Collective input impedance of micro-antenna based infrared detectors

In this article, the author leverages the concept of "input impedance" to determine in a proper manner the collective resonances of infrared devices based on square arrays of micro-dipoles, commonly obtained by the scattered field of devices under illumination. With the aid of finite-element simulations, the resistive and capacitive nature of the odd and even resonant modes of individual micro-dipoles is first unveiled. Subsequently, the micro-dipoles are incorporated into an array with lattice parameters (a_x, ay), and the dependence of the emerging collective odd and even resonant modes, on the transverse and longitudinal dipolar interaction, is evaluated. The opposite wavelength shift of these modes is unveiled and the physical mechanisms behind their behavior are discussed. By analyzing the absorbance spectra of the micro-antenna arrays, the equivalence of optical resonances counterpart, in the short and open-circuit configurations, with the odd and even modes is presented. Finally, the effect on the array's performance that results from introducing highly resistive nano-bolometers is optimized by exploiting the natural high-resistance of the collective even modes.