Induced-emission cross sections for the4F3/2→4I13/2transition in neodymium laser glasses

Induced-emission cross sections for the⁴F_{3/2} rightarrow⁴I_{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.     

A laser augmented reaction: SF6+ SiH4→S*2+ SiF4+ HF + H2· retention of isotopic selectivity during detonation

A single unfocused pulse of a free running CO2laser, area ∼ 8 cm², initiates an explosive reaction between SF6and SiH4. This occurs at a minimum energy of 4 J [full width at half maximum (FWHM)sim 1.5 /mus] of which about one half is absorbed in an 8 cm long cell; total pressure 12 torr; 0.65 <p(SiH4)/p(SF6) < 1.8. The spectral and temporal distributions of the emitted chemiluminescence depend sensitively on the fuel to oxidizer ratio, and on the pulse energy; we investigated the range 4 → 20 J. The principal emission is due to S2(B^{3}Sigma-_{u} rightarrow X^{3}Sigma-_{g}). Transitionsupsilon' (0-4) rightarrow upsilon" (2-15)were recorded. In the³Sigma-_{u}state, vibrational temperatures range from 3000-13000 K. The luminosity peaks sharply at (SiH4)/(SF6) = 1.0 ± 0.05. On each side of the maximum of the emission versus composition curve [at (SiH4)/(SF6) ≈ 0.95 and 1.22, for a 12 J pulse] the residual SF6(0.2-0.5 percent of initial amount) is enriched in³⁴SF6; the observed fractionation factors at these two compositions are 8 ± 2. The separation between the two sharply peaked optimum compositions appears to increase with increasing pulse energy. Preliminary results with other fuels suggest that the concurrent absorption of CO2laser radiation by the fuel, as well as a highly exothermic reaction, are pre-requisite for fine tuning of composition, injected power, and total pressure for optimum isotope fractionation.     

Photoexcitation and photodissociation lasers--Part I: Nitric oxide laser emissions resulting from C(2π) → A(2Σ+) and D(2Σ+) → A(2Σ+) transitions

-1-μm laser emission was detected when NO or NO2was flash-photolyzed, with or without dilution, in the vacuum UV above 165 nm. The emission was identified as theC(²π)rightarrow A(²Sigma+)     

A Gd2(MoO4)3longitudinal electrooptic modulator at 6328 Å

A Gd2(MoO4)3light modulator operating at low frequencies, from 100 Hz up to 1 MHz, is examined. Experimental results concerning the thermal behavior and stability, frequency response, and linearity performance characteristics of the system are presented. Advantages and disadvantages of the modulator are discussed.     

Temperature effects on the fluorescence characteristics of RbMnF3:Nd3+

The absorption, excitation, and fluorescence spectra and lifetimes of Mn²⁺and Nd³⁺in RbMnF3were investigated in the 5 to 300°K region. The fluorescence of Mn²⁺in these systems was found to originate from two metastable levels centered at 5820 and 6300 Å. The Nd³⁺emission appears as two groups of sharp lines centered atsim10 600and ∼8900 Å. Energy transfer from manganese to neodymium is observed even at room temperature where the Mn²⁺fluorescence is completely quenched and the energy transfer mechanism was found to be of nonradiative type. Detailed information was obtained on the temperature dependence of the fluorescence intensities and decay times of the manganese and neodymium emissions. The results give information on the kinetics of these fluorescent systems.     

Laser emission from miniaturized NdAl3(BO3)4crystals with directly applied mirrors

Laser emission from NdAl3(BO3)4crystals of various thickness with directly applied laser mirrors was investigated on a polarization-dependent basis and time-resolved spectra were recorded. CW monomode operation with an output power of 5 mW was attained. Though NAB (NdAl3(BO3)4should be electrooptic (space groupR32), no electrooptic effect was observed by determining the mode shift from the influence of an electric field during laser operation.     

Orientation and thickness dependence of contrast and brightness in Gd2(MoO4)3light valves

Bistable light valves comprising single crystal gadolinium molybdate have been proposed which utilize either the interchange of fast and slow directions in c-cut plates or the alteration of extinction directions in oblique sections upon ferroelectric switching. Several device configurations of each type are analyzed for brightness and contrast as functions of crystallographic orientation and thickness of the ferroelectric plate. The results facilitate quantitative comparisons among devices and predict the sacrifice in optical performance incurred when thickness is reduced to lower the drive voltage required for switching. For equivalent optical performance, the switching voltage should be 43 percent higher in valves of the extinction-direction type. The analysis predicts that no oblique section exists for which display brightness at maximum contrast is higher than that obtainable on a c-cut section of equal thickness.     

Spiking oscillations in diode-pumped NdP5O14and NdAl3(BO3)4lasers

Using quasi-CW sinusoidally modulated excitation from a 0.8-μm-wavelength laser diode, we have obtained driven spiking oscillations in miniature, high-Nd-concentration room-temperature lasers of NdP5O14, and NdAl3(BO3)4. With modulation indices of 0.25 or less, peak-power enhancements of 11 (at 35 kHz) and 7 (at 124 kHz), respectively, have been observed for these materials. Theoretical calculations of these and other characteristics of the driven oscillations are in good agreement with experiment.     

