The Temporal Drift Due to Polarization Noise in a Photonic Phase Reference Distribution System

Abstract

 Abstract-The temporal drift due to the polarization noise in an ultra-low temporal drift photonic phase reference distribution system is analyzed. The temporal drift is shown to be associated with the polarization changes, the differential group delay of the subsequent parts, and, the state of polarization dispersion of the photonic local oscillator signal. Such temporal drift cannot be corrected by Line Length Correction schemes. As an example, polarization changes from a fiber stretcher are presented, discussed, and identified as one of the major contributors to the system temporal drift. A numerical model is developed. The magnitude and statistical distribution (based on random coupling) of the temporal drift excited by the polarization change of the fiber stretcher are investigated. Experimental work demonstrates that reduction in the polarization change successfully reduces the temporal drift, as predicted by the theory and simulation.

Atacama Large Millimeter Array photonic local oscillator: femtosecond-level synchronization for radio astronomy

“…This is below the ALMA specification which requires phase drift to be below 18 fsec at 300 second interval. Secondary effects like polarization mode noise induced by fiber polarization mode dispersion (PMD), and polarization-to-phase conversion in the fiber stretchers, have been minimized by use of best available fiber and good installation methods, and by careful design of the line length correctors [5]. The uncorrected phase shown in the plot was not measured directly, but rather calculated by measurement of the stretcher displacements that took place during the measurement interval.…”

Photonic radio-frequency dissemination via optical fiber with high-phase stability

“…Astrophysics could also benefit from such frequency transfer development especially in very long baseline interferometers [5] and deep space network [6,7]. However, the transmission delay would change randomly because of mechanical stress and temperature variations on the fiber links which severely degrade phase stability of remote signal.So far various RF remote distribution systems, by either direct or indirect phase compensation schemes, have been proposed [8][9][10][11][12][13][14][15][16], which measures the roundtrip phase and then employs feedback loop to cancel the phase fluctuation. In direct compensation scheme, the optical delay line, which composes of a piezo-electric fiber stretcher and a temperature-controlled fiber spool, has been widely adopted to cancel the fluctuation [8-10].…”

“…However, its small compensation range and slow response limit the system's loop bandwidth and application in remote distribution system, despite its ability to achieve high-phase-drift suppression ratio and highfrequency reference distribution. Furthermore, it will induce an additional polarization mode dispersion [11] and amplitude noise. Therefore, to reach infinite compensation range and faster frequency response, voltagecontrolled oscillators (VCOs) [12][13][14][15][16] are adopted to implement the phase correction.…”

“…So far various RF remote distribution systems, by either direct or indirect phase compensation schemes, have been proposed [8][9][10][11][12][13][14][15][16], which measures the roundtrip phase and then employs feedback loop to cancel the phase fluctuation. In direct compensation scheme, the optical delay line, which composes of a piezo-electric fiber stretcher and a temperature-controlled fiber spool, has been widely adopted to cancel the fluctuation [8][9][10].…”

“…Due to the noise of the source signals and electronic components, and PMD, the frequency instability of phase locked 100-km system slightly exceeds that of 1-m system. The bump between the 100-1000 s is probably due to the PMD [9,11]. For time scale above 1000 s, the frequency stability is mainly restricted by the electronic components temperature sensitivity in the phase compensation feedback network.…”