Fig. 1. (a) Schematic diagram of a conical dipole antenna. (b) S₁₁ response of the antenna array.

Fig. 2. (a) Schematic diagram of the electric field sensor structure. (b) Mode field distribution in the FDTD simulation MMI. (c) Mode field distribution in the waveguide in the modulation region.

Fig. 3. (a) Microscope image of antenna array. (b) Microscope image of the 1 × 2 MMI. (c) Microscope image of the SSC. (d) Microscope image of the cascade MMI.

Fig. 4. (a) Schematic diagram of the device optical loss test structure. (b) Cascade 1 × 2 MMI optical loss test. (c) Transmission spectrum of the device. (d) Bandwidth of the device.

Fig. 5. Measurement setup for the electric field above 2 GHz. HPA, high-power amplifier; MPM, microwave power meter; PD, photodetector; LNA, low noise amplifier.

Fig. 6. (a) Test Images of the 16-QAM signals. (b) Test Images of the 32-QAM signals. (c) Test Images of the 64-QAM signals. (d) Error vector magnitude (EVM) variation trend with carrier frequency and modulation rate.

Fig. 7. (a) Measurement setup for the phase-frequency response test. VNA, vector network analyzer. (b) Phase-frequency response of the device.