Liquid-filled suspended-core fibers for flat and broadband supercontinuum generation

This work introduces a dispersion engineering technology for supercontinuum (SC) generation based on liquid-infiltrated suspended core fibers (SCFs), enabling efficient spectral control without modifying the fiber geometry. An SCF structure with air holes is filled with water, demonstrating a flat anomalous dispersion in a wide wavelength range. For coherent SC generation, an ethanol-filled fiber with the same core diameter of 1.7 µm is considered to shift the dispersion curves toward the normal dispersion region. The resulting dispersion profiles show good agreement between numerical simulations and experimental data. The generalized nonlinear Schrödinger equation (GNLSE) is subsequently employed to investigate the influence of pump pulse parameters on SC evolution. The simulations investigate how SC changes with pump peak power and pulse width in a 10 cm fiber when pumped at a wavelength of 1030 nm. A broadening of the SC spectrum is observed as the pump peak power at a wavelength of 1030 nm rises from 5 to 30 kW. The same trend persists for shorter pulse widths, ranging from 200 to 50 fs. Notably, the proposed water-filled SCF generates a broad spectrum spanning from 674 to 1918 nm in the anomalous regimes. Meanwhile, the generation of a flat SC spectrum from 757 to 1400 nm is obtained in the all-normal dispersion ethanol-filled fiber. These findings demonstrate the effectiveness of liquid infiltration as an experimentally accessible tool for dispersion control in SCFs, and provide new insights for infrared SC sources.