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Metamaterial metal-based bolometer. Scanning electron micrographs of one of the fabricated devices in different magnifications as indicated by the black scale bars. The active area including the connected resonant polarization-sensitive gold absorber elements is located on a 30 nm thin SiN membrane (black). The arrows on the right-hand side indicate the orientation of the linear eigen-polarizations used in the optical experiments in Fig. 2.
Optical and electrical characterization of the metamaterial bolometer. (a) Measured (solid curves) and calculated (dashed curves) extinction spectra for the two linear polarizations indicated by the blue and red arrows in Fig. 1. (b) Measured (dots) and calculated (dashed) bolometer responsivity for an rms current of 50 A. The calculated responsivity is obtained from the calculated absorbance spectra and the measured thermal conductance G. (c) The thermal conductance and the bolometer time constant are obtained from the depicted measured voltage at the third harmonic of the modulation frequency measured versus modulation frequency. The bolometer time constant of 134 results from the –3 dB decay (see left vertical logarithmic scale and dashed lines). (d) Corresponding measured phase.
Calculations on bolometer tunability. For reference, the highest frequency resonance corresponds to the parameters of Fig. 2. For the other three structures, all lateral dimensions are increased in steps of factors of two (see insets), while fixing the metal thickness, hence fixing the bolometer thermal mass. Importantly, the fundamental absorber resonances can be shifted towards significantly longer wavelengths, while maintaining the peak absorbance.
Envisioned bolometer array architecture allowing for integrated broadband spectroscopy and polarimetry without the need for any external dispersive element or any polarizer.
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