scholarly journals Circularly-polarized THz wave emission from a micro-thin water flow

2020 ◽  
Author(s):  
Hsin-Hui Huang ◽  
Saulius Juodkazis ◽  
Eugene Gamaly ◽  
Takeshi Nagashima ◽  
Tetsu Yonezawa ◽  
...  
Keyword(s):  
Water Flow ◽  
Wavelength Region ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Intense Laser ◽  
Practical Implementation ◽  
Focal Volume ◽  
Circularly Polarized ◽  
Thz Wave ◽  
Wave Emission

Abstract Intense THz wave sources are highly expected for further progresses in nonlinear THz science and practical implementation of non-ionizing radiation in sensing and communications. Solid-based sources have inherent limits of material breakdown, while intense laser irradiation of liquids is a promising emerging technique for THz wave and hard X-ray emission. Water-based THz emission shows intensity enhancements up to 103 times when laser-pulse pairs with nanosecond delay are used. Here we show circularly- polarized THz wave emission from thin water flow irradiated by two time-separated and linearly-polarized femtosecond laser pulses. THz time-domain spectroscopy reveals the circularly-polarized THz emission dominates 4.7 ns after the first pulse irradiation. THz wave detection delay in the spectroscopy and time-resolved micrography indicate that the THz wave emission originates from the rarefied volume in front of the flow. Radial relaxation of charges (currents) in the focal volume where ponderomotive charge depletion occurred is the origin for the circular polarization; tight focusing localized THz wave emission to the sub-wavelength region.

scholarly journals Circularly-polarized THz wave emission from a micro-thin water flow

2021 ◽  
Author(s):  
Hsin-hui Huang ◽  
Saulius Juodkazis ◽  
Eugene Gamaly ◽  
Takeshi Nagashima ◽  
Tetsu Yonezawa ◽  
...  
Keyword(s):  
Water Flow ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Intense Laser ◽  
Practical Implementation ◽  
Focal Volume ◽  
Time Resolved ◽  
Circularly Polarized ◽  
Thz Wave ◽  
Wave Emission

Abstract Intense THz wave sources are highly expected for further progresses in nonlinear THz science and practical implementation of non-ionizing radiation in sensing and communications. Solid-based sources have inherent limits of material breakdown, while intense laser irradiation of liquids is a promising emerging technique for THz wave and hard X-ray emission. Water-based THz emission shows intensity enhancements up to 10 times when laser-pulse pairs with nanosecond delay are used. Here we show circularly-polarized THz wave emission from thin water flow irradiated by two time-separated and linearly-polarized femtosecond laser pulses. THz time-domain spectroscopy reveals the circularly-polarized THz emission dominates 4.7 ns after the first pulse irradiation. THz wave detection delay in the spectroscopy and time-resolved micrography indicate that the THz wave emission originates from the rarefied volume in front of the flow. Radial relaxation of charges in the focal volume where ponderomotive charge depletion occurred on the optical axis is the origin for the circular polarization (due to spiraling currents). Tight focusing of fs-laser pulses localized THz wave emission to the sub-wavelength (tens-of-micrometers) region.

scholarly journals Dual THz Wave and X-ray Generation from a Water Film under Femtosecond Laser Excitation

Nanomaterials ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 523 ◽  
Author(s):  
Hsin-hui Huang ◽  
Takeshi Nagashima ◽  
Wei-hung Hsu ◽  
Saulius Juodkazis ◽  
Koji Hatanaka
Keyword(s):  
Femtosecond Laser ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Intense Laser ◽  
Pulse Excitation ◽  
Light Sources ◽  
Solution Flow ◽  
X Ray ◽  
Thz Wave ◽  
Wave Emission

Simultaneous emission of the THz wave and hard X-ray from thin water free-flow was induced by the irradiation of tightly-focused femtosecond laser pulses (35 fs, 800 nm, 500 Hz) in air. Intensity measurements of the THz wave and X-ray were carried out at the same time with time-domain spectroscopy (TDS) based on electro-optic sampling with a ZnTe(110) crystal and a Geiger counter, respectively. Intensity profiles of the THz wave and X-ray emission as a function of the solution flow position along the incident laser axis at the laser focus show that the profile width of the THz wave is broader than that of the X-ray. Furthermore, the profiles of the THz wave measured in reflection and transmission directions show different features and indicate that THz wave emission is, under single-pulse excitation, induced mainly in laser-induced plasma on the water flow surface. Under double-pulse excitation with a time separation of 4.6 ns, 5–10 times enhancements of THz wave emission were observed. Such dual light sources can be used to characterise materials, as well as to reveal the sequence of material modifications under intense laser pulses.

