Modulated Photon Emission of Eu³⁺ in Microsphere Cavity

Fused silica microsphere with a few Eu³⁺ ions on the equator is fabricated. The photon emission sharply modulated by whispering gallery (WG) modes is observed under excitation of 395nm laser, which is in agreement with the prediction in theory. The quality factor of the WG modes in microsphere is estimated larger than 3000 from the emission spectrum, which is limited by our monochrometer. It proves that pumping Eu³⁺ in microsphere cavity in free space is feasible, and this system seems suitable for realizing strong coupling in future quantum computation purposes.