Comparative high-resolution spectroscopy and emission dynamics of Nd-doped GSGG crystals and transparent ceramics

Lupeǐ, V.; Lupeǐ, A.; Gheorghe, C.; Ikesue, Akio

doi:10.1016/j.jlumin.2007.11.009

Cited by 13 publications

(8 citation statements)

References 12 publications

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“…Preliminary investigation revealed that the spectroscopic properties of these materials are similar [4]. The extended investigation reported in this work reveals that in the absorption spectrum 4 I 9/2 4 F 3/2 the transitions between the Stark components Z 2 R 1 and Z 3 R 2 are almost perfectly superimposed in the 883 nm band (Fig.…”

supporting

confidence: 64%

Spectroscopic bases for performance enhancement and power scaling of Nd: GSGG lasers

Lupeǐ

Pavel

et al. 2009

CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference

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Cr, Nd)-doped Gd 3 Sc 2 Ga 3 O 12 garnet (GSGG) gained popularity owing to its good laser performances in Q-switched regime under lamp pumping based on two circumstances: (i) good absorption of Cr 3+ ions and very efficient energy transfer to Nd 3+ , and (ii) better performance in Q-switched emission than Nd: YAG due to longer lifetime, weaker self-quenching of emission and smaller emission cross-section [1-3]. GSGG shows better stability than YAG at ionizing radiation and single crystals of large size can be grown by Czochralski method, with uniformity and reproducibility problems. However, power scaling of these lasers was hampered by the weaker heat conductivity, about half from Nd: YAG and with the advent of diode lasers for Nd 3+ , GSGG lost its popularity. The present work investigates the spectroscopic properties of Nd-doped GSGG in order to identify modalities to extend the power range by increasing the emission performances and reduction of heat generation.Spectroscopic investigation was performed with Nd-doped (up to 7-at% Nd) single crystals and with transparent ceramics produced by the solid-sate synthesis method. Preliminary investigation revealed that the spectroscopic properties of these materials are similar [4]. The extended investigation reported in this work reveals that in the absorption spectrum 4 I 9/2 4 F 3/2 the transitions between the Stark components Z 2 R 1 and Z 3 R 2 are almost perfectly superimposed in the 883 nm band (Fig. 1). The 300 K peak absorption coefficient of this band for 1at.% Nd is 1.9 cm -1 , about 3.5 times smaller than for the strong 809 nm line. This suggests the possibility to pump the Nd: GSGG lasers directly into the emitting manifold by using the 883 nm line. Compared with the 808 nm pumping, the 883 nm pumping enables an increase of the quantum defect (Stokes) ratio qd = p / em by 9.1%, with a corresponding enhancement of the laser parameters and with reduction of heat generation of ~ 30% in case of 1064 nm laser emission. The quite large Nd doping level in GSGG enables the use of this approach for a large variety of laser active components from minilasers to large size components. The calculation based on estimated quantum efficiency at different Nd concentrations indicates that the pump at 883 nm enables the scaling in power by more than 50 % larger than for the 808 nm pumping. 8700 8800 8900 9000 0 5 10 15 (Z 3 -R 2 ) k, cm -1 λ, λ, λ, λ, A Z 2 -R 1 (Z 2 -R 1 )+ Fig. 1 300 K absorption of 6-at% Nd: GSGG ceramics.Fig. 2 CW laser emission of Nd:GSGG under 809 and 883 nm diode pumpingFig. 3 Free generation and Cr 4+ :YAG passive Qswitched emission under diode pumping at 883 nm.The enhancement of CW laser emission parameters of an uncoated Nd: GSGG crystal with 1at% Nd under the 883 nm compared with 808 nm diode laser (fiber-coupled DL FA-808 and FA-885, Coherent Co., USA) pumping is demonstrated in Fig. 2: the slope efficiency increases from 0.31 to 0.39. Moreover, while in case of 809 nm pumping P out is limited to 2.2 W (for P abs =8.1 W) due to thermal effects...

