RED glass-based microcavities enabling luminescence control

Optical microcavities are structures that enable confinement of light to microscale volumes. Moreover, depending on their geometrical, compositional and structural parameters, such sub-wavelength photonic systems allow a fine tailoring of the luminescence, when activated by luminescent species. Here we focus our attention on 1-D photonic crystals and on spherical microresonators, both of them activated by Er3+ ions. The glass-derived 1-D photonic crystal is a microcavity constituted by an erbium-doped layer sandwiched between two Bragg mirrors respecting a ?/2 periodicity, where ? is the desired operating resonance wavelength. This microcavity is fabricated by rf-sputtering. The spherical microresonator consists in a silica sphere with a diameter of about 150 µm coated with a erbium-doped silica-hafnia layer of about 1 µm in thickness. The spherical substrate is obtained by melting a fiber tip and the coating is achieved by sol gel dip-coating technique. The 1-D microcavity exhibits a significant quality factor. The effect of the cavity on the 4I13/2->4I15/2 emission band is demonstrated by the narrowing of the emission band as well as by the enhancement of the Er3+ photoluminescence intensity. The Er3+ 4I13/2->4I15/2 luminescence, excited by the whispering gallery modes typical of these cavities, exhibits interesting properties as a function of the geometrical properties of the resonator.