Hyperfine spectra in iodine-129 at 612 nm

The complete hyperfine spectrum of a transition in ¹²⁹I₂ at a wavelength of 612 nm that overlaps the spectrum of ¹²⁷I₂ reported by Bennett and Cerez has been obtained, together with parts of the spectra of other transitions in ¹²⁹I₂ and ¹²⁷I₂. The lasers used for this work are described and the frequencies for the various hyperfine components are outlined.     

Optical amplifier for femtosecond frequency comb measurements near 633 nm

An optical amplifier operating at the 633-nm wavelength region is designed for absolute frequency measurements of iodine-stabilized He-Ne lasers with an optical femtosecond frequency comb generator. The same setup can also be used in other applications that require relatively high (15 mW) laser powers with good spectral characteristics. Radiation of a master laser is amplified by a microlens-coupled diode laser, which is injection locked to the frequency of the master laser. The amplifier can be reliably operated over several hours with very low phase noise. Optical amplification of more than 39 dB is demonstrated. PACS 06.20.Fn; 06.30.Ft; 42.55.Px; 42.62.Eh     

The output power of 633nm He-Ne lasers

A method is described for establishing the optimum geometry for a 633nm He-Ne laser. For a single-frequency laser, the cavity losses and the choice of tube diameter are critical. For multi-transverse-mode lasers, there exists — for maximum output power — an optimum tube diameter, especially when the cavity loss is high.Based on material originally published in Jemná Mechanika a Optika.     

Hyperfine spectra of KBr and KI

The molecular beam electric resonance technique has been used to conduct a high precision examination of the hyperfine spectra of ³⁹K⁷⁹Br, ³⁹K⁸¹Br and ³⁹K¹²⁷I. Coupling constants for the nuclear electric quadrupole interactions, the spin–rotation interactions, the tensor and scalar spin–spin interactions, as well as the electric dipole moment of KI, and their dependence on vibrational and rotational state have been determined. A few transitions observed for ⁴¹K¹²⁷I show a small shift in the iodine nuclear electric quadrupole interaction, and the fit improves somewhat with the inclusion of an iodine nuclear electric hexadecapole interaction term.     

Chemiluminescence of bromine vapor under pulsed lamp pumping

The chemiluminescence kinetics and spectrum of gaseous Br₂ under the conditions of broadband optical pumping have been investigated. It has been found that the transition A ³Π_1u → X ¹Σ _g ⁺ is the major contributor to the luminescence spectrum.     

Experimental values of the output powers of 633nm He-Ne lasers

Measurements are described on the operating parameters of 633nm He-Ne lasers, which are compared with the values calculated in the previous paper. A good overall agreement is obtained. Only for TEM₀₀ lasers with several axial modes do slight deviations occur in the conditions for selecting TEM₀₀ modes only.Based on material originally published in Jemná Mechanika a Optika.     

汞蒸汽中双光子共振四波和频产生125nm的相干辐射

利用汞原子6~1S_0—7~1S_0双光子共振四波和频产生了125nm的相干辐射.对双光子共振增强效应、双光子共振克尔(Kerr)效应进行了研究.讨论了平面波和聚焦情况下最佳相位匹配的条件.实验中还观测到了四波参量振荡和四波差频的信号输出.     

Frequency stability and reproducibility of iodine stabilised He-Ne laser at 633 nm

The frequency of a 633 nm He-Ne laser is stabilised on a hyperfine-structure-component of natural iodine vapour. The third harmonic component of an applied modulation frequency is detected and a servosystem is used to lock the laser frequency to the zero-crossing of the third harmonic component. The stability and the reproducibility of the laser are determined by beat frequency experiment.     

830 nm emission in sodium vapor

We demonstrate that the intriguing 830 nm coherent emission, which is observed when sodium vapor is pumped with a high-power pulsed laser tuned near the 3S4D two-photon transition, is due to an axially phase-matched six-wave mixing process. This conclusion is based upon the observation of emission near 584 nm, which is coupled to the 830 nm emission in the six-wave mixing process: ₁+₂=2_L–_4D4P –_4P3D . In addition, we have observed coherent emission near 1.16 m, which is due to an analogous process involving cascade through the 4S (as opposed to the 3D) state. We calculate the wavelengths of all photons involved in these processes using the standard formulas of parametric wave-mixing theory, and show that they can be predicted to within experimental uncertainties. Finally we report observations of significant blue shifts of the 830 nm and 1.16 m emissions in a mixed sodium-potassium vapor. These shifts can be readily understood by considering the effect of the potassium on the frequency-dependent refractive index of the vapor. Due to these results, other recent interpretations of the 830 nm emission as stimulated excimer emission on the Na₂ 1³ _g ⁺ 1³ _u ⁺ band must now be rejected.     

Effect of power scale of 974 and 633 nm lasers on the induced loss at 633 nm of Yb~(3+)/Al~(3+) co-doped silica fiber

Induced loss at 633 nm is tested in Yb~(3+)∕Al~(3+)co-doped silica fiber by a core pumped with a 974 nm laser and probed with a 633 nm laser. The fiber is prepared by the modified chemical vapor deposition method combined with solution doping. Different power scales of pump light and probe light are used in the tests. It is found that there is a dynamic equilibrium between photobleaching induced by 633 nm probe light and photodarkening(PD)induced by 974 nm pump light. For the first time to our knowledge, the effect of 633 nm probe laser power on an induced loss test of Yb~(3+)∕Al~(3+)co-doped silica fiber is studied quantitatively. It suggests that as long as the633 nm probe light power is less than 0.2 m W, the induced loss is mainly contributed by the PD effect of pumping light, and the deviation of induced loss is less than 5%.     

