COEO phase locking and performance optimisation

In this paper, a coupled optoelectronic oscillator (COEO) is phase locked to a low noise RF oscillator in order to reduce the phase noise close to the carrier. Biasing current of the optical semiconductor amplifier (SOA) and a varactor diode in the RF part of the COEO are used as two different actuators to perform phase locking. The lock on the optical device is finally simpler and more efficient than the lock on the RF loop. In the second part of this paper, phase noise of the COEO is reduced by more than 15 dB using a chirped Bragg filter that compensates the dispersion of the optical loop.