  Dynamics of femtosecond pulses with the telecom carrier wavelength is
investigated numerically in a subwavelength layer of an indium tin oxide (ITO)
epsilon-near-zero (ENZ) material with high dispersion and high nonlinearity.
Due to the subwavelength thickness of the ITO ENZ material, and the fact that
the pulse's propagation time is shorter than its temporal width, multiple
reflections give rise to self-interaction in both spectral and temporal
domains, especially at wavelengths longer than the ENZ point, at which the
reflections are significantly stronger. A larger absolute value of the pulse's
chirp strongly affects the self-interaction by redistributing energy between
wavelengths, while the sign of the chirp affects the interaction in the
temporal domain. It is also found that, when two identical pulses are launched
simultaneously from both ends, a subwavelength counterpart of a standing-wave
state can be established. It shows robust energy localization in the middle of
the sample, in terms of both the spectral and temporal intensity distributions.
