Neodymium-doped Phosphate Glass Research Articles

Luminescence behavior of Nd3+ions doped ZnO-BaO-(Gd2O3/GdF3)- P2O5 glasses for laser material applications

In current study Neodymium doped phosphate glasses were prepared and subsequently the Physical and luminescence properties of these glasses were thoroughly analyzed. In total, eleven absorption bands centered at 352, 431, 474, 512, 526, 583, 626, 683, 746, 803 and 875 nm were observed in absorption spectra. Similarly, the emission spectra of the prepared glasses recorded with 804 nm excitation show three radiative transitions peaks at 873, 1054 and 1333 nm. The luminescence properties of present glasses analyzed theoretically as several radiative properties studied through Judd-Ofelt theory. The emission cross section for 4F3/2→4I11/2 transition of Nd3+ ions, measured to be 11.2 × 10−20 cm2 in the case of oxide and 13.10 × 10−20 cm2 in the case of oxyfluoride glass. Similarly, the calculated and measured branching ratio for oxide glass are 54% and 51% respectively, and for oxyfluoride glass the calculated and measured branching ratios are 53% and 55% respectively. From the FTIR spectra it is noted that the bands correspond to the OH group show low transmittance intensity in oxyfluoride glass than oxide glass which is an evident of low OH contents oxyfluoride glass. In conclusion, from the results of present study reveal that the oxyfluoride glasses reported in present work can be a possible material for laser applications.

Physical, Structural, and Raman Spectroscopic Traits of Neodymium-Doped Lead Oxyfluoride Zinc Phosphate Glass

Nd3+ with composition of (60 - x) P2O5 - 10ZnO - 30PbF2 - (x) Nd2O3 where (0.0 ≤ x ≤ 2.0 mol %) was prepared using a melt-quenching approach to the development of transparent glasses. These glasses have been confirmed to be an amorphous structure through XRD analysis. The glass density, molar volume and ionic packing density were obtained in the range of 3.978-4.157 g cm−3, 41.949 - 41.073 cm3 mol−1 and 0.614-0.624, respectively. Using Fourier Transform Infrared (FTIR) and Raman Spectroscopy, the chemical functional groups and biomolecules of samples were characterised. The FTIR spectra revealed six main bands assigned to P-O, P-O-P, P=O, (PO3)2- and hydroxyl groups (O-H), while Raman shift detected five symmetric and asymmetric bands attributed to P-O-P bonds in Q1 units, (PO4)3- bonds in Q0 units, (PO3)2- bonds in Q1 units, (PO2)− bonds in Q2 units and P=O bonds in Q3 units. It is believed that the proposed oxyfluoride glasses may be useful and suitable applicant to lasing materials and sensors sensitivity.

Neodymium-doped magnesium phosphate glasses for NIR laser applications at 1.05 μm

Neodymium-doped magnesium phosphate glasses with various concentrations of active ion are prepared by melt quenching method and characterized their spectroscopic properties using absorption and emission spectra and decay measurements. Using the Judd-Ofelt analysis, various spectroscopic parameters such as intensity parameters (Ωλ, λ = 2, 4, 6), radiative transition probabilities, branching ratios and radiative lifetimes are evaluated. The near infrared emission spectra are measured by exciting the samples at 808 nm. In the emission spectra, maximum intensity is observed at 1054 nm which corresponds to the 4F3/2 → 4F11/2 transition of Nd3+ ion. The branching ratio, band width and stimulated emission cross-section for the above transition are found to be 0.51, 25 nm and 3.26 × 10–20 cm2, respectively. The decay curves for the 4F3/2 fluorescent level are single exponential nature with decreasing lifetime from 346 to 57 μs with increase in Nd3+ concentration from 0.05 to 4.0 mol%. The results suggest that PMN glasses could be useful as infrared laser sources at around 1.05 μm.

