Miniature oscillators based on optical whispering gallery mode resonators

We discuss two approaches for producing spectrally pure high frequency microwave signals using miniature photonic devices. One way is based on the hyper parametric oscillations in a solid state optical resonator possessing a cubic optical nonlinearity; the other - on the microresonator based opto-electronic oscillator.We show that the optically pumped nonlinear resonator produces optical sidebands result in generation of high frequency spectrally pure microwaves when demodulated on a fast photodiode. We also show that an opto-electronic oscillator containing a narrowband whispering gallery mode electro-optical modulator possesses low phase noise even if the optical loop of the oscillator does not contain an optical fiber delay line. We demonstrate K_a band oscillator experimentally.