We have observed, in metamaterial with hyperbolic dispersion (an array of silver nanowires in alumina membrane), a sixfold reduction of the emission lifetime of dye deposited onto the metamaterial's surface. This serves as evidence of an anomalously high density of photonic states in hyperbolic metamaterials, demonstrates the feasibility of an earlier-predicted single-photon gun, and paves the road for the use of metamaterials in quantum optics.

We have developed a simple method to fabricate lamellar metal-dielectric hyperbolic metamaterials on flat, flexible, and curvilinear substrates, which allows for functionalization of dielectric layers by dye molecules. The control of spontaneous emission of dye molecules with hyperbolic metamaterials has been studied in two different sample configurations, and the effect has been found to be much stronger when emitters are placed inside the metamaterial rather than on its surface.

The authors show that a photovoltaic device composed of a -donor-bridge–acceptor-bridge- type block copolymer thin film exhibits a significant performance improvement over its corresponding donor/acceptor blend (Voc increased from 0.14to1.10V and Jsc increased from 0.017 to 0.058mA∕cm2) under identical conditions, where donor is an alkyl derivatized poly-p-phenylenevinylene (PPV) conjugated block, acceptor is a sulfone-alkyl derivatized PPV conjugated block, and bridge is a nonconjugated and flexible unit. The authors attribute such improvement to the block copolymer intrinsic nanophase separation and molecular self-assembly that results in the reduction of the exciton and carrier losses.

Abstract:Optical cavities, plasmonic structures, photonic band crystals, interfaces, as well as, generally speaking, any photonic media with homogeneous or spatially inhomogeneous dielectric permittivity (including metamaterials) have local densities of photonic states, which are different from that in vacuum. These modified density of states environments are known to control both the rate and angular distribution of spontaneous emission. In the present study, we ask the question whether the proximity to metallic and metamaterial surfaces can affect other physical phenomena of fundamental and practical importance. We show that the same substrates and the same nonlocal dielectric environments that boost spontaneous emission, also inhibit Förster energy transfer between donor and acceptor molecules doped into a thin polymeric film. This finding correlates with the fact that in dielectric media, the rate of spontaneous emission is proportional to the index of refraction n, while the rate of the donor-acceptor energy transfer (in solid solutions with random distribution of acceptors) is proportional to n -1.5 . This heuristic correspondence suggests that other classical and quantum phenomena, which in regular dielectric media depend on n, can also be controlled with custom-tailored metamaterials, plasmonic structures, and cavities.Keywords: Förster energy transfer; metamaterials with hyperbolic dispersion; photonic density of states.

A novel class of light harvesting conjugated block copolymers, with electron-donating conjugated blocks (D) connected to electron-accepting conjugated blocks (A) via non conjugated and flexible bridge chains (B), has been designed, synthesized, and characterized. Specifically, D is a decyloxy-substituted polyphenylenevinylene (C10−PPV). A 1 and A 2 are PPVs with sulfone (SO2) acceptor moieties substituted on every other phenylene unit. A 1 carries two decyloxy groups on every phenylene unit, while in A 2 , half of the phenylene units are unsubstituted. The optical energy gaps are 2.24 eV for the donor block (D), 2.33 and 2.45 eV for A 1 and A 2 acceptor blocks. LUMO level offsets are 0.24 and 0.16 eV for D/A 1 and D/A 2 pairs, respectively. Comparing the photoluminescence from both films and solutions, very large red shifts (71 and 74 nm for A 1 and A 2 respectively) were observed in the two acceptor polymers. These red shifts in the emission spectra were more than twice as much as that observed for D (31 nm). The (DBA 1 B) n and (DBA 2 B) n block copolymer films exhibited improved processability and optoelectronic properties when compared with the corresponding films composed of donor/acceptor blends. Atomic force microscopic (AFM) studies of D, A 1 , and A 2 films were also undertaken to observe the degree of aggregation in the films. The results indicate the tendency of intermolecular aggregation increases as A 2 > D > A 1 . AFM topological images revealed that large aggregates of several hundreds of nanometers formed in donor/acceptor blend films, while in block copolymer films, domain sizes were similar to individual block sizes which are 1 order of magnitude smaller than in the blend.

We demonstrate the enhancement of magnetic dipole spontaneous emission from Eu³⁺ ions by an engineered plasmonic nanostructure that controls the electromagnetic environment of the emitter. Using an optical microscope setup, an enhancement in the intensity of the Eu³⁺ magnetic dipole emission was observed for emitters located in close vicinity to a gold nanohole array designed to support plasmonic resonances overlapping with the emission spectrum of the ions.

Nanophotonic devices offer an unprecedented ability to concentrate light into small volumes which can greatly increase nonlinear effects. However, traditional plasmonic materials suffer from low damage thresholds and are not compatible with standard semiconductor technology. Here we study the nonlinear optical properties in the novel refractory plasmonic material titanium nitride using the Z-scan method at 1550 nm and 780 nm. We compare the extracted nonlinear parameters for TiN with previous works on noble metals and note a similarly large nonlinear optical response. However, TiN films have been shown to exhibit a damage threshold up to an order of magnitude higher than gold films of a similar thickness, while also being robust, cost-efficient, bio-and CMOS-compatible. Together, these properties make TiN a promising material for metalbased nonlinear optics. Recently, TiN has been suggested as a refractory metal (melting point > 2900°C) with plasmonic properties similar to gold [19]. In addition, TiN has tunable optical properties, is chemically stable, can be grown epitaxially on magnesium oxide, c-sapphire, and silicon, and is bio-and CMOS-compatible, all in stark contrast to the noble metals [19,20]. In fact, TiN-based metasurfaces have been experimentally demonstrated to withstand temperatures and optical intensities greater than gold structures, making them potentially interesting for applications in nonlinear optics [21]. However, the inherent nonlinearities of this

A series of evolving frontier energy levels and gaps sulfone-containing thienylenevinylene-based conjugated copolymers have been synthesized via the Horner-Emmons reactions between 2,5-bisdiethoxyphosphorylmethyl-3,4-dihexyl-1,1-dioxothiophene and a series of different donor type dialdehyde comonomers. The resulting polymers (SF-PTVs) contain alternating donor (benzene or thiophene ring with/without alkoxy substituents) and acceptor (1,1-dioxothiophene) units. A range of HOMO/LUMO levels and energy gaps (between 1.0 and 2.0 eV) were achieved in these new polymers. The use of oxidized thiophene moiety brings about 0.3 eV in reduction of energy gap. Computational study on the model oligomers of P(C6OTV-SFTV) and related structures reveals that the reduction is mainly due to the removal of aromaticity of the thiophene. The donor-acceptor interaction is also responsible for about one-third or less of the energy gap reduction. Theses polymers have very good thermal stability (dynamically, 258 °C or higher), and their decomposition starts with loss of mass as in contrast to regular PTVs which decompose initially by cross-linking.