Narrow-linewidth broadly tunable Yb-doped Q-switched fiber laser using multimode interference filter.

Area of Science:

• Optics and Photonics
• Laser Physics
• Materials Science

Background:

• Q-switched fiber lasers are crucial for various applications.
• Achieving narrow linewidth and broad tunability simultaneously remains a challenge.
• Yb-doped fiber lasers offer efficient operation in the near-infrared spectrum.

Purpose of the Study:

• To develop a narrow-linewidth, broadly tunable Yb-doped Q-switched fiber laser.
• To investigate the effectiveness of a multimode interference filter (MMIF) in controlling laser parameters.
• To compare performance in both linear bulk and all-fiber ring cavity resonators.

Main Methods:

• Utilized an acousto-optic modulator and an MMIF within a linear bulk cavity resonator.
• Employed an all-fiber ring cavity resonator configuration.
• Integrated a standard polarization controller (SPC) for spectral tuning.

Main Results:

• Reduced spectral bandwidth by two orders of magnitude (from 11 nm to <0.1 nm in linear cavity, 17 nm to <0.1 nm in ring cavity).
• Achieved spectral tunability of >16 nm (1057-1073 nm) in the linear cavity and >12 nm (1038-1050 nm) in the ring cavity.
• Decreased pulse duration from ~305 ns to ~240 ns with MMIF insertion in the linear cavity.

Conclusions:

• The MMIF is effective in significantly narrowing the spectral bandwidth of Q-switched fiber lasers.
• The combination of MMIF and SPC enables broad spectral tunability.
• The developed laser architecture offers improved performance for applications requiring narrow linewidth and tunable output.