The estimation of the transmission matrix of a disordered medium is a challenging problem in disordered photonics.Usually,its reconstruction relies on a complex inversion that aims at connecting a fully controlled inp...The estimation of the transmission matrix of a disordered medium is a challenging problem in disordered photonics.Usually,its reconstruction relies on a complex inversion that aims at connecting a fully controlled input to the deterministic interference of the light field scrambled by the device.At the moment,iterative phase retrieval protocols provide the fastest reconstructing frameworks,converging in a few tens of iterations.Exploiting the knowledge of speckle correlations,we construct a new phase retrieval algorithm that reduces the computational cost to a single iteration.Besides being faster,our method is practical because it accepts fewer measurements than state-of-the-art protocols.Thanks to reducing computation time by one order of magnitude,our result can be a step forward toward real-time optical imaging that exploits disordered devices.展开更多
In this work,we experimentally demonstrate for the first time the spontaneous generation of two-dimensional exciton-polariton X-waves.X-waves belong to the family of localized packets that can sustain their shape with...In this work,we experimentally demonstrate for the first time the spontaneous generation of two-dimensional exciton-polariton X-waves.X-waves belong to the family of localized packets that can sustain their shape without spreading,even in the linear regime.This allows the wavepacket to maintain its shape and size for very low densities and very long times compared to soliton waves,which always necessitate a nonlinearity to compensate the diffusion.Here,we exploit the polariton nonlinearity and uniquely structured dispersion,comprising both positive-and negative-mass curvatures,to trigger an asymmetric four-wave mixing in momentum space.This ultimately enables the self-formation of a spatial X-wave front.Using ultrafast imaging experiments,we observe the early reshaping of the initial Gaussian packet into the X-pulse and its propagation,even for vanishingly small densities.This allows us to outline the crucial effects and parameters that drive the phenomena and to tune the degree of superluminal propagation,which we found to be in close agreement with numerical simulations.展开更多
基金Lazio Innova (A0375-2020-36761)European Research Council (694925).
文摘The estimation of the transmission matrix of a disordered medium is a challenging problem in disordered photonics.Usually,its reconstruction relies on a complex inversion that aims at connecting a fully controlled input to the deterministic interference of the light field scrambled by the device.At the moment,iterative phase retrieval protocols provide the fastest reconstructing frameworks,converging in a few tens of iterations.Exploiting the knowledge of speckle correlations,we construct a new phase retrieval algorithm that reduces the computational cost to a single iteration.Besides being faster,our method is practical because it accepts fewer measurements than state-of-the-art protocols.Thanks to reducing computation time by one order of magnitude,our result can be a step forward toward real-time optical imaging that exploits disordered devices.
基金supported by the European Research Council POLAFLOW Grant 308136 and the Italian MIUR project Beyond Nanosupported by the NCN Grant no.2012/04/M/ST2/00789+2 种基金MNiSW Iuventus Plus project no.IP 2014044873support from the FNP project FIRST TEAM/2016-2/17support from NCN Grant 2015/17/B/ST3/02273.
文摘In this work,we experimentally demonstrate for the first time the spontaneous generation of two-dimensional exciton-polariton X-waves.X-waves belong to the family of localized packets that can sustain their shape without spreading,even in the linear regime.This allows the wavepacket to maintain its shape and size for very low densities and very long times compared to soliton waves,which always necessitate a nonlinearity to compensate the diffusion.Here,we exploit the polariton nonlinearity and uniquely structured dispersion,comprising both positive-and negative-mass curvatures,to trigger an asymmetric four-wave mixing in momentum space.This ultimately enables the self-formation of a spatial X-wave front.Using ultrafast imaging experiments,we observe the early reshaping of the initial Gaussian packet into the X-pulse and its propagation,even for vanishingly small densities.This allows us to outline the crucial effects and parameters that drive the phenomena and to tune the degree of superluminal propagation,which we found to be in close agreement with numerical simulations.
