Intersubband Rabi Oscillations in Asymmetric Nanoheterostructures: Implications for a Tunable Continuous-Wave Source of a Far-Infrared and THz Radiation

2012 ◽  
Vol 12 (6) ◽  
pp. 4650-4657
Author(s):  
V. A. Kukushkin
Keyword(s):  
Continuous Wave ◽  
Far Infrared ◽  
Thz Radiation ◽  
Rabi Oscillations ◽  
Wave Source

T-Ray Sensing and Imaging

2003 ◽  
Vol 13 (02) ◽  
pp. 601-676 ◽  
Author(s):  
S. P. Mickan ◽  
X.-C. Zhang
Keyword(s):  
Millimeter Waves ◽  
Continuous Wave ◽  
State Of The Art ◽  
Far Infrared ◽  
Ultrafast Laser ◽  
Thz Radiation ◽  
Electromagnetic Spectrum ◽  
Spectral Bandwidth ◽  
Signal To Noise ◽  
The Past

Terahertz (THz) radiation occupies part of the electromagnetic spectrum between the infrared and microwave bands. Until recently, technology at THz frequencies was under-developed compared to the rest of the electromagnetic spectrum, leaving a gap between millimeter waves and the far-infrared (FIR). In the past decade, interest in the THz gap has been increased by the development of ultrafast laser-based T-ray systems and their demonstration of diffraction-limited spatial resolution, picosecond temporal resolution, DC-THz spectral bandwidth and signal-to-noise ratios above 104. This chapter reviews the development, the state of the art and the applications of T-ray spectrometers. Continuous-wave (CW) THz-frequency sources and detectors are briefly introduced in comparison to ultrafast pulsed THz systems. An emphasis is placed on experimental applications of T-rays to sensing and imaging, with a view to the continuing advance of technologies and applications in the THz band.

scholarly journals Effect of the Front and Back Illumination on Sub-Terahertz Detection Using n-Channel Strained-Silicon MODFETs

2020 ◽  
Vol 10 (17) ◽  
pp. 5959
Author(s):  
Juan A. Delgado-Notario ◽  
Jaime Calvo-Gallego ◽  
Jesús E. Velázquez-Pérez ◽  
Miguel Ferrando-Bataller ◽  
Kristel Fobelets ◽  
...  
Keyword(s):  
Continuous Wave ◽  
Thz Radiation ◽  
Strained Si ◽  
Wave Source ◽  
Electromagnetic Simulations ◽  
Terahertz Detection ◽  
Bonding Wires ◽  
Bottom Side ◽  
Photovoltaic Mode ◽  
Efficient Coupling

Plasma waves in semiconductor gated 2-D systems can be used to efficiently detect Terahertz (THz) electromagnetic radiation. This work reports on the response of a strained-Si Modulation-doped Field-Effect Transistor (MODFET) under front and back sub-THz illumination. The response of the MODFET has been characterized using a two-tones solid-state continuous wave source at 0.15 and 0.30 THz. The DC drain-to-source voltage of 500-nm gate length transistors transducing the sub-THz radiation (photovoltaic mode) exhibited a non-resonant response in agreement with literature results. Two configurations of the illumination were investigated: (i) front side illumination in which the transistor was shined on its top side, and (ii) back illumination side where the device received the sub-THz radiation on its bottom side, i.e., on the Si substrate. Under excitation at 0.15 THz clear evidence of the coupling of terahertz radiation by the bonding wires was found, this coupling leads to a stronger response under front illumination than under back illumination. When the radiation is shifted to 0.3 THz, as a result of a lesser efficient coupling of the EM radiation through the bonding wires, the response under front illumination was considerably weakened while it was strengthened under back illumination. Electromagnetic simulations explained this behavior as the magnitude of the induced electric field in the channel of the MODFET was considerably stronger under back illumination.

scholarly journals Broadband spectroscopy of astrophysical ice analogues

2019 ◽  
Vol 629 ◽  
pp. A112 ◽  
Author(s):  
B. M. Giuliano ◽  
A. A. Gavdush ◽  
B. Müller ◽  
K. I. Zaytsev ◽  
T. Grassi ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Time Domain ◽  
Complex Refractive Index ◽  
Far Infrared ◽  
Infrared Region ◽  
Thz Radiation ◽  
The Real ◽  
Thz Range ◽  
The Time Domain

