Fig. 1. Characteristics and main contents of on-chip integrated multi-dimensional optical interconnects and optical processing

Fig. 2. On-chip data transmission of multi-dimensional optical signals based on different types of integrated optical waveguides. (a) Strip waveguide microring resonator^[21]; (b) slot waveguide^[22]; (c) hybrid surface plasmon polariton (SPP) slot waveguide^[23]; (d) sub-wavelength grating (SWG) waveguide^[24]

Fig. 3. On-chip multi-dimensional multiplexing interconnects of optical signals. (a) Polarization-mode hybrid multiplexing^[40,32]; (b) polarization-wavelength hybrid multiplexing^[41]; (c) mode-wavelength hybrid multiplexing^[44]; (d)(e) wavelength-polarization-mode hybrid multiplexing^[45-46]

Fig. 4. Key integrated devices of optical interconnects. (a) VCSEL array^[47]; (b) high-speed direct modulation integrated vector laser^[48]; (c) thin-film lithium niobate modulator^[49]; (d) plasmonic modulator^[50]; (e) Si-Ge avalanche photodetector (APD)^[51]; (f) graphene photodetector^[52]

Fig. 5. Optical coupling interfaces based on vertical coupling. (a) Vertically coupled diffractive grating structure^[53]; (b) vertical coupling based on angle polished fiber^[54]; (c) vertical coupling based on micro-nano optical components^[55]

Fig. 6. Optical coupling interfaces based on end coupling. (a) End coupling structure^[56]; (b) end coupling based on integrated polymer waveguide^[57]; (c) end coupling based on in situ 3D nano-printed optical elements^[58]

Fig. 7. Photonic wire bonding (PWB) technology. (a) Photonic multi-chip system based on PWB technology^[59]; (b) connection between vertical emitting laser and end-coupling waveguide based on PWB technology^[60]

Fig. 8. On-chip photonic integrated circuits and optical modules for optical interconnects. (a) Hybrid integrated silicon photonic ransmitter^[65]; (b) fully-integrated optical transceiver network^[66]; (c) coherent two-channel transceiver^[67]

Fig. 9. On-chip wavelength conversion. (a)(b) Wavelength conversion using a silicon waveguide^[71-72]; (c) wavelength conversion using a graphene-silicon microring resonator^[73]; (d) wavelength conversion and signal regeneration using a silicon waveguide^[75]

Fig. 10. On-chip optical frequency comb. (a) Optical frequency comb generation based on a microresonator^[83]; (b) coherent optical communications with optical frequency combs^[86]

Fig. 11. On-chip mode processing. (a) Mode spot converter^[92]; (b) mode exchanger^[93]; (c) multimode switch^[94]; (d) OAM mode generation chip^[95]

Fig. 12. On-chip polarization processing. (a) On-chip polarization analyzer^[100]; (b) on-chip polarization processor^[101]; (c) chiral silicon photonic circuits^[102]

Fig. 13. All-optical programmable logic array based on SOA^[108]. (a) Microscope image of the chip; (b) operation principle; (c) measured temporal waveforms

Fig. 14. All-optical logic gates based on PPLN^[109]. (a) Experimental setup and operation principle; (b) measured temporal waveforms

Fig. 15. All-optical 2×2-bit multiplier based on HNLF^[110]. (a) Operation principle; (b) measured temporal waveforms and eye diagrams

Fig. 16. M-ary optical computing based on silicon waveguides. (a) Quaternary optical computing^[111]; (b) hexadecimal optical computing^[112]

Fig. 17. On-chip reconfigurable and programmable optical signal processing. (a) Reconfigurable waveguide Bragg grating^[113]; (b) reconfigurable waveshaper^[114]; (c) programmable multi-task photonic signal processor^[115]

Fig. 18. On-chip intelligent optical signal processing. (a) Automatic unscrambling of arbitrarily mixed modes in a multimode waveguide^[116]; (b) self-configured reconfigurable silicon photonic signal processor^[117]; (c) all-optical neural network chip architecture^[119]; (d) parallel convolutional processing using an integrated photonic tensor core^[120]

Fig. 19. Future development trend of optical interconnection and optical processing

Fig. 20. Basic architecture of ultra-large capacity silicon-based on-chip multi-dimensional multiplexing and processing