Whispering gallery modes in intrinsic TiO₂ microspheres coupling to the defect‐related photoluminescence after visible excitation

Abstract

Defect‐caused visible photoluminescence after visible excitation in anatase TiO2 microresonators couples to whispering gallery modes (WGMs). Spherical anatase TiO2 of a radius between 1.5 µm and 4 µm have been prepared by a sol–gel technique based on hydrolysis of titanium tetrabutoxide. The observation of WGMs in intrinsic anatase TiO2 without additional dopant offers new perspectives for the localisation of light at TiO2 surfaces for the design of photocatalysts. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)

Whispering Gallery Mode Devices for Sensing and Biosensing

“…Finally the intrinsic microsphere fluorescence can be exploited to achieve similar results. For example, zinc oxide [137] and titanium oxide [138] microspheres have been used for such purpose with a photoluminescence emission ranging from 550 to 750 nm.…”

“…However using smaller microspheres, especially in aqueous environments, for biosensing applications implies that the resonator's refractive index has to be large enough to achieve sufficient optical confinement. This typically requires the use of polymers such as polystyrene (PS) [132,141] or melamine formaldehyde [140], high refractive index glasses such as Er 2+ or Tm 3+ doped tellurite [134,142], or other oxides [137,138]. Fluorescent microspheres can also be used to decrease the lifetime of the fluorescent medium at the resonance wavelengths, via the Purcell effect [143].…”

Photonic Materials for Sensing, Biosensing and Display Devices

“…Omenetto reported 3DPC composed of entirely nature material, silk fibroin. By pouring the silk solution onto the PMMA opal and subsequent acetone dispose, they removed the PMMA successfully and got a silk inverse opal (SIO) [138]. Afterwards, they attempted many application areas of the SIO obtained.…”

“…Finally the intrinsic microsphere fluorescence can be exploited to achieve similar results. For example, zinc oxide [137] and titanium oxide [138] microspheres have been used for such purpose with a photoluminescence emission ranging from 550 to 750 nm.…”

Dda Calculation of Light Scattering by Birefringent and Polycrystalline Submicron Spheres

“…[6][7][8]. TiO 2 spheres have been reported to show morphology dependent resonance peaks in its scattering spectrum while interacted with light [9]. Due to such behaviour TiO 2 spheres have also been found applicable in template-guided self-assembly structures with optoelectronic applications [8].…”