Abstract-Generation of terahertz vortex pulses without any need of manipulation in the terahertz region

Qinggang Lin, Shuiqin Zheng, Qiying Song, Xuanke Zeng, Yi Cai, Ying Li, Zhenkuan Chen, Lang Zha, Xinjian Pan, and Shixiang Xu

https://www.osapublishing.org/ol/abstract.cfm?uri=ol-44-4-887

Converting a Gaussian mode to a vortex beam is much more inconvenient in the terahertz (THz) region than in the near-infrared (NIR) region due to underdevelopment of THz components and strong THz diffraction. This Letter reports the direct generation of THz vortex pulses by optical difference-frequency between two NIR chirped pulses with different topological charges (TCs). By designing a passive and transmissive device for a collinear NIR pulse pair with conjugated TCs, we have experimentally obtained stable THz vortex pulses with a TC value of 2 or −2$-2$. The process needs no THz components and so is flexible to be realized and has promising applications in the THz field.

© 2019 Optical Society of America

Abstract-Common-path spectral interferometry for single-shot terahertz electro-optics detection

Shuiqing Zheng, Xinjian Pan, Yi Cai, Qinggang Lin, Ying Li, Shixiang Xu, Jingzhen Li, and Dianyuan Fan

https://www.osapublishing.org/ol/abstract.cfm?uri=ol-42-21-4263

We propose a common-path spectral interferometer for single-shot terahertz (THz) electro-optics (EO) detection, where a probe pulse pair with orthogonal polarizations and a relative time delay are generated by simply using a birefringent plate. One of them, as the object, transmits through a THz EO crystal with THz phase modulation, while the other goes through the crystal without any phase imposed by target the THz field as the reference. The co-axial propagation of the pulse pair can effectively reduce the noises due to mechanical vibrations, air turbulences, and temperature fluctuations in the traditional non-common-path spectral interferometers. Our experiments show that, for a given target THz pulse field, the measured THz signals in a single-shot mode have a signal-to-noise ratio (SNR) of 41.2 with our THz common-path spectral interferometer, but 7.91 with a THz Mach–Zehnder spectral interferometer; thus, our design improves the SNR of the THz signal by about 5.2 times.

© 2017 Optical Society of America

Abstract-High-resolution electroluminescent imaging of pressure distribution using a piezoelectric nanowire LED array

• a, Schematic band diagram of a p-GaN/n-ZnO p–n junction before (black line) and after (red line) applying a compressive strain, where the dip created at the interface is due to the non-mobile, positive ionic charges created by the piezo phototronic effect.

• Caofeng Pan,
• Lin Dong,
• Guang Zhu,
• Simiao Niu,
• Ruomeng Yu,
• Qing Yang,
• Ying Liu
• & Zhong Lin Wang

• http://www.nature.com/nphoton/journal/v7/n9/full/nphoton.2013.191.html

Emulation of the sensation of touch through high-resolution electronic means could become important in future generations of robotics and human–machine interfaces. Here, we demonstrate that a nanowire light-emitting diode-based pressure sensor array can map two-dimensional distributions of strain with an unprecedented spatial resolution of 2.7 µm, corresponding to a pixel density of 6,350 dpi. Each pixel is composed of a single n-ZnO nanowire/p-GaN light-emitting diode, the emission intensity of which depends on the local strain owing to the piezo-phototronic effect. A pressure map can be created by reading out, in parallel, the electroluminescent signal from all of the pixels with a time resolution of 90 ms. The device may represent a major step towards the digital imaging of mechanical signals by optical means, with potential applications in artificial skin, touchpad technology, personalized signatures, bio-imaging and optical microelectromechanical systems.