标题：Pitch of GRIN fiber lens for Gaussian beam focusing
作者：Wang, Chi ;Fang, Chen ;Yu, Ying-Jie ;Li, Hong-Yu
作者机构：[Wang, Chi ;Fang, Chen ;Yu, Ying-Jie ] Department of Precision Mechanical Engineering, Shanghai University, Shanghai 200072, China;[Li, Hong-Yu ] Coll 更多
来源：Guangxue Jingmi Gongcheng/Optics and Precision Engineering
摘要：In order to optimize the design of Gradient Index (GRIN) fiber probes for Optical Coherence Tomographic (OCT) imaging, the pitch of a GRIN fiber lens for the focusing of a Gaussian beam was investigated. Firstly, based on the model of a GRIN fiber probe consisting of a single-mode fiber (SMF), a no-core fiber (NCF) and a GRIN fiber lens, the focusing properties of a GRIN fiber lens were analyzed intensively. Then, the complex beam parameter matrix transformation method was adopted to derive the mathematical expressions of focal length and waist radius of a Gaussian beam focusing through the GRIN fiber lens. Finally, the software Matlab was used to analyze the impact of the length of a GRIN fiber lens on the focusing performance of the beam. The results show that the length period of GRIN fiber lens is 1/2 pitch for the focusing of the Gaussian beam, and the GRIN fiber lens demonstrates strong focusing performance at a length of 1/4 pitch. When the range of the length of a GRIN fiber lens is chosen from 0.87 mm to 0.92 mm, the corresponding focal length of the lens is about 0.5-0.8 mm, and the waist beam radius is about 9-20 μm. Thus, the pitch of a GRIN fiber lens can be used to optimize the design of GRIN fiber probes. It can reduce the requirement for the fabrication process of the probes by increasing the length of a GRIN fiber lens properly.