Low-loss Ge-As-S glass fiber for high-power Er:YAG laser transmission and ablation

Area of Science:

• Materials Science
• Optical Engineering
• Biomedical Engineering

Background:

• Germanium-based chalcogenide (Ge-CHG) glass fibers are ideal for transmitting Er: YAG laser beams due to their high damage threshold and water stability.
• Internal particle scattering in current Ge-CHG fibers limits the transmission of high-power Er: YAG lasers.

Purpose of the Study:

• To develop a novel method for mitigating internal scattering in Ge-CHG fibers.
• To enhance the purity and transmission capabilities of Ge-As-S optical fibers for high-power Er: YAG laser applications.
• To demonstrate the potential of these fibers in biological tissue ablation for minimally invasive surgery.

Main Methods:

• Employed a micron-scale filter combined with a multi-stage dynamic distillation process to purify Ge-CHG fibers.
• Prepared Ge-As-S optical fibers using an isolation extrusion method.
• Tapered the fiber rod to enhance flexibility while maintaining high power transmission.

Main Results:

• Achieved a record low loss of 0.1 dB/m in Ge-As-S glass by reducing internal particle scattering.
• Demonstrated a Ge-As-S fiber rod capable of sustaining 13.43 W of Er: YAG laser power (684 J/cm²).
• Developed a flexible Ge-As-S fiber transmitting 4.1 W (580 J/cm²) and demonstrated its use in 3 mm biological tissue ablation.

Conclusions:

• The novel purification method significantly reduces scattering, improving Ge-CHG fiber performance for high-power laser transmission.
• Flexible Ge-As-S fibers can now handle over 5 W of Er: YAG laser power, a first for chalcogenide fibers.
• These advanced Ge-As-S fibers show great promise for high-power mid-infrared laser applications, particularly in minimally invasive surgery.