Cr3+→Nd3+ energy transfer and Nd3+ laser action studies of La3Ga5SiO14:Cr3+,Nd3+ co-doped crystal

Energy transfer between Cr³⁺ and Nd³⁺ ions has been investigated in the 4.2-300-K temperature range by using steady-state and site-selective time-resolved laser spectroscopy. Radiative and nonradiative energy transfer has been studied from the time-resolved emission spectra and the donor fluorescence decays. The transfer efficiency was calculated as a function of temperature by using the Cr³⁺ lifetimes of the single doped and co-doped samples. Laser experiments were carried out in a diffusive cavity by pumping a co-doped rod 54 mm long and 5 mm in diameter with xenon flashlamps. The laser spectral emission shows a complex structure which varies as a function of pump energy. The temporal evolution of the laser spectrum is discussed in terms of a simple four-level spectral rate-equation laser model which takes into account the existence of two main broad Nd³⁺ site distributions with a large spectral overlap     

双掺(Ce~(3+)、Nd~(3+)):YAG晶体对撞脉冲锁模的研究

一、引 言 新晶体双掺(Ce~(3+)、Nd~(3+)):YAG是一种具有高转换效率的激光增益介质~[1],它利用Ce~(3+)、Nd~(3+)的敏化途径提高激光效率。晶体中的Ce~(3+)离予通过辐射和非辐射二种方式向Nd~（3+）转     

新型Q开关材料Cr^4＋：YAG的研究概况

Cr^4 ：YAG是新型Q开关材料和近约外（NIR）可调谐激光晶体,作为新型Nd激光可饱和吸收体具有许多传统材料所没有的优点。本文概述了Cr^4 ：YAG的可饱和吸收特性,并介绍了Cr^4 ：YAG晶体生长的主要问题。     

Raman Scattering and Nd3+ Laser Operation in NaLa(WO 4)2

The continuous-wave laser operation of Nd-doped tetragonal NaLa(WO ₄)₂ crystal is studied at room temperature by optical pumping in the spectral region overlapping AlGaAs diode laser emission. This crystal has inhomogeneously broadened optical bands. From the room-temperature spectroscopic parameters determined it is found that the optimum Nd concentration for the ⁴F_3/2rarr⁴I_J laser channels must be in the 3-5 at.% range. For J=11/2 and 13/2 channels (lambdaap1.06 and 1.3 mum) the most favourable polarization configuration is parallel to the crystallographic c axis, while for J=9/2 little polarization dependence of the laser efficiency is predicted. Laser operation was achieved with a 3.35 at.% Nd-doped sample grown by the Czochralski method. The laser operation was tested in an hemispherical optical cavity pumped by a Ti:sapphire laser. Stimulated emission at lambda=1056 nm was achieved for a wide spectral pumping range, lambda=790-820 nm. Stimulated Raman scattering was achieved in the picosecond regime with an efficiency similar to that of monoclinic KY(WO₄)₂ reference compound     

Efficient integrated Nd3+ fiber laser

An efficient, integrated, low-threshold, tunable, laser-diode pumped Nd³⁺ fiber laser has been fabricated. The integrated fiber laser incorporated two highly reflecting intracore Bragg reflectors, which were formed holographically by transversely exposing the core to a UV two-beam interference pattern. When the fiber laser was diode pumped, a maximum output of 2.3 mW was observed at 1.088 μm, and a slope efficiency of 41% was measured     

Output properties of the Nd+3:SeOCl2liquid laser

Laser action in the liquid medium Nd⁺³: SeOCl2is described. Details concerning the cell construction and the dependence of output on cell geometry and optical feedback are presented. Output energies of 13 joules with a differential efficiency of 1 percent are reported. An interpretation is offered for the phenomenon of self-Q-switching or the generation of multimegawatt spikes at low values of optical feedback.     

Pulsed laser action in LiYF4:Er3+, Ho3+at 77°K

Pulsed laser action at 77°K has been demonstrated in LiYF4:Er³⁺, Ho³⁺with an emission wavelength of 2.066 μ. The laser transition is the⁵I_{7} rightarrow⁵I8in trivalent holmium, and there is evidence of energy transfer from erbium to holmium. The fluorescent lifetime is approximately 20 ms, and the pulsed threshold is 40 joules.     

Li-La磷酸盐激光玻璃Cr~(3+)→Nd~(3+)敏化

本文对Li-La磷酸盐玻璃单掺Cr~(3+)离子及双掺Cr~(3+)、Nd~(3+)离子的光谱性质进行了研究,测定了玻璃的吸收光谱、荧光光谱和荧光寿命。Li-La磷酸盐玻璃中Cr~(3+)→Nd~(3+)的能量转移效率为38％,最适当的钕离子浓度为2×10~(21)cm~(-3),Cr_2O_3含量≥0.1wt％。     

Self-Q-switched Nd3+: YAG and ruby lasers

Self-Q-switched operation of Nd³⁺: YAG lasers at 77°K and ruby lasers at 300 and 77°K pumped by the 5145-Å output of a pulsed argon ion laser is described. Self-Q-switched operation was obtained 1) by static mirror misalignment and 2) by static misalignment of the filament of the pumped laser material with respect to the mirror resonator axis. An output that consisted of a single giant pulse could be obtained for ruby by either method; for Nd³⁺: YAG, the output always consisted of one or more giant pulses and characteristic relaxation oscillations.     

Na_2(b~3Σ_g~ )→Na_2(x~3Σ_u~ )发射光谱

用XeF激光的351毫米微来激励Na_2(x~1Σ_g~ )得到c~1Π_u→2~1Σ_g~ 跃迁范围内三条受激发射谱线及b~3Σ_g~ →x~3Σ_u~ 830毫微米至900毫微米准连续发射谱。文中讨论了这两个跃迁的关联并估计了产生激光振荡的可能性。