Dmitriy Korobkin

Enhanced near-field resolution in midinfrared using metamaterials

We demonstrate that a negative-permittivity material (silicon carbide) sandwiched between two layers of positive-permittivity material (silicon oxide) can be used for enhancement of the resolution of near-field imaging via the superlensing effect. The resulting three-layer metamaterial is also shown to exhibit an enhanced transmission when its effective dielectric permittivity matches that of the vacuum. Experimental far-field diagnostics of the superlensing based on measuring transmission coefficients through the metal-coated superlens is implemented using Fourier-transformed infrared microscopy. Superlensing is shown to be a highly resonant phenomenon manifested in a narrow frequency range.

Critically coupled surface phonon-polariton excitation in silicon carbide.

We observe critical coupling to surface phonon-polaritons in silicon carbide by attenuated total reflection of mid-IR radiation. Reflectance measurements demonstrate critical coupling by a double scan of wavelength and incidence angle. Critical coupling occurs when prism coupling loss is equal to losses in silicon carbide and the substrate, resulting in maximal electric field enhancement.

Measurements of the negative refractive index of sub-diffraction waves propagating in an indefinite permittivity medium.

An indefinite permittivity medium (IPM) has been fabricated and optically characterized in mid-infrared spectral range (10.7 µm-11.3 µm). Phase and amplitude transmission measurements reveal two remarkable properties of IPMs: (i) transmission of sub-diffraction waves (as short as λ/4) can exceed those of diffraction-limited ones, and (ii) sub-diffraction waves can propagate with negative refractive index. We describe a novel double-detector optical technique relying on the interference between sub-diffraction and diffraction-limited waves for accurate measurement of the transmission amplitude and phase of the former.

Interferometric characterization of a sub-wavelength near-infrared negative index metamaterial.

Negative phase advance through a single layer of near-IR negative index metamaterial (NIM) is identified through interferometric measurements. The NIM unit cell, sub-wavelength in both the lateral and light propagation directions, is comprised of a pair of Au strips separated by two dielectric and one Au film. Numerical simulations show that the negative phase advance through the single-layer sample is consistent with the negative index exhibited by a bulk material comprised of multiple layers of the same structure. We also numerically demonstrate that the negative index band persists in the lossless limit.

Advanced TIL system for laser beam focusing in a turbulent regime

This paper discusses an advanced target in the loop (ATIL) system with its performance based on a nonlinear phase conjugation scheme that performs rapid adjustment of the laser beam wavefront to mitigate effects associated with atmospheric turbulence along the propagation path. The ATIL method allows positional control of the laser spot (the beacon) on a remote imaged-resolved target. The size of this beacon is governed by the reciprocity of two counterpropagating beams (one towards the target and another scattered by the target) and the fidelity of the phase conjugation scheme. In this presentation we will present the results of the thorough analysis of ATIL operation, factors that affect its performance, its focusing efficiency and the comparison of laboratory experimental validation and computer simulation results.

IR index sensing based on surface phonon-polaritons in SiC

We present results demonstrating the excitation of surface phonon-polaritons at the interface between SiC and different materials. The resonant nature of the excitation can be used to sense minute substance amounts or distinguish between substances.

Critical coupling to surface phonon-polaritons in SiC

We observe critically coupled surface phonon-polariton excitation in SiC, leading to maximum electric field enhancement. A double-scan of wavelength and incidence angle in the ATR configuration demonstrates critical coupling for two air gaps.

Critically coupled surface phonon-polariton excitation in silicon carbide

We observe critical coupling to surface phonon-polaritons in silicon carbide by attenuated total reflection of mid-infrared radiation. Reflectance measurements demonstrate critical coupling by a double-scan of wavelength and incidence angle. Critical coupling occurs when prism coupling loss is equal to losses in silicon carbide and the substrate, resulting in maximal electric field enhancement.

Phononic Nanophotonics: Super-Lensing in Mid-IR

We demonstrate that a layered structure of SiO2/SiC/SiO2 can act as a super-lens at mid-IR wavelength λ ∫ 11 µm due to the negative e of SiC caused by the optical phonon resonance.