All-fiber self-starting Mamyshev oscillator based on absorption-induced spectral filtering

Area of Science:

• Optics and Photonics
• Laser Physics
• Materials Science

Background:

• Mamyshev oscillators (MOs) are crucial for generating ultrashort optical pulses.
• Achieving self-starting mode-locking in fiber lasers simplifies operation and broadens applications.
• Traditional MO designs often require complex configurations or external seeding for stable operation.

Purpose of the Study:

• To propose and experimentally demonstrate a self-starting all-fiber Mamyshev oscillator (MO).
• To investigate the use of a Tm3+-based absorption filter for spectral shaping in MOs.
• To analyze the impact of filter characteristics and pump power on self-starting mode-locking and pulse generation.

Main Methods:

• Design and integration of a shortpass absorption filter utilizing Tm3+ ions near 1560 nm.
• Cascading the absorption filter with a conventional fiber filter to create an offset spectral filtering stage.
• Systematic investigation of pump power and absorption filter cutoff depth effects on MO performance.

Main Results:

• Successful demonstration of a self-starting all-fiber Mamyshev oscillator operating at 1550 nm.
• Self-starting mode-locking achieved with a pump power of 390 mW in both arms.
• Generation of ultrashort pulses with 6.52 nJ energy, 225 fs duration, and a 502 nm overall spectral bandwidth.

Conclusions:

• The developed absorption filter effectively facilitates self-starting mode-locking in the MO.
• The MO exhibits robust self-starting capabilities, operating without seed injection or auxiliary arms.
• This straightforward design offers a promising route towards novel high-energy ultrafast fiber lasers.