Compact GMN amplification system based on an all-PM SESAM-assisted figure-9 Er:fiber laser

Area of Science:

• Optics and Photonics
• Laser Physics
• Materials Science

Background:

• Polarization-maintaining (PM) figure-9 fiber lasers offer stability for high-repetition-rate pulse generation but face cavity length limitations.
• Semiconductor saturable absorber mirrors (SESAMs) are crucial components in mode-locked fiber lasers.

Purpose of the Study:

• To develop a SESAM-assisted figure-9 Er:fiber laser operating in the harmonic mode-locking (HML) regime.
• To achieve high-repetition-rate ultrashort pulse generation with tunable repetition rates and optimized pulse characteristics.

Main Methods:

• Utilized a SESAM for pulse shaping through its nonlinear reflectivity.
• Optimized pump power to control pulse repetition rate and stability.
• Employed joint gain-managed nonlinear (GMN) amplification for enhanced pulse energy and duration.

Main Results:

• Achieved tunable pulse repetition rates from 43.478 MHz to 645.16 MHz (15th harmonic).
• Stabilized central wavelength near 1532 nm for higher-order harmonics due to pump-induced gain competition.
• Generated pulses with 8.65 nJ energy and 102 fs duration, exceeding 100 nm spectral coverage (67.54 nm 3 dB bandwidth).
• Demonstrated the highest repetition rate (645.16 MHz) and shortest pulse duration (102 fs) for GMN amplification in the 1.5 µm region.

Conclusions:

• The SESAM-assisted figure-9 Er:fiber laser effectively generates high-repetition-rate ultrashort pulses.
• The developed system provides a robust platform for investigating high-energy, broadband pulses in 1.5 µm GMN systems.
• Results pave the way for advanced applications requiring high-performance fiber lasers.