A hollow light rod is a specialized optical component with a central hollow channel (typically filled with air or inert gas) and an outer dielectric cladding. Similar to solid-core optical fibers but featuring a hollow core structure, its design is inspired by hollow-core fiber technology. By optimizing the shape of the hollow channel (e.g., circular, polygonal) and the cladding material (e.g., quartz), it enables efficient transmission and control of optical signals within the hollow region¹. Compared to traditional solid-core light rods, its key distinction lies in the fact that light propagates primarily in air or gaseous media, rather than relying on total internal reflection in a solid core, thus offering unique optical properties.

II. Core Working Principles and Technical Advantages

• Working Principle: Based on the photonic bandgap effect or total internal reflection, periodic dielectric layers (e.g., multilayer coatings or photonic crystal structures) are designed around the hollow channel to confine optical energy within the hollow region, minimizing interaction with solid materials.
• Technical Advantages:
  • Low Loss and High Transparency: Light propagates in the air core, avoiding intrinsic absorption by solid media. Some models achieve transmittance above 95% with losses below 0.1 dB/cm¹.
  • Resistance to Nonlinear Effects: Nonlinear refractive index is 3–4 orders of magnitude lower than that of solid-core rods, enabling higher incident power tolerance and suitability for high-energy laser transmission.
  • Broadband Compatibility: Through structural optimization, it supports ultra-wide operating bands (e.g., above 1000 nm), covering communication bands such as O/S/C/L/U and the mid-infrared region.