Effect of the AlPO_4 join on the pump-to-signal conversion efficiency in heavily Er-doped fibers

Abstract

Heavily Er-doped fibers (EDFs) based on P(2)O(5)-Al(2)O(3)-SiO(2) (PAS) ternary glass have been studied. A unique feature of this glass is the formation of a AlPO(4) join having a structure similar to that of SiO(2) glass and a refractive index below it. It is found that the Er(3+) absorption and emission spectra in the PAS EDFs are defined by the dopant (Al(2)O(3) or P(2)O(5)) present in excess and are close to those of the corresponding binary glass (Al(2)O(3)-SiO(2) or P(2)O(5)-SiO(2)). The presence of the AlPO(4) join results in the enhancement of the pump-to-signal conversion efficiency in the PAS EDFs as compared with the EDFs based on the P(2)O(5)-SiO(2) and Al(2)O(3)-SiO(2) (with 1.5 mol. %Al(2)O(3) and less) binary glasses. The PAS host glass is advantageous in the case of large-mode-area active fibers.

High power pulsed fiber laser development for Co2 space based dial system

“…However, simultaneous incorporation of phosphorus (P) and Al (phosphoaluminosilicate composition) has been shown to mitigate this NA increase. Indeed, equimolar addition of alumina and phosphorous reduces the glass refractive index [7,8].…”

Yb-free Er-doped all-fiber amplifier cladding-pumped at 976 nm with output power in excess of 100 W

“…However at Er 2 O 3 concentrations up to 1000 mole-ppm the greatest impact on the efficiency is provided by so-called pair induced quenching (PIQ) that is upconversion in clusters that consist of two Er 3+ ions 16,17 . The number of ion pairs (and the PCE value) depends on the core composition and Erbium concentration 17,19 . The PCE is also a function of population inversion because the upconversion process is initiated only if both ions in a pair are excited.…”

“…At the same time Al 2 O 3 concentration of at least 1.5 mole % is required to increase Erbium solubility 19 . As a consequence of Aluminum refractivity, the core/cladding refractive index difference Δn is equal to or higher than 0.0025 (NA~0.08).…”

“…To evaluate influence of PIQ and background loss on PCE three situations were simulated: (i) fiber with no background loss (dotted line in Fig 1a), (ii) fiber with no clusters (dashed line in Fig 1a) and (iii) real fiber with both background loss and PIQ (solid line in Fig 1a). Dependence of ions pair number on Erbium concentration was derived from results obtained in a core-pumped scheme 19 and background loss for pump and signal were set to 30 dB/km. As follows from Fig.1 PIQ causes significant degradation of efficiency in heavily doped fibers.…”

Radiation-hardened Erbium doped LMA fiber with AlP composition from solution doping process

“…Moreover high energy fiber systems require LMA fibers with low NA that are not compatible with large Al concentration. It was shown that the phosphoalumino silicate composition allowed to limit the core refractive index increase as the equimolar addition of alumina and phosphorous reduces the glass refractive index [1,2]. The best results were recently obtained using chelate compounds as precursors [2].…”