Hybrid fiber links for accurate optical frequency comparison

• Published in: Applied physics. B, Lasers and optics Lasers and optics, 2017-05, Vol.123 (5), p.1-11, Article 161
• Main Authors: Lee, Won-Kyu, Stefani, Fabio, Bercy, Anthony, Lopez, Olivier, Amy-Klein, Anne, Pottie, Paul-Eric
• Format: Article
• Language: English
• Subjects: Applied physics; Astrophysics; Engineering; Engineering Sciences; Frequency stability; Interferometers; Lasers; Optical Devices; Optical frequency; Optics; Photonics; Physical Chemistry; Physics; Physics and Astronomy; Quantum Optics; Signal and Image processing; Synchronism
• ISSN: 0946-2171; 1432-0649
• DOI: 10.1007/s00340-017-6736-5

We present the experimental demonstration of a local two-way optical frequency comparison over a 43-km-long urban fiber network without any requirement for measurement synchronization. We combined the local two-way scheme with a regular active noise compensation scheme that was implemented on another parallel fiber leading to a highly reliable and robust frequency transfer. This hybrid scheme allowed us to investigate the major limiting factors of the local two-way comparison. We analyzed the contributions of the interferometers at both local and remote locations to the phase noise of the local two-way signal. Using the ability of this setup to be injected by either a single laser or two independent lasers, we measured the contributions of the demodulated laser instabilities to the long-term instability. We show that a fractional frequency instability level of 10 −20 at 10,000 s can be obtained using this simple setup after propagation over a distance of 43 km in an urban area.