Cascaded multiplexed optical link on a telecommunication network for frequency dissemination

Area of Science:

• Physics
• Optical Engineering
• Telecommunications

Background:

• Ultra-stable frequency dissemination is crucial for advanced scientific research and metrology.
• Existing methods often face limitations in distance and integration with existing communication infrastructure.
• The need for robust, long-distance optical clock signal distribution is growing.

Purpose of the Study:

• To demonstrate a cascaded optical link for ultrastable frequency dissemination.
• To integrate this link within existing telecommunication networks carrying data traffic.
• To achieve high fractional frequency instability over long distances.

Main Methods:

• A cascaded optical link comprising two 150 km compensated links and a repeater station was constructed.
• Each link utilized 114 km of internet fiber with dense wavelength division multiplexing (DWDM) for simultaneous data traffic.
• Bidirectional optical add-drop multiplexers were used for signal insertion/extraction, and the repeater station provided autonomous noise compensation and signal regeneration.

Main Results:

• The compensated link achieved a fractional frequency instability of 3 x 10(-15) at 1 second.
• Long-term measurements showed a fractional frequency instability of 5 x 10(-20) at 20 hours.
• The system successfully operated within a live telecommunication network.

Conclusions:

• The demonstrated cascaded optical link enables robust, ultrastable frequency dissemination over long distances.
• Integration with existing internet fiber infrastructure is feasible using DWDM and specialized multiplexers.
• This technology paves the way for widespread dissemination of ultra-stable optical clock signals between laboratories.