Effect of Optical Scattering on One-way RF Frequency Transfer Over Optical Fibers

J.P. Cahill, O. Okusaga, W. Zhou, C.R. Menyuk, G.M. Carter

Abstract:	Microwave frequency transfer over optical fibers is a promising technology due to the high bandwidth, low loss, low weight, and EMI immunity of optical fibers. Fiber-induced noise has led to challenges in implementation that are commonly resolved by using two-way signal propagation with active feedback. However, some applications require one-way frequency transfer without the use of active feedback. In this paper, we demonstrate that optical scattering can be the dominant source of fiber-induced noise and can be mitigated without active feedback. When light from a low noise laser propagates through kilometers of optical fiber, light scattering can increase the optical intensity noise by several orders of magnitude. In an RF-photonic link, this intensity noise can be converted to phase noise around the transmitted frequency. Consequently, the scattering-induced noise degrades the stability of the transferred signal. For example, we measured a 14 dB degradation of the Allan deviation after 10 km transmission. We previously showed that the scattering-induced intensity noise can be mitigated by dithering the laser current. We implemented this technique to reduce the scattering-induced frequency instability. We suppressed the Allan deviation that is induced by propagation through 10 km of fiber by 12 dB to within 2 dB of the back-to-back link.
Published in:	Proceedings of the 45th Annual Precise Time and Time Interval Systems and Applications Meeting December 2 - 5, 2013 Hyatt Regency Bellevue Bellevue, Washington
Pages:	217 - 223
Cite this article:	Cahill, J.P., Okusaga, O., Zhou, W., Menyuk, C.R., Carter, G.M., "Effect of Optical Scattering on One-way RF Frequency Transfer Over Optical Fibers," Proceedings of the 45th Annual Precise Time and Time Interval Systems and Applications Meeting, Bellevue, Washington, December 2013, pp. 217-223.
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