COMMUNICATION ENG. PROF. A.M.ALLAM TUT-2 TRANS. CHARAC. OF OPTICAL FIBERS LECTURES

COMMUNICATION ENG. PROF. A.M.ALLAM 1-A LED of radius 20 um puts out 0.2 mW. How much power is coupled in 50/125 SI fiber whose NA=0.25. Repeat for the single mode SI fiber of 5/125 with NA = 0.15 2-A LED of radius 25 um is coupled to 5 um SM fiber with numerical aperture 0.15 . Determine the coupling efficiency 3-A laser of dimensions 0.5x0.5 um2 puts power 0.2 mw. How much power is coupled to a SM fiber with numerical aperture 0.15 and radius 5um. 4-The mean optical power launched into an optical fiber link is 1.5 mW and the fiber has an attenuation of 0.5 dB/km. Determine the maximum possible link length without repeaters (assuming lossless connectors) when the minimum mean optical power level required at the detector is 2 µW. LECTURES

COMMUNICATION ENG. PROF. A.M.ALLAM 5-An 8 km optical fiber link without repeaters uses multimode graded index fiber which has a bandwidth-length product of 400 MHz km. Estimate: a-The total pulse broadening on the link b- the rms pulse broadening on the link 6- A multimode, optimum near parabolic profile graded index fiber has a material dispersion parameter of 30 ps nm-1 km-1 when used with a good LED source of rms spectral width 25 nm. The fiber has a numerical aperture of 0.4 and a core axis refractive index of 1.48. Estimate the total rms pulse broadening per kilometer within the fiber assuming waveguide dispersion to be negligible. Hence, estimate the bandwidth-length product for the fiber 7-GI fiber has a parabolic refractive index profile and core diameter of 50um. The fiber is jointed with a lateral alignment between the core axes of 3um and there is index matching. Determine the insertion loss at the joint due to lateral misalignment: a-there is a uniform illumination of all guided modes only; b-there is a uniform illumination of all guided and leaky modes LECTURES

COMMUNICATION ENG. PROF. A.M.ALLAM 8-SI fiber has a refractive index of 1.48 with numerical aperture of 0.4. The fiber is jointed with 5o angular misalignment of the core axes of 5um. Determine the insertion loss at the joint due to an angular misalignment of 5o LECTURES