We present an experimental demonstration of high precision ranging measurement over coherent optical communication, where optical carrier phase was measurement on a high data rate (10 gigabit per second) coherent optical communication system. Results show that there is no ranging performance degrading caused by data modulation. At one second average time, an accuracy 60 nm for two-way range, and 60 nm/s for two-way range rate error were achieved. This approach improves optimetric measurement sensitivity by orders of magnitude from the current RF or RF over optical based optimetrics (10 μm range error, 10 μm/s ranging rate error). The system in the demonstration includes a master terminal and a slave terminal. The master terminal equipped with an ultra-low noise laser source which is acetylene absorption line locked at 1542nm for long term wavelength stability. The slave terminal equipped with a low-noise laser which is off-set frequency (10 MHz) phase locked to the master laser for coherent optical phase loopback. For the receivers, the commercial 100 gigabit per second coherent optical receivers were used. The measurement was conducted at the master terminal, where the optical phase of the slave laser was measured against the master laser to provide the two-way phase measurements. With such high accuracy ranging measurements in a high data rate communication system, it advances the state-of-the-art for the space coherent optical communication with added high precision ranging, hence it advances the capabilities for space communication and sciences. It also enables ultra-high precision ranging and high data rate communication services to be conducted on a single platform.
