Question 1: The mean optical power launched to an optical fiber link is 1.5mW and the fiber consists of an attenuation of 0.5dB/Km. Find out the maximum possible link length devoid of repeaters when minimum mean optical power level needed at the detector is 2uW.
Question 2: The following parameters for silica are as shown below:
Fictive temperature = 1400K
Isothermal compressibility = 7 x 1011m2 N-1
Refractive index = 1.46
Photo elastic coefficient = 0.286
Boltzmann constant = 1.381 x 10-23 Jk-1
Find out attenuation due to fundamental Rayleigh scattering in decibels per kilometer at a wavelength of 0.63ms.
Question 3: A 6 Km optical link comprises of multimode step index fiber with a core refractive index of 1.5 and a relative refractive index difference of 1%. Find out:
a) The delay difference between the slowest and fastest modes at fiber output.
b) The rms pulse broadening due to intermodal dispersion on the link.
c) The maximum bit rate that might be obtained devoid of substantial errors on the link supposing only intermodal dispersion.
d) The bandwidth length product corresponding to (c).
Question 4: A multimode step index fiber consists of a NA of 0.3 and a core refractive index of 1.45. The material dispersion parameter for the fiber is 250 ps n/m/Km which makes material dispersion the totally dominating intramodal dispersion method. Determine:
a) The total rms pulse broadening per Km if the fiber is used with an LED source of rms spectral width 50 nanometer.
b) The corresponding bandwidth length product for the fiber.
Question 5: The beat length in a single mode optical fiber is around 9 cm if light from an injection LASER with a spectral line width of 1 nm and a peak wavelength of 0.9 micrometer is launched into it. Find out the model birefringence and determine the coherence length in this situation. In addition compute the difference between the propagation constants for the two orthogonal modes and check the outcome.
Question 6: The polarization mode dispersion in a consistently birefringent single mode fiber is 300 ps/Km. Compute the maximum bit rate that might be obtained on a 20 Km repeater less link supposing only polarization mode dispersion to take place.
Question 7: A multimode graded index fiber consists of a refractive index at the core axis of 1.46 with the cladding refractive index of 1.45. The critical radius of curvature that permits large bending losses to occur is 84 micrometer when the fiber is transmitting light of a particular wavelength. Find out the wavelength of the transmitted light.
Question 8: Describe the methods for measuring dispersion in optical fiber systems.