Abstract-Stokes–Mueller method for comprehensive characterization of coherent terahertz waves

                                                                   
Xin Chai, Xavier Ropagnol, Luis. Sanchez Mora, S. Mohsen Raeiszadeh, Saffiedin Safavi-Naeini, François Blanchard, Tsuneyuki Ozaki

• • https://www.nature.com/articles/s41598-020-72049-9

Ideally, the full characterization of coherent terahertz (THz) pulses would provide information on the amplitude and direction of its THz electric field, in space and in time, with unlimited dynamic range. Here, we propose and demonstrate a new approach based on the Stokes–Mueller formalism. Our approach can measure the full temporal and spatial variation of coherent THz fields, as well as its polarization state with a high dynamic range. This method employs a simple configuration, using a polarization state analyzer after the electro-optic sampling crystal. This technique could allow high sensitivity due to its ability to use thick detection crystals, which also would lead to improved spectral resolution by allowing longer scans in the time domain.

Abstract-A Low-Cost Terahertz Camera

François Blanchard,  Joel Edouard Nkeck, Dominique Matte, Riad Nechache, David G. Cooke,

https://www.mdpi.com/2076-3417/9/12/2531

Cost effective imaging is required for a wide range of scientific and engineering applications. For electromagnetic waves in the terahertz (THz) frequency range, a key missing element that has prevented widespread applications in this spectral range is an inexpensive and efficient imaging device. In recent years, vanadium oxide based thermal sensors have rapidly entered the market for night vision capability. At the same time, sensors based on this technology have been applied to the THz domain, but with two orders of magnitude larger pricing range. Here we show that, with a simple modification, a commercially available thermal imaging camera can function as a THz imaging device. By comparing a commercially available THz camera and this low-cost device, we identify the main sensitivity difference is not attributed to anything intrinsic to the devices, but rather to the analog-to-digital converter and dynamic background subtraction capability. This demonstration of a low-cost THz camera may aid in the rapid development of affordable THz imaging solutions for industrial and scientific applications

Abstract-Contactless In Situ Electrical Characterization Method of Printed Electronic Devices with Terahertz Spectroscopy

Mariia Zhuldybina, Xavier Ropagnol, Charles Trudeau,  Martin Bolduc,  Ricardo J. Zednik,  François Blanchard, 

https://www.mdpi.com/1424-8220/19/3/444

Printed electronic devices are attracting significant interest due to their versatility and low cost; however, quality control during manufacturing is a significant challenge, preventing the widespread adoption of this promising technology. We show that terahertz (THz) radiation can be used for the in situ inspection of printed electronic devices, as confirmed through a comparison with conventional electrical conductivity methods. Our in situ method consists of printing a simple test pattern exhibiting a distinct signature in the THz range that enables the precise characterization of the static electrical conductivities of the printed ink. We demonstrate that contactless dual-wavelength THz spectroscopy analysis, which requires only a single THz measurement, is more precise and repeatable than the conventional four-point probe conductivity measurement method. Our results open the door to a simple strategy for performing contactless quality control in real time of printed electronic devices at any stage of its production line.

Abstract-Terahertz microscopy assisted by semiconductor nonlinearities

François Blanchard, Xin Chai, Tomoko Tanaka, Takashi Arikawa, Tsuneyuki Ozaki, Roberto Morandotti, and Koichiro Tanaka

Fig. 1. Experimental setup. (a) THz transmission scheme using wire-grid polarizer and a LN sensor. (b) Illustration of the sample used for near-field investigations. (c) Visible image of a gold ring array structure patterned on a In0.53Ga0.47As${\mathrm{In}}_{0.53}{\mathrm{Ga}}_{0.47}\mathrm{As}$ epilayer thin film.

https://www.osapublishing.org/ol/abstract.cfm?uri=ol-43-20-4997#articleFigures

Terahertz (THz) imaging is currently based on linear effects, but there is great interest on how nonlinear effects induced by terahertz radiation could be exploited to provide extra information that is unobtainable by conventional imaging schemes. In particular, at field strengths on the order of 100  kV cm−1$100\mathrm{kV}{\mathrm{cm}}^{-1}$ to 1  MV cm−1$1\mathrm{MV}{\mathrm{cm}}^{-1}$, transmission properties inside semiconductor materials are largely affected at the picosecond time-scale, which raise the prospect of interesting nonlinear imaging applications at THz frequencies. Here, we experimentally investigate a method to map the two-dimensional nonlinear near-field distribution of an intense THz pulse passing through a thin film-doped semiconductor. By inserting a metamaterial structure between the electro-optic sensor and the doped film, the nonlinear near-field dynamics shows a different and enhanced contrast of the sample when compared to its linear counterpart.

