Dispersion and lasing characteristics of cross-coupled resonances in composite-cavity microresonators

Abstract

We report on composite-cavity microresonators comprising a vertical cavity and a distributed feedback structure. First-order diffraction on the second-order Bragg grating serves as coupling mechanism between the two resonator elements. Employing the broad emission spectrum of the small molecule system ${\mathrm{Alq}}_{3}$:DCM, dispersion characteristics of multiple resonances are recorded in continuously tunable devices and related to calculated resonances and their field profiles. In combination with the analysis of input-output measurements, the lasing characteristics of vertical and lateral resonances are controlled by adjusting specific design parameters of the system. For identical resonance energies, the distinct resonators show coherent interaction in the cross-coupled configuration, if the quality of the resonances and the cross-coupling efficiency meet the condition of strong photon-photon interaction. This resonant coupling has a fundamental impact on dispersion and lasing characteristics of the system.