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Er 3+ /Yb 3+ /Eu 3+ : SrGdGa 3 O 7 and Er 3+ /Yb 3+ /Ho 3+ : SrGdGa 3 O 7 crystals were grown by Czochralski technology and detailed spectroscopic analyses were carried out. It was found that the spectra of Er 3+ /Yb 3+ /Eu 3+ : SrGdGa 3 O 7 crystal show weaker near-infrared emission and stronger mid-infrared emission as compared with Er 3+ /Yb 3+ : SrGdGa 3 O 7 crystal. Furthermore, the lifetime of the 4 I 13/2 state decreases from 10.58 ms in Er 3+ /Yb 3+ : SrGdGa 3 O 7 crystal to 6.87 ms in Er 3+ /Yb 3+ /Eu 3+ : SrGdGa 3 O 7 crystal, that is, the self-saturation for 2.7 μm laser in Er 3+ /Yb 3+ /Eu 3+ : SrGdGa 3 O 7 crystal is suppressed greatly. These results indicate that the doping of Eu 3+ in Er 3+ /Yb 3+ : SrGdGa 3 O 7 crystal is beneficial to improve the 2.7 μm laser. In contrast, introducing Ho 3+ in Er 3+ /Yb 3+ : SrGdGa 3 O 7 crystal is adverse to realize Er 3+ -activated MIR laser operation. So Er 3+ /Yb 3+ /Eu 3+ : SrGdGa 3 O 7 crystal could be a potential MIR gain media for enhanced 2.7 μm laser. [ABSTRACT FROM AUTHOR]

The crystal of 1 at% Yb 3+ , 10 at% Er 3+ and 0.1 at% Eu 3+ triply doped La 0.3 Y 2.7 Sc 2 Ga 3 O 12 (abbr. as Yb,Er,Eu:LaYSGG) was grown for the first time by using a Czochralski technique. Its absorption, near-infrared and mid-infrared fluorescence spectra, as well as the fluorescence decay curves of Er: 4 I 13/2 and 4 I 11/2 levels were measured at room temperature. The spectroscopic properties including the absorption and emission cross-sections as well as the fluorescence lifetimes of the title crystal were revealed and compared with 10 at% Er 3+ :Y 3 Sc 2 Ga 3 O 12 crystal. Spectral analyses show that the sensitization of Yb 3+ ion leads to an enhanced 2.5–3.0 µm emission corresponding to Er 3+ : 4 I 11/2 → 4 I 13/2 transition in the grown crystal, meanwhile, the depopulation of Eu 3+ ion from Er 3+ inhibits the self-termination effect successfully. The energy transfer mechanism was discussed; the energy transfer efficiencies of Yb 3+ →Er 3+ (ET1) and Er 3+ →Eu 3+ (ET2) were estimated to be 94.8% and 93.9%, respectively. The results indicates that Yb,Er,Eu:LaYSGG crystal is a good candidate for LD pumped mid-infrared laser. [ABSTRACT FROM AUTHOR]

The Tm 3+ /Ho 3+ : SrGdGa 3 O 7 single crystal was grown by the Czochralski method. The polarized absorption spectra, emission spectra and fluorescence decay curves of the crystal were measured. The crystal exhibited a broad absorption band and a broad emission band, as well as a fluorescence lifetime of 5 I 7 multiplet of Ho 3+ ions up to 8.0 ms. End-pumped by a fiber-coupled diode laser at 808 nm, the laser operation around 2.0 µm has been realized with the a-cut and c-cut crystal samples. The maximum output power is 200 mW when a-cut crystal sample was employed. [ABSTRACT FROM AUTHOR]

Nd 3+ sensitized Er 3+ : 4 I 11/2 → 4 I 13/2 mid-infrared (MIR) emission around 2.7 μm was achieved in SrGdGa 3 O 7 single crystal for the first time. The effect of Nd 3+ on the absorption, near-infrared (NIR) and MIR fluorescence properties of Er 3+ ions were investigated. It is found that Nd 3+ greatly improves the absorption pump efficiency and thus enhances the Er 3+ ~2.7 μm emission by nearly 10 times under 808 nm laser diode (LD) excitation, at the same time quenches the ~1.5 μm near-infrared emission of the lower level Er 3+ : 4 I 13/2 and thus suppresses the self-saturation problem effectively. The luminescent mechanism for the Nd 3+ /Er 3+ :SrGdGa 3 O 7 crystal was analyzed and the possible energy transfer processes were proposed. The energy transfer efficiencies of Nd: 4 F 3/2 →Er: 4 I 11/2 and Er: 4 I 13/2 →Nd: 4 I 15/2 are estimated to be 85.8% and close to 100%, respectively. The results indicate that the introduction of Nd 3+ is very beneficial in achieving 2.7 μm laser in Er 3+ :SrGdGa 3 O 7 crystal which could act as a potential gain media for LD pumped MIR laser. [ABSTRACT FROM AUTHOR]