This paper presented a gradient-index planar waveguide (GIPW) coupler for laser diode and single mode fiber (SMF), and numerically analyzed the coupling efficiency and alignment tolerance of the couplers based on ABCD matrix. First, the components of the coupler were introduced. The coupler comprises of a gradient-index planar waveguide and a self-focusing lens. An elliptical Gauss beam emitted from an LD have different spot sizes in different direction and has mass losses when coupling with SMF directly. A method was presented by this paper to convert the elliptical beam into a circular one by a kind of gradient-index planar waveguide, and then the circular Gauss beam could be couple in SMF with a high efficiency by using a 1/4 pitch self-focusing lens. Second, we formulated the ABCD matrix of the beam propagation between LD and SMF by tracing complex rays, and obtained the expressions for spot sizes and wave-front radii of Gauss beam. Then the model for calculating coupling efficiency of the coupler was set up by overlap integral. Finally, the coupling efficiency of that coupler was investigated numerically. The coupling loss characteristic and tolerance characteristics were analyzed, and the optimized parameters of the components were given. This technique should be useful for design and manufacture of the coupler.

Date Published: 15 October 2012
PDF: 7 pages
Proc. SPIE 8420, 6th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical System Technologies for Manufacturing and Testing, 84200N (15 October 2012); doi: 10.1117/12.975635

Published in SPIE Proceedings Vol. 8420:
6th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical System Technologies for Manufacturing and Testing
Xiangdi Lin; Yoshiharu Namba; Tingwen Xing, Editor(s)