Emission Cross Section Of Nd Research Articles

Optical properties of Nd,Th:LaAlO3 demonstrates its potential in high-energy pulsed laser

Report, to the best of our knowledge, the first laser operation of perovskite oxide LaAlO3 doped with 1 at.% Nd ions and 0.2 at.%Th (Nd,Th:LaAlO3). Optical properties of Nd,Th:LaAlO3 were demonstrated. We study the influence of Th dopants on the domain structure and spectroscopic properties of LaAlO3. Under 793 nm diode-pumped excitation, we achieve a continuous-wave laser output at 1080 nm with a slope efficiency of 36 % and an optical-to-optical efficiency of 34 % under a Toc = 5 % output coupler. The emission cross section of Nd,Th:LaAlO3 reaches 3.65 × 10−20 cm2 at 1080 nm, the saturation flux is 5 J/cm2. The fluorescence lifetime reaches 317 μs and the thermal conductivity is 10.3 W/m·K at 25 °C. Considering its excellent mechanical properties and thermal conductivity, Nd,Th:LaAlO3 is a promising high-energy pulsed laser material.

Structure and properties of new fluoro-sulfo-phosphate laser glasses

<p indent=0mm>Rare-earth-doped fluoro-sulfo-phosphate (FSP) glass is characterized by excellent spectroscopic properties and high thermal and chemical stabilities. Therefore, it is a potential candidate for laser glass and high-gain active optical fiber matrix. However, the underlying contributions of compositional variations to the structure and properties of FSP glass systems are still indistinct owing to their complex mixed-anion nature. Herein, the glass-forming region, structure, physical, and luminescent properties of several FSP glasses are characterized. The results show that FSP glasses possess the advantages of fluoro-phosphate glasses such as high rare-earth ion solubility, low refractive index and phonon density of states. Meanwhile, the mixed-anion structure improves the thermal and chemical stabilities, elastic modulus and spectroscopic parameters. The fabricated FSP samples have good glass-forming ability, low nonlinear refractive index (minimum: <sc>1.2×10⁻¹³ esu</sc>), good thermal stability (∆<italic>T</italic>_max=181°C), chemical stability (DR_min=<sc>0.7×10⁻⁷ g cm⁻² min⁻¹</sc>) and relatively high elastic modulus (<italic>E</italic>_max<sc>=68.8 GPa).</sc> The maximum emission cross-section of Nd³⁺:⁴F_3/2 →⁴I_11/2 is <sc>3.3×10⁻²⁰ cm²,</sc> effective linewidth is <sc>32.1 nm,</sc> lifetime is <sc>372 μs</sc>, and FOM and gain bandwidth are <sc>1.2×10⁻²³ s cm²</sc> and<sc>105.9×10⁻²⁷ cm³,</sc> respectively. These results are higher than those of phosphate or fluoro-phosphate laser glasses, indicating the broad application prospects of FSP glasses in laser glass, fiber lasers and amplifiers.

Effects of Sr2+ content on microstructure and spectroscopic properties of Nd3+ doped Ca1-xSrxF2 transparent ceramics

CaF2-SrF2 hosts with substitution disorder of Ca2+/Sr2+ sites in the lattice provide lower local symmetry for RE3+ ions compared with pure CaF2 or SrF2 hosts, thereby facilitating more efficient 4f → 4f transitions. Here we report a study of effects of Sr2+ content on microstructure and spectroscopic properties of Nd3+ doped Ca1-xSrxF2 transparent ceramic. Phase and microstructure analyses show that when x is in the range of 0–0.25, Nd: Ca1-xSrxF2 nanoparticles keep pure CaF2 phase with their size, morphology and agglomeration degree mildly changed. Increasing x from 0 to 0.2 significantly improves the luminescence intensity, emission lifetime and emission cross-section of Nd: Ca1-xSrxF2, however, hardly affects the concentration quenching. The luminescence intensities and emission lifetimes of x = 0.2 and 0.25 samples are very close, probably indicating SrF2 phase has already formed in x = 0.25 sample. Based on the spectroscopic properties, the optimal Sr2+ content is found to be x = 0.2.

