Topological photonic crystal fiber.

Area of Science:

• Photonics
• Condensed Matter Physics
• Materials Science

Background:

• Photonic crystal fibers (PCFs) offer tunable light guiding through geometric customization.
• Conventional PCFs rely on mode-trapping mechanisms for light confinement.
• Topological concepts offer new paradigms for robust light guiding.

Purpose of the Study:

• To realize a PCF utilizing photonic band structure topology for guided modes.
• To design a fiber compatible with standard fabrication processes.
• To demonstrate low-loss and bend-resistant light propagation.

Main Methods:

• Designing a PCF with a topological crystalline insulator cross-section featuring a disclination.
• Employing theoretical methods, including a spectral localizer, to confirm topological origins of modes.
• Fabricating the PCF using the stack-and-draw method.
• Experimentally measuring light transmission losses and bending performance.

Main Results:

• Guided topological modes were generated below the cladding light line.
• The fabricated TPCF demonstrated low transmission losses (10-20 dB/km) in the visible to near-infrared spectrum.
• Losses remained low even under substantial fiber bending.
• Conventional PCFs showed significantly higher bending losses.

Conclusions:

• Topological modes provide a robust mechanism for light guiding in PCFs.
• The developed TPCF design offers improved performance, particularly in bend resistance.
• Topological optical fibers present a promising platform for advanced photonic applications.