Pure passive fiber enabled highly efficient Raman fiber amplifier with record kilowatt power

TL;DR

This paper demonstrates a record-high kilowatt-level Raman fiber amplifier using pure passive fiber, achieving high efficiency and brightness enhancement without rare-earth doping, marking a significant advancement in fiber laser technology.

Contribution

It introduces the first high-efficiency, kilowatt-level Raman fiber amplifier based solely on pure passive fiber, eliminating the need for rare-earth doping.

Findings

Achieved 1002.3 W continuous-wave power at 1060 nm with 84% efficiency.

Improved beam quality from M2 of 9.17 to 5.11, enhancing brightness.

Demonstrated the first kilowatt-level high-efficiency Raman amplifier using pure passive fiber.

Abstract

Kilowatt-level high efficiency all-fiberized Raman fiber amplifier based on pure passive fiber is proposed for the first time in this paper. The laser system is established on master oscillator power amplification configuration while a piece of graded-index passive fiber is utilized as stokes shifting as well as gain medium, which is entirely irrelevant to rare-earth-doped gain mechanism. When the pump power is 1368.8 W, we obtained 1002.3 W continuous-wave laser power at 1060 nm with the corresponding optical-to-optical efficiency of 84%. The beam parameter M2 improves from 9.17 of the pump laser to 5.11 of the signal laser through the amplification process, and the brightness enhancement is about 2.57 at maximum output power as a consequence of the beam clean-up process in the graded-index fiber. To the best of our knowledge, we have demonstrated the first kilowatt-level high efficiency Raman fiber amplifier based on pure passive fiber with brightness enhancement.