Real-Time Integrated Photonic Dehopping of Terahertz Frequency-Hopping Signals Around the 300 GHz Band Using Electro-Optically Tunable Lasers

We propose and experimentally demonstrate an integrated photonic terahertz (THz) frequency-hopping (FH)/dehopping system using electro-optically wavelength-tunable lasers to enhance physical-layer security in terahertz wireless links. The FH THz signal is generated around the 300 GHz band by photomixing a fixed-wavelength laser and an electro-optically tunable laser, while a synchronized FH local oscillator (LO) signal is generated at the receiver for secure photonic dehopping. By utilizing a waveguide-integrated THz combiner and THz detector, the FH LO remains internally coupled and unexposed to potential eavesdroppers. A signal with a 40 GHz hopping span around the 300 GHz band and a 50 Mhops/s FH rate is dehopped to a 5 GHz intermediate frequency. This system simplifies the receiver complexity while enabling secure, high-speed physical-layer terahertz communications.