© 2018 Optical Society of America

Abstract-Adaptive spatiotemporal optical pulse front tilt using a digital micromirror device and its terahertz application

Kosuke Murate, Mehraveh Javan Roshtkhari, Xavier Ropagnol, and François Blanchard

https://www.osapublishing.org/ol/abstract.cfm?uri=ol-43-9-2090&origin=search

We report a new method to temporally and spatially manipulate the pulse front tilt (PFT) intensity profile of an ultrashort optical pulse using a commercial microelectromechanical system, also known as a digital micromirror device (DMD). For our demonstration, we show terahertz generation in a lithium niobate crystal using the PFT pumping scheme derived from a DMD chip. The adaptive functionality of the DMD could be a convenient alternative to the more conventional grating required to generate a laser beam with a PFT intensity profile that is typically used for efficient optical rectification in noncollinear phase-matching conditions. In contrast to a grating, PFT using DMD does not suffer from wavelength dispersion, and exhibits overlap properties between grating and a stair-step echelon mirror.

© 2018 Optical Society of America

Abstract-Control of Spoof Localized Surface Plasmons Using Terahertz Near-field Microscope

Takashi Arikawa, Shohei Morimoto, Tomoki Hiraoka, François Blanchard, Kyosuke Sakai, Keiji Sasaki, and Koichiro Tanaka

https://www.blogger.com/blogger.g?blogID=124073320791841682#editor/target=post;postID=2704300894288992135

We performed time-resolved terahertz near-field imaging of a gold disk with sub-wavelength periodic grooves and successfully observed spoof localized surface plasmons. A selective excitation method is also demonstrated with orbital angular momentum of light.

© 2018 The Author(s)

Abstract-Dynamic creation of a light-induced terahertz guided-wave resonator

Lauren Gingras, François Blanchard, Marcel Georgin, and David G. Cooke
https://www.osapublishing.org/oe/abstract.cfm?uri=oe-24-3-2496

We demonstrate a dynamic light-induced resonator for terahertz (THz) frequency light created on ultrashort time scales inside a planar waveguide. The resonator is created by patterned femtosecond photoexcitation of a one-dimensional array of photoconductive regions inside a silicon-filled parallel plate waveguide. The metal-dielectric photonic crystal is created on a 2 ps time scale, ten times faster than the 20 ps transit time of the THz light through the array. The resonance reveals itself through narrowband THz transmission enhancement with accompanying phase modulation producing an induced group delay of up to 10.8 ps near resonance.

© 2016 Optical Society of America

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Abstract-Ultrafast Carrier Dynamics in Graphene under a High Electric Field

http://prl.aps.org/abstract/PRL/v109/i16/e166603

Shuntaro Tani^1,2,*, François Blanchard^2,3, and Koichiro Tanaka^1,2,3,†

¹Department of Physics, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
²CREST, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan

³Institute for Integrated Cell-Material Sciences (WPI-iCeMS),Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan

We investigated ultrafast carrier dynamics in graphene with near-infrared transient absorption measurement after intense half-cycle terahertz pulse excitation. The terahertz electric field efficiently drives the carriers, inducing large transparency in the near-infrared region. Theoretical calculations using the Boltzmann transport equation quantitatively reproduce the experimental findings. This good agreement suggests that the intense terahertz field should promote a remarkable impact ionization process and increase the carrier density.

Terahertz radiation induced ballistic electron transport in graphene

Shuntaro Tani, François Blanchard, Koichiro Tanaka

http://arxiv.org/abs/1206.1392

(Submitted on 7 Jun 2012)

We investigated ultrafast carrier dynamics in graphene with near-infrared transient absorption measurement after intense half-cycle terahertz pulse excitation. The terahertz electric field efficiently drives the carriers, inducing large transparency in the near-infrared region. Theoretical calculations using the Boltzmann transport equation quantitatively reproduce the experimental findings. This good agreement suggests that the intense terahertz field should promote remarkable impact ioniza- tion process, which leads to suppression of optical phonon emission and results in efficient carrier transport in graphene.

Comments:	4 pages, 3 figures
Subjects:	Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Cite as:	arXiv:1206.1392v1 [cond-mat.mes-hall]

Submission history

From: Shuntaro Tani [view email]
[v1] Thu, 7 Jun 2012 04:09:09 GMT (468kb)