Femtosecond Yb-doped tapered fiber pulse amplifiers with peak power of over hundred megawatts
Xue Cao, Qianglong Li, Feng Li, Hualong Zhao, Wei Zhao, Yishan Wang, Dong‐Juan Li, Yang Yang, Wenlong Wen, Jinhai Si
Abstract
Ultrafast fiber lasers combining high peak power and excellent beam quality in the 1-µm wavelength range have been explored to applications in industry, medicine and fundamental science. Here, we report generation of a high-energy sub 300 fs polarization maintaining fiber chirped pulse amplification (CPA) system by using a Yb-doped large mode area tapered polarization maintaining (PM) optical fiber with the core/cladding diameters of 35/250 µm at the thin end and 56/400 µm at the thick end. The taper fiber design features a confined core for selective gain amplification and multi-layer cladding for enhanced suppression of higher order modes. In this regime, we have demonstrated 266 fs pulse amplification with peak power of up to 132 MW at a repetition rate of 2 MHz and high beam quality with measured M 2 value of 1.1∼1.3. To the best of our knowledge, it is the highest peak power reported in such tapered Yb-doped fiber (T-YDF) amplifier in the femtosecond regime. This work indicates the great potential of the T-YDF to realize further power scaling, high laser efficiency, and excellent beam quality in high-power femtosecond fiber lasers.