Terahertz-to-Optical Carrier Conversion Using Optical-Comb-Injection-Locked Dual-Wavelength Laser Light and Electro-Optic Polymer Modulator

Prior to the use of microcomb, we used an electro-optic modulator optical comb (EOM comb, $f_{rep}=10\ \text{GHz}$ ). A pair of high-power CW lasers (wavelength $\sim 1550\ \text{nm}$ ) was injection-locked to two EOM-comb modes with a frequency separation of $10f_{rep}$ , and then propagated through the optical waveguide of EOP modulator. RF beat signals of unmodulated optical carriers and modulated sidebands were detected when THz waves (frequency = 101 GHz) were irradiated to the EOP device. As the frequency difference between $10f_{rep}$ and $f_{THz}$ was 1 GHz, the RF beat signal between them was observed around 1 GHz, as shown in Fig. 2.