Spectroscopic investigations of highly doped Er³⁺ : GGG and Er³⁺/Pr³⁺ : GGG crystals

Abstract

Heavily Er3+-doped and Er3+/Pr3+ co-doped Gd3Ga5O12 (abbreviated as Er : GGG and Er,Pr : GGG, respectively) laser crystals were synthesized by the Czochralski method. The synthesized laser crystals were characterized by absorption, up-conversion fluorescence, near-infrared (NIR) and mid-infrared (Mid-IR) fluorescence, and luminescence decay measurements. The optical parameters related to absorption and emission cross-sections and fluorescence lifetimes were evaluated and compared. It was found that the up-conversion and NIR fluorescence weaken, at the same time Mid-IR fluorescence intensity strengthens with the increment of Er dopant concentration or co-doping with Pr3+ in Er : GGG crystals. Furthermore, the self-termination bottleneck was broken successfully in the Er,Pr : GGG crystal, and the energy transfer efficiencies of Er3+ : 4I11/2 → Pr3+ : 1G4 and Er3+ : 4I13/2 → Pr3+ : 3F4 were determined.

Spectroscopic properties of Pr3+:Gd3Ga5O12 crystal

“…The growth procedure was similar to that of Er:GGG described in our previous publication [29]. The concentration of praseodymium ions in the crystal was measured to be 0.268 wt% by the inductively coupled plasma-atomic emission spectrometry (ICP-AES) method and the corresponding Pr 3+ concentration is 8.12 × 10 19 ions/cm 3 .…”

“…5, the luminescence decay curve of the 1 D 2 → 3 H 4 transition at the wavelength of 608 nm excited by 590 nm pumping is not singly exponential, but could be described as two exponentials, among which the lifetime of 1 and 2 components are estimated to be 63.5 and 144.6 s, respectively. And the lifetime the 1 D 2 manifold is estimated to be 118.4 s by using = (B 1 1 2 + B 2 2 2 )/(B 1 1 + B 2 2 ) [29], which is much longer than that of 3 P 0 level. The experimental lifetime value of the 1 D 2 level can be compared to that of 1 mol%Pr:GGG nanocrystalline: 110s [25], 0.5% Pr 3+ :YAG: 110s [45] and of 1% Pr 3+ :YAP: 28s [43].…”

Enhanced 2.7 μm emission and its origin in Nd3+/Er3+ codoped SrGdGa3O7 crystal

“…It is noticed that the fluorescence lifetime of 4 I 11/2 state (0.629 ms) is much shorter than that of 4 I 13/2 state (6.067 ms) in Er:SGGM crystals. As we know, the shorter lifetime of laser upper level 4 I 11/2 than lower level 4 I 13/2 will make the accumulated population in the 4 I 11/2 levels not relax rapidly enough to maintain the required population inversion, and then cause the $ 3.0 mm lasing transition to selfterminate [1,4].…”

“…This is primarily due to the strong absorption by water around this wavelength, making erbium doped lasers suitable for use in medical applications, hazardous chemical detection, remote atmospheric sensing and pollution monitoring etc. [1][2][3][4].…”

Role of Er3+ concentration in spectroscopic and laser performance of CaYAlO4 crystal

“…But, when Er 3+ ion is heavily doped, the cross-relaxation plays a dominant role and the fluorescence kinetics changes obviously. Thus, it is suggested that high Er 3+ concentration can increase the population of 4 I 11/2 and depopulate 4 I 13/2 level and so benefits 2.7 lm emission [3][4][5].…”