Novel Nanoscale Single-Metal Polarization-Sensitive Infrared Detectors

We report a vastly simplified approach to infrared (IR) detection based on a single-metal nanostructure. This integrated structure contains a dipole antenna and a thermocouple (TC). The antenna provides wavelength selectivity, and the TC provides the conversion from optical to electrical signals. Moreover, the same nanowire structure serves both as the receiving element (antenna) and as the rectifying element (TC), yielding a highly integrated detector system. This study exploits a newly discovered thermoelectric effect in single-metal nanostructures with cross-sectional discontinuities to affect the TC functionality. In order to optimize the IR response, devices with various antenna lengths are simulated and fabricated. Both simulations and experiments demonstrate that the locations of the hot and cold TC junctions reverse as the polarization of the incident IR radiation changes, which results in reversal of the output signal polarity. The fabrication complexity of these single-metal devices is greatly reduced compared to that of other IR detector approaches, and their unique polarization-dependent response makes them attractive for new classes of IR systems.