Coupled Whispering Gallery Mode Resonators via Template‐Assisted Assembly of Photoluminescent Microspheres. (28th May 2019)

• Record Type: Journal Article
• Authors: Smith, Marcus J.; Zeng, Qingji; Lafalce, Evan; Yu, Shengtao; Zhang, Shuaidi; Vardeny, Zeev Valy; Tsukruk, Vladimir V.
• Is Part Of: Advanced functional materials. Volume 29:Number 30(2019)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-05-28
• Subjects: 3D lithography -- microresonator coupling -- photoluminescent microspheres -- templated assembly -- whispering gallery mode resonators; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.201902520
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: This study reports a facile method for the assembly of large, array style, coupled dye‐doped microsphere resonators by template‐assisted, in which an aqueous suspension of colloidal microspheres assemble on a patterned template. By exploiting the high resolution of 3D (two‐photon) lithography derived templates, closely packed large arrays, hundreds to thousands of dimers with controlled gap spacing, only limited by the size of the substrate can be achieved. Dye‐doped emissive microspheres with Q ‐factors >2.5 × 10 2 can be achieved and trapped into predetermined cavity positions, thereby controlling the distance between adjacent microspheres. This design allows to scale down dimer spacing from usual 400 nm for traditional photolithography to very small spacing of 50 nm. It is found that exciting individual microspheres in the ensemble shows intense optical cavity modes, whereas closely coupled pairs show controlled mode splitting. Coupling between photoluminescent microspheres is strongly influenced by the gap distance, with strong coupling, equating to normal mode splitting, arising as the gap distance is reduced below traditional sub‐micrometer scale. The coupled dimer assemblies are promising candidates for advancing the development of large‐area coupled nanophotonic structures, beyond the spatial resolution‐limited photolithographical derived arrays. Abstract : A facile method to assemble dye‐doped microspheres is reported, by taking advantage of template‐assisted directed assembly in which templates are fabricated via 3D (two‐photon) lithography, with 200 nm instrument resolution. The unique template design enables sub‐50 nm gap spacing between adjacent microspheres, enabling strong evanescent coupling following excitation.