Tunable mode-locked fiber laser based on nonlinear multimode interference with double offset-splicing step-index...

Area of Science:

• Fiber optics
• Laser physics
• Nonlinear optics

Background:

• Mode-locking is crucial for generating ultrashort pulses in lasers.
• Few-mode fibers offer unique light propagation properties.
• Achieving stable mode-locking in all-normal dispersion regimes can be challenging.

Purpose of the Study:

• To demonstrate a tunable mode-locked all-fiber ytterbium-doped laser for the first time.
• To utilize a novel double offset-splicing step-index few-mode fiber (DOS-SIFMF) structure.
• To investigate the mode-locking characteristics and tunability of the proposed fiber laser.

Main Methods:

• Fabrication of a DOS-SIFMF by introducing an offset splicing technique.
• Integration of the DOS-SIFMF into an all-fiber ytterbium-doped laser cavity.
• Characterization of the laser output in terms of wavelength, spectrum, pulse width, and tunability.

Main Results:

• Successful demonstration of a tunable mode-locked all-fiber Yb-doped laser.
• The DOS-SIFMF acts as both a saturable absorber and filter, facilitating mode-locking.
• Achieved central wavelength of 1032 nm, spectrum of 6.15 nm, and pulse width of 28.8 ps.
• Tunable output pulse in time (168.7 ps) and spectrum (10.7 nm) domains.

Conclusions:

• The DOS-SIFMF structure enables reliable mode-locking in an all-normal dispersive region.
• The laser exhibits tunable properties with potential applications in communication and sensing.
• The study highlights the influence of mode number on interference for mode-locking.