A perfect nonabsorbing microsphere with higher refractive index than that of surrounding medium is a good microcavity.Inside such a sphere

which has a diameter of a few microns

there exist a discrete number of resonant optical modes

so-called whispering-gallery modes(WGMs).The spontaneous emission cross sections at the microcavity resonance photon energies are larger than the bulk spontaneous emission cross sections because of the modified photon density of states of the microcavity.Such microcavity structures can be used for efficient optical devices such as low-threshold laser and low-power nonlinear optical devices. In this work

The TiBa glass microspheres doped with Er

3+

for morphology dependent resonances of up conversion emission were designed. The glass sample components are 25TiO

2

-27BaCO

3

-8Ba(NO

3

)

2

-6ZnO-9CaCO

3

-5H

3

BO

3

-10SiO

2

-7water glass-3 Er

2

O

3

(wt.%).The raw materials were completely mixed in deionized water to form slurry.Then the slurry was dried and ground to small pieces

and blown off by a gas burner.The small pieces were melted and formed into microsphere

and cooled in air.We measured the Raman spectra of the microspheres and made sure that the material in the microspheres is in vitreous body. The experimental apparatus is micro-Raman spectrometer(RENISHAW System 2000).The laser beam

wavelength 633nm

was focused into a ～5μm spot by an objective lens(20x

numerical aperture 0.4) and irradiated on a singe glass microsphere under an optical microscope.Emission from the microsphere were collected by the same objective lens

and the spectra were observed by the spectrometer(with CCD). The emission spectra of TiBa glass and a TiBa glass microsphere(about 46μm in diameter) were measured under 633nm excitation and discussed.We have proved the green upconversion luminescences to be from

2

H

11/2

→

4

I

15/2

(for 525nm) and

4

S

3/2

→

4

I

15/2

(for 548nm)due to two-photon absorption.The strong morphology-dependent resonances of up-conversion luminescences in the microsphere(about 46μm in diameter) were observed.The observed resonances could be assigned by using the well-known Lorenz-Mie Formalism.