Induced Emission Cross Section Research Articles

Optical, spectroscopic properties and Judd–Ofelt analysis of Nd3+-doped photo-thermo-refractive glass

A comparative study of spectral-luminescent and Judd–Ofelt analysis of photo-thermo-refractive (PTR) glasses doped with a variable content of neodymium (0.5–2.11 mol%) has been carried out for the first time. The change of Judd-Ofelt parameters (Ω2, Ω4, Ω6), radiation lifetime, experimental lifetime, branching ratio and emission cross sections were demonstrated as a function of Nd2O3 concentration and compared to the equivalent parameters in other works. It was found that the 4F3/2 → 4I11/2 transition is enhanced in Nd-doped PTR glass. The quantum efficiency of 0.5 mol% Nd-PTR for the same transition is 90.3% and the induced emission cross section is 1.743 × 10−20 cm2. The saturation intensity for 4F3/2 → 4I11/2 laser transition in the same sample is 20.62 kW/cm2, it is lower than that in some commercially produced glasses of same Nd3+-concentration. Laser action of a 0.5 mol% Nd-PTR was demonstrated, it was found that the round-trip loss of this gain medium is 0.34%, this value is quite low, and it is comparable to that in some commercially fabricated Nd-YAG crystals.

Features of spectral properties of Sm3 + complexes with dithia- and diselenophosphinate ligands

The samarium complexes Sm(S2PPh2)3(THF)2 (1) and Sm(Se2PPh2)3(THF)2 (2) with soft-donor dithia- and diselenophosphinate ligands were synthesized and their photophysical properties were studied in detail. Both complexes displayed the metal-centered photoluminescence (PL) in visible and NIR regions corresponding to 4G5/2→6HJ (J=5/2, 7/2, 9/2, 11/2, 13/2, 15/2), 6FJ (J=1/2, 3/2, 5/2, 7/2, 9/2, 11/2) f–f transitions of Sm3+. Luminescence decay curves exhibit an initial short build-up region and can be described by double or triple exponential function owing to multiphonon relaxation from the 4F3/2 energy level to the 4G5/2 one and reversible energy transfer from the Sm3+ excited states to the triplet (3T1) state of phosphinate ligand. A Judd–Ofelt analysis was performed to estimate PL quantum efficiency (QE), branching ratios (β) and induced-emission cross section (σem) of the compounds obtained. It was found that the Judd–Ofelt parameter Ω2 of 1 is significantly greater than that of 2. This feature is responsible for large values of β (50.98%) and σem (4.29×10−21cm2) which suggest 1 as a good candidate for the development of samarium doped polymethylmethacrylate (PMMA) laser medium acting on the 4G5/2→6H9/2 transition at 645nm. The estimated room-temperature PL QE of 1 and 2 equals to 1.9 and 0.17%, respectively.

Induced emission cross section of a possible laser line in Nd:Y2O3 ceramics at 1.095μm

In this study, we measured the change of the optical transmittance for calcination temperatures, in steps of 10°, at two different sintering temperatures. It was found that the optical transmittance is highly dependent on the calcination temperature. The highest optical transmittance obtained was 70% for the transparent Y2O3 (yttria) ceramics produced without the use of additives and high injection presure in this study, higher than the highest reported value of 65%. Optical absorption and emission spectra of Nd:Y2O3 obtained from a low temperature synthesis process were measured. The energy level structure of Nd3+ in the Y2O3 ceramics was determined for a 1mol% Nd concentration. The induced emission cross section was calculated to be in the range of 3.2×10−19–1.1×10−17cm2 for the 1mol% Nd-doped Y2O3 ceramics. Furthermore, a laser line possibly has been identified in this study, in the Nd:Y2O3 ceramic at 1.095μm.

