Title

Site-Selective Spectra And Energy Levels Of Trivalent Erbium In Calcium Fluorophosphate

Abstract

Site-selective excitation and fluorescence spectra, and conventional polarized transverse and axial absorption spectra of trivalent erbium-doped single crystals of calcium fluorophosphate (Ca5(PO4)3F), a fluorapatie mineral known as FAP, have been analyzed over the wavelength range 1.60 μm to 0.34 μm at temperatures between 4 K and room temperature. There was no spectroscopic evidence to indicate a phase transition from the hexagonal phase at room temperature to the monoclinic phase around 133 K as reported earlier. Most spectra are interpreted in terms of Er3+ ions replacing Ca2+ ions in Ca(I) sites and Ca(II) sites. A majority of the Er3+ ions prefer the Ca(II) sites, where charge compensation is possible, by replacing F- with O2- during the growth process. Measured room temperature fluorescence lifetimes are reported for Er:FAP, YbEr:FAB, and Yb:FAP. Absorption cross-sections are reported for Er:FAP. The absorption cross-sections for Er3+ (4I15/2→4I13/2) are larger than the emission cross-sections for the lasing transition in Er:phosphate glass. Overlap of the two spectra makes Er:FAP a passive Q-switch for the Er:phosphate glass laser operating at 1.53 μm. A crystal-field splitting calculation for Er3+ ions in both Ca2+ sites is described. The initial crystal-field parameters were obtained from a lattice-sum calculation. By varying the initial set of crystal-field splitting parameters, Bnm(cm-1), by only a small amount, we obtained good agreement between calculated and observed Stark levels. © 1994.

Publication Date

1-1-1994

Publication Title

Optical Materials

Volume

3

Issue

2

Number of Pages

99-113

Document Type

Article

Identifier

scopus

Personal Identifier

scopus

DOI Link

https://doi.org/10.1016/0925-3467(94)90013-2

Socpus ID

0028443680 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/0028443680

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