Controllable Fabrication of ZnO Microspheres for Whispering Gallery Mode Microcavity

Abstract

Whispering gallery mode (WGM) microcavity made of ZnO microspheres is an ideal platform for photonic integration and optical biological detection. However, the fabrication and the formation mechanism of ZnO microspheres is still challenging. In this paper, we present a controllable fabrication strategy to obtain zinc oxide (ZnO) microspheres with smooth surface, good crystallinity, and excellent optical properties for improved WGM lasing performance by taking advantage of the cooperative process between reactants, annealing, and metal nanoparticles decoration. The synergic effect between the hexamethylenetetramine (C6H12N4) and citrate was experimentally observed on the formation of ZnO microspheres. Their crystallinity and surface flatness can be improved by gradually decreasing the heating rate. Due to the electron transfer process in the metal/semiconductor hybrid structure assisted by the localized surface plasmon resonance, Au NPs can match well with the photon energy of the defect emission of ZnO microsphere and induced a 1 order of magnitude increase in lasing intensity compared to the bare one. Our results hold promise for the application of ZnO microspheres in the construction of UV laser and WGM sensing technology.

An All‐Inorganic Perovskite‐Phase Rubidium Lead Bromide Nanolaser

“…As pherical microcavity shows perfect successive total internal reflection and ensures lower optical losses compared with other types of microcavity,such as squares,h exagonals,o r other shapes. [41][42][43][44][45][46][47] That is why most spherical microcavities have excellent lasing performance.T he band gap of APbX 3 perovskites is mainly dependent on the [PbX 6 ] 4+ octahedral unit, while the Ac ation influences the band structure by changing the bonding properties between the Pb and Xa toms of the octahedra. [21,22] Rb x Cs 1Àx PbBr 3 microspheres also can be obtained through ac hemical vapor deposition process.F igure 5c depicts the PL images and spectra of as-prepared samples.U niformly bright PL emission can be observed from these PL images.T he PL emission peak was red-shifted from 464 to 529 nm as the ratio of Cs + was increased.…”

“…Detailed information about single‐mode lasing at 471.2 nm can be found in the Supporting Information, Figure S3. The wavelength of lasing in a spherical resonator has been theoretically and experimentally demonstrated as: …”

“…The simulated electrical field distributions of other perovskite RbPbBr 3 microspheres can be found in the Supporting Information, Figure S4. A spherical microcavity shows perfect successive total internal reflection and ensures lower optical losses compared with other types of microcavity, such as squares, hexagonals, or other shapes . That is why most spherical microcavities have excellent lasing performance.…”

Role of urea on the structural, textural, and optical properties of macroemulsion-assisted synthesized holey ZnO nanosheets for photocatalytic applications

“…20 However, reproducible and flexible processes to produce high-quality ZnO nanostructures with tailored structures, such as sizes, exposed crystal facets, and porosity, are necessary to advance the development of ZnO-based devices. 21 To date, ZnO nanomaterials with a wide variety of morphologies have been designed and synthesized, including 1-D nanowire arrays, 22 nanotubes, 23 nanorods, 24 2-D nanosheets, 25,26 3-D hierarchical tetrapod-like structures, 27 nanoflowers, 28 microspheres, 29 and sea-urchin morphology. 30 The interest in fabricating ZnO nanostructures with different morphologies stems from the highly anisotropic growth of wurtzite ZnO crystals.…”

Light-Trapping Engineering for the Enhancements of Broadband and Spectra-Selective Photodetection by Self-Assembled Dielectric Microcavity Arrays

“…The main principle is that the whispering-gallery-mode (WGM) resonances in the sphere can enhance the light-matter interactions in the cavity [16,19,23] or couple the light into the under-layer substrate through the waveguide mode [17,20]. Consequently, improved photoelectric conversion efficiency or photo-response can be realized in the corresponding optoelectronic devices [24,25]. This concept of light trapping in thin-film solar cells by utilizing wavelength-scale resonant dielectric nanospheres was proposed by Grandidier et al with the aims to enhance the light absorption in the active layer and further photocurrent in the device [15].…”