High refractive-index microspheres as optical cavity structure

Microspheres of refractive index of n(D) > 2.0 have been investigated. The organic-in organic hybrid microspheres of n(D) = 1.72 were prepared by the vibrating orifice technique using titanium-tetra-n-butoxide (TTBu) and diphenyldimethoxysilane (DPhDMS). For lasing demonstration, Eu3+-doped microspheres were prepared using europium (III) thenoyltrifluoroacetonate [Eu(TTFA)(3)] as the dopant. The particles have good spherical shape, smooth surface and high optical transparency. The diameters of the particles could be controlled to within 0.1 mu m. Subsequent heating of the microspheres at 550 degrees C under oxygen atmosphere resulted in an increase in the refractive index up to n(D) = 2.6 with retention of the spherical shape. Resonant emission was confirmed from Eu3+-doped microspheres after heating at 400-550 degrees C, by pumping with the 514.5 nm line of a CW-Ar(+)laser.