Neodymium Phosphate Glass Research Articles

Study of active media based on microparticles of solid-state laser materials

Active media based on particles of solid-state laser materials distributed in liquid or gas may provide a new solution to the problem of heat removal from laser media. We propose active media based on particles of LiF crystal with F2 color centers, as well as of Nd3+-doped crystals and glasses. Mixtures of index-matched liquids with glass and crystal particles, methods of their preparation, and their optical characteristics are considered. The laser characteristics of the active media under excitation by nanosecond laser pulses are compared. A “slurry laser” based on a dense mixture of LiF:F2 microparticles with an index-matched liquid is demonstrated. Lasing was obtained in small neodymium pentaphosphate crystals (NdP5O14) and unpolished bulk pieces of concentrated neodymium phosphate glass in immersion liquids.

Nd : glass rod laser with an output energy of

The energy of two orthogonally polarised pulses injected into an available multistage amplifier based on neodymium phosphate glass rods was increased from 300 to (in both pulses). The second output pulse with an energy of will be used to pump an additional parametric amplifier of a petawatt laser.

Effects of side subsurface defects induced by CNC machine on the gain spatial distribution in neodymium phosphate glass

The processing method applied to the side surface is different from the method applied to the light pass surface in neodymium phosphate glass (Nd:glass), and thus subsurface defects remain after processing. The subsurface defects in the side surface influence the gain uniformity of Nd:glass, which is a key factor to evaluate the performance of amplifiers. The scattering characteristics of side subsurface defects were simulated by finite difference time domain (FDTD) Solutions software. The scattering powers of the glass fabricated by a computer numerical control (CNC) machine without cladding were tested at different incident angles. The trend of the curve was similar to the simulated result, while the smallest point was different with the complex true morphology. The simulation showed that the equivalent residual reflectivity of the cladding glass can be more than 0.1% when the number of defects in a single gridding is greater than 50.

钕玻璃抛光过程中杂质颗粒物对划痕的影响

钕玻璃抛光过程中杂质颗粒物对划痕的影响

Neodymium- and copper-bearing phosphate glasses for fabricating large rod-shaped and disk-shaped active elements of lasers and heavy-duty high-energy radiation amplifiers

This paper analyzes the requirements imposed on laser glasses intended for the fabrication of rod-shaped and large disk-shaped active elements with a large aperture for generators and heavy-duty radiation amplifiers. Quantitative data are presented concerning the maximum achievable values of the functionally important basic characteristics of domestically produced neodymium phosphate glasses and the copper-oxide-doped glasses from which absorbing shells (cladding) are fabricated that suppress superluminescence and stray lasing in disk-shaped active elements.

Neodymium glass laser with a phase conjugate mirror producing 220 J pulses at 0.02 Hz repetition rate.

For pumping multipetawatt Ti:sapphire laser facilities we developed a compact repetitively pulsed laser based on neodymium phosphate glass with pulse energy of 220 J, pulse repetition rate of 0.02 Hz, beam diameter of 43 mm, aperture fill factor of 0.8, and FWHM pulse duration of 30 ns. The phase distortions of laser radiation were compensated by optical phase conjugation via stimulated Brillouin scattering. The depolarization was reduced to 0.4% using linear compensation methods. The beam quality was 2.5 x diffraction limit (150 µrad).

Generation of negative pressures and spallation phenomena in diamond exposed to a picosecond laser pulse

The spallation phenomena in poly- and single-crystal synthetic diamonds have been experimentally investigated. A shock-wave impact on a target was implemented using a laser pulse in the Kamerton-T facility. The ablation pressure of on the front target surface was formed by pulsed radiation of a neodymium phosphate glass laser (second harmonic , pulse energy ) with an intensity as high as . The maximum diamond spall strength is found to be 24 % of the theoretical ultimate strength. Raman scattering data indicate that a small amount of crystalline diamond in the spallation region on the rear side of the target is graphitised.

How process factors affect the limiting characteristics of neodymium phosphate glasses for large disk- and rod-shaped active elements

This paper lists the requirements imposed by the designers of powerful high-energy lasers and radiation amplifiers on KGSS 0180 phosphate glasses with various neodymium concentrations, used to manufacture large disk- and rod-shaped active elements. The classical two-stage technology for melting them is described, and a quantitative characterization is given of the extent to which structural water and the neodymium concentration in the glasses affect the maximum achievable luminescence time and quantum yield. A description is given of why inactive absorption of radiation appears at the lasing wavelength and a method for reducing it in the resulting glasses. A method is indicated for reducing the number of inclusions of metallic platinum in the glass, which affect its radiation strength.

