Slow-light enhanced absorption in a hollow-core fiber

Area of Science:

• Photonics
• Optical Materials Science
• Fiber Optics

Background:

• Hollow-core photonic band-gap fibers (HC-PBGFs) offer enhanced optical path lengths due to light reflections.
• This property is promising for increasing optical absorption in infiltrated materials.
• Existing structures face limitations in balancing light slowdown and filling fraction for absorption enhancement.

Purpose of the Study:

• To quantify the absorption enhancement achievable in translationally invariant HC-PBGF structures.
• To investigate the dependence of absorption enhancement on key material parameters.
• To explore the role of absorption-induced saturation of the group index.

Main Methods:

• Theoretical analysis of light propagation in HC-PBGFs.
• Modeling of optical absorption and refractive index effects.
• Quantification of absorption enhancement and group index saturation.

Main Results:

• A trade-off exists between light slowdown and filling fraction in translationally invariant structures, limiting net absorption enhancement.
• The achievable absorption enhancement is dependent on specific material parameters.
• Absorption-induced saturation of the group index was demonstrated, further limiting maximum absorption enhancement.

Conclusions:

• HC-PBGFs offer a method for enhancing optical absorption, but intrinsic limitations must be considered.
• The study quantifies the maximum achievable absorption enhancement and identifies key limiting factors.
• Understanding the interplay between absorption and group index is crucial for optimizing HC-PBGF applications.