii)                  Acceptance angle in air for the fiber.

8          Explain numerical aperture with reference to ray theory transmission?

9          The average optical power launched into a 10-km length of fiber is 100mw and the   

            Average output power is 25 mw. Calculate

i)          The signal attenuation in dB through the fiber. It is assumed that there are no connectors or splices.                                                                                        

ii)         Signal attenuation per km of the fiber                                                         

iii)        Overall signal attenuation for the 11km optical link using the same fiber with 3 splices each having an attenuation of 0.8dB                                                    

            iv)        Numerical value of the ratio between input & output pow

10.       a).Discuss briefly about radiative losses in the optical fiber              

        b).Explain the core and cladding losses in the optical fiber and also derive the    

            expression for those losses.

11        Derive the expression for the critical radius of curvature for single mode and   

            Multimode fibers.                                                                                          

12        List the differences between intramodal & intermodal dispersions. 

13.       What are the three important mechanisms that are responsible for absorption           losses in signal through an optical fiber? Explain in brief the curve for    wavelength versus attenuation for different ranges of the signal.

14.       Derive the expression for the relationship between material dispersion and wavelength of the optical fiber with suitable examples.          

15        Describe the techniques used to give both electrical and optical confinement in        

       Multimode  injection lasers. Contrast these techniques when used in gain-guided  

       and index guided lasers.

16         Draw the schematic diagram of high radiance surface emitting LED and edge  

       Emitting double hetero junction LED and explain the working of both in detail.

17     What are the requirement of photo detector and why photodiode is preferred in  

      fiber optic communication systems?

      18  Outline the reasons for the adoption of the materials and devices used for        

      Photo-detection in optical fiber communications.

19    With respect to LED why hetero-junction devices are suitable for optical fiber communication systems?  

20    Briefly describe the direct and indirect band gap semiconductor material               

21    Explain the factors, which reduce the lifetime and internal quantum efficiency of the source.

                                                               LAST DATE OF SUBMISSION: 05-9-20011