High gain fiber-solid hybrid double-passing end-pumped Nd:YVO4 picosecond amplifier with high beam quality

• 来源期刊: 中国物理B（英文版）
• 关键词: picosecond fiber-solid hybrid double-passing amplifier high beam quality spherical-aberration self-compensation
• 年，卷（期）: 2020,（5）
• 页码范围: 311-320
• 页数: 10页
• 语种: 英文
• DOI: 10.1088/1674-1056/ab8218

摘要

We propose a fiber-solid hybrid system which consists of a semiconductor saturable absorber mirror (SESAM) mode-locked fiber seed with a pulse width of 10.2 ps and a repetition rate of 18.9 MHz, a two-level fiber pre-amplifier and a double-passing end-pumped Nd:YVO4 amplifier. In the solid-state amplifier, to enhance the gain and the extraction efficiency, a specially designed structure in which the seed light passes through the gain medium four times and makes full use of population inversion is used as the double-passing amplifier. Besides, the beam filling factor (the ratio of the seed light diameter to the pump light diameter) and the thermal lens effect of the double-passing amplifier are considered and its optical-to-optical conversion efficiency is further improved. To preserve the beam quality of the double-passing amplifier, a new method of spherical-aberration self-compensation based on the principles of geometrical optics is used and discussed. Our system achieves a maximum average power of 9.5 W at the pump power of 28 W, corresponding to an optical-to-optical efficiency of 27% . And the beam quality factor M2 reaches 1.3 at the maximum output power.