Integrated sensing and communication (ISAC) is a key pillar for future wireless networks, demanding solutions that simultaneously deliver high-capacity communication and high-accuracy sensing. The terahertz (THz) band, particularly when integrated with fiber-optic networks, emerges as a highly promising candidate, offering the potential for terabit-per-second communication data rates and millimeter-level sensing resolution. Crucially, the integrated waveform is paramount to efficiently and seamlessly combine these dual functionalities, enabling compact frontends design and streamlined baseband processing for photonic THz-ISAC systems. This article presents our recent system-level investigations into diverse integrated ISAC waveform designs. We further synthesize and discuss the latest global research and development progress in advancing this rapidly evolving field.