63^rd ANNUAL CONFERENCE OF THE SA INSTITUTE OF PHYSICS

Temporal Effect on Optical Pulse-per-second Clock Stability

28 Jun 2018, 15:00

2h

Poster Presentation Track F - Applied Physics Poster Session 2

Speaker

Mr KAGISO J LEBURU (NELSON MANDELA UNIVERSITY)

Description

Telescope array networks rely on highly stable clock tones distributed over optical fibre to each antenna for driving the digitizers, data time stamping and other monitoring and control functions. However, optical clock tones suffer from time deviation from their true periodicity, known as jitter. Jitter is contributed by noise, thermal effects and aging of clocks. In the case of buried and aerial optical fibres, a complex interplay between numbers of factors adversely affects the stability in the light-wave clock tone as it propagates within an optical fibre, key among them being temporal effect. In this paper, we experimentally demonstrate temporal effect on pulse-per-second (PPS) clock stability. A PPS clock signal is transmitted over a 3.21 km of optical fibre at 5 °C. A jitter measurement of 50.55 ps is experimentally attained. However, as the fibre temperature is increased to 25 °C, a jitter stability of 59.13 ps is measured. This is due to the fact that a typical fibre has thermal coefficient of expansion of 7 ppm/°C. Temperature changes results in expansion and contraction of optical fibre, therefore altering the flight time and jitter of PPS signals. The mastery of these factors allows for jitter correction mechanisms to effectively compensate for the jittery in such systems.

Supervisor details<br><b>If not a student, type N/A.</b><br>Student abstract submision<br>requires supervisor permission:<br>please give their name,<br> institution and email address.

Prof Tim Gibbon, Nelson Mandela University, Tim.Gibbon@mandela.ac.za