Terahertz band (0.1 THz to 10 THz) with high carrier frequency and large available bandwidth has become a promising candidate to meet the 100 Gbit/s or even 1 Tbit/s data rate required by the future six-generation (6G) mobile communication networks. Compared with the all-electrical methods to generate terahertz signals, the photon-assisted technology can break the bottleneck of the bandwidth limit of the electronics devices, and generate the terahertz signal with high frequency, large bandwidth, flexible tunability and easy integration with the large capacity fiber link. Based on the photon-assisted technology and various key techniques, devices and advanced digital signal processing algorithms, we have obtained many great achievements in different fields of broadband terahertz communication and sensing. In the field of large-capacity terahertz transmission, we realize the large system capacity of over 1 Tbit/s based on multidimensional multiplexing techniques, and the largest capacity can be up to 6.4 Tbit/s. In the field of long-distance terahertz transmission, we have designed a high-gain terahertz antenna module and realized 335 GHz THz wireless transmission of up to 400 m. In the field of real-time terahertz communication, we achieve a record-breaking 100, 2×100 GbE terahertz real-time communication system based on the commercial digital coherent optics module. In the field of integrated sensing and communication (ISAC), we generate the ISAC signal based on both time division multiplexing and frequency division multiplexing schemes, and realize the communication in the terahertz band and the high-precision sensing function at the same time. In the field of terahertz wired transmission, we realize the 1 m wired transmission of 300 GHz terahertz signal based on the Ag-coated metallic hollow core fiber, and the net system capacity is over 140 Gbit/s. In this paper, the experimental setups of the above systems have been demonstrated in detail and results have also been discussed.