Abstract-Semiconductor terahertz modulator arrays: the size and edge effect

Tianlong Wen, Chong Zhang, Xiaochen Zhang, Yulong Liao, Quanjun Xiang, Qiye Wen, Dainan Zhang, Yuanpeng Li, Huaiwu Zhang, Yulan Jing, and Zhiyong Zhong

https://www.osapublishing.org/ol/abstract.cfm?uri=ol-43-13-3021

A terahertz spatial modulator is the critical component for active terahertz imaging using compressive sensing. Here small silicon pieces were put in arrays on flexible polymer substrate to fabricate semiconductor terahertz spatial modulators. By doing this, the inter-diffusion of photo-generated charge carriers is prevented for better resolution, and flexibility is achieved. Since the size of silicon is comparable to the wavelength of the terahertz wave, and the dielectric properties of the gap are very different from silicon, the optical modulation of each element is very different from the large silicon. In this Letter, the terahertz wave interaction and optical modulation of the small silicon are systematically studied by time domain spectroscopy. Notably, a strong resonance-like absorption peak was observed in a transmittance spectrum for the small silicon due to the size and edge effect. The spatial modulation of the terahertz wave was also compared between the silicon array and the large silicon samples.

© 2018 Optical Society of America

Abstract-Efficient semiconductor source of multicycle terahertz pulses using intensity-modulated pump

Gy. Tóth, P. S. Nugraha, G. Krizsán, M. I. Mechler, Gy. Polónyi, J. Hebling,  J. A. Fülöp

https://www.osapublishing.org/abstract.cfm?uri=CLEO_AT-2018-JTh2A.191

Up to 5% conversion efficiency is predicted by numerical simulations for optimized GaP contact-grating THz sources based on optical rectification. Easy control of multicycle THz waveforms is enabled by a flexible dual-chirped OPA pump source.

© 2018 The Author(s)

Abstract-Petahertz optical drive with wide-bandgap semiconductor

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  • http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys3711.html
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• Hiroki Mashiko,
• Katsuya Oguri,
• Tomohiko Yamaguchi,
• Akira Suda
• & Hideki Gotoh

High-speed photonic and electronic devices at present rely on radiofrequency electric fields to control the physical properties of a semiconductor¹, which limits their operating speed to terahertz frequencies (10¹² Hz; ref. 2). Using the electric field from intense light pulses, however, could extend the operating frequency into the petahertz regime (10¹⁵ Hz; ref. 3). Here we demonstrate optical driving at a petahertz frequency in the wide-bandgap semiconductor gallium nitride. Few-cycle near-infrared pulses are shown to induce electric interband polarization though a multiphoton process. Dipole oscillations with a periodicity of 860 as are revealed in the gallium nitride electron and hole system by using the quantum interference between the two transitions from the valence and conduction band states, which are probed by an extremely short isolated attosecond pulse with a coherent broadband spectrum. In principle, this shows that the conductivity of the semiconductor can be manipulated on attosecond timescales, which corresponds to instantaneous light-induced switching from insulator to conductor. The resultant dipole frequency reaches 1.16 PHz, showing the potential for future high-speed signal processing technologies based on wide-bandgap semiconductors