An approximate analytical model is developed for calculating the out-of-plane coupling efficiency between an elliptical Gaussian beam from a laser diode and an angled single-mode fiber. The simulation results obtained from the model indicate that when a laser diode has no tilt the coupling efficiency varies with relative rotation angle at a period of \pi rather than remains constant, and the period changes from \pi toward 2\pi as the tilt angle of laser diode increases. A proof-of-principle experiment is performed to demonstrate the validity of the model as the elliptical factor becomes large. Potential applications by employing the model are discussed.
W. T. Chen and Lon A. Wang, "Out-of-Plane Optical Coupling Between an Elliptical Gaussian Beam and an Angled Single-Mode Fiber," J. Lightwave Technol. 16, 1589- (1998)