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Terahertz sensing and imaging based on carbon nanotubes : frequency-selective detection and near-field imaging
| Content Provider | Semantic Scholar |
|---|---|
| Author | Kawano, Yukio |
| Copyright Year | 2008 |
| Abstract | The advantageous properties of terahertz (THz) waves permeability through objects opaque for visible light, the important energy spectrum in the meV range, etc. potentially enable various applications of sensing and imaging in this band. Lowdimensional electronic structures open up novel THz technologies, such as quantum cascade laser and THz time-domain spectroscopy. In this work, by employing a carbon nanotube (CNT) and a GaAs/AlGaAs heterostructure, we have sì³®ded in developing a new type of THz sensing and imaging devices: a frequency-selective THz detector and a near-field THz imaging probe. Moreover, as an application of THz imaging to materials science research, we have achieved electron density mapping for each Landau level in a two-dimensional electron system by the use of simultaneous imaging of THz radiation and voltage. I will present the following three topics: (1) detector, (2) imaging, and (3) application of imaging. (1) THz photon-assisted tunneling in a carbon nanotube quantum dot In order to achieve ultra-highly sensitive and frequency-selective THz detection, we have studied THz response of CNT quantum dots (QDs). A charging energy of the CNTQD is typically as large as 10-50meV, which corresponds to a THz frequency. This advantageous property has allowed us to observe a photon-assisted tunnelling in the THz region, whose frequency is two or three magnitudes higher than the microwave (GHz) frequency, previously observed for conventional semiconductor QDs. We have observed THz-induced currents, whose peak position relative to a gate voltage linearly depends on THz photon energy. This provides direct evidence of THz photonassisted tunneling in the CNT-QD. (2) On-chip near-field THz imaging probe integrated with a detector Contrary to the well-established, other frequency regions, the development of near-field imaging technique in the THz region has been hindered by the lack of high transmission wave line and the low sensitivity of the commonly used detector. This issue is therefore one of the most formidable and challenging tasks of contemporary photonics research. Here, we present a new designed THz near-field imaging device, in which all components: an aperture, a probe, and a THz detector are integrated on one GaAs/AlGaAs heterostructure chip. The development of this device has made it possible to sense the evanescent field very efficiently and to avoid the influence of the far-field wave, which was not possible with other previous systems. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.jst.go.jp/inter/workshop/germany/200803/abstract/11.pdf |
| Alternate Webpage(s) | https://www.jst.go.jp/inter/workshop/germany/200803/presentation/11.pdf |
| Alternate Webpage(s) | https://www.jst.go.jp/inter/workshop/germany/200803/abstract/11.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
