Integration of vibration sensing in time and transfer infrastructure

The dissemination of precise time and coherent optical frequency over dedicated fibers or "dark" channels within Dense Wavelength Division Multiplexing (DWDM) networks is crucial for advanced scientific research, geophysical monitoring, and emerging industrial applications. By leveraging actively stabilized phase-coherent optical frequency transfer technique, we maintain ultra-low timing jitter and frequency stability over long-haul fiber links without disrupting of data channels. This contribution explores utilization of a shared dark spectrum within existing DWDM infrastructure to enable high-precision time transfer and stable optical frequency dissemination while simultaneously facilitating distributed vibration sensing. Furthermore, the integration of distributed fiber sensing within the same spectral allocation enables real-time detection of environmental disturbances such as seismic events and structural vibrations. Experimental results demonstrate the feasibility of this dual-purpose approach, showcasing its potential for enhancing geophysical monitoring, smart infrastructure, and next-generation metrology applications while optimizing the use of existing telecom networks.