Development of compact continuous-wave terahertz (THz) sources by photoconductive mixing

2011 ◽  
pp. 245-250
Author(s):  
H. Tanoto ◽  
J. H. Teng ◽  
Q. Y. Wu ◽  
M. Sun ◽  
Z. N. Chen ◽  
...  
Keyword(s):  
Continuous Wave ◽  
Thz Sources

scholarly journals Plasmonics in semiconductors and in Ag submicron wires and graphene

2016 ◽  
Vol 55 (4) ◽  
Author(s):  
Hans Hartnagel ◽  
Shihab Al-Daffaie ◽  
Oktay Yilmazoglu
Keyword(s):  
Continuous Wave ◽  
Silver Nanowires ◽  
Field Enhancement ◽  
New Device ◽  
Domain Structures ◽  
New Concepts ◽  
Metal Nanostructure ◽  
Thz Sources ◽  
Nitrogen Ion ◽  
Optical Focusing

Some 50 years ago discussions of plasmonics in semiconductors lead to many new concepts such as travelling domain structures with applications leading even to logic systems. Now plasmonics of submicron wires of Ag and graphene bring new device concepts for the fabrication of compact THz sources and optical focusing of the beat signal into the active area. Here as an experimental example such new opportunities are involved with compact THz sources based on optical laser mixing. They include resonant plasmonic structures at THz and optical frequencies to locally enhance the electromagnetic fields at THz as well as optical frequencies by the combination of semiconductor-graphene plasmons respectively by the semiconductor-metal-nanostructure plasmons. Of particular interest is the usage of graphene, which is optically transmitting and which is either a semimetal or can be transformed into a semiconductor by reducing the width of its strips to about 30 nm, opening a band gap in the meV to tens of the meV range. A successful experimental structure for continuous-wave THz photomixing is fabricated using 1D and 2D nanocontacts either on low-temperature-grown (LTG) GaAs or on nitrogen ion-implanted (N+i) GaAs and graphene sheets. The overlaying 1D and 2D nanocontacts were formed by silver nanowires with a diameter of 60 or 120 nm. They can handle currents of >10 and >30 mA, respectively, without electromigration enabling reliably high photocurrents and field enhancement at THz frequencies by plasmonic effects. The nanomaterial structurization in connection with present-day plasmonic applications is now to be discussed in a similar manner as past opportunities with semiconductor plasmonics.

scholarly journals Room temperature continuous wave, monolithic tunable THz sources based on highly efficient mid-infrared quantum cascade lasers

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Quanyong Lu ◽  
Donghai Wu ◽  
Saumya Sengupta ◽  
Steven Slivken ◽  
Manijeh Razeghi
Keyword(s):  
Room Temperature ◽  
Continuous Wave ◽  
Quantum Cascade Lasers ◽  
Mid Infrared ◽  
Quantum Cascade ◽  
Highly Efficient ◽  
Thz Sources ◽  
Cascade Lasers

scholarly journals Ultra-narrow-linewidth continuous-wave THz sources based on multiplier chains

2008 ◽  
Vol 95 (1) ◽  
pp. 55-61 ◽  
Author(s):  
S. Schiller ◽  
B. Roth ◽  
F. Lewen ◽  
O. Ricken ◽  
M. C. Wiedner
Keyword(s):  
Continuous Wave ◽  
Narrow Linewidth ◽  
Thz Sources

scholarly journals Ultra-narrowband and highly-directional THz thermal emitters based on the bound state in the continuum

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Kaili Sun ◽  
Zongshan Zhao ◽  
Yangjian Cai ◽  
Uriel Levy ◽  
Zhanghua Han
Keyword(s):  
Continuous Wave ◽  
Bound State ◽  
New Physics ◽  
High Resistivity ◽  
Wave Form ◽  
Practical Applications ◽  
Thermal Emitters ◽  
Thermal Emitter ◽  
Thz Sources ◽  
The Continuum

