Design of a single-mode fiber coupling system based on the modified Gerchberg–Saxton algorithm

Abstract

The efficiency of a hollow beam received by the Cassegrain antenna coupling into a single-mode fiber is low, and converting the hollow beam into a solid beam can remarkably improve the coupling efficiency. In this paper, shaping diffractive optical elements (DOEs) are designed through a modified Gerchberg–Saxton algorithm (MGS) with Fresnel diffraction. Further, the MGS algorithm can be applicable in the issue of circular symmetric beam shaping. The properties of the system with/without shaping DOEs are analyzed and compared. According to the simulation results, in consideration of the energy loss of the antenna, DOEs, and coupling lens, the total transmission efficiency of the receiving antenna system at 1550 nm wavelength can reach 77.81%. In addition, the system with shaping DOEs can better adapt for coupling lenses with different focal lengths, and the variation of the maximum coupling efficiency of the DOEs shaping system at different focal lengths studied in this paper is within 2.00%, which is 6.73% lower than that of the lens shaping system. The research results provide an idea of reverse design for improving a coupling system, which can also provide inspiration for other optical system designs.