  During the last few decades, solid-core photonic crystal fibers (PCFs) have
been extensively explored to generate broadband, high-coherence supercontinua
(SC). Limited by the material absorption and relatively low nonlinearity of
fused silica, spectral broadening in silica PCF-based SCs is usually restricted
to the blue to near-infrared spectral regions, even in developed commercial
sources. The output spectra of these sources are missing short wavelengths of
the full range. Many efforts have been spent to break the limitation. Among
them, dispersive-wave (DW) generation has been investigated for triggering new
frequencies in short wavelengths. With satisfied phase-matching conditions,
excessive energy can be directly transferred from solitons of the anomalous
dispersion region to DWs of the short wavelengths. However, a systematical
study of factors, including phase-matched DWs, strongly related to the
dispersion tailoring of higher-order modes (HOMs), has rarely been shown. This
study reports the experimental observations of HOM-enhanced phase-matchings for
the DW generation in the deep-blue and ultraviolet regions. A solid-core
PCF-based, UV-extended SC source spanning a 2.8-octave-wide (350 nm to 2500 nm)
is demonstrated. Meanwhile, we carefully verify our findings via numerical
calculations.
