A Quality Factor Enhanced Dual-loop Optoelectronic Oscillator

A conventional dual-loop optoelectronic oscillator (OEO) usually employs a long and a short optical fiber loops. However, the equivalent quality factor (Q) of a dual-loop OEO actually acts as an average of the long-loop's high Q and the short loop's low Q. Then, the quality factor of a dual-loop OEO is somewhat affected by the short loop. In this paper, we propose an improved OEO that uses a long optical fiber as a common path to construct dual fiber loops. The measurement results show that the proposed OEO can generate a pure signal with phase noise of-82 dBc/Hz at 10-Hz offset. And, the structure is also helpful to suppress the spurious modes.