scholarly journals Driven Qubit by Train of Gaussian-Pulses

Mathematics ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 628
Author(s):  
Rania A. Alharbey
Keyword(s):  
Laser Pulses ◽  
Pulse Number ◽  
System A ◽  
Intensity Correlation Function ◽  
Transient Spectra ◽  
Repetition Time ◽  
Analytical Formulas ◽  
Fluorescent Radiation ◽  
Atomic States ◽  
Atom System

The simplest non-dissipative 2-level atom system, a qubit, excited by a train of resonant n-Gaussian laser pulses is investigated. This concerns examination of the averaged atomic variables, the intensity-intensity correlation function, and the transient fluorescent radiation. Analytical formulas for the above expressions are obtained. Computational results show that the transient spectra with the initial ground and coherent atomic states exhibit asymmetric Mollow structure with dip structure, dense oscillation, and narrowing, and depends on the pulse number (n), the repetition time (τR), and the observed time.

Precise Measurements of Transient Excess Carrier Lifetimes in II-VI Films and Superlattices

1989 ◽  
Vol 161 ◽  
Author(s):  
W. O. Doggett ◽  
Michael W. Thelander ◽  
J. F. Schetzina
Keyword(s):  
Molecular Beam ◽  
Statistical Data ◽  
Laser Pulses ◽  
Statistical Data Analysis ◽  
Analysis Techniques ◽  
Excess Carrier ◽  
Carrier Lifetimes ◽  
System A ◽  
Transient Photoconductivity ◽  
Photoconductivity Decay

ABSTRACTA system has been developed for accurately measuring lifetimes for photo-induced excess current carriers in semiconductors using the transient photoconductivity decay method. The specifications of state-of-the-art equipment, considerations peculiar to the capture of fast transient pulses, and sophisticated statistical data analysis techniques are discussed. Experimental results are presented to demonstrate the capability of the system (a) to measure lifetimes in the 40-ns - 75-µs range for temperatures varying from 77K to 300K with 10% accuracy for single lifetime decays and 30% accuracy for individual effective lifetimes in a multi-component decay, and (b) to use a 300-ns lifetime photoconductor as a detector to measure nanosecond-time-scale structure of laser pulses. The predominant excess carrier lifetimes of HgCdTe samples grown at NCSU by photoassisted molecular beam epitaxy (PAMBE) ranged from 46 ns at 300K to 341 ns at 77K. CdTe samples and CdMnTe-CdTe superlattices exhibited a multi-component decay with the two longest components having effective lifetimes of 26 µs and 4 µs for CdTe and 75 µs and 10 µs for CdMnTe-CdTe. These values were relatively insensitive to temperature variation.

scholarly journals Overcoming Multidrug Resistance by On-Demand Intracellular Release of Doxorubicin and Verapamil

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Jianwei Jiang ◽  
Shaojuan Liu ◽  
Chunlei Wang ◽  
Hongyan Zhang
Keyword(s):  
Multidrug Resistance ◽  
Laser Irradiation ◽  
Pulsed Laser ◽  
Laser Pulses ◽  
Chemotherapeutic Agents ◽  
Pulse Number ◽  
Phospholipid Bilayer ◽  
Multidrug Resistance Proteins ◽  
High Concentration ◽  
On Demand

Multidrug resistance (MDR) is one of the major obstacles to the successful application of cancer chemotherapy. Herein, we developed light-responsive doxorubicin-and-verapamil-coencapsulated gold liposomes to overcome MDR. Upon ns-pulsed laser irradiation, the highly confined thermal effect increased the permeability of the phospholipid bilayer, triggering the release of doxorubicin and verapamil, leading to high concentrations in cells. Free verapamil efficiently inhibited the membrane multidrug resistance proteins (MRPs), while the high concentration of doxorubicin saturated MRPs, thus overcoming MDR. We showed that nanosecond- (ns-) pulsed laser- (532 nm, 6 ns) induced doxorubicin release from gold liposomes depended on laser fluence and pulse number. More than 58% of the doxorubicin was released with a 10-pulse irradiation (100 mJ/cm2). Furthermore, ns laser pulses also liberated doxorubicin from endocytosed gold liposomes into the cytosol in MDA-MB-231-R cancer cells. The cytotoxicity of doxorubicin coencapsulated with verapamil was significantly enhanced upon laser irradiation. This study suggested that light-triggered on-demand release of chemotherapeutic agents and MRP inhibitors could be used advantageously to overcome multidrug resistance.

