Photonic Time-Crystals (PTCs) are materials in which the refractive index varies periodically
and abruptly in time. This medium exhibits unusual properties such as momentum bands …

Recent advances in ultrafast, large-modulation photonic materials have opened the door to
many new areas of research. One specific example is the exciting prospect of photonic time …

We present an experimental study of optical time-refraction caused by time-interfaces as
short as a single optical cycle. Specifically, we study the propagation of a probe pulse …

Temporal modulation recently draws great attentions in wave manipulations, with which one
can introduce the concept of temporal multilayer structure, a temporal counterpart of spatially …

When an electromagnetic (EM) wave propagates in a medium whose properties are varied
abruptly in time, the wave experiences refractions and reflections known as time-refractions …

Time crystals are an eagerly sought phase of matter with broken time-translation symmetry.
Quantum time crystals with discretely broken time-translation symmetry have been …

The article reviews general properties of time-varying dispersive materials. We first briefly
discuss different dispersion models that have been proposed in the literature, the role of the …

We predict novel topological phases with broken time-reversal symmetry supporting the
coexistence of opposite chiral edge states, which are fundamentally different from the …

Time reflection and refraction are temporal analogies of the spatial boundary effects derived
from Fermat's principle. They occur when classical waves strike a time boundary where an …

The engineering of the spatial and temporal properties of both the electric permittivity and
the refractive index of materials is at the core of photonics. When vanishing to zero, those …