Tamm plasmons are electromagnetic states located at the interface between a dielectric Bragg mirror and a metal . Contrary to conventional surface plasmons, Tamm plasmons can exist in both TE and TM polarization and its parabolic dispersion lies above the light cone which allow a direct optical excitation at normal incidence. Besides, the Tamm mode confinement can be obtained by simply patterning the thin metallic film, such as microdisks [2,3] or microrectangles . Here, we aim at obtaining ultimate confinement using photonic crystal periodic structures in the metallic layer.
The samples are constituted by a DBR with 4 pairs of l/4n layers of Si and SiO2 above which periodic metallic patterns are defined using e-beam lithography and a 50nm gold deposition. Lift-off is performed at the end of the process. The period of the gratings is chosen to obtain a Tamm Bloch mode around 1.3micrometer.
Microreflectivity experiments show that Tamm Bloch modes exist in such 1D periodic structures. Using an original design, we create a 1D photonic band gap as large as 140nm. Finally, we will present experimental results on cavity-confined Tamm Bloch modes. All results are in good agreement with numerical calculations.
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Localized and delocalized plasmons in metallic nanoparticles are associated with a strongly confined electromagnetic field, inducing an enhanced interaction with emitters located in the close environment of the metal. When the plasmon/emitter interaction becomes predominant compared to the damping in the system, the system is in strong coupling regime leading to light matter hybridization. This strong coupling has been observed with a large number of materials, in particular disordered materials. These materials are constituted by a collection of independent emitters (molecules, semiconductor quantum dots...). The hybrid light/matter state can be described by considering a homogeneous absorbing system using coupled oscillator model. But if the microscopic structure of the molecular film close to a metallic film is considered, collective effects between the delocalized plasmon and the set of molecules are present. The spatial and dynamic properties of a set of molecules in strong coupling are dramatically modified compared to the same molecules in weak coupling (the usual configuration of emission). The excitations are not localised in a single particle anymore but delocalised on a large number of particles due to the formation of an extended hybridised state on several microns. We will describe some properties of disordered systems strongly coupled to surface plasmons and experimental demonstrations of the collective phenomena associated with the strong coupling. In particular we will present an experimental study of the coherent character of the emission of different emitters with a Young’s interferences setup. The system studied consists of J-aggregated dye (TDBC) in interaction with a surface plasmon on silver. The extension of the coherent state will also be discussed.
Tamm plasmons are interface modes formed at the boundary between a metallic layer and a dielectric Bragg mirror.
They present advantages associated both to surface plasmons and to microcavities photonic modes. One of their
striking properties is that they can be spatially confined by structuring only the metallic part of the structure, thus
reducing the size of the mode and allowing various geometries without altering the optical properties of the active
layer. These modes are very good candidates for optimizing the emission properties of semiconductor
nanostructures. In particular, due to the relatively low damping and the versatility of the Tamm geometries, they
open new perspective for the development of hybrid metal/semiconductor lasers. In this paper, we will show that a
laser effect can be achieved in a bidimensional Tamm structure under pulsed optical pumping. We will also
demonstrate that the mode can be spatially confined, and that this results in a reduction of the pump power at
The fabrication and the studies of sol gel-microcavities strongly doped with CdSe nanocristals are presented. The Fabry-Perot microcavities are fabricated by a Distributed Bragg Reflectors which is covered with an active layer and a silver mirror. The matrix of the doped layer is the ZrO2 material. These microcavities are characterized by reflectometry. The resonant peak is enlarged when his spectral position corresponds to their first absorption line. This means a strong interaction between the narrow peak of the cavity mode and the large first absorption line of the nanocrystals.
The fabrication and the optical properties of sol-gel high quality DBRs and microcavities are described and the emission of the europium ions included in the cavity observed. The microcavities are constituted of an SiO2 half wave Eu3+ doped active layer inserted between two sol-gel Bragg reflectors. These reflectors are formed by a stack of alternated quarter wave films of SiO2 and TiO2. Films were deposited by a dip coating method. To fabricate high quality Bragg mirrors, a large number of layers has to be stacked, but sol gel thin layers develop internal stresses during the drying and firing processes, leading to defects and cracks into the stacked films. The study of the stresses in the layers shows that a short 900°C layer annealing solves this problem and the number of stacked layers can be greater than 60 without cracks. A microcavity with 7 doublets Bragg mirrors has been fabricated using this process. Eu3+ luminescence modification due to the cavity effect, intensity enhancement and modification of the lineshape, has been observed, showing a cavity quality factor of 1200. The reflectivity factor of the associated Bragg mirrors reaches 99.8% for seven alternated SiO2/TiO2 layers.