High-power, Joule-class, temporally shaped multi-pass ring laser amplifier with two Nd:glass laser heads

A high-power, Joule-class, nanosecond temporally shaped multi-pass ring laser amplifier system with two neodymium-doped phosphate glass (Nd:glass) laser heads is demonstrated. The laser amplifier system consists of three parts: an all-fiber structure seeder, a diode-pumped Nd:glass regenerative amplifier and a multi-pass ring amplifier, where the thermally induced depolarization of two laser heads is studied experimentally and theoretically. Following the injection of a square pulse with the pulse energy of 0.9 mJ and pulse width of 6 ns, a 0.969-J high-energy laser pulse at 1 Hz was generated, which had the ability to change the waveform arbitrarily, based on the all-fiber structure front end. The experimental results show that the proposed laser system is promising to be adopted in the preamplifier of high-power laser facilities.

Large Optics for the National Ignition Facility

The National Ignition Facility (NIF) laser with its 192 independent laser beams is not only the world’s largest laser but also the largest optical system ever built. With its 192 independent laser beams, the NIF requires a total of 7648 large-aperture (meter-sized) optics. One of the many challenges in designing and building NIF has been to carry out the research and development on optical materials, optics design, and optics manufacturing and metrology technologies needed to achieve NIF’s high output energies and precision beam quality. This paper describes the multiyear, multisupplier development effort that was undertaken to develop the advanced optical materials, coatings, fabrication technologies, and associated process improvements necessary to manufacture the wide range of NIF optics. The optics include neodymium-doped phosphate glass laser amplifiers; fused-silica lenses, windows, and phase plates; mirrors and polarizers with multilayer, high-reflectivity dielectric coatings deposited on BK7 substrates; and potassium di-hydrogen phosphate crystal optics for fast optical switches, frequency conversion, and polarization rotation. Also included is a discussion of optical specifications and custom metrology and quality-assurance tools designed, built, and fielded at supplier sites to verify compliance with the stringent NIF specifications. In addition, a brief description of the ongoing program to improve the operational lifetime (i.e., damage resistance) of optics exposed to high fluence in the 351-nm (3ω) is provided.

Investigation of Refractive Index Profile Induced with Femtosecond Pulses into Neodymium Doped Phosphate Glass for the Purposes of Hybrid Waveguiding Structures Formation

The technique of writing depressed cladding waveguides into Nd:phosphate glass with relatively large mode field diameter in 2-line geometry was reported for the purposes of waveguiding structures formation. The easy to use and accurate technique of induced refractive index measurement was proposed, and it was shown the inefficiency of widespread indirect (numerical aperture) technique of refractive index measurement for such femtosecond written waveguides.

Synthesis and near-infrared fluorescence of K5NdLi2F10 nanocrystals and their dispersion with high doping concentration and long lifetime.

K5NdLi2F10 nanocrystals were synthesized by a novel synthetic route in the liquid phase, which could improve the morphology and reduce the size effectively, for the first time. The luminescence intensities of the K5NdLi2F10 nanocrystals and their dispersion in polyethylene glycol 400 (PEG-400) approximate to that of neodymium doped phosphate glass (3 mol%), while the lifetimes of the nanocrystals alone and when dispersed with Nd(3+) ions (1 × 10(20) cm(-3)) are 303.4 μs and 174.6 μs respectively. Based on the Judd-Ofelt analysis, the emission quantum yield of the dispersion reaches 39.57%. In all, the K5NdLi2F10 nanocrystals and their dispersion have promising applications as liquid laser materials and biological fluorescent markers.

掺钕磷酸盐异形内包层结构光纤激光的输出

掺钕磷酸盐异形内包层结构光纤激光的输出

Waveguides fabricated by femtosecond laser exploiting both depressed cladding and stress-induced guiding core

We report on the fabrication of stress-induced optical channel waveguides and waveguide splitters with laser-depressed cladding by femtosecond laser. The laser beam was focused into neodymium doped phosphate glass by an objective producing a destructive filament. By moving the sample along an enclosed routine in the horizontal plane followed by a minor descent less than the filament length in the vertical direction, a cylinder with rarified periphery and densified center region was fabricated. Lining up the segments in partially overlapping sequence enabled waveguiding therein. The refractive-index contrast, near- and far-field mode distribution and confocal microscope fluorescence image of the waveguide were obtained. 1-to-2, 1-to-3 and 1-to-4 splitters were also machined with adjustable splitting ratio. Compared with traditional femtosecond laser writing methods, waveguides prepared by this approach showed controllable mode conduction, strong field confinement, large numerical aperture, low propagation loss and intact core region.

