EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Mid-infrared (MIR) light sources have been demanded for sensing applications because MIR absorptions are finger prints of various materials. In particular, MIR lasers based on nanomaterials have recently attracted attention for device integration. The MIR nanolaser was achieved using InAs and PbS nanowires at wavelengths of 2.6 and 3 μm, respectively [1, 2]. Black phosphorus, which is a narrow-bandgap layered material, also exhibits strong MIR emission and lasing action at 4 μm [3, 4]. To examine the optical quality of such nanomaterials and the ultrafast dynamics of carriers and emissions, time-resolved micro-spectroscopy is needed for MIR emission.
In this study, we measured time-resolved MIR emission from thick InAs nanowire lasers at a low temperature. The InAs nanowires grown by self-catalyst vapor-liquid-solid method show the nonlinear dependence of emission intensity at a wavelength of around 2.6 μm as an optical pump fluence changes, which indicates laser oscillation [1]. Furthermore, to observe the transient dynamics of laser emission, we developed a time-resolved MIR micro-photoluminescence measurement setup with a wavelength up-conversion technique [5], where MIR emission was converted to visible light in a lithium niobate crystal and sampled in the time domain by an optically delayed near-infrared probe laser pulse. The time-resolved data show a fast stimulated emission spike within the first 200 ps after optical pumping, and the turn-on delay decreases when the optical pump fluence exceeds the threshold. This result shows the potential for fast modulation of MIR nanowire lasers.
[1] H. Sumikura et al., Nano Lett. 19, 8059 (2019).
[2] F. Fang et al., Nano Lett. 20, 470 (2020).
[3] C. Chen et al., Nano Lett. 19, 1488 (2019).
[4] Y. Huang et al., ACS Photon. 6, 1581 (2019).
[5] H. Sumikura et al., Appl. Phys. Express 14, 032008 (2021).