Study of Fractal Bond Connectivity of Neodymium Phosphate Glasses by Ultrasonic Technique

Sifat-sifat kenyal untuk kaca neodimium fosfat xNd2O3(1-x)P2O5 dengan komposisi yang berbeza dari 10 hingga 25% mol Nd2O3 telah dikaji melalui kaedah ultrasonik, sebagai fungsi suhu dari 270 K hingga 303 K. Sifat-sifat kenyal yang dikaji antaranya ialah pemalar kekenyalan adiabatik C11, C44 dan modulus pukal, B yang telah diperolehi dari data pengukuran eksperimen. Dalam kajian ini menunjukkan bahawa sifat-sifat kenyal bersandar kepada suhu dan seterusnya memberi maklumat tentang hubungan ikatan fraktal bagi kaca neodimium fosfat yang terletak di antara 2.00 hingga 2.70. Keputusan dari kajian ini menunjukkan bahawa kaca neodimium fosfat mempunyai struktur yang tersusun dalam rangkaian di antara dua dan tiga dimensi. Kata kunci: sifat kenyal; kaca neodimium fosfat; kajian ultrasonik The elastic properties of neodymium phosphate xNd2O3(1-x)P2O5 glasses with different compositions containing from 10 to 25 mole % Nd2O3 has been studied by ultrasonic technique, as functions of temperature from 270 K to 303 K. The elastic properties like adiabatic elastic stiffness coefficients, C11, C44 and bulk modulus, B of the glasses have been determined using the experimental data. The temperature dependence of the elastic properties were used to explores useful information about the fractal bond connectivity of the neodymium phosphate glasses which lies between 2.00 and 2.70. This result indicates that the neodymium phosphate glasses were connected in an array between two and three dimensional network. Key words: elastic properties; neodymium phosphate glasses; ultrasonic studies

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).

Efficient wide-aperture neodymium glass rod amplifiers

Amplifiers based on neodymium phosphate glass rods 60 — 100 mm in diameter are experimentally studied. The amplifiers are pumped by INP-16/250 tubular flash lamps placed in a universal pump cavity with a two-section mirror reflector. A compact high-voltage capacitive energy storage with a preionisation circuit was developed to supply the lamps.

Laser Initiation of Energetic Materials: Selective Photoinitiation Regime in Pentaerythritol Tetranitrate

We describe and analyze the selective (resonance) laser-induced initiation of chemical decomposition reactions in pentaerythritol tetranitrate (PETN, C5H8N4O12) and propose a potential mechanism for the phenomenon. On the basis of our experiments, the photoinitiation of PETN is a two-stage process that is comprised of a laser-induced optical excitation of the molecule with an activation energy of 1.17 eV (1060 nm) by a neodymium phosphate glass laser followed by the thermal decomposition of the excited state with an energy barrier of 0.4 eV. We also illustrate that the small efficiency of the optical absorption of PETN at this wavelength can be enhanced by the MgO light-scattering additives, which significantly increase the absorption due to multiple scattering incidents in PETN. The resonance photoinitiation clearly demonstrates a possibility for designing tunable explosive material systems and identifies ways to control the sensitivity of the materials to rapid decomposition.

Pulse synchronisation in passively Q-switched lasers emitting at 1.053 and 1.064 μm

Pulse synchronisation with an accuracy of no worse than ±5 ns is demonstrated in passively Q-switched neodymium phosphate glass and Nd:YAG lasers. Two operating regimes are realised: the 'sub-threshold' regime (when the slave Nd:YAG laser does not generate a giant pulse if its passive Q switch is not irradiated by the master Nd:glass laser) and the 'above-threshold' regime (when the pulse irradiating the passive Q switch of the slave laser advances its generation).

Influence of the melting temperature and rate of cooling the melt to the glass making temperature on the redox equilibria Fe2+ ⇄ Fe3+ and Cu+ ⇄ Cu2+ in aluminum potassium barium phosphate glasses

This paper reports on the results of the investigation of aluminum potassium barium phosphate glasses that contain copper and iron additives and have compositions similar to the composition of the matrix of the KGSS 0180/35 neodymium phosphate glass used for fabricating large-sized active elements intended for high-power laser amplifiers with a high output energy. The redox equilibrium of iron ions has been studied as a function of the melting temperature of the glass (850, 1100, and 1300°C). The redox equilibrium of iron or copper ions and their contributions to the nonactive absorption coefficient of glasses prepared at the melting temperature (1100°C) or after cooling of the glass melt at different rates to the glass making temperature (850°C) have been investigated. It has been established that a decrease in the melting temperature of the glass leads to a shift in the redox equilibrium of iron ions toward the formation of Fe3+ ions. During cooling of the glass melt from 1100 to 850°C, the redox equilibrium of copper (iron) ions shifts toward the formation of Cu2+ (Fe3+) ions; in this case, the lower the rate of cooling the melt, the larger the shift. At the minimum rate of cooling the glass melt (250°C for 180 min), the contribution of copper ions to the nonactive absorption coefficient increases by 25%, whereas the corresponding contribution of iron ions decreases by 40%.

