Laser characteristics of KCL:O-2

Amplified spontaneous emission and laser action have been observed at 77 K in KCL crystals containing the superoxide ion (O^-₂). The laser operates in two bands of width ～50 Å centered at 6350 Å and 5984 Å. These bands are the (lattice) phonon sidebands of vibronic transitions of the superoxide ion. At lower temperatures (～6 K) amplified spontaneous emission is observed in the zero phonon line at 6294 Å.     

Direct observation of fluorescence narrower than the natural linewidth

Forty-MHz-wide fluorescence has been seen using the 80-MHz-wide 2852 Å transition of ²⁴Mg atoms in an atomic beam irradiated by a doubled cw dye laser.     

A coherent light source,widely tunable down to 16 μm by stimulated Raman scattering

An infra-red emission tunable down to 16 μm is produced by a hydrogen Stokes shifted dye laser. The peak power measured at 16 μm is of ca. 50 kW in 2 ns within a one millimeter diameter beam. The corresponding light flux of the order of 5 MW cm^-2 could allow a multi-step vibrational excitation of molecules absorbing down to 16 μm. Simultaneous emissions from the laser and from the previous Stokes bands are available at: 0.76, 1.62, 2.09 μm with respective peak powers of 550, 50 and 20 MW. Spectral widths of 0.8 cm^-1 and of ca. 7 × 10^-2 cm^-1 are obtained for the dye laser and for each of the Stokes band respectively.     

Microfabrication techniques used in Japan for VLSI and other devices

Lead films of thickness 100 Å, 250 Å. and 350 Å were vacuum deposited on AI and laser treated in air using single pulses (7 ns FWHM) from a Nd: glass laser operating in TEM₀₀ mode, at peak energy densities of 1.5-5.0 J/cm². Rutherford back-scattering of 1.8 MeV He⁺ ions was employed to determine the depth profiles of Pb in Al. Up to about 1.4 J/cm², we observe only evaporation loss of Pb and formation of Pb-rich cells on the surface. At higher energies, liquid phase diffusion of Pb is observed up to 4 J/cm², beyond which convection effects are seen. A quantitative analysis of data for 350 Å film at 3.0 J/cm² shows evidence of nonequilibrium segregation effects.     

Volume effect of laser produced plasma on X-ray emissions

An investigation of x-ray emission from Cu plasma produced by 1.054 μm Nd:glass laser pulses of 5 ns duration, at 2 × 10¹² − 2 × 10¹³ W cm⁻² is reported. The x-ray emission has been studied as a function of target position with respect to the laser beam focus position. It has been observed that x-ray emissions from ns duration plasma show a volume effect similar to subnanosecond plasmas. Due to this effect the x-ray yield increases when target is moved away relative to the best focal plane of the laser beam. This result supports the theoretical model of Tallents and has also been testified independently using suitably modified theoretical model for our experimental conditions. While above result is in good agreement with similar experimental results obtained for sub-nanosecond laser produced plasmas, it differs from result claiming filamentation rather than pure geometrical effect leading to x-ray enhancement for ns plasmas.     

Impurity photoluminescence in GaAs/Ga1−xAlxAs multiple quantum wells

Luminescence experiments have been performed on Multiple Quantum Wells structures with well thicknesses varying between 100 Å and 1000 Å. Varying the laser excitation density between 10mW cm^?2 and 5 kW cm^?2 allows to separate different bands related to hydrogenic impurities. The position of these bands are compared to the results of theoretical calculations on the binding energy of the impurity and on subband position. All our results are consistent with the calculations.     

The electronic spectrum of tantalum hydride and deuteride

The diatomic molecule tantalum hydride (TaH) and its isotopologue tantalum deuteride (TaD) have been detected for the first time by laser excitation spectroscopy. The gas-phase molecules were produced in a hollow cathode discharge. Two red-degraded bands, one arising from TaH at 636 nm and the other from TaD at 635 nm, have been recorded at sub-Doppler resolution by intermodulated fluorescence spectroscopy. A rotational analysis shows that both bands are Ω = 2←2 in character, with well-resolved Ω-doubling in the upper state of TaH. Analysis of the ¹⁸¹Ta magnetic dipole and electric quadrupole hyperfine structure reveals that the lower X³Φ₂ electronic state of the two transitions arises from a σ²πδ electronic configuration, in agreement with previous theoretical calculations. The bond length in the TaH X³Φ₂ (v = 0) level is found to be 1.756960(4) Å.     