Energy transfer upconversion on neodymium doped phosphate glasses investigated by Z-scan technique

Time-resolved Z-scan measurements were employed to characterize energy transfer upconversion on the phosphate glass matrix, named PAN (P2O5–Al2O3–Na2CO3), doped with increasing Nd3+ concentrations. It was observed a linear dependence of the upconversion parameter with the dopant agent, which indicates the presence of a static and dynamic energy transfer processes. The critical inversion density was also evaluated for the same set of samples.

Buried waveguide in neodymium-doped phosphate glass obtained by femtosecond laser writing using a double line approach

We fabricate a buried channel waveguide in neodymium-doped phosphate glass using a double line approach by femtosecond laser writing. Raman spectra reveal an expansion of the glass network in the laser irradiated region. Given the stress-induced positive refractive index change, waveguiding between two separated tracks is demonstrated. The refractive index difference profile of the waveguide is reconstructed from the measured near-field mode. Propagation loss is measured by scattering technique. Microluminescence spectra reveal that the Nd3+ fluorescence property is not significantly affected by waveguide formation process, which indicates that the inscribed waveguide is a good candidate for active device.

Determination of the thermo-optic coefficient dn/dT of ytterbium doped ceramics (Sc2O3, Y2O3, Lu2O3, YAG), crystals (YAG, CaF2) and neodymium doped phosphate glass at cryogenic temperature

In this paper, we report the measurements of the thermal expansion coefficient and the thermo-optic coefficient dn/dT for the ytterbium doped cubic sesquioxides (Sc2O3, Y2O3, Lu2O3) at cryogenic temperature. These materials appear to have very interesting properties for setting up high average power laser chains useful for plasma physics and for inertial fusion energy drivers. Measurements have also been done on YAG ceramic and crystal, CaF2 crystal, and neodymium phosphate glass (Hoya, LHG-8).

Concentration dependent fluorescence quantum efficiency of neodymium doped phosphate glass matrix

Abstract In this work, we have studied the optical and thermal properties of Nd-doped phosphate glass matrix. The studied samples have concentration ranging from 0.5 to 5 wt% of Nd 2 O 3 . Here we report the measurements of fluorescence quantum efficiency, η , obtained through the thermal lens technique using a reference sample. Also, the refractive index, n , specific heat, c p , mass density, and the thermal diffusivity and conductivity measurements were performed. The knowledge of these characteristics as a function of neodymium concentration is very important to design optical devices, especially high power solid state lasers.

Efficiency of laser initiation and absorption spectra of PETN

A comparative study of the efficiency of the laser initiation of PETN by the first and second harmonics (1060 and 530 nm) of a neodymium-doped phosphate glass laser was performed. A significant difference in the efficiency of PETN initiation by the different harmonics was revealed: as the initial temperature of the sample increased from 373 to 450 K, the threshold initiation fluence decreased from 3.0 to 0.5 J/cm2; at the same time, the second harmonic failed to initiate PETN even at a fluence of 10 J/cm2. The absorption spectrum of PETN was found to have a weak absorption band with a maximum at λ m = 1020 nm. It was assumed that the high efficiency of initiation by the first harmonic is associated with light absorption (photo-initiation) by this band

Influence of temperature and excitation procedure on the athermal behavior of Nd3+-doped phosphate glass: Thermal lens, interferometric, and calorimetric measurements

In this work, thermal and optical properties of the commercial Q-98 neodymium-doped phosphate glass have been measured at low temperature, from 50 to 300 K. The time-resolved thermal lens spectrometry together with the optical interferometry and the thermal relaxation calorimetry methods were used to investigate the glass athermal characteristics described by the temperature coefficient of the optical path length change, ds/dT. The thermal diffusivity was also determined, and the temperature coefficients of electronic polarizability, linear thermal expansion, and refractive index were calculated and used to explain ds/dT behavior. ds/dT measured via thermal lens method was found to be zero at 225 K. The results provided a complete characterization of the thermo-optical properties of the Q-98 glass, which may be useful for those using this material for diode-pumped solid-state lasers.

