Preface 1. Planck's radiation law and the Einstein coefficients 2. Quantum mechanics of the atom-radiation interaction 3. Classical theory of optical fluctuations and coherence 4. Quantization of the radiation field 5. Single-mode quantum optics 6. Multimode and continuous-mode quantum optics 7. Optical generation, attenuation and amplification 8. Resonance fluorescence and light scattering 9. Nonlinear quantum optics Index

The quantum theory of light.

In working with nanoparticles, researchers still face two fundamental challenges: how to fabricate the nanoparticles with controlled size and shape and how to characterize them. In this Account, we describe recent advances in laser technology both for the synthesis of organic nanoparticles and for their analysis by single nanoparticle spectroscopy. Laser ablation of organic microcrystalline powders in a poor solvent has opened new horizons for the synthesis of nanoparticles because the powder sample is converted directly into a stable colloidal solution without additives and chemicals. By tuning laser wavelength, pulse width, laser fluence, and total shot number, we could control the size and phase of the nanoparticles. For example, we describe nanoparticle formation of quinacridone, a well-known red pigment, in water. By modifying the length of time that the sample is excited by the laser, we could control the particle size (30−120 nm) for nanosecond excitation down to 13 nm for femtosecond irradiation. ...

https://ir.nctu.edu.tw:443/bitstream/11536/8083/1/000261767600023.pdf

Laser Fabrication and Spectroscopy of Organic Nanoparticles

We demonstrate focusing coherent light on a nanoparticle through turbid media based on digital optical phase conjugation of second harmonic generation (SHG) field from the nanoparticle. A SHG active nanoparticle inside a turbid medium was excited at the fundamental frequency and emitted SHG field as a point source. The SHG emission was scattered by the turbid medium, and the scattered field was recorded by off-axis digital holography. A phase-conjugated beam was then generated by using a phase-only spatial light modulator and sent back through the turbid medium, which formed a nearly ideal focus on the nanoparticle.

Digital phase conjugation of second harmonic radiation emitted by nanoparticles in turbid media

Luminescent markers play a key role in imaging techniques for life science since they provide a contrast mechanism between signal and background. We describe a new type of marker using second harmonic generation (SHG) from noncentrosymmetric BaTiO_3 nanocrystals. These nanoparticles are attractive due to their stable, non-saturating and coherent signal with a femtosecond-scale response time and broad flexibility in the choice of excitation wavelength. We obtained monodispersed BaTiO_3 nanoparticles in colloidal suspensions by coating the particle surface with amine groups. We characterized the SHG efficiency of 90-nm BaTiO_3 particles experimentally and theoretically. Moreover, we use the coherent SHG signal from BaTiO_3 nanoparticles for three-dimensional (3D) imaging without scanning. We built a harmonic holographic (H^2) microscope which records digital holograms at the second harmonic frequency. For the first time, high-resolution 3D distributions of these SHG markers in mammalian cells are successfully captured and interpreted by the H^2 microscope.

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Three-dimensional harmonic holographic microcopy using nanoparticles as probes for cell imaging

Nonlinear optical nanocrystals have been recently introduced as a promising alternative to fluorescent probes for multiphoton microscopy. We present for the first time a complete survey of the properties of five nanomaterials (KNbO3, LiNbO3, BaTiO3, KTP, and ZnO), describing their preparation and stabilization and providing quantitative estimations of their nonlinear optical response. In the light of their prospective use as biological and clinical markers, we assess their biocompatibility on human healthy and cancerous cell lines. Finally, we demonstrate the great potential for cell imaging of these inherently nonlinear probes in terms of optical contrast, wavelength flexibility, and signal photostability.

Harmonic Nanocrystals for Biolabeling: A Survey of Optical Properties and Biocompatibility

We elucidate the crystalline nature and the three-dimensional orientation of isolated organic nanocrystals embedded in a sol-gel matrix, using a polarized nonlinear microscopy technique that combines two-photon fluorescence and second harmonic generation. This technique allows the distinction between monocrystalline structures and nanoscale polycrystalline aggregates responsible for incoherent second harmonic signals.

https://hal.archives-ouvertes.fr/hal-00000570/document

In situ diagnostics of the crystalline nature of single organic nanocrystals by nonlinear microscopy.

We present high resolution two-photon excitation microscopy studies combining two-photon fluorescence (TPF) and second harmonic generation (SHG) in order to probe orientational distributions of molecular ensembles at room temperature. A detailed polarization analysis of TPF and SHG signals is used in order to unravel the parameters of the molecular orientational statistical distribution, using a technique which can be extended and generalized to a broad variety of molecular arrangements. A polymer film containing molecules active for TPF and/or SHG emission is studied as a model system. Polarized TPF is shown to provide information on specific properties pertaining to incoherent emission in molecular media, such as excitation transfer. SHG, being highly sensitive to a slight departure from centrosymmetry such as induced by an external electric field in the medium, complements TPF. The response of each signal to a variable excitation polarization allows investigation of molecular behavior in complex environments which affect their orientations and interactions.

Monitoring of Orientation in Molecular Ensembles by Polarization Sensitive Nonlinear Microscopy

We present high resolution two-photon excitation microscopy studies combining two-photon fluorescence (TPF) and second harmonic generation (SHG) in order to probe orientational distributions of molecular ensembles at room temperature. A detailed polarization analysis of TPF and SHG signals is used in order to unravel the parameters of the molecular orientational statistical distribution, using a technique which can be extended and generalized to a broad variety of molecular arrangements. A polymer film containing molecules active for TPF and/or SHG emission is studied as a model system. Polarized TPF is shown to provide information on specific properties pertaining to incoherent emission in molecular media, such as excitation transfer. SHG, being highly sensitive to a slight departure from centrosymmetry such as induced by an external electric field in the medium, complements TPF. The response of each signal to a variable excitation polarization allows investigation of molecular behavior in complex enviro...

https://hal.archives-ouvertes.fr/hal-00000533/document

Véronique Le Floc'h

Papers

In situ diagnostics of the crystalline nature of single organic nanocrystals by nonlinear microscopy.

Monitoring of Orientation in Molecular Ensembles by Polarization Sensitive Nonlinear Microscopy

Monitoring of Orientation in Molecular Ensembles by Polarization Sensitive Nonlinear Microscopy

Single photon emission from a single molecule

L'émission de photons uniques par une molécule individuelle