Double-pass pre-chirp managed amplification with high gain and high average power

Area of Science:

• Fiber optics
• Laser technology
• Nonlinear optics

Background:

• High-power fiber amplifiers are crucial for various applications.
• Managing nonlinear effects is essential for maintaining beam quality in high-gain systems.
• Static mode degradation (SMD) is a limiting factor in fiber amplifier performance.

Purpose of the Study:

• To demonstrate the first double-pass pre-chirp managed fiber amplifier.
• To investigate the relationship between nonlinear phase shift (NPS) and static mode degradation (SMD).
• To optimize the amplifier for high output power and pulse quality.

Main Methods:

• Utilizing a rod-type Yb-fiber in a double-pass configuration.
• Implementing a pre-chirp management technique to control nonlinear effects.
• Studying the impact of accumulated nonlinear phase shift on mode degradation.
• Employing grating pairs and chirped mirrors for pulse compression.

Main Results:

• Achieved 38 dB gain, amplifying picosecond pulses from 20 mW to 113 W.
• Demonstrated a compact system with 102 W amplified power after optimization.
• Observed that higher NPS leads to stronger nonlinear polarization evolution and a lower SMD threshold.
• Compressed amplified pulses to 37-55 fs with 90-100 W average power.

Conclusions:

• The double-pass configuration simplifies pre-chirp managed fiber amplifiers, enabling compact systems.
• Effective management of nonlinear phase shift is key to mitigating static mode degradation.
• The developed amplifier offers a promising solution for high-power, high-quality ultrashort pulse generation.