Induced emission cross sections of near-stoichiometric LiNbO3:Mg, Nd

Optical absorption and emission spectra are measured on Nd3+ ion in near-stoichiometric LiNbO3 single crystals codoped with MgO. From the decomposition of the nonpolarized spectra, the Stark splitting scheme is established for 2wt% Nd3+ ion in the near-stoichiometric LiNbO3:Mg, Nd system. The induced emission cross sections are calculated to be 2.70×10−19 and 5.57×10−20cm2 for the π and σ polarizations, respectively, based on the decomposition of the polarized spectra. These values agree well with the reported values of 1.8×10−19 and 5.1×10−20cm2 for the π and σ polarizations of the conventional congruent-melt composition crystal through the branching ratio of emission spectra despite the different approach of calculations and difference in the near-stoichiometric and congruent-melt compositions. This fact shows that the slight difference in the host composition does not affect the cross section. The population inversion threshold is calculated to be 2.0×1016 for the Nd(2wt%) near-stoichiometric LiNbO3:Mg, Nd in the π polarization, the value of which is almost the same as that of 1.5×1016 for Nd:Y3Al5O12, one of the representative laser materials.

Raman scattering, differential scanning calorimetry and Nd 3+ spectroscopy in alkali niobium tellurite glasses

Alkali niobium tellurite glasses have been prepared and some of their properties measured by differential scanning calorimetry and Raman scattering. The vitreous domain was established in the pseudo ternary phases diagram for the system TeO 2–Nb 2O 5–(0.5K 2O–0.5Li 2O). Raman scattering shows that for samples in the TeO 2 rich part of the phase diagram the vitreous structure is composed essentially of (TeO 4) units connected by the vertices, as in the α-TeO 2 crystal. The addition of alkali and niobium oxides causes depolymerization to occur with structures composed essentially of (TeO 3) and (NbO 6) units. Samples with the composition (mol%) 80TeO 2–10Nb 2O 5–5K 2O–5Li 2O, stable against crystallization, were prepared containing up to 10% mol Nd 3+. The addition of this oxide increases the rigidity of the vitreous network shifting characteristic temperatures to higher temperatures. For the 10% Nd 3+ sample amorphous phase separation is assumed to exist from the observation of two glass transition temperatures. Spectroscopic properties such as Judd–Ofelt Ω λ intensity parameters, radiative emission probabilities, and induced emission cross sections were calculated. From these results and also from the emission quenching observed as a function of Nd 3+ concentration, we suggest that these glasses could be utilized in optical amplifying devices.

Stark splitting scheme and an induced emission cross section of TbAlO3

Detailed absorption and emission spectra on TbAlO3 are measured at room temperature and liquid-nitrogen temperature. By decomposition of the spectra, the Stark splitting scheme is established for F76, F75, and D54 multiplets of Tb3+ ions in TbAlO3 together with the peak energies in the Fourier transform infrared spectrum at liquid-nitrogen temperature. The multiplets are split into their maximum number of levels, which shows that the point symmetry is low for the Tb3+ ion site in TbAlO3. An induced emission cross section is estimated using the results of decomposition at liquid-nitrogen temperature to be 3.55×10−19 cm2. This value is comparable to the cross sections reported for Nd:Y3Al5O12, which is a well known solid-state laser material. The population inversion threshold is also estimated for TbAlO3 in comparison with Nd:Y3Al5O12. It is found that the threshold value for TbAlO3 is only about three times larger than that for Nd:Y3Al5O12. This TbAlO3 may have the potential to be a laser material with a visible wavelength at least at low temperature.

Strong Tb3+ emission of TbAlO3 at room temperature

Optical spectra are measured for transparent and colorless TbAlO3 single crystals grown by the Czochralski method in a reducing atmosphere, although those grown in an inert atmosphere show blackbody color due to broadband absorption of Tb4+ ions. This is a report on strong Tb3+ emission spectrum at room temperature of aluminates and relevant crystals which contain the Tb ion as a stoichiometric agent. All fine structures in absorption and emission spectra can be assigned to the intra-4f transitions of Tb3+ ions. Similar concentration quenching is observed in TbxGd1−xAlO3 system to that in the Nd:YAG crystals; however, the quenching is found to be very small compared with that of the Nd:YAG. An order estimate of the induced emission cross section for the strongest emission line is calculated to be about 6×10−21 cm2.

