Optoelectronic Microwave Oscillator. Advantages and Disadvantages. Noise Sources in an OEO

The results of the experimental study and analysis of the prototype of an optoelectronic (OE) microwave oscillator based on a fiber optic delay-line (DL) are presented. The advantages of the OE oscillator are indicated: low level of phase noise, relatively high frequency stability. The following disadvantages are indicated: complexity of the design, ambiguity of the generation frequency, high level of discrete components in the spectrum of the output oscillation, high level of amplitude noise. The main sources of noise and the possibility of reducing the level of phase noise without lengthening the fiber optic link were quantitatively determined.In the prototype of OE microwave oscillator based on a 2 km long DL a phase noise spectral density of -130 dBc/Hz was obtained at 10 kHz offset at a frequency of 6.69 GHz. The phase noise level can be reduced by another 20…30 dB by selecting the generator components and not by lengthening the fiber optic delay line.