High frequency optical mixing in 50-nm gate HEMTs to 211 GHz

Optical-millimeter wave interactions in semiconductor devices have attracted much recent interest because of applications that can take advantage of both lightwave and millimeter wave techniques. Applications that can benefit from a merging of these areas include phased array radar, remote sensing, spectroscopy and communications. One technique, optical mixing, is a promising method to generate continuously tunable millimeter wave frequencies. The generated signals are of high quality in terms of stability, noise and spectral purity. In this paper, we report the extension of optical mixing techniques to difference frequencies of 211 GHz in 50-nm gate-length pseudomorphic HEMTs. To our knowledge, this is the highest frequency optical mixing to date for three terminal devices. Although two-terminal devices have been used almost exclusively in this role, three-terminal devices are becoming increasingly competitive because of their inherent gain. Moreover, the presence of a third terminal adds a degree of freedom in controlling the mixing process and allows for baseband information signals to be imposed on the optically generated carriers