Abstract-Terahertz and Photoelectron Emission from Nanoporous Gold Films on Semiconductors

Junyi Nan, Min Li, Ling Zhang, Shuai Yuan, Boqu He,  Heping Zeng,

https://www.mdpi.com/2079-4991/9/3/419

Efficient terahertz and photoelectron emission were observed from nano-porous gold (NPG) films deposited on an intrinsic gallium arsenide (GaAs) semiconductor substrate stimulated by femtosecond laser with pulse width of 60 fs. Time-domain THz emission and reflection spectroscopy confirmed that the free charges accelerated by irradiated femtosecond laser pulses transferred from the NPG films into the GaAs substrates. Accordingly, charges accumulation was reduced in the NPG films, resulting in a stronger emission of THz pulse than that from NPG films deposited on SiO₂ substrate. Charges injected into the GaAs substrate enforced an observable decrease of the THz refractive index proportional to the intensity of incident light. In comparison, for NPG deposited on glass substrates, laser induced free charges were accumulated in the NPG films, and femtosecond laser pulses irradiating on the NPG films made no changes of the THz refractive index of the glass substrates

Abstract-Terahertz modulation induced by filament interaction

Boqu He, Junyi Nan, Min Li, Shuai Yuan, and Heping Zeng

https://www.osapublishing.org/ol/abstract.cfm?uri=ol-42-5-967

We experimentally demonstrated that nonlinear filament interaction could spectrally modulate terahertz (THz) radiation generated from asymmetric two-color filaments. It was the spatial plasma density modulation in plasma channels that induced the THz spectral modulation. As a result of optical manipulation of electron density in the filamentary plasma gratings, the proportion of high-frequency THz spectra increased, while that of low-frequency THz spectra decreased, indicating that the increase of free electron density in the filamentary plasma grating brought about THz frequency upshifts.

© 2017 Optical Society of America

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