  For crystalline materials with long-range orders, the phonon modes involved
in the phonon-assisted radiation process are generally involving one or several
phonons with specific vibration frequencies 1-4. In some glassy material, the
phonon modes broaden in a short range 5-7. However, the locally distinct
chemical environments or mass disorder in high-entropy systems can induce an
anharmonic phonon-phonon coupling and composition disorder, which leads to
significant phonon broadening 8,9.The terminology of high-entropy comes from
the high configuration entropy larger than 1.5R (R is the gas constant), which
results from randomly distributed multiple nearly equal components in a crystal
lattice 10,11. Inspired by the high-entropy strategy, we deployed a
high-entropy glass system (HEGS) doped with neodymium ions, which exhibits a
complex structure with tetrahedral voids filled by different ions, including,
Li+, Zn2+, Si4+, P5+, S6+, etc. Phonon spectral broadening up to thousands of
wavenumbers in the HEGS allows strong wide-band absorption in both the
near-infrared and mid-infrared ranges and assists the system radiation, i.e.,
broadened phonon-assisted wide-band radiation (BPAWR). The subsequent
low-threshold self-absorption coherence modulation (SACM) was also observed in
the HEGS, modulated by changing excitation wavelengths, sample size, and doping
concentrations. The time delay of the BPAWR signal is up to 1.66 ns relative to
the zero-delay signal, while the time delay of the Raman process is typically
in the order of fs to ps, rarely up to 10 ps 12-15.The BPAWR-SACM can be
applied to realize signal amplification of the centered non-absorption band
when dual-wavelength lasers pump the HEGS sample, and signal amplification can
be up to 26.02 dB. The spectral characteristics of the BPAWR and the dynamics
of the energy distribution of the excited species are investigated in detail.
