Nanosecond mid-infrared pulse generation via modulated thermal emissivity

TL;DR

This paper demonstrates a novel method to generate nanosecond mid-infrared pulses by rapidly modulating thermal emissivity in semiconductors, achieving significantly faster modulation than previous techniques.

Contribution

The work introduces a new approach for nanosecond mid-infrared pulse generation using fast thermal emissivity modulation in unpatterned silicon and gallium arsenide, with enhanced speed and tunability.

Findings

Nanosecond mid-infrared pulses achieved via emissivity modulation.

Modulation speed is three orders of magnitude faster than previous methods.

The process is well described by a multiphysics model.

Abstract

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, leading to nanosecond pulsed thermal emission. To our knowledge, the nanosecond thermal-emissivity modulation demonstrated in this work is three orders of magnitude faster than what has been previously demonstrated. We also indirectly observed sub-nanosecond 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.