Berlin 2018 – wissenschaftliches Programm
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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 5: Whispering Gallery Mode Resonators II
KFM 5.3: Vortrag
Montag, 12. März 2018, 15:50–16:10, EMH 025
High-Q Integrated lithium niobate thin film Whispering Gallery Resonators for Frequency Conversion — •Richard Wolf1, Ingo Breunig1,2, and Karsten Buse1,2 — 1Department of Microsystems Engineering - IMTEK, University of Freiburg, 79110 Freiburg, Germany — 2Fraunhofer Institute for Physical Measurement Techniques, 79110 Freiburg, Germany
For realizing non-linear optical frequency converters, lithium niobate whispering-gallery-resonators (WGRs) are most promising due to their high field enhancement by small mode volumes and high Q-factors. Thus, with bulk-WGRs in millimeter size, e.g. optical parametrical oscillation with µW-threshold and conversion efficiencies could be demonstrated. However, WGRs are still rare in commercial products due to the serial and thus expensive fabrication like diamond-blade-cutting with subsequent mechanical polishing. Therefore, integrating WGRs on chip by parallel MEMS fabrication techniques becomes a substantive topic. Compared to bulk WGRs also a 1000 times smaller mode volume can be achieved, especially by using lithium niobate thin film substrates ridge-waveguide WGRs with high refractive index contrast and thus strong light confinement. We report on integrated WGRs based on lithium niobate thin films, made by parallel and thus scalable MEMS fabrication techniques. By using a coupling scheme with tunable coupling efficiency we could couple more than 95 % of pump light into our resonators and achieved intrinsic Q-factors higher than 106. We studied non-linear optical effects like second harmonic generation, sum frequency generation and stimulated Raman scattering.