Highly crystalline and smooth 1% Ho3+ doped ZnO microspheres with diameters ranging from 0.5 to 15 μm were synthesized using laser ablation technique. Near band edge whispering gallery mode (WGM) resonances from Ho:ZnO microspheres with a single oscillation route in the UV range are observed with 355 nm excitation. Apart from the significantly enhanced visible WGM resonances associated with intrinsic oxygen vacancy defects by Ho3+ doping, the visible range WGM resonances associated with the Ho3+ 5F5 → 5I8 emission at 629-690 nm are also observed with a 488 nm excitation. The WGMs of Ho3+ f-f emission possess lower threshold and high Q-factor values. © 2018 Author(s).

K. Fabitha

M. S. Ramachandra Rao

II-VI semiconductors

Laser ablation

Microspheres

Optical resonators

Oxygen vacancies

Q factor measurement

Resonance

Whispering gallery modes

Zinc oxide

Doped ZnO

high Q factor

LASER ABLATION TECHNIQUE

NEAR BAND EDGE

OXYGEN VACANCY DEFECTS

Spectral range

Spherical cavities

Visible range

Holmium compounds

Fulltext

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Room temperature WGM resonances in the red spectral range from Ho3+ activated ZnO micro-spherical cavities

Applied Physics Letters

As an approach to design efficient visible luminescent material at nano scale, Ho3 ion-doped single-phase zinc oxide (ZnO) nano phosphor to obtain red emission suitable for LED/laser applications is reported. Ho3-doped ZnO nanoparticles with various concentrations of Ho3 have been prepared by a simple solgel synthesis technique. Under the excitation of 488 nm, the photoluminescence emission spectra of the nano phosphor exhibit an intense emission with multiple and well-resolved narrow splitting peaking in the range from 640 to 667 nm, which is identified as the emission from the Ho3 ion, corresponding to 5F5 → 5I8 transition with multiple splitting due to the ZnO crystal field. The required excitation threshold for these emissions is, surprisingly, as low as 33.8 kW∕cm2, and the narrow line width (FWHM &lt; 2 nm) is found to be persistent even at higher temperatures. Such sharp emission from Ho3:ZnO nanoparticles could be used for lasing applications. © 2017 Optical Society of America.

Journal of the Optical Society of America B: Optical Physics

Ho3+-doped ZnO nano phosphor for low-threshold sharp red light emission at elevated temperatures

Journal of Applied Physics

Observation of defect-assisted enhanced visible whispering gallery modes in ytterbium-doped ZnO microsphere

Scientific Reports

Fabrication of single-crystalline microspheres with high sphericity from anisotropic materials

Strong correlation between oxygen vacancy and ferromagnetism in Yb-doped ZnO thin films

Optics Express

Ultraviolet electroluminescence from hetero p-n junction between a single ZnO microsphere and p-GaN thin film

Journal	Data powered by TypesetApplied Physics Letters
Publisher	Data powered by TypesetAmerican Institute of Physics Inc.
ISSN	00036951
Open Access	No