Imaging nano-objects by linear and nonlinear optical absorption microscopies

Devadas, Mary Sajini; Devkota, Tuphan; Johns, Paul; Li, Zhong‐Ming; Lo, Samuel Chun‐Lap; Yu, Kuai; Huang, Libai; Hartland, Gregory V.

doi:10.1088/0957-4484/26/35/354001

Cited by 18 publications

(19 citation statements)

References 187 publications

(499 reference statements)

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“…All three directions (in plane x and y and out-of-plane z) are considered for the application of the electric field in order to find the most efficient way of tuning multilayer PQDs electronic and optical properties. The results presented hereafter could be verified by the spatial modulation spectroscopy technique which is a state-of-the-art tool for direct measurements of individual nanoobjects absorption spectra [33][34][35].…”

Section: Introductionmentioning

confidence: 58%

Multilayer phosphorene quantum dots in an electric field: Energy levels and optical absorption

Abdelsalam

Saroka

Luk’yanchuk

et al. 2018

Journal of Applied Physics

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Triangular and hexagonal multilayer phosphorene quantum dots with armchair and zigzag terminations are investigated with the orthogonal tight-binding model. The effect of increasing the number of layers is revealed. The obtained results show that in a small size multilayer quantum dot the edge states are as sensitive to the out-of-plane external electric fields as the edge states in a single layer dot to the in-plane external electric fields. The investigated optical absorption cross sections show that armchair phosphorene quantum dots have a regular behavior which should be useful for infrared detectors. In particular, it was found that in hexagonal armchair phosphorene dots absorption peaks can be increased, decreased, or totally removed from the low-energy region depending on the orientation of the applied electric field. The effect of spurious doping can suppress the transitions < 0.4 eV, while effect of the finite temperature is almost negligible.

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Section: Introductionmentioning

confidence: 58%

Multilayer phosphorene quantum dots in an electric field: Energy levels and optical absorption

Abdelsalam

Saroka

Luk’yanchuk

et al. 2018

Journal of Applied Physics

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“…To obtain the maximum thermal lensing signal, the probe beam requires an axial offset with respect to the pump beam at the focal plane. To control this axial offset, the probe lens (L pr ) was mounted on a translational stage and used for fine-tuning of the signal level. , The overall signal was a summation of in-phase and out-of-phase signals, but we consider only the positive (in-phase) signal. The positive Gaussian signal minus the toroidal signal is what we observed in the field of view.…”

Section: Results and Discussionmentioning

confidence: 99%

Label-Free Optical Microscope Based on a Phase-Modulated Femtosecond Pump–Probe Approach with Subdiffraction Resolution

et al. 2020

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A far-field optical microscope (OM) is a powerful noninvasive, nondestructive tool to study sub-micrometer structures and organisms, which has been used for decades to study the interactions between light and matter in the spatial domain. We report here a sophisticated label-free OM method with superspatial resolution to visualize ZnO nanoparticles. Of three femtosecond pulses, two served as pumps at 1000 nm and the other one served as a probe at 774 nm. The two pumps (one of Gaussian shape and the other of toroidal shape) were generated with a phase difference of 180°. When the conventional pump−probe approach was used in the absence of a second toroidal pump, a ZnO nanoparticle was observed to show a particle size of 445 nm because of the limit of diffraction. In contrast, when the second toroidal pump was applied out of phase, the obtained OM image showed a ZnO nanoparticle down to 96 nm. We demonstrated for the first time that the reported phase-modulated pump−probe approach has an ability for spatial resolution beyond its optical diffraction limit and a potential for label-free imaging applications in nanomaterials and life sciences.

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“…A last important class of microscopy methods that are widely used for NP characterization is represented by absorption microscopy [110]. These techniques typically rely on the existence of large imaginary dielectric permittivity in correspondence of specific wavelengths, leading to large absorption cross-section.…”

Section: Digital Detection Of Bionanoparticlesmentioning

confidence: 99%

Emerging applications of label-free optical biosensors

et al. 2017

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Abstract:Innovative technical solutions to realize optical biosensors with improved performance are continuously proposed. Progress in material fabrication enables developing novel substrates with enhanced optical responses. At the same time, the increased spectrum of available biomolecular tools, ranging from highly specific receptors to engineered bioconjugated polymers, facilitates the preparation of sensing surfaces with controlled functionality. What remains often unclear is to which extent this continuous innovation provides effective breakthroughs for specific applications. In this review, we address this challenging question for the class of label-free optical biosensors, which can provide a direct signal upon molecular binding without using secondary probes. Label-free biosensors have become a consolidated approach for the characterization and screening of molecular interactions in research laboratories. However, in the last decade, several examples of other applications with high potential impact have been proposed. We review the recent advances in label-free optical biosensing technology by focusing on the potential competitive advantage provided in selected emerging applications, grouped on the basis of the target type. In particular, direct and real-time detection allows the development of simpler, compact, and rapid analytical methods for different kinds of targets, from proteins to DNA and viruses. The lack of secondary interactions facilitates the binding of small-molecule targets and minimizes the perturbation in single-molecule detection. Moreover, the intrinsic versatility of label-free sensing makes it an ideal platform to be integrated with biomolecular machinery with innovative functionality, as in case of the molecular tools provided by DNA nanotechnology.

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Imaging nano-objects by linear and nonlinear optical absorption microscopies

Cited by 18 publications

References 187 publications

Multilayer phosphorene quantum dots in an electric field: Energy levels and optical absorption

Multilayer phosphorene quantum dots in an electric field: Energy levels and optical absorption

Label-Free Optical Microscope Based on a Phase-Modulated Femtosecond Pump–Probe Approach with Subdiffraction Resolution

Emerging applications of label-free optical biosensors

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