Fabrication of Hybrid Antiresonant Negative Curvature Optical Fiber With GeO 2 ‐Doped Rings Enabling Dual‐Guidance Mechanism

Abstract

In this paper, the fabrication and characterization of hybrid antiresonant negative curvature optical fiber (Hybrid‐ARNCF) are presented to understand unique dual‐guidance mechanism based on total internal reflection (TIR) and antiresonant reflecting optical waveguide (ARROW) principle. The fabrication of the Hybrid‐ARNCF is extensively presented, beginning with the deposition of GeO 2 ‐layer via modified chemical vapor deposition (MCVD) method to form resonant ring in the final fiber structure. Various process parameters, including the doped layer thickness, capillary and rod drawing steps, and the structured assembly into jacketing tube, are optimized to develop final fiber preform. This preform is then drawn into an optical fiber featuring a 32 μm core surrounded by eight microchannels, each lined with a resonant ring of ⁓1.05 μm thickness. The developed Hybrid‐ARNCF exhibits sharp, highly sensitive resonant peaks, which show pronounced spectral shifts in response to the refractive index variations within the cladding microchannels, which aligns well with our simulations and theoretical expression of the resonant wavelengths. These RI‐dependent resonant shifts were used to experimentally validate the dual‐guidance mechanism and the influence of asymmetry factor on the resonant peaks, which are important for optimizing the Hybrid‐ARNCF in terms of high‐power fiber laser applications.