Regensburg 2019 – wissenschaftliches Programm
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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 4: Focus: Whispering-Gallery-Mode Resonators
KFM 4.5: Vortrag
Montag, 1. April 2019, 11:00–11:20, H47
Dielectric tuning of millimeter-wave whispering-gallery modes for electro-optic phase matching — •Gabriel Santamaria Botello1, Kerlos Atia Abdalmalak1, Daniel Segovia Vargas1, Luis Enrique Garcia Muñoz1, and Zoya Popovic2 — 1Universidad Carlos III de Madrid — 2University of Colorado Boulder
It has been shown that highly efficient electro-optic modulators can be designed in millimeter-sized high-Q whispering-gallery (WG) disk resonators made of nonlinear crystals, where a resonant optical field mixes with the modulating microwave field to produce a resonant sideband. This is potentially useful for high-sensitivity millimeter-wave detection, optical comb generation and up-conversion of quantum states. The interaction takes place only when the optical and microwave modes are phase matched, implying that the angular velocity is matched in the case of fundamental WG modes. Due to the high optical Q, the phase-matching condition is sensitive to fabrication tolerances of the resonator requiring an accuracy within less than 10um in all dimensions. In past demonstrations, a time-consuming iterative polishing process was performed to adjust the radius in small steps. In this work, we show that the phase-matching point can be found by perturbing the microwave mode with low-loss dielectric layer loadings on one or both sides. Thus, millimeter-sized lithium niobate resonators can be fabricated with tolerances up to 20um in height and 100um in radius. The conversion efficiency is not appreciably affected with this approach since no significant degradation of the microwave Q and field distribution is observed.