All-Fiber Laser With Agile Mode-Switching Capability Through Intra-Cavity Conversion

Agile mode switching between LP 01 and LP 11 modes in an all-fiber laser is demonstrated by exploiting an acoustically induced fiber grating within the laser cavity. The laser exploits a cladding pump configuration and can deliver up to 5.85 W of stable output power in LP 11 mode at 1070.07 nm and 6.06 W in LP 01 mode at 1070.48 nm, with a slope efficiency near 50%. Complete mode-switching speed with 250 Hz and partial mode-switching speed with 1 kHz are demonstrated. Based on the obtained switching time between LP 11 and LP 01 mode, the maximum complete mode-switching speed is calculated to be ∼555.56 Hz. Moreover, variable output beam profiles could be obtained by adjusting the frequency of the modulation signal applied on the acoustically induced fiber grating. This paper could provide an example of realizing a high-power, mode-switchable fiber laser source for practical use.