0000000000740995
AUTHOR
Rocio Camacho-morales
Transient guided-mode resonance metasurfaces with phase-transition materials
We investigate transient, photo-thermally induced metasurface effects in a planar thin-film multilayer based on a phase-transition material. Illumination of a properly designed multilayer with two obliquely incident and phase-coherent pulsed pumps induces a transient and reversible temperature pattern in the phase-transition layer. The deep periodic modulation of the refractive index, caused by the interfering pumps, produces a transient Fano-like spectral feature associated with a guided-mode resonance. A coupled opto-thermal model is employed to analyze the temporal dynamics of the transient metasurface and to evaluate its speed and modulation capabilities. Using near-infrared pump pulses…
Fundamental limits for transmission modulation in VO2 metasurfaces
The interest in dynamic modulation of light by ultra-thin materials exhibiting insulator–metal phase transition, such as VO 2 , has rapidly grown due to the myriad industrial applications, including smart windows and optical limiters. However, for applications in the telecommunication spectral band, the light modulation through a thin VO 2 film is low due to the presence of strong material loss. Here, we demonstrate tailored nanostructuring of VO 2 to dramatically enhance its transmission modulation, reaching a value as high as 0.73, which is 2 times larger than the previous modulation achieved. The resulting designs, including free-topology optimization, demonstrate the fundamental limit i…
Opto-thermal dynamics of thin-film optical limiters based on the VO2 phase transition
Protection of human eyes or sensitive detectors from high-intensity laser radiation is an important challenge in modern light technologies. Metasurfaces have proved to be valuable tools for such light control, but the actual possibility of merging multiple materials in the nanofabrication process hinders their application. Here we propose and numerically investigate the opto-thermal properties of plane multilayered structures with phase-change materials for optical limiters. Our structure relies on thin-film VO2 phase change material on top of a gold film and a sapphire substrate. We show how such a multi-layer structure can act as a self-activating device that exploits light-to-heat conver…