A recent proposal that the metamaterial approach to dielectric response engineering may increase the critical temperature of a composite superconductor-dielectric metamaterial has been tested in experiments with compressed mixtures of tin and barium titanate nanoparticles of varying composition. An increase of the critical temperature of the order of ΔT ~ 0.15 K compared to bulk tin has been observed for 40% volume fraction of barium titanate nanoparticles. Similar results were also obtained with compressed mixtures of tin and strontium titanate nanoparticles.

We demonstrate a novel artificial optical material, the “photonic hyper-crystal”, which combines the most interesting features of hyperbolic metamaterials and photonic crystals. Similar to hyperbolic metamaterials, photonic hyper-crystals exhibit broadband divergence in their photonic density of states due to the lack of usual diffraction limit on the photon wave vector. On the other hand, similar to photonic crystals, hyperbolic dispersion law of extraordinary photons is modulated by forbidden gaps near the boundaries of photonic Brillouin zones. Three dimensional self-assembly of photonic hyper-crystals has been achieved by application of external magnetic field to a cobalt nanoparticle-based ferrofluid. Unique spectral properties of photonic hyper-crystals lead to extreme sensitivity of the material to monolayer coatings of cobalt nanoparticles, which should find numerous applications in biological and chemical sensing.

Extraordinary light rays propagating inside a hyperbolic metamaterial look similar to particle world lines in a 2 + 1 dimensional Minkowski spacetime. Magnetic nanoparticles in a ferrofluid are known to form nanocolumns aligned along the magnetic field, so that a hyperbolic metamaterial may be formed at large enough nanoparticle concentration nH. Here we investigate optical properties of such a metamaterial just below nH. While on average such a metamaterial is elliptical, thermal fluctuations of nanoparticle concentration lead to transient formation of hyperbolic regions (3D Minkowski spacetimes) inside this metamaterial. Thus, thermal fluctuations in a ferrofluid look similar to creation and disappearance of individual Minkowski spacetimes (universes) in the cosmological multiverse. This theoretical picture is supported by experimental measurements of polarization-dependent optical transmission of a cobalt based ferrofluid at 1500 nm.

We demonstrate a novel artificial optical material, the ''photonic hyper-crystal'', which combines the most interesting features of hyperbolic metamaterials and photonic crystals. Similar to hyperbolic metamaterials, photonic hyper-crystals exhibit broadband divergence in their photonic density of states due to the lack of usual diffraction limit on the photon wave vector. On the other hand, similar to photonic crystals, hyperbolic dispersion law of extraordinary photons is modulated by forbidden gaps near the boundaries of photonic Brillouin zones. Three dimensional self-assembly of photonic hyper-crystals has been achieved by application of external magnetic field to a cobalt nanoparticle-based ferrofluid. Unique spectral properties of photonic hyper-crystals lead to extreme sensitivity of the material to monolayer coatings of cobalt nanoparticles, which should find numerous applications in biological and chemical sensing. Over the last few decades a considerable progress has been made in developing artificial optical materials with novel and often counterintuitive properties. Revolutionary research by Yablonovitch and John on photonic crystals 1,2 was followed by the development of electromagnetic metamaterial paradigm by Pendry 3 . Even though considerable difficulties still exist in fabrication of three-dimensional (3D) photonic crystals and metamaterials, both fields exhibit considerable experimental progress 4,5 . On the other hand, on the theoretical side these fields are believed to be complementary but mutually exclusive. Photonic crystal effects typically occur in artificial optical media which are periodically structured on the scale of free space light wavelength l, while electromagnetic metamaterials are required to be structured (not necessarily in a periodic fashion) on the scale, which is much smaller than the free space wavelength of light. For example, in metal nanowire-based hyperbolic metamaterials 6 schematically shown in Fig. 1A the inter-wire distance must be much smaller than l. Here we report experimental realization of 3D ''photonic hyper-crystals'' which bridge this divide by combining the most interesting properties of hyperbolic metamaterials and photonic crystals.Our concept of the photonic hyper-crystal 7 is based on the fact that dispersion law of extraordinary photons in hyperbolic metamaterials does not exhibit the usual diffraction limit. In such uniaxial metamaterials the in-plane e xy and out-of-plane e z components of the dielectric permittivity tensor have opposite signs (e.g. the metal wire array hyperbolic metamaterial shown in Fig. 1A may have e z , 0 and e xy . 0 8 ), so that the photon wave vector components k i are not bounded at a given frequency of light v. Existence of large k-vector modes in a broad range of frequencies is responsible for such unusual effects as hyperlens-based super-resolution imaging [8][9][10][11] and broadband divergence of photonic density of states in hyperbolic metamaterials 12 . On the other hand, this also means that periodic modulation ...

We demonstrate a novel artificial optical material, the ''photonic hyper-crystal'', which combines the most interesting features of hyperbolic metamaterials and photonic crystals. Similar to hyperbolic metamaterials, photonic hyper-crystals exhibit broadband divergence in their photonic density of states due to the lack of usual diffraction limit on the photon wave vector. On the other hand, similar to photonic crystals, hyperbolic dispersion law of extraordinary photons is modulated by forbidden gaps near the boundaries of photonic Brillouin zones. Three dimensional self-assembly of photonic hyper-crystals has been achieved by application of external magnetic field to a cobalt nanoparticle-based ferrofluid. Unique spectral properties of photonic hyper-crystals lead to extreme sensitivity of the material to monolayer coatings of cobalt nanoparticles, which should find numerous applications in biological and chemical sensing. Over the last few decades a considerable progress has been made in developing artificial optical materials with novel and often counterintuitive properties. Revolutionary research by Yablonovitch and John on photonic crystals 1,2 was followed by the development of electromagnetic metamaterial paradigm by Pendry 3 . Even though considerable difficulties still exist in fabrication of three-dimensional (3D) photonic crystals and metamaterials, both fields exhibit considerable experimental progress 4,5 . On the other hand, on the theoretical side these fields are believed to be complementary but mutually exclusive. Photonic crystal effects typically occur in artificial optical media which are periodically structured on the scale of free space light wavelength l, while electromagnetic metamaterials are required to be structured (not necessarily in a periodic fashion) on the scale, which is much smaller than the free space wavelength of light. For example, in metal nanowire-based hyperbolic metamaterials 6 schematically shown in Fig. 1A the inter-wire distance must be much smaller than l. Here we report experimental realization of 3D ''photonic hyper-crystals'' which bridge this divide by combining the most interesting properties of hyperbolic metamaterials and photonic crystals.Our concept of the photonic hyper-crystal 7 is based on the fact that dispersion law of extraordinary photons in hyperbolic metamaterials does not exhibit the usual diffraction limit. In such uniaxial metamaterials the in-plane e xy and out-of-plane e z components of the dielectric permittivity tensor have opposite signs (e.g. the metal wire array hyperbolic metamaterial shown in Fig. 1A may have e z , 0 and e xy . 0 8 ), so that the photon wave vector components k i are not bounded at a given frequency of light v. Existence of large k-vector modes in a broad range of frequencies is responsible for such unusual effects as hyperlens-based super-resolution imaging [8][9][10][11] and broadband divergence of photonic density of states in hyperbolic metamaterials 12 . On the other hand, this also means that periodic modulation ...