Thulium-doped all-PM fiber chirped pulse amplifier delivering 314 W average power

• Published in: High power laser science and engineering Vol. 11
• Main Authors: Ren, Bo, Li, Can, Wang, Tao, Guo, Kun, Wu, Jian, Zhou, Pu
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.01.2023
• Subjects: Amplifiers; chirped pulse amplification; Coiling; Diodes; Doped fibers; Efficiency; Electrons; high average power; Lasers; Noise intensity; Phase modulation; Polarization; Pulse duration; Relative intensity noise; Strehl ratio; Temperature effects; Thulium; thulium-doped fiber laser; Timing jitter; ultrafast laser; Ultrafast lasers; ultrafast laser; chirped pulse amplification; high average power; thulium-doped fiber laser
• ISSN: 2095-4719; 2052-3289
• DOI: 10.1017/hpl.2023.68

A high-power all polarization-maintaining (PM) chirped pulse amplification (CPA) system operating in the 2.0 μm range is experimentally demonstrated. Large mode area (LMA) thulium-doped fiber (TDF) with a core/cladding diameter of 25/400 μm is employed to construct the main amplifier. Through dedicated coiling and cooling of the LMA-TDF to manage the loss of the higher order mode and thermal effect, a maximum average power of 314 W with a slope efficiency of 52% and polarization extinction ratio of 20 dB is realized. The pulse duration is compressed to 283 fs with a grating pair, corresponding to a calculated peak power of 10.8 MW, considering the compression efficiency of 88% and the estimated Strehl ratio of 89%. Moreover, through characterizing the noise properties of the laser, an integrated relative intensity noise of 0.11% at 100 Hz−1 MHz is obtained at the maximum output power, whereas the laser timing jitter is degraded by the final amplifier from 318 to 410 fs at an integration frequency of 5 kHz to 1 MHz, owing to the self-phase modulation effect-induced spectrum broadening. The root-mean-square of long-term power fluctuation is tested to be 0.6%, verifying the good stability of the laser operation. To the best of our knowledge, this is the highest average power of an ultrafast laser realized from an all-PM-fiber TDF-CPA system ever reported.