We are pleased to invite you to share your latest research progress in this Special Issue organized by IEEE Photonics Journal (PJ). In this Special Issue, original research articles and reviews are welcome. Research areas may include (but not limited to) the following:O-ISAC based on optical fiber interferometerO-ISAC based on the scattering in the fiberO-ISAC based on power profile envelope analysisO-ISAC based on polarization analysis of the communication dataAdvanced digital signal processing (DSP) algorithms for O-ISAC, incorporating machine learning and artificial intelligenceNovel modulation and demodulation techniques for O-ISACHigh-performance optoelectronic devices and optical fibers tailored for O-ISACPerformance analysis and optimization of O-ISAC systemsInstrumentation development for O-ISACO-ISAC applications: results reporting and analysisOther related works