SRS suppression in multi-kW fiber lasers with a multiplexed CTFBG

Abstract

In this paper, we present experimental studies on newly developed multiplexed chirped tilted fiber Bragg gratings (MCTFBGs) for stimulated Raman scattering (SRS) suppression for high-power fiber laser systems. The MCTFBG device is composed of five continuous segments of chirped tilted fiber Bragg gratings (CTFBGs), which are inscribed into the large-mode-area (LMA, 25/400μm) fibers. The SRS suppression capability of the MCTFBG device has been successfully demonstrated with a master oscillator power amplification (MOPA) fiber laser system at the output level of 3.4 KW. The experimental observation thus indicates the MCTFBG’s excellent SRS suppression capability at a very high power level (∼15 dB under >3 kW) and high thermal handling capacity (∼1.48℃/kw). Our work thus provides a key development of essential fiber grating components that can effectively suppress the SRS suppression at a very high power level.

High‐Power Laser Systems

“…Another chirped fiber grating has direct Raman filtering capabilities under kW‐level average power. [ 80 ] In the future, breakthroughs in manufacturing larger core diameters by fs‐laser direct etching technology will be a powerful way to achieve higher‐intensity filter gratings. It is conceivable that this direct multiphoton etching process without high‐pressure hydrogen treatment is promising to directly etch multiple integrated filter gratings on the gain fiber, which can not only filter out the residual Raman light but also achieve ASE suppression.…”

“…By integrating them into a MOPA system of a new recorded 3.4 kW output, extra SRS suppression of ≈15 dB has been obtained at 1134.5 nm, and the temperature rise of the multiplexed CTFBGs device registered at the maximum output was only about 5 °C. [ 80 ]…”

“…Some typical designs of fiber and filter gratings are shown in Figure 1j. [77][78][79][80] 2. Solid-State Lasers with High-Peak-Power 2.1.…”

2.58 kW Narrow Linewidth Fiber Laser Based on a Compact Structure with a Chirped and Tilted Fiber Bragg Grating for Raman Suppression

“…Many methods have been used to suppress SRS in high-power fiber lasers, including the large-mode-area (LMA) fibers, spectrally selective fibers, long-period fiber gratings, chirped tilted fiber Bragg gratings (CTFBGs), and so on [26][27][28][29][30][31]. Among these methods, CTFBG is considered a comparatively suitable component for SRS suppression.…”

“…In 2017, we firstly proposed and demonstrated using CTFBG to suppress SRS in high-power fiber amplifier [26]. Then, with the improvement of CTFBG fabrication technology, the power handling capability of CTFBGs kept refreshing, which has increased from hundred watts to the kilowatts level [27][28][29][30][31]. These studies are all based on the conventional high-power fiber laser, whose linewidth is in several nanometers level and not belongs to narrow linewidth.…”