Robust all-PM fiber few-cycle pulse source at 1560 nm and its second-harmonic generation

Area of Science:

• Optics and Photonics
• Ultrafast Lasers
• Nonlinear Optics

Background:

• Fiber laser systems are crucial for various scientific applications.
• Achieving stable, few-cycle pulse generation is challenging.
• All-polarization-maintaining (all-PM) fiber integration enhances system robustness.

Purpose of the Study:

• To demonstrate a compact and robust all-PM fiber laser system.
• To achieve few-cycle pulse generation at 1560 nm and its second-harmonic generation (SHG) at 780 nm.
• To evaluate the system's stability, reliability, and performance for precision applications.

Main Methods:

• Utilized a simplified architecture with a PM seed oscillator and PM fiber power amplifier.
• Integrated a periodically poled lithium niobate (PPLN) module for SHG.
• Employed full-field reconstruction and noise analysis for validation.

Main Results:

• Generated few-cycle pulses at 1560 nm with ~25.4 fs duration and 139 mW average power.
• Achieved stable mode-locking with high signal-to-noise ratio (~106 dB).
• Produced 780 nm SHG pulses with ~55 fs duration and demonstrated low noise characteristics.

Conclusions:

• The robust all-PM fiber laser system provides high-fidelity temporal and noise characteristics.
• This compact source is a promising alternative for precision frequency metrology, nonlinear imaging, and ultrafast spectroscopy.
• The system's environmental immunity and long-term reliability are key advantages.