Coupling Light Between Optical Fibers and Noncircular Beams

Cylindrical lenses can be used to increase the efficiency of coupling of light between (1) beams with circular or nearly circular cross sections propagating in single-mode optical fibers and (2) free-space beams with noncircular cross sections and with different radii of curvature of wavefronts on mutually perpendicular meridional planes. Beams of the second type are generated by semiconductor optoelectronic devices (e.g., diode lasers and amplifiers) that contain stripe waveguides; the waist-cross-section aspect ratios of such beams can be as large as 3:1.