Dynamic vortex mode-switchable erbium-doped Brillouin laser pumped by high-order mode

Area of Science:

• Photonics and Optical Engineering
• Fiber Laser Technology
• Mode Control in Lasers

Background:

• All-fiber lasers offer robust and compact solutions for various applications.
• Controlling and switching laser modes, particularly vortex modes, is crucial for advanced optical systems.
• Brillouin lasers provide narrow linewidths and tunable wavelengths, but dynamic mode switching remains a challenge.

Purpose of the Study:

• To experimentally demonstrate dynamic switching of transversal vortex modes in an erbium-doped all-fiber Brillouin laser.
• To achieve oscillation of high-order modes (HOM) within the laser cavity using a tailored Brillouin pump (BP).
• To enable tunable output wavelength and narrow linewidth for the HOM Brillouin-shifted laser.

Main Methods:

• Utilizing a high-order mode (HOM) Brillouin pump (BP) to excite HOM oscillation in the fiber laser cavity.
• Cascading an acoustically induced fiber grating (AIFG) and a mode selection coupler (MSC) for core-mode conversion.
• Employing frequency shift keying (FSK) modulation on the AIFG signal for dynamic mode switching.

Main Results:

• Successfully switched transversal modes between the fundamental LP01 and vortex modes.
• Achieved output vortex mode purities exceeding 82%.
• Demonstrated tunable Brillouin-shifted laser output from 1545-1560 nm with linewidths under 4 kHz.

Conclusions:

• Dynamic switching of vortex modes in fiber Brillouin lasers is feasible using HOM BP and FSK modulation.
• The developed method offers a promising approach for generating tunable, high-purity vortex modes in fiber lasers.
• This technique opens avenues for advanced applications requiring controlled spatial beam profiles and tunable wavelengths.