Yellow stimulated emission from Dy$^{3+}$-doped silica glass microspheres

TL;DR

This paper demonstrates yellow stimulated emission from Dy$^{3+}$-doped silica glass microspheres, showcasing their potential as narrow-linewidth visible light sources through whispering gallery mode resonances.

Contribution

It introduces Dy$^{3+}$-doped silica microspheres fabricated by fiber fusion splicing that exhibit stimulated emission in the yellow spectrum.

Findings

Observed stimulated emission at 450 nm excitation

Microspheres show whispering gallery mode filtering

Potential for narrow-linewidth visible light sources

Abstract

Dy$^{3+}$-doped silica glass whispering gallery mode microspheres are fabricated by fiber fusion splicing. They present an almost ideal spherical morphology with a radius ranging from 60 to 67 ${\mu}$m as determined by confocal laser microscopy. The host composition of the microsphere is close to that of the fiber core. The dopant Dy$^{3+}$ ions are uniformly distributed across the microsphere as evidenced by ${\mu}$-luminescence studies and present a luminescence lifetime. The Dy$^{3+}$-doped glass microspheres were excited via evanescent field coupling using a half-tapered fiber and a blue 450-nm GaN laser diode (direct pumping scheme). The yellow fluorescence of Dy$^{3+}$ ions is filtered by the whispering gallery modes (free spectral range: 0.5 nm for 67-${\mu}$m radius microsphere). The onset of stimulated emission is further observed highlighting the potential of such microresonators for narrow-linewidth light sources directly emitting visible light.