Spectroscopic properties of Tb 3+-doped fluoride glasses

In this paper, the preparation is reported of a new family of Tb-doped fluoride glasses with the following composition: 30BaF 2 + 30InF 3 + 10ThF 4 + 9ZnF 2 + 20RF (where RF = LiF, NaF and KF). These glasses have been used for a systematic study on the optical absorption, excitation and photoluminescence spectral properties from the near UV to the NIR. On the basis of the measured values of densities and refractive indices, the dielectric constant, reflection losses, molar-refraction, Tb 3+ ion concentration in glasses, and several other physical properties were determined. From the measured absorption spectral intensities of five different states, the validity of the Judd-Ofelt model was examined in the evaluation of the intensities, transition probabilities, relaxation rates and radiative lifetime of the 5D 4 luminescent level. The lifetime of the 5 D 4 → 7 F j fluorescence was examined at both 300 K and 77 K and it was found it compared well with the theoretical value. The effects of the alkali cation change on the induced emission cross-section, quantum efficiency and branching ratios of this luminescent level based on the measured and computed fluorescence lifetimes were also studied.

Induced emission cross section of Nd:Y3Al5O12 ceramics

Optical absorption and emission spectra have been measured for Nd-doped Y3Al5O12 ceramics obtained by a urea precipitation method. The optical properties of the ceramics are almost the same as those of single crystals grown by the Czochralski method and floating-zone method, except for a higher background absorption of 2.5–3 cm−1. The energy-level structure for Nd3+ in the Y3Al5O12 ceramics is determined for a 1-at. % Nd concentration. The induced emission cross section for the 1-at. %-Nd-doped ceramic is calculated to be 4.9×10−19 cm2, which falls in the range reported for the Nd:Y3Al5O12 single crystals. The Nd concentration dependence of the emission decay time at the 1064-nm laser wavelength was also measured, and typical concentration quenching was observed. The decay time of the 1-at. %-Nd-doped ceramic is 219 μs, which is slightly smaller than the reported values for single crystals.

Optical properties of Ho 3+: Alkali mixed fluoride glasses

Optical absorption, fluorescence and laser characteristics of Ho 3+ incorporated (1 % molar) glass systems of 48ZrF 4-23BaF 2-8A1F 3-20RF (RF = LiF-NaF or NaF-KF pair) were examined. Physical properties such as density, refractive index, mean atomic volume, molar refractivity and dielectric constant were measured. The measured absorption intensities were matched with the best fit Judd-Ofelt intensity parameters. The effects of the holmium glass chemical compositions were examined for properties such as spontaneous emission probabilities, branching ratios and radiative lifetimes of lasing transitions by the use of the Judd-Ofelt model. Studies were also carried out to understand the mixed alkali fluoride effects on the measured values of induced emission cross sections for the observed luminescent transitions 5 I 7.6, 5 F 5 and 5 S 2 → 5 I 8 of holmium glasses.

Induced emission cross section of Nd:Y3Al5O12 grown by floating zone method

Optical spectra and emission lifetimes are measured for three Nd:Y3Al5O12 crystals grown by the floating zone method. The properties are almost the same as those of crystals grown by the conventional Czochralski method. The induced emission cross sections obtained for the three samples are 7.4, 5.3, and 7.0×10−19 cm2. These values are comparable to those reported so far.

Measurement of induced-emission cross section and line broadening of copper laser lines4pP322−4SD522and4pP122−4SD322

The induced-emission cross section of the copper laser lines $4p^{2}P_{\frac{3}{2}}\ensuremath{-}4S^{2}D_{\frac{5}{2}}$ (5106 \AA{}) and $4p^{2}P_{\frac{1}{2}}\ensuremath{-}4S^{2}D_{\frac{3}{2}}$ (5782 \AA{}) have been measured for He and Ne as buffer gases at different pressures by using an amplification-gain technique. The line broadenings are deduced from the experimental data and compared to the values predicted by a pressure-broadening impact theory.

Glasses with a large laser effect: Nd-phosphate and Nd-fluorophosphate

Nd-phospate glasses with a great laser effect are described. They have large induced-emission cross sections and low thermal distortion. Those glasses can be used in small and medium laser equipment for processing of materials and for measuring techniques. Addition of fluorine (fluorophosphate glasses) produces a lowering of the nonlinear refractive index. Those glasses are particularly suitable for the final stages of large amplifier chains for nuclear fusion experiments. The nonlinear refractive index can be reduced as low as 0.5 x 10(-13) esu.

