Over the last two decades, a great deal of attention has been devoted to optical metamaterials providing new means for controlling wave propagation which are not achievable with conventional media [1–3]. A special class of uniaxially anisotropic metamaterials, called hyperbolic metamaterials (HMMs), have emerged as a particularly prospective media, due to their relatively high technological feasibility as well as wide applicability, including diffractionless lensing [4], biosensing [5–8], optical signal buffering/storing[9], efficient spectral and spatial filtering [11], as well as many others [12,13]. Our research is focused on further reduction of restrictions related to controlling electromagnetic response of metamaterials via two distinctively different mechanism, namely active tunability by means of external stimulus and controlled nonlocal response by means of appropriate geometry structurization.

Our key findings related to tunable HHM structures have shown that planar hyperbolic structures may be employed to act as a tunable edge- and narrowband filters of nanoscaled dimensions operating in mid-infrared spectral range, suitable for free space communications or thermal signatures detection. Moreover, we have demonstrated that unique properties of HMM structures may be also controlled and utilized in integrated waveguide systems, which allows to obtain full control of propagation properties in a single waveguide, including light stopping and power flow reversing, as well as fully tunable intermodal coupling in multi-waveguide systems. The scope of our research in the field of tunable active HMMs has also covered controlling gain and absorption in bulk HMM structures as well as lasing phenomena in DFB lasers based on hyperbolic media. In particular, we have demonstrated possibility of obtaining a single-frequency generation with high side-mode suppression and controllable wavelength of operation. Another area of our research is related to the role of spatial dispersion in shaping properties of planar hyperbolic metamaterials. According to our research, nonlocality (spatial dispersion) may serve as a new degree of freedom in controlling optical properties of HMM structures. Within our work we have demonstrated that structurization of a HMM’s unit cell may lead to strong nonlocal response, which may be employed to obtain a number of new optical effects, that are not possible when spatial dispersion is negligible, such as optical isolation, without use of external magnetic field and nonlinear effects, or orthogonally polarized beam generation at different frequencies in a single laser structure. The scope of our analysis has also included the role on nonlocality in shaping optical properties of optical filters, waveguides and lasers based on hyperbolic metamaterials. We believe that both presented our mechanisms paves strong foundations for hyperbolic media as photonic platform for versatile optical applications.

References:

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