Polarization-maintaining, large-effective-area, higher-order-mode fiber.

Area of Science:

• Optics and Photonics
• Materials Science

Background:

• Higher-order-mode (HOM) fibers are essential for high-power laser applications due to their large effective areas (Aeff).
• Polarization-maintaining (PM) capabilities are desirable for advanced applications like coherent beam combination and polarization multiplexing.

Purpose of the Study:

• To report a novel polarization-maintaining higher-order-mode (PM-HOM) fiber.
• To demonstrate its capability in guiding Bessel-like modes with a large effective area.
• To evaluate its polarization properties for practical high-power laser systems.

Main Methods:

• Fabrication and characterization of a novel PM-HOM fiber.
• Measurement of effective area (Aeff) for guided Bessel-like modes.
• Quantification of fiber birefringence and polarization extinction ratio (PER) over meter-long lengths.

Main Results:

• The PM-HOM fiber successfully guides Bessel-like modes with Aeff ranging from 1200 to 2800 μm².
• The fiber exhibits a birefringence comparable to conventional single-mode PM fibers (2×10⁻⁴).
• A polarization extinction ratio (PER) between 13-23 dB was achieved over meter-long fiber sections.

Conclusions:

• The developed PM-HOM fiber is a promising platform for next-generation high-power fiber laser systems.
• It enables deterministic control of polarized Bessel-like modes, beneficial for fundamental studies and applications.
• The fiber's properties are suitable for practical amplifier systems requiring polarization preservation.