title: Semiconductor laser to single-mode fiber coupler.
abstract: Promising results of various coupling experiments between laser diodes and single-mode fibers to determine the optimum coupling method are reported. The cylindrical lens method is shown to be most efficient, with a coupling loss of 1.8 dB under optimum alignment conditions. More than -2 dB coupling efficiency is attained with a cylindrical lens whose radius is less than 8 microm. The laser to fiber coupling characteristics are estimated by Gaussian beam approximation. The optimum radius of a cylindrical lens, which gives maximum coupling efficiency, is derived by theoretical calculation, using the ray matrix method. The cylindrical lens alignment tolerance is also shown theoretically and experimentally.
authors.forename: M
authors.initials: M
authors.lastname: Saruwatari
authors.forename: K
authors.initials: K
authors.lastname: Nawata