Operation of a high power,broadly tunable infrared dye laser

We discuss the operation and performance of a ruby pumped infrared dye laser with a wide tuning range and a high out-put power. The longitudinally pumped infrared laser was operated in the Littrow configuration without an intracavity beam expander. The dye, IR 125, exhibited a tunability range that extended from 8325 Å to 9375 Å. The dye laser had a pulse duration of 20 ns and an output power of 12.5 MW with a 2.3 joule ruby pump. The maximum output power of the infrared laser was limited by the damage threshold of the tuning element.     

Narrow linewidth,short pulse operation of a nitrogen-laser-pumped dye laser

Subnanosecond pulses, of 0.02 Å bandwidth, are generated by a nitrogen-laser-pumped dye laser with intracavity double prism beam expander, and holographic diffraction grating. Pulsewidths to below 450 ps, with peak powers greater than 10 kW, are obtained from 200 kW, 3.5 ns pumping pulses.     

Dye Laser for Absorption Trace Analysis of Sodium

The advent of organic dye lasers made possible many experiments in physics, chemistry and biology. Most of these applications are based on the possibility to tune dye laser emission almost at any wavelength between 3400 Å and 12000 Å.This quality combined with high light power made feasible multiphotone absorption, selective absorption and fluorescence experiments. Recently a group of authors published the papers: “Enhancement of absorption spectra by dye laser quenching I and II”^1,2 which start a new field of applications of dye lasers. Namely if a weak absorber is placed inside the broad band laser cavity the absorption is enhanced and this results in the same absorption bands or lines observable in the spectrally resolved laser output. This effect can be used for detection of the traces of elements as a complementary method to the classical absorption spectroscopy but with much higher sensitivity. Same method could be also very useful for detection of transient species with a very short lifetimes.     

Ionenlaser hoher Leistung

Investigations on ion lasers with large bored tubes (7 ... 15 mm I.D.) without additional axial magnetic field are performed. An axial magnetic field is shown to be not necessary to achieve high laser power. By absence of additional magnetic fields the laser construction is considerably simplified. Experimental criterions for maximum laser power are derived by means of a previously published theoretical paper. 120 W total power summed up over the 4p-4s Argon II transitions in the visible part of the spectrum, and 1.5 W ultraviolet power in Argon (3638 Å, 3511 Å) and Krypton (3507 Å) are obtained in continuous mode operation. High inversion densities of 7 · 10⁹ cm^?3 give rise to non-resonant laser oscillations. By multipass amplification the spontaneous emission is amplified up to 20 W/cm², having a beam divergence of about 10^?4 rad. All results are pointing out the influence of radiation trapping effects on the laser power to be smaller than estimated and measured by other authors using conditions deviating from our optimum conditions for maximum laser power.     

人脑脊液中的光偏振及荧光特性

本工作对基本正常人的脑脊液和有神经系统疾病的人脑脊液进行了光偏振及荧光物理特性的测量,对脑脊液的荧光5450Å进行荧光平均寿命测量,并在Ar激光4880Å的监控下,测量了荧光5450Å的强度与照射时间的关系,得到了一些有益的提示。除此之外,我们还测量了OH键Raman带在振动频率Δv=3392cm-1的退偏度,退偏度POH=0,计算了吸收振子和被辐射振子之间的夹角,证明了在人的脑脊液分子中的OH键振动是完全对称的振动,其极化强度是各向同性的。     

The Rotational Analysis of the Five new Vibronic Bands of No2 in the Range 5050-5200 Å

The five new vibrational bands in the range 5050-5200 Å of the laser induced fluorescence excitation spectra of NO₂ were measured and rotationally assigned at room temperature. Though the spectra were rather congested, we can determine the band origins, and rotational and spin-rotation constants for these bands. All rotational structures analyzed are of the parallel type. It was shown that the electronic excited state òB₂ were heavily perturbed by the high lying vibration levels of ground state [Xtilde] ² A ₁ and that the interactions between these two electronic states was the main rationale for the complexity of NO₂ visible spectra.     

