Phase Stable RF-over-fiber Transmission using Heterodyne Interferometry

Abstract

We demonstrate stable transmission of 3GHz over 300m of fiber with less than 0.017 degree (17fs) RMS phase error. An interferometer measures optical phase delay, providing information to a feed-forward correction of RF phase. ©2010 Optical Society of America OC1S codes: (060 5625) Radio frequency photonics, (060.2360) Fiber optic links and subsystems 1. Introduction New scientific applications require phase-stabilized RF distribution to multiple remote locations. These include phased-array radio telescopes [1] and short pulse free electron lasers [2]. RF modulated onto a CW optical carrier and transmitted via fiber is capable of low noise, but commercially available systems aren't long term stable enough for these applications. Typical requirements are for less than 50fs long term temporal stability between receivers, which is 0.05 degrees at 3GHz. Good results have been demonstrated for RF distribution schemes based on transmission of short pulses [3], but these require specialized free-space optics and high stability mechanical infrastructure. We report a method which uses only standard telecom optical and RF components, and achieves less than 20fs RMS error over 300m of standard single-mode fiber.