Detection and Sensing Using Coupled Oscillatory Systems at the Synchronization Edge

We theoretically investigate the sensitivity of the beat frequency in a coupled oscillatory system comprising two originally synchronized similar or dissimilar oscillators up on weak perturbation of the frequency of one of the oscillators. Based on the well-known Kuramoto model, we analytically show that the variation of the beat frequency near the synchronization edge of two coupled oscillators induced by external perturbation of one of the oscillators, is much larger than the frequency shift of an isolated oscillator induced by the same level of perturbation. The theoretical predications are validated by experimental measurements of the response of two different coupled oscillatory systems to external perturbation: 1) Two bidirectionally coupled electronic Colpitts oscillators, when a photo induced current is applied to one of them. 2) An electronic oscillator unidirectionally coupled to an optoelectronic oscillator (OEO), when the temperature of the delay line of the OEO is changed.