Graphene-channel FETs for photonic frequency double-mixing conversion over the sub-THz band

We report on photonic frequency double-mixing conversion utilizing a graphene-channel FET (G-FET). Optoelectronic properties of graphene are exploited to perform single-chip photonic double-mixing functionality, which is greatly advantageous in future broadband technological conversion between optical fiber and sub-terahertz wireless communications. A 1-GHz modulation signal on a 125-GHz carrier is electrically input to the gate, whereas a 1.58-μm dual wavelength CW laser beam having a frequency difference of 112.5 GHz impinges on the G-FET. The G-FET works as a photomixer generating a 112.5-GHz local signal which is then electrically mixed to the 1-GHz modulated 125-GHz carrier signal, resulting in the down-conversion of the 1-GHz signal to a 12.5-GHz intermediate frequency (IF) signal.