CW laser properties of Nd:GdYAG,Nd:LuYAG,and Nd:GdLuAG mixed crystals

Three mixed crystals, Nd:GdYAG, Nd:LuYAG, and Nd:GdLuAG, were grown by Czochralski method. We report the continuous-wave (CW) Nd:GdYAG, Nd:LuYAG, and Nd:GdLuAG laser operation under laser diode pumping. The maximum output powers are 4.11, 5.31, and 7.47 W, with slope efficiency of 73.0, 55.3, and 57.1%, respectively. With replacing Lu³⁺ or Y³⁺ ions with large Gd³⁺ ions, the pump efficiency increases.     

Comparison of cw laser performance of Nd:KGW, Nd:YAG, Nd:BEL, and Nd:YVO4 under laser diode pumping

4 crystals under low-power laser diode end-pumping. Output power dependencies on the pump power and the pump wavelength of these diode-pumped solid state lasers were investigated. The high Nd³⁺ concentration of the Nd:KGW samples used in our measurements as well as up-conversion and exited-state absorption processes in Nd:KGW cause the reduced laser output power dependence on the pump wavelength which was experimentally observed. At pump levels up to 270 mW a slope efficiency of η_sl≈46% was reached for the Nd:KGW laser. Nd:KGW microchip laser operation with a slope efficiency of η_sl≈50% was demonstrated. Thermal lensing in Nd:KGW at pump powers up to 3 W was measured. Received: 4 August 1997     

Effective moment of inertia in132Ce,134Nd and136Nd

The effective moment of inertiaI _eff ⁽²⁾ of¹³²Ce,¹³⁴Nd and¹³⁶Nd produced in⁴⁰Ar induced reactions has been deduced from continuumγ-ray spectra measured by sum spectrometer methods. Results concerning the deformation of these nuclei are obtained by comparison of the experimental data and calculations in the frame of a cranking Nilsson — Strutinsky model.     

Effect of Nd concentration on the Nd:KGW laser

The effect of Nd concentration on the laser performance at 1064 nm from Nd:KGW has been studied in a single flash-lamp cavity. The Nd concentrations used were 3, 5, and 6 at.% in 6 mm diameter and 80 mm long KGW rods. The 5 at % Nd-doped KGW rod was found to have the highest laser extraction efficiency as compared to the 3 at.% and 6 at.% rods.     

Infrared spectroscopy of the Nd3+ ion in Nd2BaCuO5 and Nd2BaZnO5

Absorption spectra of the Nd³⁺ ion in the Nd₂BaCuO₅ and Nd₂BaZnO₅ ternary oxides were measured within broad spectral (1500–17000 cm^?1) and temperature (4.2–200 K) intervals. The positions and widths of the Stark sublevels were determined. The exchange splittings of the Nd³⁺ Kramers doublets in several multiplets were found for the magnetically ordered state of Nd₂BaCuO₅ (T _N =7.5 K).     

Enhanced susceptibility in LNiO3 perovskites ( L = La,Pr,Nd,Nd0.5Sm0. 5)

The temperature dependence of the resistivity rho(T) and of the dc magnetic susceptibility chi(T) were measured on high-quality LNiO3 (L = La,Pr,Nd,Nd0.5Sm0.5) samples synthesized under high oxygen pressure. Subtraction of the rare-earth contribution to chi(T) allows the presentation of the evolution of the susceptibility of the NiO3 array from Pauli to Curie-Weiss paramagnetism with decreasing bandwidth. A metal-insulator transition occurring at a temperature T(t) = T(N) is first order for L = Pr and Nd; it becomes second order and produces no anomaly in chi(-1)(T) at a T(t)>T(N) for L = Nd0.5Sm0.5. In the antiferromagnetic domain T相似文献   

Laser properties of yag: Nd,Cr, Ce

Summary Transient absorption of a long lifetime ( 20 s) of YAG: Nd is typical of pure material. It is the main reason of thermal deformation of the laser rods accompanied with power decreases at higher CW input. It may be prevented by an admixture of Fe, Ti or Cr. Using a small admixture ( 10^–3 wt.%) of Ti or Cr the energy transfer among Nd ions and the gain coefficient may be increased. Cr in a higher concentration absorbs the pumping light and serves as earlier described coactivator (sensitizer) only. Fe impurity fully prevents any increase of the gain of YAG: Nd containing Ti or Cr and causes slow but irreversible degradation of the active parameters. Ce favourably modifies properties of YAG: Nd, Cr. YAG: Nd, Cr, Ce free of iron impurity is advisable active material for powerfull CW lasers.     

Large-field-of-view, high-gain, compact diode-pumped Nd:YAG amplifier

We present a compact diode-end-pumped Nd:YAG amplifier with a FWHM angular bandwidth of 100 degrees . Using a 1.064-microm probe beam, we measured a 2-pass gain of 23 (13.6dB) and a 4-pass gain of 420 (26.2dB). High-gain image amplification with such a laser amplifier is also demonstrated.     

