M. A. Kaliteevski

Diffraction and transmission of light in low-refractive index Penrose-tiled photonic quasicrystals

We report the measurements of the diffraction pattern of a two-dimensional Penrose-tiled photonic quasicrystal, obtained by etching air cylinders in a silica substrate, and the modelling of the light propagation and dispersion relations of photons inside such a structure. The calculated transmission spectra exhibit dips whose positions are insensitive to the direction of propagation and whose depth increases with increasing structure length. An approach is developed for the calculation of the dispersion relations which is based on a set of reciprocal vectors defined by the diffraction pattern. The dispersion curves exhibit gap-like features at frequencies corresponding to the dips in the transmission spectra.

Hybrid states of Tamm plasmons and exciton polaritons

Channeling of exciton polaritons in the plane of semiconductor microcavities can be achieved by the deposition of metallic mesas on the top of the semiconductor structure. We show theoretically that the regime of strong coupling between cavity polaritons and Tamm surface plasmons is possible in such structures. The effect is favorable for the spatial confinement of polaritons and the formation of hybrid one-dimensional plasmon-polariton modes.

Two-dimensional Penrose-tiled photonic quasicrystals: from diffraction pattern to band structure

We report measurements of the diffraction pattern of a two-dimensional photonic quasicrystal structure and use the set of plane waves defined by the diffraction pattern as the basis of a theoretical approach to calculate the photonic band structure of the system. An important feature of the model is that it retains the essence of the rotational and inflational properties of the quasicrystal at all levels of approximation: properties lost in approximate models which artificially introduce elements of periodicity. The calculated density of modes of the quasicrystals is found to display a weakly depleted region analogous to the bandgap that occurs in a periodic system. The calculated transmission spectra for different polarizations and directions of propagation show features that correlate with the behaviour of the density of modes.

Parabolic polarization splitting of Tamm states in a metal-organic microcavity

We observe hybrid states of cavity photons and Tamm plasmons in an organic microcavity with an incorporated thin silver layer of increasing thickness up to 40 nm. Via μ-photoluminescence spectroscopy, we investigate their angular dependence. At oblique angles, we observe a TE-TM polarization splitting of more than 40 meV for each mode. An analytical model is developed to describe the coupling of Tamm plasmons and cavity photons and to account for the splitting of the orthogonally polarized resonances.

Terahertz frequency bandpass filters

The design, measurement, and analysis of a range of artificial materials for use at terahertz frequencies are described. The chosen structures consist of arrays of cylindrical gold-plated pillars with period comparable to the wavelength of incident radiation. An ultraviolet (UV) micromachining approach to the fabrication of these high aspect-ratio pillars is described using the negative epoxy-based resin SU8. Lattice fence structures are also realized using the same method. Terahertz (THz) frequency time domain spectroscopy is performed on these structures in the range 200 GHz to 3.0 THz and the relative transmission of the structures is determined. The pass and stop bands are observed with peak transmission of up to 97%. Finite difference time domain simulations and complex photonic band structure calculations are shown to provide good descriptions of the electromagnetic properties of the structures and are used to interpret the observed transmission spectra.

Stimulated emission of terahertz radiation by exciton-polariton lasers

We show that planar semiconductor microcavities in the strong coupling regime can be used as sources of stimulated terahertz radiation. Emitted terahertz photons would have a frequency equal to the splitting of the cavity polariton modes. The optical transition between upper and lower polariton branches is allowed due to mixing of the upper polariton state with one of the excited exciton states and is stimulated in the polariton laser regime.

Passband filters for terahertz radiation based on dual metallic photonic structures

This paper reports on the development of two-dimensional metallic microstructures for the filtering of terahertz radiation. These structures are fabricated using ultraviolet-based processing of thick SU8 resist. This micromachining technique enables the array patterns, dimensions, and consequently the filter characteristics to be readily defined. In particular, we demonstrate that a filter with an isolated near-square-shaped passband can be realized on the basis of a combination of two different metallic photonic arrays of optimized design.

Terahertz filter based on refractive properties of metallic photonic crystal.

We propose a new type of pass-band filter, in this case designed to operate in the terahertz frequency regime, possessing two separate passbands utilizing the distinction between positive and negative refraction in a photonic crystal prism. The prism is formed from a two-dimensional hexagonal arrangement of metallic rods. In order to understand the operation of the filter we both consider the photonic bandstructure of the associated infinite photonic structure and carry out simulations of the refraction properties of the prism using finite-difference time-domain software.

Nonlinear terahertz emission in semiconductor microcavities.

We consider the nonlinear terahertz emission by the system of cavity polaritons in the regime of polariton lasing. To account for the quantum nature of terahertz-polariton coupling, we use the Lindblad master equation approach and demonstrate that quantum microcavities reveal a rich variety of nonlinear phenomena in the terahertz range, including bistability, short terahertz pulse generation, and terahertz switching.

Terahertz generation by GaAs nanowires

The investigation of terahertz generation by the surface of n-InAs layers and by GaAs nanowires grown on n-GaAs (111) substrates is presented. It was observed that the terahertz radiation power efficiency is significantly higher in the second case.