Femtosecond precision optical frequency and timing distribution for radio astronomy

Frequency and timing (F&T) distribution systems are the backbone of astronomical telescopes providing the required temporal resolution for challenging space missions. Currently, most telescope networks and arrays employ conventional distribution systems based on electronic detection and coaxial distribution which limits the long-term frequency stability to typically < 1 x10(-15) at 1000 s(1). Recently, optical F&T distribution systems have been developed and successfully implemented in large scale laser facilities providing residual femtosecond timing jitter and drift(2). In this paper, we review optical F&T distribution methods based on continuous wave (CW) and pulsed lasers and their feasibility for radio astronomy. We present experimental results on the F&T distribution performance of fiber links stabilized by both methods. Our CW link reaches 4.1 x 10(-17) at 1000 s for microwave transmission, whereas our pulsed link achieves 2.1 x 10(-17) at 1000 s for microwave transmission and 1.2 x 10(-18) at 1000 s for optical timing transmission. Finally, we conclude the paper with a trade-off analysis between these two methods.