| 概 要 |
Two examples of applications developed with erbium doped materials synthesised in the laboratory will be exposed.
First, whispering-gallery mode lasers have been obtained with erbium doped fluoride glasses.
High Q dielectric microcavity, in which light is trapped internally as whispering gallery mode resonances, have attractive interest in applications as diverse as quantum optics and optical communications. In this frame, rare earth doped glass microsphere lasers have been demonstrated as potentially compact laser sources.
Fluoride glasses with composition, 51ZrF4 16BaF2 5LaF3 3AlF3 20LiF 5PbF2, revealing a high stability with regard to crystallisation processes have been elaborated. The high stability of this glass family enable the fabrication of microspheres without any crystallisation risk. Samples with various erbium concentrations were prepared by melting of high purity fluoride compounds, pouring and quenching inside an argon purified glove box to avoid moisture and oxygen contamination. Many glass microspheres were prepared by fusion of glass powder through the flame of a microwave plasma torch.
Glass microsphere lasers have been studied around 1550 nm under pumping at 1480 nm. As the pump and laser wavelengths are close enough, the coupling with the microspheres was performed with one single half-tapered fiber. Fluorescence spectra of the microspheres exhibit typical discrete whispering gallery modes features. When reaching the laser threshold, one single mode is oscillating near the maximum of the gain curve of erbium ions in the glass. Multimode laser emission lines are observed for higher pumping rates.
Simultaneous visible emission arising the two neighbouring excited levels, 2H11/2 and 4S3/2, after up conversion process allows the precise determination inside the lasing microsphere.
Second, a nanoprobe made of erbium doped fluoride glass or PbF2 crystal allows the thermal mapping of the surface of electronic circuit by using the same thermal effect between the 2H11/2 and 4S3/2 levels or erbium. A specific experimental setup allowing to record simultaneously the Atomic Force Microscopy and the thermal image was developed and will be exposed. Also, near-field optical images of various surfaces.
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