A simplified method for determination of the induced-emission cross section of neodymium doped glasses

Induced-emission cross sections for the <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">F_{3/2}\rightarrow</tex> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_{11/2}</tex> and <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">F_{3/2} \rightarrow</tex> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_{13/2}</tex> transitions of Nd <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> in glasses can be determined with a satisfactory precision by a simplified method, based on the Judd-Ofelt theory, from the measurement of the integrated absorbance of the 750-nm band and of the effective linewidth of the fluorescence band.

Dependence of the4F&lt;inf&gt;3/2&lt;/inf&gt;&amp;#8594;4I&lt;inf&gt;11/2&lt;/inf&gt;induced-emission cross section for Nd3+on glass composition

Systematic studies of spectral intensities using the Judd-Ofelt (J-O) theory for crystal-field-induced electric-dipole transitions demonstrate that Nd-doped glasses can be tailored for specific laser applications by proper selection of the glass constituents. Variations with glass composition are reported for the following properties: induced-emission cross section, peak fluorescence wavelength, effective fluorescence bandwidth, radiative lifetime, transition probabilities, and fluorescence branching ratios. Both glass network formers and network-modifier ions were changed. In these studies the induced-emission cross section for the Nd <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> , <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">F_{3/2} \rightarrow</tex> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_{11/2}</tex> laser transition was varied by more than a factor of 4 by changing the glass host.

Induced-emission cross sections for the4F3/2&amp;#8594;4I13/2transition in neodymium laser glasses

Induced-emission cross sections for the4 F_{3/2} \rightarrow 4 I_{13/2} transition of Nd3+in several commercial and experimental laser glasses have been determined using spectroscopic data and the Judd-Ofelt treatment of electric-dipole transition probabilities.

Tailoring Nd-doped glasses for laser applications: Dependence of induced-emission cross sections on composition

Tailoring Nd-doped glasses for laser applications: Dependence of induced-emission cross sections on composition

The Spectroscopy of Pr3+ Ions in Aprotic Solvents

Experimental results are reported for a spectroscopic study of Pr3+ ions dissolved in aprotic solvents. A spectroscopic determination of the induced emission cross section for the 3P0 → 3F2 and 3P0 → 3H6 transitions is described; the values obtained were 4.3 × 10−19 cm2 and 2.0 × 10−19 cm2 respectively. Mechanisms for the nonradiative quenching of the fluorescence of the 3P0 level are discussed; radiative efficiency of the 3P0 level was 9.6 × 10−2.

Induced-emission cross sections in neodymium laser glasses

A method for calculating induced-emission cross sections in neodymium laser glasses, based on simple absorbance measurements, has been demonstrated. Absorption and emission transition probabilities of four silicate-base neodymium laser glasses have been characterized in terms of the Judd-Ofelt (JO) model of crystal-field-induced electric-dipole transitions. Absolute absorption intensities in 3669A, ED-2, LSG-91H, and S33 glasses were measured and used to determine three phenomenological intensity parameters for each glass which accounted for the measured intensities to within 5 percent (rms). Emission intensities between the metastable4 F_{3/2} and terminal4 I J levels were then calculated for each glass, together with the4 F_{3/2} radiative lifetime, fluorescence branching ratios, and radiative quantum efficiency. Calculated values of these quantities for 3669A and S33 glasses are compared with measured values appearing in the literature. Using experimental line shapes for the4 F_{3/2} \rightarrow 4 I_{11/2} transitions at 1.06μ, induced-emission cross sections for these glasses were calculated.

Intrinsic Flux Limits for Continuous and Q-Pulse Gain for the 10.6-μ Line of CO2

The limits on flux gain for the 10.6-μ line of CO2 are discussed on the basis of saturation and spectral hole burning. Although an individual P transition is homogeneously saturable, the entire collection of rotational transitions provides a quasi-inhomogeneous character for single-transition operation, which is due to collisional coupling among rotational levels. The experimentally determined cross section for induced emission is shown to agree with the theoretical value upon assuming that approximately 100 rotational levels of the 10°0 vibrational state of CO2 are strongly coupled by collisions. Thus, the induced-emission cross section for a single vib-rotor P branch transition of the 10.6-μ line is found to be 2×10−16 cm2. Using experimentally determined collision cross relaxation rates the cw hole-burning flux is found to be of order 7×105 W/cm2. The hole-burning flux for Q-pulse amplification is estimated to be 1% of the cw value from which one can infer the saturation flux for a single vib-rotor transition to be approx 0.25 W/cm2.