Fig. 1. D-PCA and MSPCA. (a) Micrograph of D-PCA. (b) Structure and parameters of SRRs. (c) Micrograph of MSPCA-A. (d) Micrograph of MSPCA-B.

Fig. 2. Optical propagation trajectory of THz time domain spectroscopy system.

Fig. 3. Pumping position of femtosecond laser at (a) MSPCA-A and (b) MSPCA-B.

Fig. 4. THz characteristics of femtosecond laser pumping on the D-PCA, MSPCA-A, and MSPCA-B. Comparison of (a) amplitude and normalized amplitude of THz time domain spectra, and (b) power and normalized power of THz frequency domain spectra.

Fig. 5. Comparison of the characteristics of the THz radiation for femtosecond laser pumping on the split positions of SRR of MSPCA and on the electrode edge of the D-PCA. (a) THz amplitude and normalized THz amplitude of MSPCA-A and D-PCA, (b) THz power and normalized THz power of MSPCA-A and D-PCA, (c) THz amplitude and normalized THz amplitude of MSPCA-B and D-PCA, and (d) THz power and normalized THz power of MSPCA-B and D-PCA.

Fig. 6. Comparison of THz time domain spectrum for femtosecond laser pumping at different positions. THz amplitude and normalized THz amplitude of (a) MSPCA-A when the pumping light is incident on −90 μm and −100 μm and (b) MSPCA-B when the pumping light is incident on −110 μm and −100 μm. Pattern of THz time domain spectral peak-to-peak value of (c) MSPCA-A and (d) MSPCA-B.

Fig. 7. Patterns at the maximum bias voltage when the femtosecond laser is pumped onto different positions of (a) MSPCA-A and (b) MSPCA-B. The electrostatic field of the (c) positive electrode and (d) negative electrode of the MSPCA.