1. A point sorce of ligth is 12 cm below the surface of a large body of water (n = 1.33). What is the radius of the largest circle on the water surface through whichthe light can emerge?

2. Consider a parabolic index waveguide with n1 =1.75 ,n2 = 1.677 and core radius25 micro meter. Calculate the numerical aperture at the axis and at a point 20micro meter from the axis

3. Define numerical aperture of a step index fiber4. Define mode-field diameter5. Commonly available single mode fibers have beat lengths in the range 10 cm < Lp

<2 m . What range of refractive index diffrences does this correspond to? (forwavelength = 1300 nm)

6. Define mode field diameter

7. What is the fundamental parameter of a single mode fiber?8. A step index fiber has a normalized frequency V = 26.6 at 1300 nm wavelength.

If the core radius is 25 pm, find the numerical aperture9. What are the advantages and disadvantages of the ray optics theory?10. A typical relative refractive index difference for an optical fiber designed for long

distance transmission is 1%.Estimate the numerical aperture for the fiber when the core index is 1.47.

11. Define group delay.12. An LED has radiative and nonradiative recombination times of 30 and 100 ns

respectively.Determine the internal quantum efficiency.13. Define responsivity of a photodetector.14. Compare the performance of APD and PIN diode.

15. Discuss signal distortion in single mode fibers16. Discuss pulse broadening in graded index fibers with necessary equations17. Discuss the propagation modes in single -mode fiber18. Discuss the structure of graded index fiber19. What is meant by 'material dispersion'? Derive its expression20. Discuss the pulse broadening in graded index fibers21. What are fiber modes? Explain mode theory for optical fibers in detail 22. Compare Single mode fibers and Graded index fibers. Explain the requirements for

fiber materials.23. What are fiber modes? Explain mode theory for optical fibers in detail.24. Compare Single mode fibers and Graded index fibers. Explain the requirements for

fiber materials.25. Discuss various kinds of losses that an optical signal might suffer while propagating

through fiber

26. With neat diagram explain the construction and working of high radiance surface emitting LED.

27. Discuss in detail digital receiver performance calculation and sensitivity calculation in detail.

28. Discuss in detail Fiber splicing and connectors. Explain the operation principles of WDM.

29. Define normalized propagation constant30. Give expression for the effective number of modes guided by a curved multimode

fiber31. What are the causes of absorption32. Find the coupling loss for two fibers having core refractive index profiles alpha E =

2.0 and alpha R = 1.5 .33. What causes mode coupling34. Mention the two causes of intra-modal dispersion.35. Define fiber loss.36. What is meant by hetero junction?

37. Briefly explain the evolution of fiber optic system38. Derive the expression for wave guide dispersion39. List the advantages of optical fiber communication40. Draw the elements of an optical fiber transmission link and explain41. Discuss the mode theory of circular waveguide

42. Draw the structures of edge-emitting LED and surface emitting LED andexplain the operation

43. Derive the internal quantum efficiency of an LED44. Define responsivity of photodiode.45. Define quantum efficiency of a photodetector46. Define responsivity47. A given APD has a quantum efficiency of 65 % at a wavelength of 90 nm . If 0.5

micro watt of optical power produces a multiplied photocurrent of 10 micro Ampere, find the multiplication

48. What is meant by quantum limit?49. A photodiode is constructed of GaAs, which has band gap energy of 1.43 eV at

300 K. What is meant by long wavelength cutoff?50. Draw the schematics of pin photodiode and APD and explain.51. Explain the fundamental receiver operation in optical communication

52. An InGaAs pin photodiode has the following parameters at a wavelength of1300 nm : I D = 4 nA, ? = 0.9, RL = 1000 ohms and the surface leakage current isnegligible. The incident optical power is 300 nw (- 35 dBm), and the receiverbandwidth is 20 MHz . Find the various noise terms of the receiver

53. Discuss the performance of digital receiver by defining the probability oferror

54. Discuss in detail digital receiver performance calculation and sensitivitycalculation in detail.

55. What is meant by soliton?56. What is meant by modal noise?57. Write the basic concept of soliton generation58. List the key requirements needed in analyzing a link.

59. Explain various types of fiber splicing techniques and fiber connectors60. Discuss the operational principles of WDM61. Describe the key features of WDM.62. Discuss briefly about linearly polarized modes. 63. Draw the structures of single and multimode step index fibers and graded index

fiber with typical dimensions.64. Explain the scattering and the bending losses that occur in an optical fiber with

relevant diagrams and expressions 65. Discuss polarization mode dispersion and its limitations 66. Explain the mechanical misalignments that can occur between two joined fibers

with necessary diagrams.67. Discuss with necessary expressions the different types of noise that affect the

performance of a photodetector.68. When 3´1011photons each with a wavelength of 0.85 mm are incident on a

photodiode, on an average 1.2´1011 electrons are collected at the terminals of the device. Determine the quantum efficiency and responsivity of the photodiode at 0.85 mm

69. Explain the salient features of solitons using relevant expressions and diagrams 70. Give a brief account of the different types of losses to be considered in the design of

an optical link.71. Draw and explain the basic format of an STS-N SONET frame