Hyperbolic metamaterials (HMMs) represent a novel class of fascinating anisotropic plasmonic materials, supporting highly confined bulk plasmon polaritons in addition to the surface plasmon polaritons. However, it is very challenging to tailor and excite those modes at optical frequencies using prism coupling technique because of the intrinsic difficulties to engineer non-traditional optical properties using artificial nanostructures and the unavailability of high refractive index prisms for matching the momentum between the incident light and the guided modes. Here, we experimentally demonstrate the excitation of both surface and bulk plasmon polaritons in a HMM through a grating coupling technique of surface plasmon excitation that makes use a hypergrating, which is a combined structure of metallic diffraction grating and HMM. Initially, we propose an optical hyperbolic metamaterial based on Au/TiO₂ multilayers and confirm the hyperbolic dispersion, and the presence of high-k modes in the fabricated HMM. Reflection measurements as a function of incident angle and excitation wavelength show the existence of both surface and bulk plasmon polaritons inside the hypergrating. The proposed configuration is expected to find potential applications in bio-chemical sensors, integrated optics and optical sub-wavelength imaging.

In recent years, considerable research efforts have been focused on near-perfect and perfect light absorption using metamaterials spanning frequency ranges from microwaves to visible frequencies. This relatively young field is currently facing many challenges that hampers its possible practical applications. In this paper, we present grating coupled-hyperbolic metamaterials (GC-HMM) as multiband perfect absorber that can offer extremely high flexibility in engineering the properties of electromagnetic absorption. The fabricated GC-HMMs exhibit several highly desirable features for technological applications such as polarization independence, wide angle range, broad- and narrow- band modes, multiband perfect and near perfect absorption in the visible to near-IR and mid-IR spectral range. In addition, we report a direct application of the presented system as an absorption based plasmonic sensor with a record figure of merit for this class of sensors.

Hyperbolic metamaterial (HMM), a sub-wavelength periodic artificial structure with hyperbolic dispersion, can enhance the spontaneous emission of quantum emitters. Here, we demonstrate the large spontaneous emission rate enhancement of an organic dye placed in a grating coupled hyperbolic metamaterial (GCHMM). A two-dimensional (2D) silver diffraction grating coupled with an Ag/Al₂O₃ HMM shows 18-fold spontaneous emission decay rate enhancement of dye molecules with respect to the same HMM without grating. The experimental results are compared with analytical models and numerical simulations, which confirm that the observed enhancement of GCHMM is due to the outcoupling of non-radiative plasmonic modes as well as strong plasmon-exciton coupling in HMM via diffracting grating.

Distributed feedback microstructures play a fundamental role in confining and manipulating light to obtain lasing in media with gain. Here, we present an innovative array of organic, color-tunable microlasers which are intrinsically phase locked. Dye-doped helixed liquid crystals were embedded within periodic, polymeric microchannels sculptured by light through a single-step process. The helical superstructure was oriented along the microchannels; the lasing was observed along the same direction at the red edge of the stop band. Several physical and technological advantages arise from this engineered heterostructure: a high quality factor of the cavity, ultralow lasing threshold, and thermal and electric control of the lasing wavelength and emission intensity. This level of integration of guest-host systems, embedded in artificially patterned small sized structures, might lead to new photonic chip architectures.