Frequency-Tripling OEO based on Frequency Multiplication in Saturated Low Phase Noise Amplifier

A Frequency-Tripling optoelectronic oscillator (FT-OEO) based on frequency multiplication in saturated low phase noise amplifier (LPNA) has been proposed and demonstrated. In the FT-OEO, the LPNA works in the saturated region and generates significant harmonic signals. The harmonic signals are coupled out from the loop and filtered as the output of the FT-OEO. A prototype of the FT-OEO, which oscillated at 2GHz, was constructed and the frequency-tripling signal at 6GHz was generated as the desired output. Comparison of the measured phase noise power spectrum density (PSD) of the fundamental signal with the frequency-tripling signal indicated that the additive phase noise of the amplifier is insignificant. Utilizing the saturated LPNA driven by the in-loop high-power oscillating signal, this FT-OEO provides a simple and cost-efficient scheme for frequency tripling.