On the stability & phase locking to a system reference of an optoelectronic oscillator with large delay

Abstract

<p>This paper reports the findings of a study of an optoelectronic oscillator (OEO) with large delay under proportional and proportional integral control by a phase-locked loop (PLL). The study is the first to fully account for the OEO delay in responding to a tuning stimulus including the location of all the countable infinity of poles of the system function.</p>

Simulation of optoelectronic oscillator injection locking, pulling & spiking phenomena

“…1). The low loss of optical fibre (~ 0.2 dB/km) permits delay line lengths of ~ 5 km offering, for example, OEO phase noise performance of -145 dBc/Hz at 10 kHz offset from a 10 GHz carrier 3 . However, the frequency interval between adjacent oscillation modes decreases in inverse proportion to the delay (40 kHz for 5 km), and a practical RF resonator cannot provide sufficient selectivity to suppress the multitude of sidemode resonances.…”

“…However, the frequency interval between adjacent oscillation modes decreases in inverse proportion to the delay (40 kHz for 5 km), and a practical RF resonator cannot provide sufficient selectivity to suppress the multitude of sidemode resonances. Multimode operation is an artefact of an OEO with profound consequences on its behaviour 3,4 .…”

“…Even when the initial condition corresponds to a single-mode oscillation state the presence of multiple attractors is manifest by any perturbation of a multimode oscillator including: fluctuations & noise, which excite sidemodes and give rise to spurious resonances in the phase noise spectrum; intra-loop phase modulation, especially at frequencies resonant with the intermodal frequency that gives rise to giant phase modulation, frequency combs & mode-locking; tuning scans and transients that, if rapid, excite sidemodes or, if slow, may cause mode-hops. In addition, giant phase modulation is a source of a modulational instability in a phase lock loop (PLL) controlled OEO 3 .…”