RESUMO
Mie-resonant dielectric metasurfaces are excellent candidates for both fundamental studies related to light-matter interactions and for numerous applications ranging from holography to sensing to nonlinear optics. To date, however, most applications using Mie metasurfaces utilize only weak light-matter interaction. Here, we go beyond the weak coupling regime and demonstrate for the first time strong polaritonic coupling between Mie photonic modes and intersubband (ISB) transitions in semiconductor heterostructures. Furthermore, along with demonstrating ISB polaritons with Rabi splitting as large as 10%, we also demonstrate the ability to tailor the strength of strong coupling by engineering either the semiconductor heterostructure or the photonic mode of the resonators. Unlike previous plasmonic-based works, our new all-dielectric metasurface approach to generate ISB polaritons is free from ohmic losses and has high optical damage thresholds, thereby making it ideal for creating novel and compact mid-infrared light sources based on nonlinear optics.
RESUMO
We apply the Pancharatnam-Berry phase approach to plasmonic metasurfaces loaded by highly nonlinear multiquantum-well substrates, establishing a platform to control the nonlinear wave front at will based on giant localized nonlinear effects. We apply this approach to design flat nonlinear metasurfaces for efficient second-harmonic radiation, including beam steering, focusing, and polarization manipulation. Our findings open a new direction for nonlinear optics, in which phase matching issues are relaxed, and an unprecedented level of local wave front control is achieved over thin devices with giant nonlinear responses.
RESUMO
The Si-compatibility of perovskite heterostructures offers the intriguing possibility of producing oxide-based quantum well (QW) optoelectronic devices for use in Si photonics. While the SrTiO3/LaAlO3 (STO/LAO) system has been studied extensively in the hopes of using the interfacial two-dimensional electron gas in Si-integrated electronics, the potential to exploit its giant 2.4 eV conduction band offset in oxide-based QW optoelectronic devices has so far been largely ignored. Here, we demonstrate room-temperature intersubband absorption in STO/LAO QW heterostructures at energies on the order of hundreds of meV, including at energies approaching the critically important telecom wavelength of 1.55 µm. We demonstrate the ability to control the absorption energy by changing the width of the STO well layers by a single unit cell and present theory showing good agreement with experiment. A detailed structural and chemical analysis of the samples via scanning transmission electron microscopy and electron energy loss spectroscopy is presented. This work represents an important proof-of-concept for the use of transition metal oxide QWs in Si-compatible optoelectronic devices.