R.M.K. ENGINEERING COLLEGE, RSM NAGAR, KAVARAIPETTAI – 601 206Unit Test Questions – July 2013

Sub. Code: 2402 Sub. Title : Optical Communication and Networking Class: B.E. 7th Semester –ECE

Duration : minutes Max. Marks: -------------------------------------------------------------------------------------------------------------------------------

Answer all questions Part A - (5 x 2 = 10), Part B - (2 x 16 + 1 x 8 = 40)--------------------------------------------------------------------------------------------------------------------------------

1. List any four major advantages of optical fiber communication system 2. Define acceptance angle for the fiber3. Write the expression for n(r), the index profile of graded index fiber4. An optical fiber in air has a numerical aperture 0.4. Compare the acceptance angle for

meridional rays with that for the skew rays which changes the direction by 1000 at each reflection

5. (a) Explain mode propagation in circular waveguides. Obtain its wave equation and modal equations for step index fiber (16)

(b) With the help of suitable diagrams, explain the following concepts in optical fiber transmission (i) Evanescent field (ii) Goos-Haenchen shift, (iii) mode coupling (iv) Mode field diameter

6. (a) calculate the fractional refractive index change and the largest core size of single mode operation of a parabolic profile with n1 = 1.465, n2 = 1.46 and

Operating wavelength = 1250nm. (8) (b) Explain the various attenuation mechanisms in the optical fiber (16)7. (a) Derive the expression for the numerical aperture of step index fiber (8) (b) Distinguish step index and graded index fibers with help of neat schematic

and their typical dimensions (8)8. (a) Explain mode propagation in circular waveguides. Obtain its wave equation and modal

equations for step index fiber (10) (b)Derive the approximation of NA = n1√2Δ for Δ<<1. What is the difference in the approximate and exact expressions for the value of NA if n1 = 1.49 and n2 =1.48 (10)

9. (a) With the help of suitable diagrams, explain the following concepts in optical fiber transmission (i) Evanescent field (ii) Goos-Haenchen shift, (iii) mode coupling

(iv)Mode field diameter (10) (b) Calculate the fractional refractive index change and the largest core size of

Single mode operation of a parabolic profile with n1 = 1.465, n2 = 1.46 and Operating wavelength = 1250nm. (10)----------------------------------------------------------------------------------------------

1. Define total internal Reflection (2)2. Distinguish between single mode and multimode fiber (2)3. Define Numerical aperture (2)4. Write the expressions for V number and number of modes for SI fiber (2)5. Specify the wavelength of operation of 3 windows (2)6. List any four major advantages of optical fiber communication system (2)7. Define acceptance angle for the fiber (2)8. Write the expression for n(r), the index profile of graded index fiber (2)9. Distinguish between SI and GI fiber (2)10. Distinguish between cladding mode and leaky modes (2)11. Define total internal Reflection (2)12. Distinguish between single mode and multimode fiber (2)13. Define Numerical aperture (2)14. Write the expressions for V number and number of modes for SI fiber (2)