scholarly journals Size Dependent Optical Nonlinearity and Optical Limiting Properties of Water Soluble CdSe Quantum Dots

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Anju K. Augustine ◽  
S. Mathew ◽  
P. Radhakrishnan ◽  
V. P. N. Nampoori ◽  
M. Kailasnath
Keyword(s):  
Quantum Dots ◽  
Nonlinear Behavior ◽  
Optical Limiting ◽  
Optical Nonlinearity ◽  
Water Soluble ◽  
Saturable Absorption ◽  
Reverse Saturable Absorption ◽  
Cdse Quantum Dots ◽  
Cdse Qds ◽  
High Laser

We present third-order optical nonlinear absorption in CdSe quantum dots (QDs) with particle sizes in the range of 4.16–5.25 nm which has been evaluated by the Z-scan technique. At an excitation irradiance of 0.54 GW/cm2 the CdSe QDs exhibit reverse saturation indicating a clear nonlinear behavior. Nonlinearity increases with particle size in CdSe QDs within the range of our investigations which in turn depends on the optical band gap. The optical limiting threshold of the QDs varies from 0.35 GW/cm2 to 0.57 GW/cm2 which makes CdSe QDs a promising candidate for reverse-saturable absorption based devices at high laser intensities such as optical limiters.

Optimized Synthesis of Water-Soluble and Small-Size CdSe Quantum Dots

2011 ◽  
Vol 266 ◽  
pp. 46-50
Author(s):  
Jiao Yun Xia ◽  
Jun Long Tang
Keyword(s):  
Aqueous Solution ◽  
Quantum Dots ◽  
Water Soluble ◽  
Cdse Quantum Dots ◽  
Key Factors ◽  
Cdse Qds ◽  
High Quality ◽  
Synthesis Route ◽  
Initial Ph

An optimized synthesis route was applied for controlling the preparation of CdSe quantum dots (QDs) in an aqueous solution. Some key factors which influencing the properties of CdSe QDs, such as initial pH, ratio of precursor etc, were investigated. The as-prepared products have been characterized by TEM, XPS, XRD, UV-Vis and fluorescence (FL) spectra. The result showed that the high-quality CdSe QDs with 3 nm was obtained. The experiments also conformed that the CdSe QDs with better FL properties were obtained with properly initial pH, 5, suitably [Cd2+] / [SeSO3 2-], range from 1:0.25 to 1:0.75 and the ratio of [Cd2+] / [TGA] is 1:2~1:3.

Synthesis of High-Performance Aqueous CdSe Quantum Dots Based on Combination of Se Source as Vapor-Phase and Hydrothermal Method

2010 ◽  
Vol 663-665 ◽  
pp. 96-99
Author(s):  
Heng Kang Qiu ◽  
Yue Shen ◽  
Lin Jun Wang ◽  
Jian Cheng Zhang ◽  
Kai Feng Qin
Keyword(s):  
Quantum Dots ◽  
Hydrothermal Method ◽  
Vapor Phase ◽  
High Performance ◽  
Hydrothermal Reaction ◽  
Water Soluble ◽  
Quantum Yields ◽  
Cdse Quantum Dots ◽  
Cdse Qds ◽  
Visible Absorption

High performance aqueous CdSe quantum dots (QDs) have been prepared by combination of Se source as vapor-phase and hydrothermal method. The main advantages of this approach included: one is to utilize H2Se vapor as a higher pure selenium source to make the prepared QDs have little other impurities, another is to obtain the QDs with characteristics of more rapid growth in the hydrothermal reaction. The as-prepared products have been characterized by ultraviolet-visible absorption spectra, photoluminescence spectroscopy (PL), X-ray powder diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and energy dispersive spectroscopy (EDS) analysis etc. The results show the as-synthesized water-soluble CdSe nanoparticles possess higher purity and quantum yields (QY), favorable narrow photoluminescence band with full width of half-maximum (FWHM) down to 40 nm, better photo-stability, and less synthetic time as compared with aqueous CdSe QDs obtained by other methods.

