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Optical sources that deterministically produce single photons with a high suppression of multi-photon emission and a negligible background component are promising candidates for standard sources for quantum metrology, quantum communication and foundations of quantum mechanics. In this paper, the photon number distribution of non-classical light emitted by nitrogen vacancy (NV) centres in nano-diamonds is studied by three different experimental techniques. The photon number resolving transition edge sensor (TES) detector and the On/Off detection method are applied to determine the diagonal elements of the optical density matrix. From the data measured by the two methods the second order correlation function at time delay zero is calculated and compared with the g 2 (0)-values obtained by Hanbury Brown-Twiss (HBT) interferometric measurements. Among the g 2 (0)-values evaluated with the three techniques, we found good agreement in the results for a single photon emitter with a g 2 (0)-value close to zero and a multi-photon source with a g 2 (0)-value of approximately 0.5.

The two dimensional In addition a quantitative visualization of concentration fields of different fluids that participate in the mixing process of a microfluidic system was enabled by Planar Spontaneous Raman Scattering (PSRS). It was utilized that different species of molecules are distinguishable from another by their characteristic "spectral fingerprints" (their Raman spectra

Abstract. Two-dimensional Molecular-Tagging-Velocimetry (2D-MTV) has been used to investigate velocity fields of liquid flow in a micro mixer. Optical tagging was realized by using caged dye. For the first time patterns were generated by structured laser illumination using optical masks. This allows the generation of nearly any imaginable pattern. The flow induced deformation of the optically written pattern is tracked by imaging of laser induced fluorescence. Quantitative analysis of raw image series is carried out by novel "optical flow" based techniques. A comparison to the standard technique of µPIV has also been conducted. Additionally Planar Spontaneous Raman Scattering (PSRS) was applied in order to determine concentration fields for mixtures of ethanol and water.

In this work we report on the optical investigation of Zn doped GaN films fabricated by metal organic chemical vapor deposition. The samples show bright emission in the blue spectral range around 2.9 eV when Si codoping is provided. This emission is suggested to be used for single‐photon emission, thus the density of the Zn‐Si pairs was drastically reduced leading to a decrease of the blue luminescence. For electrically excited single‐photon sources these Zn‐Si pairs have to be incorporated into LEDs, therefore we fabricated GaN‐based nano‐LEDs which show electroluminescence at 430 nm (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)