Metamaterial and metasurfaces
Metamaterial are man made materials made of sub-wavelength inclusions that can have extreme electromagnetic properties not found in nature.
Metal insulator metal resonant filters
We present a modal analysis of metal–insulator–metal (MIM)-based metamaterials in the far infrared region. These structures can be used as resonant reflection bandcut spectral filters that are independent of the polarization and direction of incidence. We show that this resonant reflection dip is due to the excitation of quasimodes (modes associated with a complex frequency) leading to quasi-total absorption. We have fabricated large area samples made of chromium nanorod gratings on top of Si/Cr layers deposited on silicon substrate. Measurements by Fourier transform spectrophotometry show good agreement with finite element simulations. A quasimodal expansion method is applied to obtain a minimal resonant model that fits well full wave simulations and that highlights excitation conditions of the modes.
- B. Vial, G. Demésy, F. Zolla, A. Nicolet, M. Commandré, C. Hecquet, T. Begou, S. Tisserand, S. Gautier, and V. Sauget, Resonant metamaterial absorbers for infrared spectral filtering: Quasimodal analysis, design, fabrication, and characterization. J. Opt. Soc. Am. B 31 (6):1339, (2014)
Anular appertures metasurfaces
The diffractive behavior of arrays of square coaxial apertures in a gold layer is studied. These structures exhibit a resonant transmission enhancement that is used to design tunable bandpass filters for multispectral imaging in the 7–13μm wavelength range. A modal analysis is used for this design and the study of their spectral features. Thus we show that the resonance peak is due to the excitation of leaky modes of the open photonic structure. Fourier transform infrared (FTIR) spectrophotometry transmission measurements of samples deposited on Si substrate show good agreement with numerical results and demonstrate angular tolerance of up to 30 degrees of the fabricated filters.
- B. Vial, M. Commandré, G. Demésy, A. Nicolet, F. Zolla, F. Bedu, H. Dallaporta, S. Tisserand, and L. Roux, Transmission enhancement through square coaxial aperture arrays in metallic film: When leaky modes filter infrared light for multispectral imaging. Opt. Lett. 39 (16):4723, (2014)
- M. Commandré, B. Vial, S. Tisserand, L. Roux, H. Dallaporta, F. Bedu, G. Demésy, A. Nicolet, and F. Zolla, Design, fabrication and characterization of resonant metamaterial filters for infrared multispectral imaging. Thin Solid Films, (2015)