A reconfigurable optoelectronic oscillator based on cascaded coherence-controllable recirculating delay lines

Abstract

A novel optoelectronic oscillator (OEO) using cascaded recirculating delay lines (RDLs) is proposed and experimentally demonstrated. In the proposed OEO, instead of the use of an electronic microwave ðlter, two infinite impulse response (IIR) photonic microwave ðlters (PMFs) formed by two RDLs are employed to select oscillation frequencies. Specifically, an amplified spontaneous emission (ASE) source is adopted to avoid self-interference of each RDL, and two approximately equal gain RDLs are employed to reduce the influence of mutual interference between the two RDLs. Therefore, a stable microwave signal can be generated from the OEO loop. In the experiment, by tuning the lengths of RDLs, microwave signals at different frequencies, such as 194.1MHz, 648.5MHz and 2.99GHz, have been generated. The phase noise performance of the generated microwave signal is also investigated. The proposed approach has the potential for the generation of microwave signals up to tens of GHz with the use of integrated micro-ring devices.