Compact 300-J/300-GW Frequency-Doubled Neodymium Glass Laser—Part II: Description of Laser Setup

All the basic elements of a 300 J/1 ns Nd:glass laser with high-efficiency (70%) frequency conversion are described in detail. These include a seed laser, a system shaping the spatial structure of the beam, a six-cascade amplifier based on neodymium phosphate glass rods 10-100 mm in diameter, and a second-harmonic generator on a DKDP crystal with ooe interaction. Reliable and easy operation guaranteed long-term functioning of the laser as a pump for the output cascade of a chirped pulse parametric amplifier in a petawatt laser complex.

Diode-array-pumped repetitively pulsed neodymium phosphate glass laser

Repetitively pulsed generation (200 μs, 40 Hz) was obtained in a neodymium phosphate glass laser pumped by a 870-nm diode array. The maximum slope lasing efficiency with respect to the optical pump energy equal to 13% is restricted by the factor (≈0.23) of active-medium filling by the mode field. By adjusting the laser cavity, the single-transverse mode regime, in particular, the generation of the TEM00 mode is obtained in the entire range of pump energies.

Formation of a beam profile at the input to a high-energy laser amplifier

A device consisting of a pin-hole line and an apodizing aperture, which provides the fill factor of the laser amplifier aperture equal to 0.8, is proposed and studied experimentally. The use of this device allowed the generation of 300-J, 1-ns pulses due to the efficient energy extraction from a six-stage neodymium phosphate glass amplifier with the final stage aperture equal to 10 cm.

Generation of high-order Hermite–Gaussian modes in a flashlamp-pumped neodymium phosphate glass laser and their conversion to Laguerre–Gaussian modes

The Hermite–Gaussian modes up to the third order inclusive are generated in a flashlamp-pumped neodymium phosphate laser and converted to the corresponding Laguerre–Gaussian modes in an astigmatic converter. It is also shown that, by using a laser with the gain minimum on the axis of a plane-spherical resonator and changing its Fresnel number, it is possible to excite efficiently Laguerre–Gaussian modes with the field amplitude dependence .

Prototype disc amplifier for ISKRA-6 facility

Eight-channel disk amplifiers of the ISKRA-6 facility are made up of sections. An amplifier section consists of eight active elements (2 x 4) made of KGSS 0180/35-grade neodymium phosphate glass 400 x 690 x 40 mm in size located in frames at the Brewster angle. Twenty flashlamps are arranged in one amplifier module. The flashlamps have an inter electrode distance of 1600 mm, the tube is 40mm in inner diameter. There are presents the results of numerical investigations into the dynamics of high-current pulse radiation discharge. The investigations were carried out by the RMHD-model. The experimental results of spectral measurements and light efficiency of the flashlamps depending on specific power and value of energy contribution are presented.

Effect of coloring impurities on the absorption in neodymium phosphate laser glass at a lasing wavelength

This paper reports on the results of the investigation of KGSS 0180/35 neodymium phosphate glasses produced on an industrial scale under oxidizing conditions and glasses prepared under experimental conditions in which iron and copper in small amounts rather than neodymium are introduced into the glass composition. The experimental glasses are synthesized by varying the redox conditions of melting. The oxidation states of transition metal impurities (Cu, Fe, V, Ni, Co) and the nonactive absorption coefficients of glasses at the lasing wavelength are determined. It is revealed that the main contribution to the nonactive absorption coefficient of the KGSS 0180/35 glass produced on an industrial scale is made by Cu2+ ions at a concentration higher than 0.5 ppm. At a lower copper concentrations, the total contribution of Fe2+, V4+, Ni2+, and Co2+ impurity ions to the nonactive absorption coefficient is comparable to that of Cu2+ ions. It is demonstrated that a decrease in the concentration of coloring impurities in glasses and the optimization of redox conditions of melting make it possible to prepare phosphate laser glasses with a nonactive absorption coefficient of the order of 0.001 cm−1. In terms of the nonactive absorption coefficient, these glasses are on a par with similar glasses of foreign manufacture and satisfy the requirements imposed on glasses by developers of high-power high-energy laser facilities.