ANSWERS TO QUESTIONS Q1. THROUGH Q48.

A1. Photons.
A2. Transverse-wave motion.
A3. Light waves are either transmitted, refracted, reflected, or absorbed.
A4. Transparent.
A5. Opaque.
A6. The law of reflection states that the angle of incidence is equal to the angle of reflection.
A7. When the wave is nearly parallel to the reflecting surface.
A8. When the wave is perpendicular to the reflecting surface.
A9. The law of reflection.
A10. Depends on the bending caused by the velocity difference of the wave traveling through different mediums.
A11. Transmitted.
A12. Diffusion.
A13. The ray theory and the mode theory.
A14. The index of refraction.
A15. Light will travel faster in an optical material that is less dense.
A16. Part of the light ray is reflected back into the glass and part of the light ray is refracted (bent) as it enters the air.
A17. Total internal reflection occurs when the angle of refraction approaches 90 degrees. This condition occurs when the angle of incidence increases to the point where no refraction is possible.
A18. Critical angle of incidence.
A19. Core, cladding, and coating or buffer.
A20. Core.
A21. The ray theory.
A22. Total internal reflection.

A23. Smaller.
A24. NA measures the light-gathering ability of an optical fiber.
A25. Skew ray angle.
A26. Modes of the fiber.
A27. Direction, amplitude, and wavelength of propagation.
A28. Yes, the wavefront will disappear because the total amount of phase collected must be an integer multiple of 2π. (If the propagating wavefronts are out of phase, they will disappear. The wavefronts that are in phase interfere with the wavefronts out of phase. This type of interference is called destructive interference.)
A29. Cutoff wavelength.
A30. Multimode fiber.
A31. The order of a mode is indicated by the number of field maxima within the core of the fiber. The order of a mode is also determined by the angle that the wavefront makes with the axis of the fiber.
A32. Mode coupling is the exchange of power between two modes.
A33. Increase.
A34. V ≤ 2.405.
A35. Decrease.
A36. Core diameter, NA, and index profile properties.
A37. Light absorption, scattering, and bending losses.
A38. Attenuation is the loss of optical power as light travels along the fiber.
A39. Intrinsic and extrinsic material properties.
A40. Ultraviolet absorption region (below 400 nm) and infrared absorption region (above 2000 nm).
A41. The first, second, and third windows of operation are 850 nm, 1300 nm, and 1550 nm, respectively.
A42. Rayleigh scattering.
A43. (a) Mie scattering; (b) Rayleigh scattering.
A44. Uneven coating applications, improper cabling procedures, and external force.
A45. Fiber sensitivity to bending losses can be reduced if the refractive index of the core is increased and/or if the overall diameter of the fiber increases.
A46. Material dispersion and waveguide dispersion.
A47. Waveguide dispersion.
A48. Modal dispersion.