Fiber Bragg gratings in active multimode XLMA fibers for high-power kW-class fiber lasers

Functional Fibers and Functional Fiber-Based Components for High-Power Lasers

“…Later, the output power was further boosted to exceed 5.2 kW [54] by employing a similar system configuration and remaining the dual-end FBGs. Through writing FBG with femtosecond pulses into one port of the gain fiber, a spatially structured fiber oscillator with an output power of 8 kW was constructed [57]. This achievement demonstrates the prospect of FBGs inscription with femtosecond laser in improving the traditional hydrogen-carrying method and increasing the reliability of FBG resonators [58,61,62].…”

“…On the basis of cladding-pump technology, high-power multimode LDs at 790 nm and highly Tm-doped fibers, the output power of HPFLs exploiting Tm-doped fibers has exceeded the power level of Er-doped fibers gradually and a kilowatt-level output [102] has been achieved as early as 2010, representing the highest CW output power produced by Tm-doped fiber reported publicly currently. In 2018, a Tm-doped chirped pulse amplifier system with a record average power of up to 1150 W and the peak power of more than 5 GW was demonstrated, which brings exciting prospects for [46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63], c all-fiber laser amplifiers operating at ~ 1 μm [13, 14, 16-19, 35, 64-83], d all-fiber Er-doped lasers and Er-Ybco-doped lasers operating at ~ 1.5 μm , e all-fiber Tm-doped lasers operating at ~ 2 μm [94][95][96][97][98][99][100][101][102][103][104][105][106][107][108][109][110][111][112][113]. f Emission cross sections of Er 3+ , Ho 3+ and Dy 3+ ions in mid-infrared waveband [114].…”

“…2 a Schematical diagram of energy level transitions for some representative rare-earth ions. b-e Power evolution trends of some representative results for b all-fiber laser oscillators operating at ~ 1 μm[46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63], c all-fiber laser amplifiers operating at ~ 1 μm[13, 14, 16-19, 35, 64-83], d all-fiber Er-doped lasers and Er-Ybco-doped lasers operating at ~ 1.5 μm, e all-fiber Tm-doped…”

1200 W monolithic all-fiber laser with fs-written fiber Bragg gratings and side-pumping coupler

“…Moreover, the splice misalignment could degrade beam quality and even excite high-order mode, which reduces the threshold of transverse mode instability (TMI). In the past, researchers have made some works to reduce the number of splice points in the fiber laser system by directly writing FBGs [4][5][6][7] or fabricating side-pumping couplers [8,9] in active fibers. However, combining FBGs and side-pumping couplers on the same active fiber to form a monolithic fiber laser oscillator is a gap of research.…”