We demonstrate the generation of nanosecond mid-infrared pulses via fast modulation of thermal emissivity enabled by the absorption of visible pump pulses in unpatterned silicon and gallium arsenide. The free-carrier dynamics in these materials result in nanosecond-scale modulation of thermal emissivity, which leads to nanosecond pulsed thermal emission. To our knowledge, the nanosecond thermal-emissivity modulation in this work is three orders of magnitude faster than what has been previously demonstrated. We also indirectly observed subnanosecond thermal pulses from hot carriers in semiconductors. The experiments are well described by our multiphysics model. Our method of converting visible pulses into the mid infrared using modulated emissivity obeys different scaling laws and can have significant wavelength tunability compared to approaches based on conventional nonlinearities.

我们演示了通过热发射率的快速调制来产生纳秒级中红外脉冲，该快速发射是通过吸收未图案化的硅和砷化镓中可见的泵浦脉冲而实现的。这些材料中的自由载流子动力学导致纳秒级的热发射率调制，从而导致纳秒级脉冲热发射。据我们所知，这项工作中的纳秒级热发射率调制比以前演示的速度快三个数量级。我们还间接观察到来自半导体中热载流子的亚纳秒热脉冲。我们的多物理场模型很好地描述了实验。