scholarly journals Generation of Terahertz Radiation by Two-Color Ionizing Laser Pulses with Arbitrary Intensity Ratios

Photonics ◽  
2020 ◽  
Vol 7 (2) ◽  
pp. 38
Author(s):  
Ivan Laryushin
Keyword(s):  
Terahertz Radiation ◽  
Laser Pulses ◽  
Numerical Calculations ◽  
Analytical Formulas ◽  
Optimal Intensity ◽  
Intensity Ratios ◽  
Frequency Ratios ◽  
Arbitrary Intensity ◽  
Color Components

The dependence of the terahertz energy generated by two-color femtosecond ionizing pulses on intensities of both one-color components is studied. The numerical calculations are supported with analytical formulas which help to reveal the nature of these dependences. The optimal intensity ratios in the cases when the frequency ratios in two-color pulse are equal to 2, 3/2 and 4 are found.

Effect of Laser Parameters in the Micromachining of Silicon by Femtosecond Pulse Laser

2007 ◽  
Vol 339 ◽  
pp. 136-140
Author(s):  
N. Geng ◽  
Xing Fu ◽  
H.X. Li ◽  
X.C. Ni ◽  
Xiao Tang Hu
Keyword(s):  
Material Properties ◽  
Silicon Surface ◽  
Femtosecond Pulse ◽  
Single Crystal Silicon ◽  
Laser Pulses ◽  
Pulse Number ◽  
Direct Write ◽  
Crystal Silicon ◽  
Laser Parameters ◽  
Laser Fluences

A 775nm femtosecond laser is applied to single crystal silicon by direct-write processing in air. A series of holes are drilled with 150fs duration pulses, various numbers of laser pulses and laser fluences on silicon wafer. Different laser parameters and material properties influence the size of fabricated holes. The diameter and depth of holes are gradually enlarged with the increase of laser fluence and pulse number. The periodic ripple structure on silicon surface is found and explained at the same time.

scholarly journals Structure-Mediated Excitation of Air Plasma and Silicon Plasma Expansion in Femtosecond Laser Pulses Ablation

Research ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Qingsong Wang ◽  
Lan Jiang ◽  
Jingya Sun ◽  
Changji Pan ◽  
Weina Han ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Femtosecond Laser Ablation ◽  
Longitudinal Direction ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Pulse Number ◽  
Air Plasma ◽  
Laser Material ◽  
Anisotropic Expansion ◽  
Multiple Pulses

Femtosecond laser-induced surface structures upon multiple pulses irradiation are strongly correlated with the pulse number, which in turn significantly affects successive laser-material interactions. By recording the dynamics of femtosecond laser ablation of silicon using time-resolved shadowgraphy, here we present direct visualization of the excitation of air plasma induced by the reflected laser during the second pulse irradiation. The interaction of the air plasma and silicon plasma is found to enhance the shockwave expansion induced by silicon ablation in the longitudinal direction, showing anisotropic expansion dynamics in different directions. We further demonstrate the vanishing of air plasma as the pulse number increases because of the generation of a rough surface without light focusing ability. In the scenario, the interaction of air plasma and silicon plasma disappears; the expansion of the silicon plasma and shockwave restores its original characteristic that is dominated by the laser-material coupling. The results show that the excitation of air plasma and the laser-material coupling involved in laser-induced plasma and shockwave expansion are structure mediated and dependent on the pulse number, which is of fundamental importance for deep insight into the nature of laser-material interactions during multiple pulses ablation.

