Amplification of random lasing enables a 10-kW-level high-spectral-purity Yb–Raman fiber laser

Abstract

By amplifying the cascaded random Raman fiber laser (RRFL) oscillator and ytterbium fiber laser oscillator, we present the first, to the best of our knowledge, demonstration of a 10-kW-level high-spectral-purity all-fiber ytterbium–Raman fiber amplifier (Yb-RFA). With a carefully designed backward-pumped RRFL oscillator structure, the parasitic oscillation between the cascaded seeds is avoided. Leveraging the RRFL with full-open-cavity as the Raman seed, the Yb-RFA realizes 10.7-kW Raman lasing at 1125 nm, which is beyond the operating wavelengths of all the reflection components used in the system. The spectral purity of the Raman lasing reaches 94.7% and the 3-dB bandwidth is 3.9 nm. This work paves a way to combine the temporal stability of the RRFL seed and the power scaling of Yb-RFA, enabling the wavelength extension of high-power fiber lasers with high spectral purity.

Design and optimization methods towards a 10 kW high beam quality fiber laser based on the counter tandem pumping scheme

“…The strength of these sub-peaks increases rapidly as the power increases, resulting in a rapid broadening in the 10 dB spectral linewidth. Although many research groups have achieved more than 10 kW monolithic fiber laser, the beam qualities of which are far from single mode [23,24,40,41] . Our work achieved an M…”

“…For tandem-pumped YDFLs, one common and practical method is to enlarge the fiber core, as the Raman Stokes gain is inversely proportional to the fiber core area. This method has enabled the experimental demonstration of 10 kW level tandem-pumped fiber amplifiers with an ultra-large core (＞44 μm) YDF [21][22][23][24] . However, the beam quality was not good due to lack of mode control https://doi.org/10.1017/hpl.2024.…”

2 kW random fiber laser based on hybrid Yb-Raman gain [Invited]

“…RDFLs have attracted much attention in recent years due to their distinctive operating principle. Existing research on RDFLs can be categorized into topics such as power/brightness enhancement [4][5][6][7] , spectral manipulation [8][9][10] , temporal modulation [11,12] , and transverse mode control [13,14] . These advances have led to practical applications of RDFLs in sensing [15][16][17] , communication [18,19] , imaging [20,21] , and nonlinear frequency conversion [22,23] .…”

“…One of the main research topics concerning RDFLs is highpower operation. On the one hand, an RDFL can serve as a robust seed for high-power fiber amplifiers [5,[24][25][26] ; on the other hand, it can directly achieve high-power output [4,[27][28][29] . Early RDFLs relied on several or even tens of kilometers of passive fiber to provide sufficient distributed feedback [30] , thus enabling low-threshold random lasing output.…”