Ultraviolet whispering-gallery-mode lasing in ZnO micro/nano sphere crystal

Abstract

We report ultraviolet (UV) whispering-gallery-mode (WGM) lasing in a zinc oxide (ZnO) micro/nanosphere crystal fabricated by simply ablating a ZnO sintered target, which was much more productive method without any time-consuming crystal-growth process. The lasing spectral mode spacing was controlled by changing the diameters, and single-mode lasing was realized from a ZnO nanosphere. Experimental results were in good agreement with predictions from WGM theories. Since the ZnO sphere can operate as an active WGM refractometric sensor for small molecules in UV region, high sensitivity enhanced by high quality factor, refractive index, and wavelength dispersion can be expected.

Boosted UV emission at 349 nm from mesoporous ZnS

“…These microstructures are made of mesoporous nanoregime structures which can generate UV radiation corresponding to their band gap when this system is suitably pumped by radiation having higher frequency. Thus, the generated UV radiation will be amplified by the whispering gallery modes (WGMs) of the elliptical microstructures [34]. So, the unusual enhancement in the UV radiation at 349 nm is partially contributed by WGM activation of the ZnS microstructures.…”

Correlation between structural and electronic order–disorder effects and optical properties in ZnO nanocrystals

“…[60][61][62][63] The UV peak is due to the excitonrecombination process while the visible emission centered at about $600 nm ranging from 480 to 800 nm is associated with oxygen vacancies due to the formation of deep levels in the band gap; this observation is also consistent with results reported by other groups. 7 In particular, Willander et al 61 have reported a comprehensive review on the subject.…”

“…Although dened ZnO nanostructures with different morphologies have been reported using a variety of procedures, [7][8][9][10][11][12]29 existing methods require either harsh conditions, complex procedures or long reaction times. In addition, although it is well-known that the presence of lattice defects plays a key role in the physical and chemical properties of ZnO nanostructures, 10,11 many questions still remain due to the lack of conclusive evidence for defects responsible for luminescence properties.…”

Observation of whispering gallery modes from hexagonal ZnO microdisks using cathodoluminescence spectroscopy

“…[12][13][14][15][16][17] While some attributed the emission enhancement to the presence of WGMs, most of previous works showed excitonic WGM is in the ultraviolet range, 15,[18][19][20] which is not suitable for visible applications. In addition, the ZnO structures were not well separated from each other, which make it challenging for realistic applications to WGMs resonators.…”