4.6 kW linearly polarized and narrow-linewidth monolithic fiber amplifier based on a fiber oscillator laser seed

Abstract

In this work, a record output power of 4.6 kW linearly polarized and narrow-linewidth fiber amplifier based on an optimized fiber oscillator laser (FOL) seed was realized by employing a homemade polarization-maintaining Yb-doped fiber (PMYDF), corresponding to a slope efficiency of 79.5% and a 3 dB linewidth of 0.3452 nm. Through an effective strategy relying on decreasing the transmission fiber length from 200 m to 120 m and adding a chirped and tilted fiber Bragg grating (CTFBG), the stimulated Raman scattering (SRS) effects were well-suppressed. By applying the forward combiner with the interconnection between the pump arms into the MOPA system, the MI threshold is increased by more than 560 W and the slope efficiency of the upgraded MOPA system is boosted by 5%. During the experimental process of power amplification, the polarization extinction ratio (PER) remains higher than 15 dB, and a near-diffraction-limited output beam at the laser power of 2980 W was measured with the M2x = 1.314 and M2y = 1.311.

Brightness enhancement on a narrow-linewidth fiber Bragg grating-based master oscillator power amplification fiber laser

“…However, the recorded output power of high brightness NLFA based on fiber oscillator laser seed is no more than 5 kW level [20][21][22][23]. The highest reported power is 4.6 kW with 3 dB linewidth of 0.35 nm and M 2 factor of 1.31 [23].…”

“…However, the recorded output power of high brightness NLFA based on fiber oscillator laser seed is no more than 5 kW level [20][21][22][23]. The highest reported power is 4.6 kW with 3 dB linewidth of 0.35 nm and M 2 factor of 1.31 [23]. The phase modulated single frequency laser seed maintains good properties of single frequency but has to use a complex multi-stages amplification configuration.…”

“…The higher power laser with linewidth less than 1 nm have also been intensively researched, which is useful for SBC system whose linewidth requirements are not as strict as CBC. The power scaling of such high power NLFAs is affected by TMI and various nonlinear effects including SBS, stimulated Raman scattering (SRS) and four-wave mixing (FWM) [17][18][19][20][21][22][23]. In 2022, Ma et al reported a 7.03 kW near single mode NLFA with 3 dB linewidth of 0.76 nm, which is based on the phase modulated single frequency laser seed [19].…”