HW #4due 2/23/12 5PMNo later than 2/27/12 5PM1. An optical fiber has a core diameter of 10μmand numerical aperture of 0.2.a) What is the maximum source diameter and numerical aperture for optimum coupling?b) For a laser beam with wav elength of 1. 55μmand the maximum source diameter in a), what is the divergenceangle? Considering the size and angle issues, does this beam provide optimum coupling?c) To ensure optimum coupling, what is the maximum distance between the laser and the fiber.d) Is it wise to reduce the beam diameter to 25% of the value used in b)?Justify your answer with the newdivergence angle.Notice: This has advantage of relaxing the requirements on alignment.2. Consider a fiber with a core diameter of 100μm, core refractive index of 1.485 and a cladding refractiveindex of 1.455 atλo=850nm.Consider operating this fiber atλo=850nmand laser source with linewidth of2nm. Assumethe material has zero dispersion wav elengthλ0=1360nmand dispersion slope ofS0=0. 09ps/km-nm2.
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