Figure 3

Spectra of the generated microwaves from the OEO at different harmonic frequencies from 2 to 4 GHz.
By adjusting the centre frequency of the electronic filter group, a widely tunable free-running OEO range of 2 to 4 GHz is achieved with a fine frequency step of 144.5 MHz. The frequencies of the microwaves match the harmonics of the OFC.