High-efficiency subwavelength diffractive element patterned in a high-refractive-index material for 633 nm

We propose the use of high-index materials for the fabrication of subwavelength diffractive components operating in the visible domain. This approach yields a reduction of fabrication constraints and an improvement of theoretical performance. A blazed grating with subwavelength binary features and with a period of 5.75 wavelengths is designed and fabricated in a TiO(2) layer coated upon a glass substrate. The first-order diffraction efficiency measured with a He-Ne laser beam is 83%, which is slightly larger than that achieved theoretically by the best standard (continuous profile) blazed grating fabricated in glass with the same period.     

Observation of 280 nm and 298 nm ultraviolet emissions in sodium vapor

Dye laser output around 578 nm is utilized to pump sodium vapor confined in a heatpipe. Fixed wavelength ultraviolet emissions at 280 nm and 298 nm are observed for the first time and can be explained by anti-Stokes Raman scattering and two photon emission respectively. In addition, there are tunable emission lines around 280 nm and 298 nm, the frequencies of which vary with pump laser wavelength. These tunable lines can be explained by four-wave mixing schemes.     

Hyperfine magnetic anomaly in the atomic spectra of rare-earth elements

Hyperfine-splitting constants in the optical spectra of rare-earth elements, Nd, Eu, Gd, and Lu, were measured using the laser-induced resonance fluorescence in a low-divergence atomic beam. Values of the hyperfine magnetic anomaly for different atomic levels were determined by comparing the ratios of the magnetic dipole constants of neighboring isotopes with odd numbers of protons or neutrons. The relation of these values to the special features of the atomic and nuclear structure of the investigated elements is discussed.     

Hyperfine structure in optical spectra of LiYF4-Ho

We report high resolution infrared absorption spectra of LiYF₄-Ho exhibiting well resolved nuclear hyperfine structure (hfs). The halfwidths of some hfs components do not exceed 0.03 cm^?1. Magnetic field at the nucleus is evaluated. Non-radiative relaxation rates due to phonon emission are estimated. With the help of experimentally found 〈Γ₃|J_z|Γ₃〉 matrix elements g-factors of the excited crystal field levels are calculated. Some hfs peculiarities are discussed.     

Two-beam coupling of a series of reduced BaTiO3:Rh at wavelengths of 514 nm and 633 nm

Dedicated to Prof. Dr. Eckard Kr?tzig on the occasion of his 60th birthday.Five annealed BaTiO₃:Rh crystals, including as-grown and those reduced at 10^-5 atm, 10^-10 atm, 10^-12 atm, and 10^-14 atm oxygen partial pressures, were produced and investigated by two-beam coupling at wavelengths of 514 nm and 633 nm. The carrier type is a function of reduction degree and incident wavelength. The compensation points are around 10^-3 atm and 10^-11 atm oxygen partial pressures for 514 nm and 633 nm, respectively. The electrooptic gain is controlled by the photoconductivity–dark conductivity ratio, effects from the deep and shallow traps, and hole–electron competition, which are dependent on the reduction degree and incident wavelength. Received: 23 November 1998 / Revised version: 10 February 1999 / Published online: 12 April 1999     

Theoretical assignment of the observed hyperfine structure in the saturated absorption spectra of I2129 and I127I129 vapors in the 633 nm wavelength region

The detailed structure observed in the saturated absorption spectrum of I₂¹²⁹ vapor in the 633 nm wavelength region in the spectral interval reported by Knox and Pao, has been interpreted to be the overlap between the hyperfine lines of the 8-4 P(54) line of I₂¹²⁹ and the 6-3 P(33) line of the I¹²⁷I¹²⁹ vapor. In this assignment, the nuclear electric quadrupole and nuclear magnetic terms in the Hamiltonian were diagonalized exactly and certain molecular parameters were varied to obtain the best fit with the observed spectrum. For I₂¹²⁹, the calculated distance (separation) of the center of the 8-4 P(54) line from the line center of the Ne²⁰ 633 nm laser transition is 0.04 cm^?1 and the RMS deviation between the theoretical and experimental hyperfine spectra is 0.3 MHz. Although the calculated frequency of R(60) transition in the 8-4 band is only 0.03 cm^?1 from the center of the laser line, we conclude on the basis of the larger RMS error (0.5 MHz) that this latter transition is less likely to be that responsible for the structure discussed in this paper.     

Hyperfine structure of submillimeter EPR spectra of non-Kramers lanthanide ions in crystals

The hyperfine structures of submillimeter EPR spectra of CsCdBr₃:Tm³⁺ and CaF₂:Dy²⁺ single crystals have been resolved and analyzed. The crystal field parameters and the magnetic hyperfine constants are obtained from fitting the envelopes of the simulated spectra to the measured signals. From the specific peculiarities of the hyperfine structure the energy of the interion interaction in the thulium dimers in CsCdBr₃ is determined. The isotopic shift of the crystal field splitting in energy patterns of dysprosium isotopes in CainF₂ is estimated.