We study light propagation in a medium with a homogeneous refractive index that varies randomly in time. We find that, in stark contrast to spatial disorder, temporal disorder causes exponential increase of the light intensity.
Abstract We demonstrate the nonreciprocal propagation of optical pulses in a linear dispersive medium with a time-varying refractive index. The change of refractive index with time breaks the time-translation symmetry of the spatially homogeneous medium compelling it to be inherently nonreciprocal. A time-reversal asymmetric field ratio of the counter-propagating optical pulses along with a frequency shift leading to spectral nonreciprocity in such dynamic media have been observed. The findings have emerged a new avenue to realize nonreciprocal light flow in dynamically tuned integration-feasible photonic systems.
Abstract Random resonant media being one of the possible realizations of disordered metamaterials open a room of opportunities for achieving new fundamental effects and designing advanced nanophotonic devices. Strongly nonlinear optical properties of such media attract ever increasing attention nowadays from both theoretical and experimental points of view. Hereinafter, the case of the photonic‐crystal‐like structure with a randomly varying light–matter coupling provided by the random density of quantum particles is considered. Using numerical solution of the Maxwell–Bloch equations, the effects of the pulse collisions in the medium are studied. It is shown that disorder enables the qualitative changes of the system's response for co‐propagating pulses, whereas this is not the case for the counter‐propagating ones. The scheme for an all‐optical transmission modulation due to the disorder‐induced inelasticity of collisions of co‐propagating pulses is proposed. The ability of precise tuning the modulation via the inter‐pulse distance and background refractive index adjustment is revealed. This novel approach for light control can be utilized for some high demand applications, such as modulation and switching of a pulsed radiation.
Temporal modulation of materials offers unprecedented control over light, sparking recent interest in the quantum theory of light interaction with time-varying materials. In this presentation, through the lens of quantum optics, we evaluate the von Neumann entropy transformation induced by an electromagnetic time interface, in which the refractive index of an isotropic, homogeneous, nondispersive dielectric medium uniformly undergoes an abrupt change in time. We demonstrate that the entropy increases across such an interface, with the magnitude of the increase correlating positively with the refractive index contrast. Additionally, we analyze how photon population in the incident modes governs entropy evolution. We hope that our study advances both the fundamental physics of time interfaces and their potential applications in quantum information technology.