We investigate circular grating resonators (CGR) with a very small footprint. Photonic devices based on circular
grating resonators are computationally designed, optimized and studied in their functionality using finite
difference time-domain (FDTD) method. A wide variety of critical quantities such as transmission and reflection,
resonant modes, resonant frequencies, and field patterns are calculated. Due to their computational size some
of these calculations have to be performed on a supercomputer (e.g. parallel Blue Gene machine). The devices
are fabricated in SOI using the computational design parameters. First they are defined by electron-beam
lithography. Then the pattern transfer is achieved by an inductively coupled reactive-ion etch process. Finally,
the devices are characterized by coupling light from a tunable laser with a tapered lensed fiber. As predicted
from the simulations the measured transmission spectra exhibit a wide range of different type of resonances with
quality factors exceeding 1000.
We report on experiments where a single quantum dot is strongly coupled to a high-Q mode of a micropillar
cavity. Photon correlation measurements confirm that the observed avoided crossing originates from strong
coupling of a single quantum dot to the cavity mode. Cross-correlations between the cavity mode and the
spectrally detuned quantum dot enabled us to assign the unexpected strong cavity emission to a coupling with
the single quantum dot. The coupled quantum dot-microcavity system displays an Purcell factor of 61 and
represents a single-photon source with an efficiency of 97%.
In this paper we discuss different configurations of experiments where two nanoemitters are coupled through exchange of photons via shared cavity modes. We introduce an experimental setup where we combine microspheres as optical resonators with the techniques of scanning confocal and scanning near-field microscopy. The emission of fluorescence light from a single nanoemitter in high-Q whispering-gallery modes is demonstrated. Also first experiments with a novel type of stable active nanoprobe are reported. These results demonstrate the feasibility of experiments where optical modes mediate interactions between few quantum emitters in a controlled manner.
We measured the coupling of the florescence from semiconductor nano-crystals and sub-micron sized dye-doped beads to high-Q whispering gallery modes (WGM) of a microsphere resonator. With Q-factors as high as 109 the florescence could be extracted in a controlled way via a prism coupler. We observed nearly 100 % modulation in
the spectrum which reflects the coupling to the WGMs. With the help of a beam scanning confocal microscope we were able to address a single 500 nm sized dye-doped bead on the sphere’s surface and to collect and analyze its florescence in a well defined manner via the prism coupler.