Context. Reliable, directly measured optical properties of astrophysical ice analogues in the infrared and terahertz (THz) range are missing from the literature. These parameters are of great importance to model the dust continuum radiative transfer in dense and cold regions, where thick ice mantles are present, and are necessary for the interpretation of future observations planned in the far-infrared region. Aims. Coherent THz radiation allows for direct measurement of the complex dielectric function (refractive index) of astrophysically relevant ice species in the THz range. Methods. We recorded the time-domain waveforms and the frequency-domain spectra of reference samples of CO ice, deposited at a temperature of 28.5 K and annealed to 33 K at different thicknesses. We developed a new algorithm to reconstruct the real and imaginary parts of the refractive index from the time-domain THz data. Results. The complex refractive index in the wavelength range 1 mm–150 μm (0.3–2.0 THz) was determined for the studied ice samples, and this index was compared with available data found in the literature. Conclusions. The developed algorithm of reconstructing the real and imaginary parts of the refractive index from the time-domain THz data enables us, for the first time, to determine the optical properties of astrophysical ice analogues without using the Kramers–Kronig relations. The obtained data provide a benchmark to interpret the observational data from current ground-based facilities as well as future space telescope missions, and we used these data to estimate the opacities of the dust grains in presence of CO ice mantles.

scholarly journals Application of a Terahertz System Combined with an X-Shaped Metamaterial Microfluidic Cartridge

Micromachines ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 74
Author(s):  
Shih-Ting Huang ◽  
Shen-Fu Hsu ◽  
Kai-Yuan Tang ◽  
Ta-Jen Yen ◽  
Da-Jeng Yao
Keyword(s):  
Far Infrared ◽  
Infrared Region ◽  
Microfluidic System ◽  
Electromagnetic Response ◽  
Thz Radiation ◽  
Similar Species ◽  
Label Free ◽  
Plasmonic Sensor ◽  
Molecular Fingerprint ◽  
Highly Sensitive Detection

Terahertz (THz) radiation has attracted wide attention for its ability to sense molecular structure and chemical matter because of a label-free molecular fingerprint and nondestructive properties. When it comes to molecular recognition with terahertz radiation, our attention goes first towards the absorption spectrum, which is beyond the far infrared region. To enhance the sensitivity for similar species, however, it is necessary to apply an artificially designed metamaterial sensor for detection, which confines an electromagnetic field in an extremely sub-wavelength space and hence receives an electromagnetic response through resonance. Once the resonance is caused through the interaction between the THz radiation and the metamaterial, a minute variation might be observed in the frequency domain. For a geometric structure of a metamaterial, a novel design called an X-shaped plasmonic sensor (XPS) can create a quadrupole resonance and lead to sensitivity greater than in the dipole mode. A microfluidic system is able to consume reagents in small volumes for detection, to diminish noise from the environment, and to concentrate the sample into detection spots. A microfluidic device integrated with an X-shaped plasmonic sensor might thus achieve an effective and highly sensitive detection cartridge. Our tests involved not only measurements of liquid samples, but also the performance of a dry bio-sample coated on an XPS.

scholarly journals Dynamical theory calculations of spin-echo resolved grazing-incidence scattering from a diffraction grating

2010 ◽  
Vol 43 (3) ◽  
pp. 455-465 ◽  
Author(s):  
Rana Ashkar ◽  
P. Stonaha ◽  
A. L. Washington ◽  
V. R. Shah ◽  
M. R. Fitzsimmons ◽  
...  
Keyword(s):  
Diffraction Grating ◽  
Continuous Wave ◽  
Spin Echo ◽  
Grazing Incidence ◽  
Grating Period ◽  
Dynamical Theory ◽  
Neutron Spin ◽  
Wave Source ◽  
Rectangular Profile ◽  
Good Account

Neutrons scattered or reflected from a diffraction grating are subject to a periodic potential analogous to the potential experienced by electrons within a crystal. Hence, the wavefunction of the neutrons can be expanded in terms of Bloch waves and a dynamical theory can be applied to interpret the scattering phenomenon. In this paper, a dynamical theory is used to calculate the results of neutron spin-echo resolved grazing-incidence scattering (SERGIS) from a silicon diffraction grating with a rectangular profile. The calculations are compared with SERGIS measurements made on the same grating at two neutron sources: a pulsed source and a continuous wave source. In both cases, the spin-echo polarization, studied as a function of the spin-echo length, peaks at integer multiples of the grating period but there are some differences between the two sets of data. The dynamical theory explains the differences and gives a good account of both sets of results.

Sign in / Sign up

Export Citation Format

Share Document