scholarly journals Silicon twisted cone structure produced by optical vortex pulse with structure evaluation by radiation hydrodynamic simulation

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Daisuke Nakamura ◽  
Ryohei Tasaki ◽  
Miki Kawamoto ◽  
Hiroki Oshima ◽  
Mitsuhiro Higashihata ◽  
...  
Keyword(s):  
Single Pulse ◽  
Optical Vortex ◽  
Incident Laser ◽  
Initial Profile ◽  
Hydrodynamic Simulation ◽  
Cone Structure ◽  
Si Substrates ◽  
Incident Laser Power ◽  
Irradiation Period ◽  
Structure Evaluation

AbstractWe demonstrate a radiation hydrodynamic simulation of optical vortex pulse-ablated microcone structures on silicon (Si) substrates. Doughnut-shaped craters were formed by single pulse irradiation on the Si substrate, and a twisted cone structure with a height of 3.5 µm was created at the center of the irradiation spot by the circularly polarized optical vortex pulse. A two-dimensional (2-D) radiation hydrodynamic simulation reproduced the cone structure well with a height of 3 µm. The central part of the incident laser power was lowered from the initial profile due to plasma shielding over the laser pulse duration for an inverted double-well laser profile. The acute tip shape of the silicon surface can survive over the laser irradiation period.

scholarly journals Size dependent efficiency of photophoretic swimmers

2015 ◽  
Vol 184 ◽  
pp. 381-391 ◽  
Author(s):  
Andreas P. Bregulla ◽  
Frank Cichos
Keyword(s):  
Particle Size ◽  
Laser Power ◽  
Symmetry Axis ◽  
Particle Surface ◽  
Finite Size ◽  
Optical Power ◽  
Surface Flow ◽  
Incident Laser ◽  
Size Dependent ◽  
Incident Laser Power

We investigate experimentally the efficiency of self-propelled photophoretic swimmers based on metal-coated polymer particles of different sizes. The metal hemisphere absorbs the incident laser power and converts its energy into heat, which dissipates into the environment. A phoretic surface flow arises from the temperature gradient along the particle surface and drives the particle parallel to its symmetry axis. Scaling the particle size from micro to nanometers, the efficiency of converting optical power into motion is expected to rise with the reciprocal size for ideal swimmers. However, due to the finite size of the metal cap, the efficiency of a real swimmer reveals a maximum depending sensitively on the details of the metal cap shape. We compare the experimental results to numerical simulations.

A Novel Multibranched Chromophore Containing Carbazole Moiety for Two-Photon Microfabrication

2012 ◽  
Vol 485 ◽  
pp. 566-569
Author(s):  
Zhi Yuan Hu ◽  
Fu Quan Guo ◽  
Hao Liang ◽  
Bin Guo
Keyword(s):  
Cross Section ◽  
Laser Power ◽  
Photon Absorption ◽  
Structural Motif ◽  
Incident Laser ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Incident Laser Power ◽  
Potential Applications ◽  
Pentaerythritol Triacrylate

A novel multibranched chromophore containing carbazole moiety，4, 4´, 4´´-tris(9-carbazyl-trans-styryl) triphenylamine (TCSTPA)，was synthesized and characterized by 1HNMR and elemental analysis. A larger two-photon absorption (TPA) cross section of the chromophore was obtained as high as 2350 GM compared to that of the traditional linear chromophore when pumped by a femtosecond laser at 800 nm. Microstructure based on TPA induced polymerization with a spatial resolution of submicron was fabricated under much lower incident laser power using TCSTPA as a TPA photoinitiator and a multifunctional resin of pentaerythritol triacrylate (PETA) as a polymerizable monomer. The result indicates potential applications of this kind of chromophores with multibranched structural motif in the fabrication of polymer and functional microdevices.

scholarly journals Photostability of Uranine via Crossed-Beam Thermal Lens Technique

2007 ◽  
Vol 2007 ◽  
pp. 1-5
Author(s):  
M. Zein El-Din ◽  
K. Elsayed ◽  
S. M. Al-Sherbini ◽  
M. A. Harith
Keyword(s):  
Thermal Lens ◽  
Laser Power ◽  
Modulation Frequency ◽  
Wavelength Modulation ◽  
Incident Laser ◽  
Diagnostic Aid ◽  
Sample Concentration ◽  
Incident Laser Power ◽  
Experimental Parameters ◽  
Photochemical Quantum Yield

Uranine is a diagnostic aid in ophthalmology and is used as an immunohistological stain. A photostability study on this important compound using a crossed-beam thermal lens (TL) technique was carried out. The study is based on the photodegradation (PD) behavior and rate regarding some experimental parameters such as the incident laser power, wavelength, modulation frequency, and sample concentration. The effects of such parameters on the TL signal and PD rate are discussed in details. It has been found that the PD rate is proportional to the power of the pumping laser and the concentration of the sample within the investigated range. However, the modulation frequency is found not to influence the PD rate. The photochemical quantum yield has been measured using potassium ferrioxalate actinometry and it was found to be very low.

