Design And Optical Investigation On Fluorescent Small Molecule Materials Based WGM Microcavities

Whispering gallery mode(WGM)microcavities confine light within the micro/nano-scale cavity via multiple total internal reflection,greatly enhancing the interaction of light and matter.They have attracted wide attention in the field of lab-on-chip application,biological integrated systems,microsensors and related fields.Fluorescent small molecule materials have large absorption cross section or rich excited process to achieve high gain,high efficiency and rich color.Moreover,they usually have good compatibility with a variety of optical resonators and can be directly connected into the microcavities,which makes the microcavities based on gain materials of organic fluorescence small molecule show advantages containing convenient and low-cost preparation,wide tunable range and so on.Therefore,fluorescent organic small molecule materials are the ideal gain medium of organic microcavities.However,due to high packing between molecules,traditional organic small molecule fluorescent materials often suffer self-quenching effect at aggregated state,reducing the luminous efficiency and limiting further application.Therefore,developing WGM microcavities based on highly efficient luminescent materials becomes an important research topic.In our work,we prepared high quality WGM microcavities via liquid phase methods,and introduced aggregation induced emission(AIE)fluorophores as gain material to obtain low threshold organic microlasers.Furthermore,we experimentally explored the application of the organic microcavities and their core-shell structures in different fields.Our detailed research includes the following three parts:(1)Based on design principles of organic WGM microcavities,we set about selecting the host materials and gain materials for purpose.PMMA polymer with good transparency and low crystallinity are suitable for host materials,and BDTO based AIE small molecules are competent gain material.We compared different strategies to explore the best for the preparation of organic active WGM microcavity with high quality,so that active WGM microcavities with smooth surface and uniform gain medium were obtained by surface tension assisted self-assembly method,which provides significant experimental support for the realization of WGM microlasers.(2)Owing to the good flexibility and compatibility of polymer materials,we doped TCz PBDTO and TPA-BDTO into active WGM microcavities respectively,which fundamentally solves the problem of concentration quenching.At the same time,low threshold microlasers were output at 610 nm and 653 nm from TCz P-BDTO-PMMA and TPA-BDTO-PMMA microbottles,which lay foundation for further exploration in the application of organic WGM microlaser.(3)The mechanical properties and optical stability of TPA-BDTO-PMMA WGM microcavities are favorable for the application of the organic WGM microcavities in strain sensing.PMMA with low modulus of elasticity was used as the matrix material in the TPABDTO-PMMA microsensor,so that the sensitivity were improved up to 0.34 pm /??.As a sensing signal,low threshold microlaser also greatly improved the sensing resolution.In addition,due to the optical stability and micro-size of TPA-BDTO-PMMA microcavity,we designed the core-shell microcavities with the gain of TPA-BDTO and G-1 to achieve dualwavelength emission.Their emission change regularly with the change of excitation position,which is expected to be used in the precise counterpoint-detection of display devices,promoting the rapid development of the display industry.