Abstract The development of novel and cost-effective THz emitters, with properties superior to current THz sources, is an active and important field of research. In this work, we propose and numerically demonstrate a simple yet effective approach of realizing terahertz sources working in continuous-wave form, by incorporating the new physics of bound state in the continuum (BIC) into thermal emitters. By deliberately designing the structure of slotted disk array made of high-resistivity silicon on top of a low index dielectric buffer layer supported by a conducting substrate, a quasi-BIC mode with ultra-high quality factor (∼104) can be supported. Our results reveal that the structure can operate as an efficient terahertz thermal emitter with near-unity emissivity and ultranarrow bandwidth. For example, an emitter working at 1.3914 THz with an ultranarrow linewidth less than 130 MHz, which is roughly 4 orders of magnitude smaller than that obtained from a metallic metamaterial-based thermal emitter, is shown. In addition to its high monochromaticity, this novel emitter has additional important advantages including high directionality and linear polarization, which makes it a promising candidate as the new generation of THz sources. It holds a great potential for practical applications where high spectral resolving capability is required.

Microstructures of Laser Processed Fe-Cr Surface Alloys

1981 ◽  
Vol 39 ◽  
pp. 328-329
Author(s):  
P. A. Molian ◽  
K. H. Khan ◽  
W. E. Wood
Keyword(s):  
Cooling Rate ◽  
Pure Iron ◽  
Continuous Wave ◽  
Laser Surface ◽  
Material Surface ◽  
Constitution Diagram ◽  
Incident Power ◽  
Surface Alloying ◽  
Laser Surface Alloying ◽  
Spot Diameter

In recent years, the effects of chromium on the transformation characteristics of pure iron and the structures produced thereby have been extensively studied as a function of cooling rate. In this paper, we present TEM observations made on specimens of Fe-10% Cr and Fe-20% Cr alloys produced through laser surface alloying process with an estimated cooling rate of 8.8 x 104°C/sec. These two chromium levels were selected in order to study their phase transformation characteristics which are dissimilar in the two cases as predicted by the constitution diagram. Pure iron (C<0.01%, Si<0.01%, Mn<0.01%, S=0.003%, P=0.008%) was electrodeposited with chromium to the thicknesses of 40 and 70μm and then vacuum degassed at 400°F to remove the hydrogen formed during electroplating. Laser surface alloying of chromium into the iron substrate was then performed employing a continuous wave CO2 laser operated at an incident power of 1200 watts. The laser beam, defocussed to a spot diameter of 0.25mm, scanned the material surface at a rate of 30mm/sec, (70 ipm).

1848: Revolix 70 Watt 2 Micron Continuous Wave Laser Vaporesection of the Prostate. Preliminary Results After a One Year Follow-Up

2007 ◽  
Vol 177 (4S) ◽  
pp. 614-614
Author(s):  
Thorsten Bach ◽  
Thomas R.W. Herrmann ◽  
Roman Ganzer ◽  
Andreas J. Gross
Keyword(s):  
Continuous Wave ◽  
Continuous Wave Laser ◽  
Preliminary Results ◽  
Wave Laser ◽  
One Year

Leitlinien zur peripheren Gefäßdiagnostik mit der direktionalen continuous-wave (CW) Doppler-Sonographie

Phlebologie ◽  
2000 ◽  
Vol 29 (05) ◽  
pp. 142-145
Author(s):  
T. Hertel ◽  
B. Kahle ◽  
H. G. Kluess ◽  
M. Marshall ◽  
E. Rabe ◽  
...  
Keyword(s):  
Continuous Wave

Investigating the Nonlinear Optical Response of Pepper Oil under Low Power Irradiation with Continuous Wave Visible Laser Beam

2020 ◽  
pp. 131-138
Keyword(s):  
Refractive Index ◽  
Nonlinear Refractive Index ◽  
Nonlinear Optical ◽  
Continuous Wave ◽  
Diffraction Integral ◽  
Visible Laser ◽  
Limiting Property ◽  
Kirchhoff Diffraction Integral ◽  
Theoretical Results ◽  
Good Agreement

The nonlinear optical properties of pepper oil are studied by diffraction ring patterns and Z-scan techniques with continuous wave beam from solid state laser at 473 nm wavelength. The nonlinear refractive index of the sample is calculated by both techniques. The sample show high nonlinear refractive index. Based on Fresnel-Kirchhoff diffraction integral, the far-field intensity distributions of ring patterns have been calculated. It is found that the experimental results are in good agreement with the theoretical results. Also the optical limiting property of pepper oil is reported. The results obtained in this study prove that the pepper oil has applications in nonlinear optical devices.

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