Diode-pumped actively Q-switched Nd:GGG laser operating at 938 nm

The stimulated emission cross-section of Nd:GGG crystal in 938 nm transition was measured by the amplifier approach. It is 2.3×10 −20 cm 2. A quasi-continuous-wave diode pumped, actively Q-switched Nd:GGG laser operating at 938 nm was demonstrated. Pumped by laser diodes with 900 W peak power and 300 μs pulse duration, it generated 168 mJ energy in long pulse mode. The slope efficiency was 36%. Q-switched by a KD⁎P Pockels cell, 41 mJ output pulse energy was obtained. The pulse duration and peak power were 120 ns and 340 kW, respectively. The optical to optical efficiency was 7%.

Variation of the stimulated emission cross section in Nd:YAG caused by the structural changes of Russell-Saunders manifolds

It was experimentally found that electronic structures of Russell-Saunders manifolds in Nd:YAG depended on the Nd3+-doping concentration (CNd) and its fabrication process. Both of the bandwidth and the branching ratio in fluorescent transitions in Nd:YAG varied almost linearly depending on CNd, and a fabrication process has its own diluted limit of the bandwidth and the branching ratio. Also dependences of Stark splitting in Nd:YAG were also observed. Nd3+-doping causes 1.9% and 4.5% reduction in the stimulated emission cross section of Nd:YAG per 1at.% of CNd at 1.064 μm and 1.319 μm, respectively.

Temperature dependence of the emission cross section of Nd:YVO_4 around 1064 nm and consequences on laser operation

We propose an accurate measurement of the evolution of the emission cross section of Nd:YVO4 versus temperature around 1064&#x2009;nm. This was done by using two complementary methods involving spectrum acquisition and laser oscillator small signal gain measurement. We observed a 44% decrease of the peak emission cross section for a 64&#x2009;&#xB0;C temperature increase but also a shift of the peak emission cross section wavelength at a rate of 3&#x2009;pm/&#xB0;C. The influence of the crystal temperature on the performance of a laser oscillator in continuous wave was also investigated.

Spectroscopic properties of Nd 3+ doped transparent oxyfluoride glass ceramics

In this paper, the spectroscopic properties of Nd 3+ doped transparent oxyfluoride glass ceramics containing LaF 3 nano-crystals were systematically studied. The formation and distribution of LaF 3 nano-crystals in the glass matrix were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Based on Judd–Ofelt theory, the intensity parameters Ω t ( t = 2, 4, 6), spontaneous emission probability, radiative lifetime, radiative quantum efficiency, width of the emission line and stimulated emission cross-section of Nd 3+ were evaluated. Particularly, the effect of Nd 3+ doping level on them was discussed. With the increase of Nd 3+ concentration in the glass ceramic, the experimental luminescence lifetime, radiative quantum efficiency and stimulated emission cross-section vary from 353.4 μs, 78.3% and 1.86 × 10 −20 cm 2 to 214.7 μs, 39.9% and 1.52 × 10 −20 cm 2, respectively. The comparative study of Nd 3+ spectroscopic parameters in different hosts suggests that the investigated glass ceramic system is potentially applicable as laser materials for 1.06 μm emission.

Comparative study on the spectroscopic properties of Nd:GdVO/sub 4/ and Nd:YVO/sub 4/ with hybrid process

We have proposed a hybrid procedure for determining spectroscopic parameters for uniaxial solid-state laser crystals. Using our procedure, the spectroscopic properties of Nd:GdVO/sub 4/ were evaluated and compared to those of Nd:YVO/sub 4/. As a result, the peaks of absorption and stimulated emission cross sections of Nd:GdVO/sub 4/ in /spl pi/-polarization were determined to be 2.6 and 10.3/spl times/10/sup -19/ cm/sup 2/, respectively, and were smaller than those of Nd:YVO/sub 4/. On the other hand, the fluorescence lifetime of 1 at% Nd:GdVO/sub 4/ was evaluated to be 83.4 /spl mu/s, and was similar to 84.1 /spl mu/s of 1 at% Nd:YVO/sub 4/. Therefore, the product of stimulated emission cross section and fluorescence lifetime (/spl sigma//sub em//spl tau//sub f/ product) of Nd:GdVO/sub 4/ was smaller than that of Nd:YVO/sub 4/ under 1 at% of Nd/sup 3+/ doping concentration. The radiative lifetime of spontaneous emission of Nd:GdVO/sub 4/ was 168 /spl mu/s and was 1.9 times longer than that of Nd:YVO/sub 4/. Because of the low value of radiative quantum efficiency of Nd:GdVO/sub 4/ (50%), careful cavity design is required for creating a well performing solid-state laser with Nd:GdVO/sub 4/, based on the larger /spl sigma//sub em//spl tau//sub f/ product rather than the /spl sigma//sub em//spl tau//sub f/ product of Nd:YAG.