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supporting

confidence: 64%

Spectroscopic bases for performance enhancement and power scaling of Nd: GSGG lasers

Lupeǐ

Pavel

et al. 2009

CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference

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“…The high-resolution absorption spectra of the Nd:GSGG crystals and ceramics are identical [10], without any satellite structure that could reveal the presence of garnet antisites, as observed in the melt-grown YAG or GGG crystals but absent in the corresponding ceramics. However, in both types of materials the low temperature absorption lines show identical concentration-dependent asymmetries, with shoulders caused by unresolved crystal field perturbations inside the nearestneighbor and next-nearest-neighbor Nd 3+ pairs, whereas the farther pairs contribute to inhomogeneous line broadening.…”

Section: Spectroscopic Bases For Selection Of Pump Wavelength and Nd ...mentioning

confidence: 81%

“…Although the fairly weak cross-sections of the narrow absorption lines of Nd 3+ that are visible make the broad-band visible pumping such as with flash-lamps less favorable, efficient sensitized Nd 3+ emission was obtained by co-doping with Cr 3+ [6][7][8][9]. The transparent Nd-doped GSGG ceramics have spectroscopic properties similar to the single crystals [10]. GSGG has remarkable intrinsic resistance to the ionizing radiation [11] that could be increased by doping with Cr 3+ and this recommends Nd:GSGG or Cr, Nd:GSGG for lasers working in a radiation field such as cosmic space or nuclear physics.…”

Section: Introductionmentioning

confidence: 99%

Improved laser efficiency by direct diode laser pumping of the radiation-resistant Nd:gadolinium–scandium–gallium garnet

Lupeǐ¹,

Pavel²,

Lupeǐ³

2014

Laser Phys.

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Spectroscopic investigation of the radiation-resistant Nd:GSGG crystals and ceramics reported in this paper evidences that the absorption line at 883 nm corresponding to the unusual situation of quasi-degenerate absorption transitions 4 I 9/2 (2) → 4 F 3/2 (1) and 4 I 9/2 (3) → 4 F 3/2 (2) can be used for efficient direct diode laser pumping of this material, with stable absorption over an extended temperature range. It is inferred that the reduction of the quantum defect at this wavelength of pump compared to the traditional 807 nm pumping could improve the laser parameters and reduce drastically the heat generation, leading to a considerable extension of the power scalability. This possibility is demonstrated for the first time in the case of the 1061 nm laser emission in a continuous-wave and in the repetitive active acousto-optic and passive Q-switched laser emission. In all regimes this manifests in the reduction of the laser threshold, increase of slope efficiency and extension of the average power range. Additionally, in the active Q-switching this enables increased pulse energy and reduced pulse duration. The direct pumping could revitalize the utilization of Nd:GSGG for construction of lasers with storage of population inversion or working in an ionizing radiation environment.

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“…The optical spectra of Nd:GSGG single crystals and ceramics are similar. [27] The P i satellites are absent and the satellites M i are identical in both materials and show as shoulders on the absorption line of the main center N. The second derivative of the absorption lines shows that the structure of satellites M i in Nd:GSGG is similar to Nd:YAG: in several electronic transitions the satellite M 2 is split in two components and their global intensity is practically double to that of satellite M 1 .…”

mentioning

confidence: 88%

Multicenter Structure and Dynamical Processes in the Rare Earth Doped Garnet and Sesquioxide Laser Crystals and Ceramics

Lupeǐ

Ikesue³

2010

Spectroscopy Letters

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Comparative high-resolution spectroscopy and emission dynamics of Nd-doped GSGG crystals and transparent ceramics

Cited by 13 publications

References 12 publications

Spectroscopic bases for performance enhancement and power scaling of Nd: GSGG lasers

Spectroscopic bases for performance enhancement and power scaling of Nd: GSGG lasers

Improved laser efficiency by direct diode laser pumping of the radiation-resistant Nd:gadolinium–scandium–gallium garnet

Multicenter Structure and Dynamical Processes in the Rare Earth Doped Garnet and Sesquioxide Laser Crystals and Ceramics

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