F. Treussart

Detection of Single Photoluminescent Diamond Nanoparticles in Cells and Study of the Internalization Pathway

Diamond nanoparticles are promising photoluminescent probes for tracking intracellular processes, due to embedded, perfectly photostable color centers. In this work, the spontaneous internalization of such nanoparticles (diameter 25 nm) in HeLa cancer cells is investigated by confocal microscopy and time-resolved techniques. Nanoparticles are observed inside the cell cytoplasm at the single-particle and single-color-center level, assessed by time-correlation intensity measurements. Improvement of the nanoparticle signal-to-noise ratio inside the cell is achieved using a pulsed-excitation laser and time-resolved detection taking advantage of the long radiative lifetime of the color-center excited state as compared to cell autofluorescence. The internalization pathways are also investigated, with endosomal marking and colocalization analyses. The low colocalization ratio observed proves that nanodiamonds are not trapped in endosomes, a promising result in prospect of drug delivery by these nanoparticles. Low cytotoxicity of these nanoparticles in this cell line is also shown.

Strain-tunable high-Q optical microsphere resonator

Abstract We demonstrate the tuning of high- Q optical whispering-gallery modes in a fused silica microsphere by applying mechanical strain. The measured total tunability is over 0.3 nm in the near-infrared band, with the undercoupled quality-factor being Q >1×10 8 . The tunability of mode frequencies in this high- Q solid-state microcavity expands its applicability in quantum optics and photonics.

Simple interferometric technique for generation of a radially polarized light beam

We present a theoretical and experimental investigation of an interferometric technique for converting a linearly polarized Gaussian beam into a radially polarized doughnut beam. The experimental setup accomplishes the coherent summation of two orthogonally polarized TEM01 and TEM10 beams that are obtained from the transformation of a TEM00 beam by use of a simple binary diffractive optical element. We have shown that the degree of radial polarization is maximum at a given distance from the interferometer output port that depends on the diameter of the incident beam at the interferometer input port.

Surface-induced charge state conversion of nitrogen-vacancy defects in nanodiamonds

We present a study of the charge state conversion of single nitrogen-vacancy (NV) defects hosted in nanodiamonds (NDs). We first show that the proportion of negatively charged

Evidence for intrinsic Kerr bistability of high-Q microsphere resonators in superfluid helium

{\text{NV}}^{\ensuremath{-}}

Direct measurement of the photon statistics of a triggered single photon source.

defects, with respect to its neutral counterpart

Quantized atom-field force at the surface of a microsphere

{\text{NV}}^{0}

Single-photon wavefront-splitting interference An illustration of the light quantum in action

, decreases with the size of the ND. We then propose a simple model based on a layer of electron traps located at the ND surface which is in good agreement with the recorded statistics. By using thermal oxidation to remove the shell of amorphous carbon around the NDs, we demonstrate a significant increase in the proportion of

Photon antibunching in the fluorescence of a single dye molecule embedded in a thin polymer film

{\text{NV}}^{\ensuremath{-}}

Formation of color centers in nanodiamonds by plasma assisted diffusion of impurities from the growth substrate

defects in 10 nm NDs. These results are invaluable for further understanding, control, and use of the unique properties of negatively charged NV defects in diamond.