Controlling subsurface damage in neodymium-doped phosphate glass

We investigate the removal mechanism of neodymium-doped phosphate glass dominated in loose abrasive grinding and bound abrasive grinding. Moreover, we investigate the surface roughness and subsurface damage change with optical fabrication parameters, such as different spindle speed, load and abrasive size under different grinding processes in details. For a range of experimental conditions, we find that fracture is the principal removal mechanism for loose abrasive grinding, while plastic scratching is the dominating mechanism for bound abrasive grinding. The load has more influence on subsurface damage for bound abrasive grinding than for loose abrasive grinding. However, the spindle speed has different effect on subsurface damage produced with loose abrasive grinding and bound abrasive grinding. Moderate spindle speed and low load is preferred to produce smaller subsurface damage for loose abrasive grinding. Moreover, higher spindle speed and lower load are preferred to plastic scratching for bound abrasive grinding. Bound abrasive grinding produces 4 times lower surface roughness and 3 times lower subsurface damage than loose abrasive grinding.

Silica-clad neodymium-doped lanthanum phosphate fibers and fiber lasers

We have fabricated a neodymium-doped phosphate glass fiber with a silica cladding and used it to form a fiber laser. Phosphate and silicate glasses have considerably different glass transition temperatures and softening points making it hard to draw a fiber from these two glasses. A bulk phosphate glass of composition (Nd <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> )/sub 0.011/(La <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> )/sub 0.259/(P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> )/sub 0.725/(Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> )/sub 0.005/ was prepared and the resultant material was transparent, free from bubbles and visibly homogeneous. The bulk phosphate glass was drawn to a fiber while being jacketed with silica and the resultant structure was of good optical quality, free from air bubbles and major defects. The attenuation at a wavelength of 1.06 μm was 0.05 dB/cm and the refractive index of the core and cladding at the pump wavelength of 488 nm was 1.56 and 1.46, respectively. The fibers were mechanically strong enough to allow for ease of handling and could be spliced to conventional silica fiber. The fibers were used to demonstrate lasing at the <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> 2/- <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> I/sub 11/2/ (1.06 μm) transition. Our work demonstrates the potential to form silica clad optical fibers with phosphate cores doped with very high levels of rare-earth ions (27-mol % rare-earth oxide).

Spectroscopic properties of Nd-doped phosphate glass with a high emission cross section

Neodymium doped phosphate glasses have been prepared by the semi-continuous melting technique. Their absorption and emission spectra have been recorded at room temperature. The Judd-Ofelt theory has been applied to evaluate the stimulated emission cross sections of 4F3/2→4I11/2 transition for Nd3+. The higher stimulated emission cross section, 4.0×10-20cm2, is obtained. The fluorescence decays of the 4F3/2→4I11/2 transition of Nd3+ are measured for the samples doped (0.7-10) wt% of Nd2O3 at room temperature. The concentration quenching of Nd-doped phosphate glass is mainly attributed to cross-relaxation and energy migration. The site-dependent properties of fluorescence spectra and the fluorescence lifetime of the Nd3+-doped phosphate glass (with 2.2wt% Nd2O3) are studied using laser-induced fluorescence line narrowing techniques and the site-to-site variations of optical properties are observed at low temperature.

Optical characterization of Nd^3+:AgBr

The luminescence of silver bromide crystals, doped with neodymium, was investigated over the visible and near-infrared spectral ranges. The emission, excitation, and absorption spectra were measured over a broad temperature range. The absolute luminescence quantum yield was estimated by comparing the luminescence with that of a neodymium-doped phosphate glass, for which the manufacturer gives a value of 0.4. The Judd-Ofelt analysis was applied to both materials, and transition rates, branching ratios, and quantum efficiencies were calculated for all the observed bands. Good agreement was obtained between theory and experiment.

Optical Studies on Rare Earth Lasting Materials

Neodymium-doped borate and phosphate glass specimens have been prepared by melt-quenching technique. Their absorption spectra have been recorded in the region 400 -900 nm. From observed absorption spectra,Judd Ofelt (J0), Omega/sub t/, parameters (t = 2, 4 and 6) have been computed. They have been used to calculate the laser parameters, viz., spontaneous emission probability (A), fluorescence branching ratio (Beeta) and stimulated emission cross-section (Sigma). They exhibit the suitability of the present glass specimen for laser action. The effects of composition and concentration of the dopant on these parameters have been discussed. A comparative study of stimulated emission cross-section of different types of doped glasses has also been made.