Switchable multiwavelength ytterbium-doped double-clad fiber laser based on a multimode fiber grating

Area of Science:

• Photonics and Laser Technology
• Optical Engineering
• Materials Science

Background:

• Fiber lasers are crucial for various applications, but achieving switchable multiwavelength operation remains a challenge.
• Existing multiwavelength fiber laser designs often suffer from complexity, high splicing loss, and limited tunability.

Purpose of the Study:

• To demonstrate a simple and compact switchable multiwavelength double-clad fiber laser.
• To investigate the laser's ability to operate in different multiwavelength states by utilizing a multimode fiber Bragg grating (MMFG).

Main Methods:

• Fabrication of a multimode fiber Bragg grating (MMFG) directly within the active double-clad fiber.
• Integration of the MMFG as the wavelength-selective component in a fiber laser cavity.
• Adjustment of a polarization controller to switch between different multiwavelength operation states.

Main Results:

• Stable single-, dual-, and triple-wavelength operations were achieved at room temperature by adjusting the polarization controller.
• The laser exhibited switchable operation between single and dual wavelengths at lower pump levels, and dual and triple wavelengths at higher pump levels.
• A high slope efficiency of 41% and a maximum output power of 6.2 W were recorded.

Conclusions:

• The developed MMFG-based fiber laser offers a simple, compact, and efficient solution for switchable multiwavelength operation.
• The direct fabrication of the MMFG in the fiber minimizes splicing loss and enhances system stability.
• This technology holds potential for applications requiring tunable multiwavelength fiber lasers.