Kilowatt-level, narrow linewidth, polarization-maintained all-fiber amplifiers based on multi-phase coded signal modulation and laser gain competition

3.96 kW All-Fiberized Linearly Polarized and Narrow Linewidth Fiber Laser with Near-Diffraction-Limited Beam Quality

“…Normally, the methods of generating narrow linewidth laser seeds mainly include: narrow linewidth laser diode [ 9 , 10 ], multi-longitudinal-mode fiber oscillator [ 11 , 12 , 13 ], filtered superfluorescent source [ 14 , 15 , 16 ], and phase modulated single-frequency laser [ 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ]. Among them, phase modulation has been proved to be a preferable method to acquire narrow linewidth high power fiber laser without obvious spectral broadening and high SRS threshold [ 17 , 18 , 19 ].…”

Investigation of the confined-doped fiber on single-mode operating and power scaling in all-fiber single-frequency amplifiers

“…Till now, a variety of approaches have been reported to provide effective suppression on these two effects, separately. For example, approaches like enlarging the mode area or shortening fiber length [7][8][9], employing acoustically tailoring technique [10], introducing strain or temperature gradient [11][12][13], using gain competition strategy [14][15][16] and counter-pumping scheme [17,18] are always applied to suppress the SBS effect. Meanwhile, plenty of effective methods are utilized in the high-power laser systems to mitigate the TMI effect, such as coiling active fiber [19,20], optimizing pumping wavelength or signal wavelength [21][22][23], suppressing the noise property [24,25], reducing the fiber core to pump cladding ratio [26,27], and using gain-tailoring technique [28,29].…”