High-gain Tm-doped fluoride fiber amplifier

Area of Science:

• Optics and Photonics
• Laser Physics
• Fiber Optics

Background:

• Diode-pumped fiber amplifiers are crucial for various laser applications.
• Thulium-doped fibers offer unique emission properties near 1.9 micrometers.
• Efficient amplification of short diode laser pulses at high repetition rates remains a challenge.

Purpose of the Study:

• To report a diode-pumped thulium-doped fiber amplifier.
• To investigate the amplification of short diode laser pulses near 1.9 micrometers.
• To optimize the amplifier's performance regarding gain, output power, and signal quality.

Main Methods:

• Utilizing a diode-pumped Tm-doped fiber architecture.
• Amplifying short (20-40 ns) laser diode pulses.
• Investigating different pump-signal propagation geometries.
• Measuring small-signal gain, peak power, repetition rate, and amplified spontaneous emission (ASE).

Main Results:

• Achieved a small-signal gain exceeding 30 dB at 1870 nm.
• Generated output pulses with up to 3-W peak power at 1-60 kHz repetition rates.
• Demonstrated that output signal quality is dependent on pump-signal propagation direction.
• Showcased an optimum pump geometry that increases pulse energy up to 20 times the ASE energy.

Conclusions:

• Successfully developed a high-performance Tm-doped fiber amplifier for 1.9-micrometer applications.
• The propagation scheme significantly impacts amplified spontaneous emission suppression and signal quality.
• This work represents a novel advancement in high-repetition-rate fiber amplification of short diode laser pulses near 1.9 micrometers.