scholarly journals Giant Enhancement of THz Wave Emission under Double-Pulse Excitation of Thin Water Flow

2020 ◽  
Vol 10 (6) ◽  
pp. 2031 ◽  
Author(s):  
Hsin-hui Huang ◽  
Takeshi Nagashima ◽  
Tetsu Yonezawa ◽  
Yasutaka Matsuo ◽  
Soon Hock Ng ◽  
...  
Keyword(s):  
Water Flow ◽  
Low Frequency ◽  
Emission Spectra ◽  
Femtosecond Laser Pulses ◽  
Pulse Excitation ◽  
Experimental Conditions ◽  
X Ray ◽  
Thz Wave ◽  
Wave Measurements ◽  
Wave Emission

Simultaneous measurements of THz wave and hard X-ray emission from thin and flat water flow when irradiated by double femtosecond laser pulses (800 nm, 35 fs/transform-limited, 0.5 kHz, delay times up to 15 ns) were carried out. THz wave measurements by time-domain spectroscopy and X-ray detection by Geiger counters were performed at the transmission and the reflection sides of the flow. THz wave emission spectra show their dynamic peak shifts toward the low frequency with the highest intensity enhancements more than 1.5 × 10 3 times in |E| 2 accumulated over the whole spectrum range of 0–3 THz at the delay time of 4.7 ns between the two pulses. On the other hand, X-ray intensity enhancements are limited to about 20 times at 0 ns under the same experimental conditions. The mechanisms for the spectral changes and the intensity enhancements in THz wave emission are discussed from the viewpoint of laser ablation on the water flow induced by the pre-pulse irradiation.

Depolarization of the supercontinuum induced by linearly and circularly polarized femtosecond laser pulses in water

2021 ◽  
Vol 104 (5) ◽  
Author(s):  
Jing Li ◽  
Wenjiang Tan ◽  
Jinhai Si ◽  
Shiyun Tang ◽  
Yang Yang ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Circularly Polarized

scholarly journals Broadband THz Sources from Gases to Liquids

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Yiwen E ◽  
Liangliang Zhang ◽  
Anton Tcypkin ◽  
Sergey Kozlov ◽  
Cunlin Zhang ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Laser Pulses ◽  
High Energy ◽  
Wave Generation ◽  
High Energy Density ◽  
Intense Laser ◽  
Thz Radiation ◽  
Flowing Liquid ◽  
Thz Wave ◽  
Thz Sources

Matters are generally classified within four states: solid, liquid, gas, and plasma. Three of the four states of matter (solid, gas, and plasma) have been used for THz wave generation with short laser pulse excitation for decades, including the recent vigorous development of THz photonics in gases (air plasma). However, the demonstration of THz generation from liquids was conspicuously absent. It is well known that water, the most common liquid, is a strong absorber in the far infrared range. Therefore, liquid water has historically been sworn off as a source for THz radiation. Recently, broadband THz wave generation from a flowing liquid target has been experimentally demonstrated through laser-induced microplasma. The liquid target as the THz source presents unique properties. Specifically, liquids have the comparable material density to that of solids, meaning that laser pulses over a certain area will interact with three orders more molecules than an equivalent cross-section of gases. In contrast with solid targets, the fluidity of liquid allows every laser pulse to interact with a fresh area on the target, meaning that material damage or degradation is not an issue with the high-repetition rate intense laser pulses. These make liquids very promising candidates for the investigation of high-energy-density plasma, as well as the possibility of being the next generation of THz sources.

Ultrafast gain dynamics in N^+_2 lasing from highly excited vibrational states pumped by circularly polarized femtosecond laser pulses

2015 ◽  
Vol 13 (5) ◽  
pp. 050201-50205 ◽  
Author(s):  
Kaixuan Zhai Kaixuan Zhai ◽  
Ziting Li Ziting Li ◽  
Hongqiang Xie Hongqiang Xie ◽  
Chenrui Jing Chenrui Jing ◽  
Guihua Li Guihua Li ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Vibrational States ◽  
Circularly Polarized ◽  
Highly Excited Vibrational States
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