Simple Nanosecond to Minutes Transient Absorption Spectrophotometer

2005 ◽  
Vol 59 (12) ◽  
pp. 1534-1540 ◽  
Author(s):  
Aleksandr V. Mikhonin ◽  
Marta K. Maurer ◽  
Chad E. Reese ◽  
Sanford A. Asher
Keyword(s):  
Optical Switching ◽  
Optical Pumping ◽  
Fiber Optic ◽  
Transient Absorption ◽  
Laser Pulses ◽  
High Signal ◽  
Near Ir ◽  
Transient Spectra ◽  
Specific Configuration ◽  
Crystalline Colloidal Array

We built a transient absorption spectrophotometer that can determine transient absorption spectral changes that occur at times as fast as ∼200 ns and as slow as a minute. The transient absorption can be induced by a temperature-jump (T-jump) or by optical pumping from the deep ultraviolet (UV) to the infrared (IR) by use of single ns Nd:YAG laser pulses. Our use of a fiber-optic spectrometer coupled to a XeF flashlamp makes the collection of transient spectra easy and convenient in the spectral range from the near IR (1700 nm) down to the deep UV (200 nm), with high signal-to-noise (S/N) ratios. The spectral resolution is determined by the specific configuration of the fiber-optic spectrometer (grating groove density, fiber diameter, slit width) and varies between 0.3 and 10 nm. The utility of this spectrometer was demonstrated by measuring the rate at which a polymerized crystalline colloidal array (PCCA) of poly(N-isopropylacrylamide) nanogel particles optically switch light due to a T-jump induced by nanosecond 1.9 μm laser pulses. In addition, we measured the rate of optical switching induced by a 3 ns 355 nm pump pulse in PCCA functionalized with azobenzene.

Thermally Activated Transmissive Optical Elements for Rejection of Laser Radiation

1994 ◽  
Vol 374 ◽  
Author(s):  
H. O. Marcy ◽  
L. F. Warren ◽  
P. H. Cunningham
Keyword(s):  
Large Fraction ◽  
Optical Power ◽  
Optical Element ◽  
Laser Pulses ◽  
Optical Systems ◽  
Incident Laser ◽  
Optical Elements ◽  
Thermally Activated ◽  
System A ◽  
Optical Power Limiting

AbstractThe sacrificial thermal shutter/reflector concept is suitable for optical power limiting in optical systems containing an intermediate focus and uses a thermally activated chemical process to form a mirror that reflects a large fraction of the incident laser light. Under normal illumination, the thermal reflector component is a transmissive optical element at or near a focal plane of an optical system. A pulse from an incident laser beam heats a film of precursor chemicals on the optical element and thereby converts it to a localized reflective metallic mirror. For visible laser pulses longer than 0.1 ms, the thermal shutter provides optical limiting at energies below the ANSI Maximum Permissible Exposure (MPE) standard for laser eye protection. For shorter pulses, near-MPE limiting is achieved. See-through during exposure is also possible with these elements. Various thermal shutter chemistries and efforts to form optically clear thin precursor films are described. The laser testing results highlight the importance of the substrate and absorber in these devices.

Melting, Vaporization, and Resolidification in a Thin Gold Film Irradiated by Multiple Femtosecond Laser Pulses

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Yijin Mao ◽  
Yuwen Zhang ◽  
J. K. Chen
Keyword(s):  
Liquid Phase ◽  
Femtosecond Laser ◽  
Phase Change ◽  
Gold Film ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Pulse Number ◽  
Ablation Depth ◽  
Maximum Temperature ◽  
Clapeyron Equation

Melting, vaporization, and resolidification in a gold thin film subject to multiple femtosecond laser pulses are numerically studied in the framework of the two-temperature model. The solid-liquid phase change is modeled using a kinetics controlled model that allows the interfacial temperature to deviate from the melting point. The kinetics controlled model also allows superheating in the solid phase during melting and undercooling in the liquid phase during resolidification. Superheating of the liquid phase caused by nonequilibrium evaporation of the liquid phase is modeled by adopting the wave hypothesis, instead of the Clausius–Clapeyron equation. The melting depth, ablation depth, and maximum temperature in both the liquid and solid are investigated and the result is compared with that from the Clausius–Clapeyron equation based vaporization model. The vaporization wave model predicts a much higher vaporization speed, which leads to a deeper ablation depth. The relationship between laser processing parameters, including pulse separation time and pulse number, and the phase change effect are also studied. It is found that a longer separation time and larger pulse number will cause lower maximum temperature within the gold film and lower depths of melting and ablation.

Sign in / Sign up

Export Citation Format

Share Document