High-power Nd:GdVO 4 laser at 1.34 μm end-pumped by laser-diode-array

A diode-end-pumped high-power Nd:GdVO 4 laser operating at 1.34 μm has been demonstrated. The maximum continuous-wave output power of 4.62 W was obtained at the incident pump power of 14.75 W, with the corresponding optical conversion efficiency of 31.3% and the average slope efficiency of 33.1%. By using the experimentally measured threshold pump power and slope efficiency, the stimulated emission cross-section of Nd:GdVO 4 crystal at 1.34 μm was determined to be 1.78×10 −19 cm 2 .

Compact and efficient 32-W diode-pumped Nd:YVO_4/KTP green laser

We demonstrate a simple way to achieve single-frequency operation by using fiber-coupled diode-pumped Nd:YVO(4)/KTP green lasers in a short standing-wave linear cavity. A single-mode output with 3.2-W green power was generated with a 12.6-W pump power corresponding to a conversion efficiency of 25.4%. The single-mode operation was obtained through the combined action of the anisotropic emission cross section of Nd:YVO(4) and the KTP crystal acting as a birefringent filter.

Theoretical and experimental studies of single-mode operation in diode pumped Nd:YVO 4/KTP green laser: influence of KTP length

We present a theoretical study of the single-mode operation in a diode pumped Nd:YVO 4/KTP green laser by considering the combined action of the anisotropic emission cross-section of Nd:YVO 4 and the KTP crystal acting as a birefringent filter. The influence of the KTP length on the performance of single-mode operation was investigated. Comparison between theoretical predictions and experimental results is presented.

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.

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.

CW laser operation of Nd:YLF

CW laser operation of Nd:YLF is reported for the first time and, in a comparison to Nd:YAG, exhibits a lower threshold and higher single-mode average power. The TEM 00 mode volume of Nd: YLF was observed to be a factor of four larger than Nd:YAG, resulting in twice the TEM 00 mode average power. This result is attributed to the substantially lower thermal lensing of YLF with respect to YAG. In comparative measurements the stimulated emission cross section of Nd:YLF was found to be 1.8 \times 10^{-19} cm2for the π oscillation and 1.2 \times 10^{-19} cm2for the σ oscillation, as compared to 2.4 \times 10^{-19} cm2for Nd:YAG. The spectroscopic and lasing parameters of Nd:YLF indicate a potential for this material in high peak and average power Q -switched applications.

Laser emission cross section of Nd:YAG at 1064 nm

The stimulated emission cross section of Nd:YAG (yttrium aluminum garnet) (4F3/2→4I11/2) was compared to the known cross section of Nd:ED-2 glass at 1060 nm. Small samples of Nd:YAG and ED-2 glass were end pumped with a chopped cw 514.5-nm argon-ion laser in an identical geometrical arrangement. The stimulated emission cross section obtained for Nd:YAG at 1064 nm was found to be 7.6 ×10−19 cm.

Large stimulated emission cross section of Nd 3+ in chlorophosphate glass

We have investigated the spectroscopic properties of Nd 3+ in a series of sodium chlorophosphate glasses. Glasses with 30–40 mol.% ZnCl 2 have the largest stimulated emission cross section for the 4 F 3/2 → 4 I 11/2 transition we have measured for any glass. The large cross section in this mixed anion glass is attributed to a combination of a large line strength, narrow emission bandwidth, and favorable nephelauxetic shift.