scholarly journals Tunneling-induced optical limiting in quantum dot molecules

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Mohadeseh Veisi ◽  
Seyedeh Hamideh Kazemi ◽  
Mohammad Mahmoudi
Keyword(s):  
Quantum Dot ◽  
Optical Power ◽  
Optical Limiting ◽  
Input Voltage ◽  
Optical Nonlinearity ◽  
Saturable Absorption ◽  
Reverse Saturable Absorption ◽  
Absorption Mechanism ◽  
Probe Field ◽  
Limiting Behavior

Abstract We present a convenient way to obtain an optical power limiting behavior in a quantum dot molecule system, induced by an interdot tunneling. Also, the effect of system parameters on the limiting performance is investigated; interestingly, the tunneling rate can affect the limiting performance of the system so that the threshold of the limiting behavior can be a function of the input voltage, allowing the optimization of the limiting action. Furthermore, by investigating the absorption of the probe field, it is demonstrated that the optical limiting is due to a reverse saturable absorption mechanism; indeed, analytical results show that this mechanism is based on a cross-Kerr optical nonlinearity induced by the tunneling. Additionally, the limiting properties of the system are studied by using a Z-scan technique.

Optical limiting properties of water-soluble phthalocyanine derivatives

2003 ◽  
Vol 07 (06) ◽  
pp. 447-451 ◽  
Author(s):  
Shuang Zhang ◽  
Zhou Yang ◽  
Hongwei Liu ◽  
Fu Xi ◽  
Zhi-xin Guo ◽  
...  
Keyword(s):  
Cross Section ◽  
Excited State Absorption ◽  
Optical Limiting ◽  
Water Soluble ◽  
Saturable Absorption ◽  
Reverse Saturable Absorption ◽  
Solubility In Water ◽  
Practical Applications ◽  
Good Solubility ◽  
532 Nm

The optical-limiting properties of several water-soluble phthalocyanine derivatives in aqueous solution were measured at 532 nm with 10 ns pulses. The excited state absorption cross-section σex of the derivatives were determined with the Z-scan technique. The results showed that the phthalocyanine derivatives are materials for reverse saturable absorption. It was noted that the optical limiting performance of the phthalocyanine derivatives in aqueous solutions can be controlled through the addition of alkalis. These phthalocyanine derivatives possess good solubility in water and optical limiting controllability, which give rise to their use for practical applications.

OPTICAL NONLINEARITY OF CdSe AND CdSe-C60 QUANTUM DOT

2008 ◽  
Vol 22 (32) ◽  
pp. 3207-3213 ◽  
Author(s):  
HAO SONG ◽  
YUE-YING ZHAI ◽  
ZHANG-KAI ZHOU ◽  
ZHONG-HUA HAO ◽  
LI ZHOU
Keyword(s):  
Quantum Dots ◽  
Nonlinear Refraction ◽  
Refraction Index ◽  
Optical Nonlinearity ◽  
Cdse Quantum Dots ◽  
Cdse Qds ◽  
Third Order ◽  
Picosecond Pulses ◽  
Nonlinear Properties ◽  
The Third

The third-order optical nonlinear properties of CdSe quantum dots (QDs) and CdSe - C 60 QDs are investigated by Z-scan technique with picosecond pulses at the wavelength of 800 nm. The value of the nonlinear absorption coefficient β of CdSe - C 60 QDs is measured to be 2.9 cm/GW, which is about two times larger than that of CdSe QDs. The nonlinear refraction index γ of CdSe - C 60 QDs is -2.8 × 10-3 cm 2/ GW , which is about seven times larger than that of CdSe QDs. Presence of C 60 contributes to the larger optical nonlinearity of CdSe - C 60 QDs comparing with CdSe QDs.

