Fig. 1. Schematic diagram of THz-TDS system

Fig. 2. 1×2 GaAs PCA. (a) PCAV; (b) PCAL; (c) physical diagram of 1×2 GaAs PCA; (d) schematic diagram of 1×2 GaAs PCA

Fig. 3. Amplitude of reference signals used in the experiment

Fig. 4. Schematic diagram of the photoconductive antenna circuit

Fig. 5. Correlation data of PCAV after series fixed resistor. (a) Comparison of the amplitude between the reference signal and the signal series fixed resistor; (b) polarization direction of the reference signal; (c) polarization direction of the signal series resistor of 15 kΩ; (d) polarization direction of the signal series resistor of 100 kΩ

Fig. 6. Experimental data of PCAV series sliding rheostat. (a) Amplitude of the signals when the sliding rheostat with different resistance value; (b) polarization direction of THz wave radiated by 1×2 GaAs PCA when the resistance of the sliding rheostat in series is the intermediate value; (c) polarization direction of THz wave radiated by 1×2 GaAs PCA when the resistance of the sliding rheostat in series is the maximum value