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Lead halide perovskites (LHPs) have excellent semiconductor properties. They have been used in many applications such as solar cells. Recently, the hot carrier dynamics in this type of material have received much attention as they are useful for enhancing the performance of optoelectrical devices fabricated from it. Here, we study the ultrafast hot carrier dynamics of a single CsPbBr3 microplate using femtosecond Kerr-gated wide-field fluorescence spectroscopy. The transient photoluminescence spectra have been measured under a variety of excitation fluences. The temporal evolution of bandgap renormalization and the competition between hot carrier cooling and the recovery of the renormalized bandgap are clearly revealed. [ABSTRACT FROM AUTHOR]

A split-step birefringence simulation method is proposed to investigate the gating efficiency and intensity distribution of the Kerr signal field considering the evolution of the switch beam and probe beam in their path. Using this simulation method, we investigated the switch-beam power-dependent gating efficiency and conducted an experiment to prove its reliability. Furthermore, we analyzed the optical intensity distribution of the Kerr signal exiting the Kerr medium under different switch-beam powers. This study provides an effective theoretical tool for the design and optimization of optical Kerr gates. [ABSTRACT FROM AUTHOR]

The influence of the size parameter of the scatterers on ultrafast optical Kerr gate (OKG) imaging is investigated in highly scattering poly-disperse turbid media. The results show that in a poly-disperse turbid medium, which in our case, is a suspension of two different sized mono-disperse microspheres, the temporal and spatial behaviors of the light pulses transmitted through it are dominated by the smaller microspheres. The contrasts of the OKG images for the poly-disperse microsphere sample are closer to the contrasts of the OKG images for the smaller sized mono-disperse microsphere sample. [ABSTRACT FROM PUBLISHER]

We demonstrated the time-gated ballistic imaging technique using a femtosecond optical Kerr gate (OKG) of bismuth–plumbum oxide glass, the nonlinear optical properties of which were also investigated. The third-order nonlinear refractive-indexn2of the bismuth–plumbum oxide glass was measured to be 2.19?×?10?15?cm2/W, and the nonlinear response time was estimated to be shorter than 180?fs. For the time-gated ballistic imaging, the maximum measurable optical density of turbid media using the OKG of bismuth–plumbum oxide glass was 9.3, while only 7.0 for the OKG of quartz glass. And the intensities of the images for the bismuth–plumbum oxide glass were approximately two orders of magnitude higher than that for the quartz glass. The experimental results indicated that the bismuth–plumbum oxide glass was an excellent optical material for nonlinear optical applications. [ABSTRACT FROM AUTHOR]

An optical Kerr gate (OKG) is an ultrafast optical switch based on the optical Kerr effect. The performance of a conventional OKG depends mainly on Kerr materials. Traditional Kerr materials do not demonstrate both large optical nonlinearity and an ultrafast response time. Therefore, the performance of a conventional OKG is limited by an inherent trade-off between high signal transmittance and fast switching time, which limits its application in many fields. We propose an improved femtosecond OKG with double gate pulses, based on the use of a birefringent crystal to realize an ultrashort switching time, even with a slow-response optical Kerr medium. We assessed the dependence of the double gate pulsed OKG (D-OKG)'s performance on the intensity ratio of the double gate pulses. A transmittance of 50% and a switching time of 142 fs were achieved. The D-OKG is convenient to construct, and its integrated performance is superior to that of a conventional OKG. [ABSTRACT FROM AUTHOR]

• A theoretical model of optical Kerr gate with a double gate pulses (D-OKG) was proposed. • The dependence of the D-OKG performance on the relative intensity and the relative delay time of the two gate pulses was investigated with our theoretical model. We demonstrated an improved optical Kerr gate with double gate pulses (D-OKG) to realize an ultrashort switching time even with a slow-response optical Kerr medium. A theoretical model of D-OKG was established and the dependence of the D-OKG performance on the relative intensity and the relative delay time of the two gate pulses was investigated. An integrated optimal condition was predicted. The D-OKG was experimentally built and optimized according to the simulation. The dependence of the D-OKG performance on the two gate pulses was confirmed. In our experiment, the achieved values for transmittance and switching time were 45 % and 150 fs, respectively. Compared to the conventional OKG, the D-OKG owns an integrated optimal performance in the femtosecond regime, and has the potential for a wide range of ultrafast optical switch applications. [ABSTRACT FROM AUTHOR]