Microwave signal generation based on the optoelectronic oscillator with a dual-long-loop configuration

Abstract

We propose a method of microwave signal generation based on the optoelectronic oscillator (OEO) with an ultra-compact dual-long-loop configuration. In this OEO structure, the delay time difference between two feedback loops is equal to the period of the generated microwave signal. By tuning the delay time difference, a single-tone microwave signal with a frequency tuning range from 20 to 40 GHz is achieved in the numerical calculation. The different oscillation modes have the same level in term of the single sideband (SSB) phase noise. The SSB phase noise is 149.9 dBc/Hz at the offset frequency of 10 kHz, when the fiber loop has a length of 1 km. The SSB phase noise can be further improved by increasing the length of the fiber loop. This proposed OEO features the inherent single-tone oscillation in the frequency tuning range and do not require any optical or electrical filter. Moreover, our OEO structure has a potential for the generation of microwave signal with higher frequency and the frequency tuning ability with a larger frequency range.