Distinguishing Laser Induced Thermal and Photochemical Surface Reactions by Photodeposit Morphology

1987 ◽  
Vol 101 ◽  
Author(s):  
Wesley C. Natzle
Keyword(s):  
Power Density ◽  
Attenuated Total Reflectance ◽  
Incident Laser ◽  
Ir Spectrometry ◽  
Total Reflectance ◽  
Incident Laser Power ◽  
Optical Attenuation ◽  
Reflected Light ◽  
Incident Power Density ◽  
A Cell

ABSTRACTCr containing deposits were formed by focussing a chopped (2000Hz) 325nm CW He-Cd laser on the inner surface of the quartz window of a cell containing 110-150 mTorr of Cr(C0)6 precursor. The deposit thickness and the chemical identity of contaminants were determined by stylus profilometry and attenuated total reflectance IR spectrometry. In certain regimes of incident laser power density, deposits exhibit a dual morphology, with a narrow inner deposit up to several microns in thickness on top of a wider deposit less than 0.16 microns in thickness. Changes in the morphology with incident power density and changes in transmitted and reflected light during the deposition enables assignment to photothermal and photochemical mechanisms. A deposition rate for each mechanism and an optical attenuation coefficient for the photochemical deposit at 325nm were determined from the deposit thicknesses as a function of time.

Effect of incident laser power and incorporating polariton effects in GaN microrods

2019 ◽  
Vol 209 ◽  
pp. 328-332
Author(s):  
Poulami Ghosh ◽  
Dapeng Yu ◽  
Mingyuan Huang
Keyword(s):  
Laser Power ◽  
Incident Laser ◽  
Incident Laser Power

scholarly journals Plasmon-driven surface catalytic reaction of 4-ethynylaniline in a liquid environment

RSC Advances ◽  
2018 ◽  
Vol 8 (37) ◽  
pp. 20499-20504
Author(s):  
Yu Liu ◽  
Caiqing Ma ◽  
Yanqiu Yang ◽  
Yuanchun Zhao ◽  
Shiwei Wu ◽  
...  
Keyword(s):  
Exposure Time ◽  
Catalytic Reaction ◽  
Laser Power ◽  
Incident Laser ◽  
Interesting Phenomenon ◽  
Liquid Environment ◽  
Incident Laser Power ◽  
Raman Intensities

The mechanism of Ag NP induced dimerization of PEAN was investigated by using SERS spectra. A very interesting phenomenon was discovered, that is where the relative Raman intensities of b2 modes increased either with increasing incident laser power or exposure time.

scholarly journals Investigation of thermostability of Mo6S3I6 nanowires using Raman spectroscopy

2009 ◽  
Vol 63 (3) ◽  
pp. 217-220
Author(s):  
Jelena Todorovic ◽  
Dejan Djokic ◽  
Zorana Dohcevic-Mitrovic ◽  
Dragan Mihailovic ◽  
Zoran Popovic
Keyword(s):  
Raman Spectroscopy ◽  
Raman Spectra ◽  
Room Temperature ◽  
Group Analysis ◽  
Temperature Treatment ◽  
Incident Laser ◽  
Chevrel Phase ◽  
Incident Laser Power ◽  
Raman Modes ◽  
Good Agreement

The thermostability (phase stability) of Mo6S3I6 nanowires was investigated by Raman spectroscopy, varying the incident laser power (1-9 mW) or by gradual heating of the sample from room temperature to 600?C. We have noticed 18 Raman modes in the room temperature Raman spectra, which is in good agreement with the factor group analysis prediction for P1 space group. We confirmed that the vibrations of Mo6S8 clusters dominate in vibrational properties of the Mo6S3I6 nanostructure, since nanowires Raman spectra are similar to Chevrel phase Raman spectra. During the temperature treatment, it was established that in the temperature range between 300 and 400?C a new Raman mode appeares. This mode can be ascribed to molybdenum oxide (MoO3). With further temperature increase, the intensity of this mode increases, drawing a conclusion that at temperature above 300?C the phase separation takes place in this system followed by a formation of oxide layer.

scholarly journals Demonstration of temperature-plateau superheated liquid by photothermal conversion of plasmonic titanium nitride nanostructures

Nanoscale ◽  
2018 ◽  
Vol 10 (39) ◽  
pp. 18451-18456 ◽  
Author(s):  
Satoshi Ishii ◽  
Ryosuke Kamakura ◽  
Hiroyuki Sakamoto ◽  
Thang D. Dao ◽  
Satish L. Shinde ◽  
...  
Keyword(s):  
Titanium Nitride ◽  
Laser Power ◽  
Superheated Liquid ◽  
Liquid Temperature ◽  
Incident Laser ◽  
Photothermal Conversion ◽  
Incident Laser Power ◽  
Conductive Substrate ◽  
Temperature Plateau

When photothermally superheated liquid is on a high thermal conductive substrate, the liquid temperature stays constant for a certain range of incident laser power before bubbles are formed.

Laser-Induced High Local Temperature in Carbon Nanotube

2007 ◽  
Vol 121-123 ◽  
pp. 331-336 ◽  
Author(s):  
Ming Liu ◽  
K.L. Jiang ◽  
Q.Q. Li ◽  
H.T. Yang ◽  
S.S. Fan
Keyword(s):  
Carbon Nanotube ◽  
Peak Position ◽  
Local Temperature ◽  
Wave Number ◽  
Incident Laser ◽  
Lower Wave Number ◽  
Band Shift ◽  
Laser Illumination ◽  
Nanotube Bundles ◽  
Incident Laser Power

Laser irradiated carbon nanotubes in vacuum can emit dazzling yellow light due to the laser heating effect. We investigated the phonon frequency shifts of as irradiated carbon nanotube bundles by Raman spectroscopy under ultraviolet laser illumination (325 nm, 2.4 mW), the G band peak position was found to shift 50 cm-1 to lower wave number. By considering the temperature coefficient of the G band shift, the local temperature of the illuminated spot was predicted to be nearly 2000K. This temperature had a linear relationship with the incident laser power, and also was greatly influenced by the pressure of the vacuum chamber. The photoluminescence of the CNT bundle was also studied, which exhibits an oscillation of 0.1 eV, a possible origin of the oscillation was discussed.

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