One-Step Synthesis of CdSe Quantum Dots by Using Hydrazine Hydrate Reduction of Selenium Dioxide

2018 ◽  
Vol 71 (7) ◽  
pp. 524 ◽  
Author(s):  
Rongfang Wang ◽  
Xingming Wei ◽  
Jun Xie ◽  
Bomei Wang ◽  
Xiaotong He
Keyword(s):  
Quantum Dots ◽  
Hydrazine Hydrate ◽  
Selenium Dioxide ◽  
Water Soluble ◽  
Molar Ratio ◽  
Cdse Quantum Dots ◽  
Cdse Qds ◽  
Original Solution ◽  
Transmission Electron ◽  
Average Size

Hydrazine hydrate was used as a novel reducing agent for the synthesis of water soluble and stable cadmium selenide (CdSe) quantum dots (QDs). The as-prepared CdSe quantum dots were investigated by X-ray powder diffraction, high-resolution transmission electron microscopy, photoluminescence, and UV-vis absorption spectroscopy analyses. The results show that the as-prepared CdSe QDs possess a cubic crystal structure and an average size of 2 nm. The effects of the pH of the original solution, thioglycollic acid (TGA)/Cd2+ molar ratio (nTGA/nCd2+), and the Cd/Se molar ratio on the luminescence properties of CdSe QDs were also systematically analysed.

scholarly journals One-Step Synthesis of High-Quality Water-Soluble CdSe Quantum Dots Capped byN-Acetyl-L-cysteineviaHydrothermal Method and Their Characterization

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Chunjin Wei ◽  
Jinyu Li ◽  
Fang Gao ◽  
Shuxia Guo ◽  
Yongcui Zhou ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Photoelectron Spectroscopy ◽  
Ph Value ◽  
Water Soluble ◽  
Molar Ratio ◽  
Cdse Quantum Dots ◽  
Cdse Qds ◽  
Hydrothermal Route ◽  
Experimental Conditions ◽  
One Step

Novel water-soluble CdSe quantum dots (QDs) have been prepared withN-acetyl-L-cysteine as new stabilizer through a one-step hydrothermal route. The influence of experimental conditions, including reaction time, molar ratio of reactants, and pH value, on the luminescent properties of the obtained CdSe QDs has been systematically investigated. The characterization of as-prepared QDs was carried out through different methods. In particular, we realized qualitative and semiquantitative studies on CdSe QDs through X-ray photoelectron spectroscopy and electron diffraction spectroscopy. The results show that the as-prepared CdSe QDs exhibit a high quantum yield (up to 26.7%), high stability, and monodispersity and might be widely used in biochemical detection and biochemical research.

Enhanced reverse saturable absorption and optical limiting properties in a protonated water-soluble porphyrin

2013 ◽  
Vol 15 (5) ◽  
pp. 055206 ◽  
Author(s):  
Xiao-Liang Zhang ◽  
Xu-Dong Chen ◽  
Xiao-Chun Li ◽  
Cui-Feng Ying ◽  
Zhi-Bo Liu ◽  
...  
Keyword(s):  
Optical Limiting ◽  
Water Soluble ◽  
Saturable Absorption ◽  
Reverse Saturable Absorption ◽  
Water Soluble Porphyrin

scholarly journals Intense Visible Luminescence in CdSe Quantum Dots by Efficiency Surface Passivation with H2O Molecules

2012 ◽  
Vol 2012 ◽  
pp. 1-6
Author(s):  
Hyeoung Woo Park ◽  
Do-Hyung Kim
Keyword(s):  
Heat Treatment ◽  
Quantum Dots ◽  
Quantum Yield ◽  
Surface Passivation ◽  
Cdse Quantum Dots ◽  
Cdse Qds ◽  
Effect Of Water ◽  
Visible Luminescence ◽  
Luminescence Efficiency

We have investigated the effect of water (H2O) cooling and heat treatment on the luminescence efficiency of core CdSe quantum dots (QDs). The photoluminescence (PL) quantum yield of the CdSe QDs was enhanced up to ~85%, and some periodic bright points were observed in wide color ranges during the heat treatment of QDs mixed with H2O. The PL enhancement of QDs could be attributed to the recovery of QDs surface traps by unreacted ligands confined within the hydrophilic H2O molecule containers.

Reverse saturable absorption and optical limiting in indanthrone dyes

1996 ◽  
Vol 62 (3) ◽  
pp. 293-297 ◽  
Author(s):  
Rama Chari ◽  
S. R. Mishra ◽  
H. S. Rawat ◽  
S. M. Oak
Keyword(s):  
Optical Limiting ◽  
Saturable Absorption ◽  
Reverse Saturable Absorption
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