Mixing of 28 THz (10.7 μm) CO2-laser radiation by nanometer thin-film NiNiONi diodes with difference frequencies up to 176 GHz

Difference frequencies up to 176 GHz between CO₂-laser transitions at 28 THz (10.7 μm) are generated by thin-film nanometer-scale Ni---NiO---Ni diodes (MOM, MIM) with integrated bow-tie antennas and rhodium waveguides. A signal-to-noise (S/N) ratio of 47 dB was measured for a 58.7 GHz difference frequency and a 100 kHz bandwidth, while a S/N ratio of 14 dB was observed for a 176.2 GHz difference frequency and a 300 kHz bandwidth. The frequencies reported are considerably higher than those reported previously for thin-film diodes. The comparison of the mixing signals for the antenna parallel and perpendicular to the E-polarization of the infrared radiation yields a ratio of over 34 dB. These results imply the extension of millimeter-wave techniques to the infrared.