六束高功率钕玻璃激光器

本文描述了用于辐照[(CD₂)_n]微球靶的六束高功率钕玻璃激光系统的概貌、有关技术细节以及输出光束特性。激光脉宽在1—4毫微秒内可调。在脉宽为2毫微秒时,每束输出能量约为50焦耳,光束发射角为0.4毫弧度,六束总输出功率约为1.5×10¹¹瓦。 关键词：     

Observations on the electronic spectrum of gaseous FeO

About 400 lines are assigned to FeO emission bands in the region 5580 to 6265 Å. The lower state of all the bands analyzed is identified as the ground state of the molecule, for the value of the lower-state vibration frequency (ω_e = 880.61 ± 0.02 cm^?1) is in excellent agreement with that observed in low-temperature matrix isolation, itself confirmed by isotopic substitution. This state is also observed as the lower state in laser-induced fluorescence. However, 880 cm^?1 is significantly smaller than the value found in laser photodetachment studies of FeO^? (970 ± 60 cm^?1). The rotational analysis is consistent with a parallel transition, ΔΛ = 0, but the value of Λ is not determined. According to theoretical calculations, the orange bands most probably arise from a ⁵Σ-⁵Σ transition. There is at least one nearby excited state, for all analyzed upper levels are perturbed.     

Long pulse ultraviolet laser emissions in an aerodynamically cooled electron-beam excited Ne-NF3 mixture

Long pulse laser action has been achieved at 3378.28 and 3481.96 Å in an electron beam excited supersonic flow. These laser emissions, attributed to NeII transitions, have been obtained when a mixture of Ne and NF₃ at a pressure of 0.2 atm. and aerodynamically cooled to 80 K was excited by a medium intensity electron beam. Laser pulse duration, about 350 ns fwhm for both lines, was only limited by the electron beam pulse length. The second of these laser lines had not been previously reported.     

Laser-induced fluorescence of metastable xenon ions

Xenon ions in the metastable state 5d ⁴D_{$\text{7}\text{2}$} are excited by means of a tunable dye laser at 6051 Å. The excitation is monitored by non-resonant fluorescence at 5292 Å.     

Fourier spectroscopic investigations of 130Te2 infrared fluorescence and new optically pumped continuous laser lines

Laser-induced fluorescence of ¹³⁰Te₂, excited by Ar⁺ 4765-Å and 4579-Å lines, has been recorded in the infrared by Fourier transform spectrometry. Twelve fluorescence series have been identified and analyzed. A local perturbation has been observed using rotational relaxation lines. With a sealed-off cell of 7 cm leghth at a temperature around 650°C, continuous laser operation on 13 new lines in the range of 0.8 to 1.3 μm has been achieved. Typical threshold pump powers are about 100 mW. Pump and laser transitions are assigned using the obtained Fourier spectroscopic data.     

High-power dye laser in the near infrared

A tunable wavelength, laser beam of very high spectral luminance in the near infrared is obtained by amplification of a monochromatic laser line emitted by a tunable dye oscillator. Optical pumping of the oscillator and the four-stage amplifier is effected by a giant pulse ruby laser. The energy obtained with a solution of 3,3′ dimethyl 2,2′ oxatricarbocyanine iodide (D.O.T.C.) in dimethyl sulfoxyde is 1 J at 7699 Å. The laser pulse of spectral width Δλ = 0.065 Å is emitted at a rate of 0.1 Hz. The half-peak pulse duration is 15 ns.     

Highly efficient,kW peak power, 1.55 µm all-fiber MOPA system with a diffraction-limited laser output beam

We report a high-efficiency, single-mode, all-fiber pulsed laser system built in a master oscillator power amplifier format, operating in the eye-safe (λ ~1,549 nm) spectral range, providing over 1.5 W of average output power with up to 51 dB of total signal gain. It comprises the flexibility of smooth pulse duration control from single ns to 260 ns with independently tunable repetition rate ranging from 40 kHz to 1 MHz. Pulses as short as 4 ns with up to 20 μJ energy and corresponding peak power of 5 kW are demonstrated. The laser system delivered a nearly diffraction-limited beam with M ² ~1.