Excitation of higher-order modes in optofluidic photonic crystal fiber

TL;DR

This paper demonstrates controlled excitation of higher-order modes in water-filled hollow-core photonic crystal fibers using a spatial light modulator, enabling advanced sensing and optical manipulation applications.

Contribution

It introduces a method to selectively excite higher-order modes in liquid-filled HC-PCF with high efficiency, matching simulations and enabling new microreactor sensing techniques.

Findings

Achieved 10-20% launch efficiency for higher-order modes.

Modes closely match numerical simulations and air-filled counterparts.

Provides a framework for mode-based sensing and manipulation.

Abstract

Higher-order modes up to LP$_{33}$ are controllably excited in water-filled kagom\'{e}- and bandgap-style hollow-core photonic crystal fibers (HC-PCF). A spatial light modulator is used to create amplitude and phase distributions that closely match those of the fiber modes, resulting in typical launch efficiencies of 10-20% into the liquid-filled core. Modes, excited across the visible wavelength range, closely resemble those observed in air-filled kagom\'{e} HC-PCF and match numerical simulations. Mode indices are obtained by launching plane-waves at specific angles onto the fiber input-face and comparing the resulting intensity pattern to that of a particular mode. These results provide a framework for spatially-resolved sensing in HC-PCF microreactors and fiber-based optical manipulation.