Heat transfers in terahertz nanostructured membrane: from near-field imaging of electromagnetic mode to THz imagery

Imaging in the Terahertz (THz) is an active field of research that finds numerous applications such as non-destructive industrial testing, security or chemical identification. However, the high cost and low sensitivity of terahertz detectors constitute a serious obstacle for a wide range of applications. In this context, exalted thermal conversion in metasurfaces promises to be a cost effective alternative technique. In this talk, I will present nanostructured ultra-thin PET membranes that are designed to absorb the THz wave and effectively heat up thus emitting in the infrared.First, we image the heat transfers in the terahertz metasurface from the first time of heating up to the steady states and compare it to finite element modelling coupling electromagnetic and thermal physics. Interestingly, the THz metasurface is easily resolved through an infrared camera leading to the demonstration of far field acquired image of the near field modes of the metasurface. Then, we characterize the convection and conduction impact on the membrane efficiency and response time in order to design an optimized printed split-ring resonator based membrane for the imagery of a THz focused beam.