Optical properties of phosphorus-related point defects in silica fiber preforms
2009; American Physical Society; Volume: 80; Issue: 20 Linguagem: Inglês
10.1103/physrevb.80.205208
ISSN1550-235X
AutoresG. Origlio, Fabrizio Messina, M. Cannas, R. Boscaino, Stéphane Girard, A. Boukenter, Y. Ouerdane,
Tópico(s)Photonic Crystal and Fiber Optics
ResumoWe report an experimental study on phosphorus-related point defects in amorphous silica, based on photoluminescence, absorption, and electron spin resonance measurements carried out on P-doped ${\text{SiO}}_{2}$ fiber preforms. By photoluminescence measurements excited by laser or synchrotron light we detect an emission band peaked at 3.0 eV with a lifetime in the range of ms. The excitation spectrum of the 3.0 eV emission consists of two transitions peaked at 4.8 and 6.4 eV, the former giving rise also to a measurable absorption band. We attribute this optical activity to a P-related point defect embedded in ${\text{SiO}}_{2}$, based on the spatial correlation between the emission intensity and the P doping level. A detailed spectroscopical investigation allows us to propose a scheme of the electronic levels of this P-related defect, in which the 4.8 and 6.4 eV excitation channels arise from transitions from the ground to two-excited singlet states, while the long-lived 3.0 eV emission is associated to a spin-forbidden transition from an excited triplet to the ground state. Finally, electron spin resonance measurements on $X$-irradiated samples lead us to propose a tentative microscopic model of the defect as a diamagnetic four-coordinated P impurity substitutional to a Si atom.
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