Fig. 1. Electro-optical modulator is a pivotal hub for converting electrical signals to optical signals

Fig. 2. Host polymer Poly (NDI) and guest chromophores C1 & C2

Fig. 3. Structures of HPB2 and DFTC-1. (a) Formation of HPB2 by hydrogen bonding between PMMA-co-PHPM and P4VP; (b) DFTC-1

Fig. 4. Structure of main-chain electro-optical polymer based on polyimide

Fig. 5. Y-shaped polycarbonate electro-optical polymers

Fig. 6. Different side-chain electro-optical polymers and chromophores

Fig. 7. Synthesis of GL-S-1

Fig. 8. Electro-optical polymers. (a) Side-chain type electro-optical polymer; (b) side-chain type electro-optical polymer with optimized structure

Fig. 9. Anthracene-modified acrylic esters undergo cross-linking via Diels-Alder addition reaction

Fig. 10. Polymer AJP12 cross-linked with chromophores EOD1 and EOD2 via Huisgen cycloaddition

Fig. 11. Polymer cross-linking reaction involving hydroxyl groups and isocyanates

Fig. 12. Electro-optical modulators with electro-optical polymer as the waveguide core^[41]. (a) Structure schematic; (b) tested bandwidth

Fig. 13. MZI modulators. (a) Sol-gel SiO₂ combined with electro-optical polymer for electro-optical modulator and its driving voltage testing^[42]; (b) optical waveguide cross-section combining titanium dioxide with electro-optical polymer, and the relationship between the thickness variation of titanium dioxide slab layer and optical waveguide loss or electro-optical overlap^[43]

Fig. 14. Ultra-compact electro-optical modulator. (a) Silicon slot structure and 112 Gb/s eye diagram^[44]; (b) Plasmonic structure and bandwidth testing results^[45]

Fig. 15. Electro-optical modulator with high thermal-stability^[33]. (a) Physical image of the electro-optical modulator with high thermal-stability and its modulation parameters at different temperatures; (b) vertical electrode structure of the electro-optical modulator with high thermal-stability and its bit error rate at different temperatures

Fig. 16. Micro-ring modulators. (a) Local top view of silicon slot and electro-optical polymer hybrid micro-ring modulator and its electro-optical response at 6 MHz^[46]; (b) cross-sectional view of silicon strip waveguide and electro-optical polymer hybrid waveguide micro-ring modulator and its spectral changes with voltage^[47]

Fig. 17. Micro-ring modulators. (a) Silicon slot combined with electro-optical polymer for micro-ring modulator and its spectral shifts at different voltages^[48]; (b) etching-free ring micro-ring modulator schematic and its bandwidth testing results^[49]

Fig. 18. High-performance modulator with heterogeneous integration of electro-optical polymers on SiN^[52]

Table 1. Basic parameters of electro-optical materials

Table 2. Electro-optical polymer modulators