稀土Nd,Ce掺杂硅基薄膜光致发光特性

测量了Nd,Ce稀土离了注入Si基晶片，在不同离子注入剂量、不同退火条件下的室温光致发光（PL）谱，结果表明它们均具有蓝、紫发光峰，且发光稳定。在一定范围内发光效率随掺杂浓度的增加而增大，随退火条件的不同而改变。运用原子力显微镜（AFM）对样品的表面形貌进行了观察，结果显示，样品表面颗粒大小、粗糙度将影响其发光效率。表面颗粒大小均匀，均方根粗糙度小的样品发光效率较高。通过对样品的卢瑟福背散射（RBS）能谱测量，对样品的表面结构进行了探讨，并讨论了表面结构与光致发光特性之间的联系。对样品的发光机理作了初步探讨。     

Laser properties of YAG: Nd,Ti

YAG: Nd containing 10^–3 wt% Ti showed slightly increased losses at 1·064 m but a substantially increased gain coefficient if compared with a material containing no Ti. The increased losses may be attributed to the increased absorption near 1·064 nm and the increased gain to the better energy coupling among Nd³⁺ ions occupying nonequivalent sites due to the presence of Ti³⁺ ions. YAG: Nd, Ti may be used as a high performance pulsed laser.     

250 mJ, self-adaptive, diode-side-pumped Nd:YAG slab laser

A scheme of self-adaptive, closed-loop, diode-side-pumped Nd:YAG slab laser was presented. As a result of four-wave mixing of standing waves intersecting at a small angle in a closed-loop cavity, the self-adaptive process of beam cleaning leading to fundamental mode operation despite severe asymmetry of the inversion profile and thermal-optical distortion was achieved. The output beam was extracted from the cavity as the first- order diffraction beam on the dynamic gain gratings created in an active medium. The near-diffraction-limited (parameter M(2)<1.4, divergence of 1 mrad) output beam of 250 mJ energy and the optical slope efficiency of 30% at a repetition rate of up to 25 Hz in a free-running regime were demonstrated.     

High-power, longitudinally fiber-pumped, passively Q-switched Nd:YAG oscillator-amplifier

A longitudinally fiber-pumped, passively Q-switched Nd:YAG laser oscillator-power amplifier system is reported with which a maximum pulse energy of 68 mJ was achieved at high pulse stability, beam quality, and efficiency. Therefore, a compact fiber-coupling interface was developed for stacked arrays of quasi-cw diode lasers, providing a pump power of 1 kW at the fiber end.     

Edge-pumped, folded zig-zag Nd:YAG slab laser

 We report the design and performance of conduction-cooled, edge-pumped, folded zig-zag continuous wave Nd:YAG slab laser. The Nd:YAG slab is pumped with waveguide coupled laser diode bars. The coupling efficiency of waveguide to laser diode radiation is 97%. In a folded zig-zag resonator, a maximum output power of 37 W in multimode operation is achieved for an incident pump power of nearly 180 W on the Nd:YAG slab. This corresponds to an optical-to-optical conversion efficiency of 20% and slope efficiency of 32%. We obtained more than 10 W of output power with the beam quality factors in the width dimension and in the thickness dimension equal to 8.     

Highly Stable, Diode-Pumped Nd：YLF Regenerative Amplifier

We present the design and experimental results for a diode pumped Nd：YLF regenerative amplifier applied to amplify a nanosecond laser pulse. Numerical simulation shows that the maximum output energy and the best stability can be obtained when the regenerative amplifier operates in a saturated mode for all pulse duration and temporal profiles. Using extra post-pulse is a good method to decrease the square-pulse distortion caused by gain saturation effect. The amplifier shows output energy of 4.2mJ with a total energy gain of more than 10^7 and output energy stability of better than 1% rms. When extra post-pulse is added, square-pulse distortion is decreased from 1.33 to 1.17 for the amplifier that is seeded with an optical pulse of 3ns.     

Efficient diode-end-pumped dual-wavelength Nd, Gd:YSGG laser

We demonstrate a dual-wavelength laser based on a new laser material-Nd, Gd:YSGG, or Nd:GYSGG for short-for the first time to our knowledge. Besides its attractive properties such as antiradiation, high segregation coefficient, etc., this kind of laser crystal also shows excellent laser performance. For continuous-wave operation, the maximum output power is 10.1 W with the absorbed power of 18.45 W at 808 nm, corresponding to the slope efficiency of nearly 60%. The maximum single pulse energy and peak power reach 277 μJ and 4.6 kW (60 ns) when the absorbed pump power is 11.4 W for acousto-optic Q-switched operation.     

Energy transfer in Ce, Nd, and Yb co-doped YAG phosphors

A Dy3+-doped LiYF4 single crystal capable of generating white light by simultaneous blue and yellow light emission of phosphorescent centers is produced.Chromaticity coordinates and photoluminescence intensity vary with excitation wavelength.Under 350,365,and 388 nm excitation,the crystal shows excellent white light emission.The most efficient wavelength for white light is 388 nm.The CIE coordinates are x=0.316 and y =0.321,and the color temperature(Tc) is 6 368 K.These results indicate that the studied crystal is a potential candidate for ultraviolet light-excited white light-emitting diodes.     

Radially polarized,actively Q-switched,and end-pumped Nd:YAG laser

In this paper, we demonstrated an actively Q-switched, radially polarized, and laser-diode end-pumped Nd:YAG laser with an acousto-optic modulator as the Q switch and a photonic crystal grating as the output coupler. The laser generated pulses of 26.4–67.2 ns duration, and the repetition rate can be continuously adjusted from 500 Hz to 9.238 kHz with peak power up to 7.75 kW. Such a radially polarized pulse would facilitate numerous applications.     

Nd pentaphosphate lasers

Nd pentaphosphate is a crystalline material with very high Nd concentration (30 times higher than 1 % Nd doped YAG) and yet low concentration quenching. It is an excellent material to construct optically pumped, miniaturized, low threshold lasers, oscillating at 1.05sm. Material characteristics including spectroscopic properties relevant to laser properties are reviewed. Experiments on pulsed and CW laser action in this material including the recent achievement of a miniaturized fibre laser with only 12×12 um cross section are summarized.