Efficiency Enhancing Technique for Rod Fiber Picosecond Amplifiers with Optimal Mode Field Matching

Danni Liu; Xiaojie Mao; Guojiang Bi; Tianqi Li; Dawei Zang; Ninghui Sun

doi:10.3390/mi14020450

Efficiency Enhancing Technique for Rod Fiber Picosecond Amplifiers with Optimal Mode Field Matching

Micromachines (Basel). 2023 Feb 15;14(2):450. doi: 10.3390/mi14020450.

Authors

Danni Liu¹, Xiaojie Mao², Guojiang Bi², Tianqi Li³, Dawei Zang¹, Ninghui Sun¹

Affiliations

¹ Institute of Computing Technology, Chinese Academy of Sciences, Beijing 100190, China.
² Science and Technology on Solid-State Laser Laboratory, North China Research Institute of Electro-Optics, Beijing 100015, China.
³ The Science and Technology on Inertial Laboratory, School of Instrumentation and Opto-Electronics Engineering, Beihang University, Beijing 100191, China.

Abstract

A high power and high quality picosecond laser is crucial in MEMS fabrication regarding micromachines. Optimal seed beam coupling is an important precondition to enhance laser efficiency. However, empirical coupling limits its development. In this paper, the physical parameters related to coupling are determined. The relationships among them are established under optical mode matching constraints to satisfy optimal seed beam coupling. According to a theoretical analysis, the focal length cut-off and the optimal coupling position of the coupling lens are acquired. A maximum transmittance of 87.2% is acquired with a 6 W input seed power in the validation experiment. In further power amplification experiments, a diffraction-limited beam quality is achieved, with M²_X = 1.111, M²_Y = 1.017, an optical efficiency of 60.5% and a slope efficiency of 66%, benefiting from the previous theoretical guidance.

Keywords: fiber coupling; mode field matching; picosecond amplifier; rod fiber.

Grants and funding

This work is partially supported in part by the Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 61902373), by the Foundation of the Chinese Academy of Sciences, China (Grant No. JCPYJJ 22013), by the Strategic Priority Research Program of the Chinese Academy of Sciences, China (Grant No. XDB24050300, XDB44030300).