Excitation of the fundamental and low-order modes of optical fiber waveguides with gaussian beams. 2: offset beams.

The excitation efficiencies of the dominant and low-order modes in an optical fiber are theoretically determined for an incident Gaussian beam that is offset with respect to the fiber axis. The excitation efficiencies are shown to be strongly influenced by both the numerical aperture of the fiber and the wavefront curvature of the incident beam.