Fine structure of second-harmonic resonances in ?⁽²⁾ optical microresonators

Owing to the discrete frequency spectrum of whispering gallery resonators (WGRs), resonance and phase-matching conditions for interacting waves in case second-harmonic generation (SHG) cannot generally be fulfilled simultaneously. To account this, we develop a model describing SHG WGRs with non-zero detunings at both pump frequencies. Our predicts strong distortions line shape resonances similar linewidths frequencies; much larger frequency, this behavior is absent. Furthermore, it describes efficiency as function detuning. Experimentally, one can change WGR eigenfrequencies, thus relative detuning between by number means, example electro-optically thermally. Using lithium niobate WGR, show an excellent quantitative agreement our experimental results model. Also, predicted absent but present cadmium silicon phosphide expected from involved.