Stuttgart 2012 – wissenschaftliches Programm
Q 35.82: Poster
Mittwoch, 14. März 2012, 16:30–19:00, Poster.I+II
Studying Photon Antibunching of Bunched Emitters — •Silke Peters, Johannes Dühn, Helmuth Hofer, Waldemar Schmunk, and Stefan Kück — Physikalisch-Technische Bundesanstalt, Bundesallee 100, D-38116 Braunschweig
We report on the emission characteristics of bunched NV-centers in nano-diamonds by focusing on different spatial areas of the emission spot. The results show that the common expression g(2)(0) < 0.5 does not sufficiently prove single center emission. In our setup, the emitted fluorescence is detected by a scanning confocal microscope setup and spectral filtering at (697 ± 37) nm. Due to the spot size of the 532 nm pulsed excitation laser, which is orders of magnitude larger than the dimensions of the NV-centers, the observed light might be emitted by more than one NV-center being present. To study this possibility the g(2)-function is measured for various scan positions of two emitting centers 1 and 2 by a fiber coupled Hanbury-Brown-Twiss interferometer. For center 1, a g(2)(0)=0.16 is found independent from the laser focal position within the region around this center. For center 2, a g(2)(0)=0.4 is observed at the local count rate maximum of the center. In contrast, a significantly lower value of 0.196 is determined at the boundary of the center. These variations cannot be induced only by the influence of the detector dark count rate, the remaining background light, or an electronic timing jitter. A possible explanation is that the spot actually contains more than one NV-centers, yet, by shifting the focus to the side, fewer centers are being excited and therefore less simultaneous photon coincidences occur.