Browsing by Subject "Spontaneous Emission"

Now showing 1 - 4 of 4

Open Access
Enhancement and inhibition of photoluminescence in hydrogenated amorphous silicon nitride microcavities
(Optical Society of America, 1997-09-01) Serpenguzel, A.; Aydınlı, Atilla; Bek, A.
A Fabry-Perot microcavity is used for the enhancement and inhibition of photoluminescence in hydrogenated amorphous silicon nitride. The amplitude of the photoluminescence is enhanced 4 times, while its linewidth is reduced 8 times with respect to the bulk hydrogenated amorphous silicon nitride. The transmittance, reflectance, and absorptance spectra of the microcavity were also measured and calculated. The calculated spectra agree well with the experimental ones. (C) 1997 Optical Society of America
Open Access
Highly directional enhanced radiation from sources embedded inside three-dimensional photonic crystals
(Optical Society of America, 2005) Caglayan, H.; Bulu, I.; Özbay, Ekmel
We have experimentally studied emission of microwave radiation from a monopole source embedded in a three-dimensional photonic crystal. We have demonstrated enhancement of microwave radiation at the band edge and cavity mode frequencies. Furthermore, we have shown that it is possible to obtain highly directive microwave radiation sources operating at the band edge of the three-dimensional photonic crystal. We have measured half power beam widths of 13 degrees for both E and H planes, corresponding to a maximum directivity of 245. (c) 2005 Optical Society of America.
Open Access
Hyperbolic metamaterials based on quantum-dot plasmon resonator nanocomposites
(Optical Society of America, 2014) Zhokovsky, S. V.; Ozel, T.; Mutlugun, E.; Gaponik, N.; Eychmuller, A.; Lavrinenko, A. V.; Demir, Hilmi Volkan; Gaponenko, S. V.
We theoretically demonstrate that nanocomposites made of colloidal semiconductor quantum dot monolayers placed between metal nanoparticle monolayers can function as multilayer hyperbolic metamaterials. Depending on the thickness of the spacer between the quantum dot and nanoparticle layers, the effective permittivity tensor of the nanocomposite is shown to become indefinite, resulting in increased photonic density of states and strong enhancement of quantum dot luminescence. This explains the results of recent experiments [T. Ozel et al., ACS Nano 5, 1328 (2011)] and confirms that hyperbolic metamaterials are capable of increasing the radiative decay rate of emission centers inside them. The proposed theoretical framework can also be used to design quantum-dot/nanoplasmonic composites with optimized luminescence enhancement. (C) 2014 Optical Society of America
Open Access
Physics and applications of coupled-cavity structures in photonic crystals
(2002) Bayındır, Mehmet
We proposed and demonstrated a new type of propagation mechanism for the electromagnetic waves in photonic band gap materials. Photons propagate through coupled cavities due to interaction between the highly localized neighboring cavity modes. We reported a novel waveguide, which we called coupled-cavity waveguide (CCW), in two- and three-dimensional photonic structures. By using CCWs, we demonstrated lossless and reflectionless waveguide bends, efficient power splitters, and photonic switches. We also experimentally observed the splitting of eigenmodes in coupled-cavities and formation of defect band due to interaction between the cavity modes. We reported the modification of spontaneous emission from hydrogenated amorphous silicon-nitride and silicon-oxide multilayers with coupled Fabry-Perot microcavities. We observed that the spontaneous emission rate is drastically enhanced at the coupledmicrocavity band edges due to very long photon lifetime. We also simulated our photonic structures by using the Transfer-Matrix-Method (TMM) and the Finite-Difference-Time-Domain (FDTD) method. The tight-binding (TB) approach, which was originally developped for the electronic structure calculations, is applied to the photonic structures, and compared to our experimental results. The measured results agree well with the simulations and the prediction of TB approximation. The excellent agreement between the measured, simulated, and the TB results is an indication of potential usage of TB approximation in photonic structures. Our achievements open up a new research area, namely physics and applications of coupled-cavities, in photonic structures. These results are very promising to construct for the future all-optical components on a single chip.