We propose a mid-infrared device based on thermocouple optical antennas for light sensing and energy harvesting applications. We numerically demonstrate that antennas are able to generate low-power dc signals by beneficing of the thermoelectric properties of the metals that constitute them. We theoretically evaluate the optical-to-electrical conversion efficiency for harvesting applications and finally discuss strategies to increase its performance. Thermocouple optical antennas therefore open the route toward the design of photovoltaic devices.

Arrays of metallic thermocouples in the shape of spiral nanoantennas are proposed as infrared detectors, which use the thermoelectric properties of the metallic interfaces to generate electrical DC signals. The responsivity of these types of antennas is evaluated from both theoretical and numerical perspectives pointing out its potential as infrared sensors. Moreover, the same structures can be used to characterize the state of polarization of the optical near fields with a spatial resolution comparable to the wavelength.

Optical interference fringe measurements of the thickness of weakly absorbing media can be rapid, accurate, and nondestructive. When the refractive indexn of the sample is known, it will give us the layer thickness d. If, however, n is unknown, at least two independent spectrophotometric measurements are needed to obtain both n and d. A statistically based scheme is proposed to analyze the interference pattern in order to determine the refractive index and the thickness of the sample. The absolute interference order is also determined with the proposed technique. The major approximation inherent in the method is that the layer must be weakly absorbing and nondispersive over the wavelength region of interest. The method is applied to determine the optical constants of a uniaxial medium with the optical axis parallel to the faces.