Cruciform cylindrical lens for elliptical beam transformation

摘要

A system for providing efficient coupling between an elliptical mode laser source and a single mode transmission fiber is disclosed. In one embodiment, the system comprises a cruciform cylindrical lens formed as a pair of perpendicular cylindrical lenses to provide for separate magnification of the "fast" diverging component (i.e., this component passes through a "fast" cylindrical lens) and the "slow" diverging component of the beam (i.e., this component passes through a "slow" cylindrical lens). By decoupling the magnification requirements of the components of the elliptical beam, the beam may be transformed into an essentially circular beam, appropriate for coupling into a single mode fiber. In one arrangement of the present invention, a coupling efficiency of approximately 90% is possible (as compared with prior art coupling efficiency of about 44%). In an alternative embodiment, the pair of cylindrical lenses may be replaced by a monolithic lens, formed to comprise orthogonal front and rear cylindrical surfaces.