ABSTRACT
Two-frequency operation of an 850 nm semiconductor optical amplifier was achieved by simultaneously injection seeding it with two diode lasers. The two frequencies could be independently amplified without strong interference when they were separated by more than 10 GHz, and the spectral purity was preserved by the amplification process. At frequency differences below 10 GHz, unbalanced two-frequency output was observed, which can be explained by a two-mode interaction driven by the refractive index modulation at the beat frequency. The laser system is suitable for the difference-frequency generation of coherent terahertz radiation in ultra-fast photoconductors or nonlinear optical media.
Subject(s)
Amplifiers, Electronic , Lasers , Light , Optics and Photonics , Radio Waves , Astronomical Phenomena , Astronomy , Physical Phenomena , Physics , Semiconductors , Spectrum AnalysisABSTRACT
A small cryogenic Fabry-Perot étalon was fabricated for the far-infrared region. This design used freestanding metal meshes for the reflecting elements. Using a combination of gold-coated copper mesh on stainless steel, we reproduced the spacing to 1 part in 10(6) with repeated cooling. The properties and methods used for alignment and calibration are presented.
ABSTRACT
A description and summary of the latest edition of the AFGL HITRAN molecular absorption parameters database are presented. This new database combines the information for the seven principal atmospheric absorbers and twenty-one additional molecular species previously contained on the AFGL atmospheric absorption line parameter compilation and on the trace gas compilation. In addition to updating the parameters on earlier editions of the compilation, new parameters have been added to this edition such as the self-broadened halfwidth, the temperature dependence of the air-broadened halfwidth, and the transition probability. The database contains 348043 entries between 0 and 17,900 cm(-1). A FORTRAN program is now furnished to allow rapid access to the molecular transitions and for the creation of customized output. A separate file of molecular cross sections of eleven heavy molecular species, applicable for qualitative simulation of transmission and emission in the atmosphere, has also been provided.
ABSTRACT
The optimum therapy for hydrogen sulfide poisoning is unclear. Adjuncts used in the treatment of cyanide poisoning have been advocated because of the shared mechanism of toxicity between hydrogen sulfide and cyanide. Following success in cyanide poisoning, hyperbaric oxygen therapy (HBO) has been suggested for use in treating hydrogen sulfide poisoning. A case of severe hydrogen sulfide poisoning was successfully treated with HBO after standard therapy was apparently ineffective. HBO as a therapeutic adjunct in hydrogen sulfide poisoning and the rationale for its use are discussed.
Subject(s)
Hydrogen Sulfide/poisoning , Hyperbaric Oxygenation , Adult , Emergencies , Humans , Hydrogen Sulfide/metabolism , Male , Methemoglobinemia/etiology , Nitrites/therapeutic useABSTRACT
An inductive mesh was measured for transmission as a function of frequency, incidence angle, and polarization. The experimental data agree well with Chen's waveguide theory for meshes as long as an adequate number of modes are included in the calculations. To simplify calculations of mesh transmission a lumped circuit model has been developed to fit Chen's theory. This model predicts transmission for the two major polarizations and a variety of angles to within 1%.
ABSTRACT
Profiles of stratospheric ozone and chlorine monoxide radical (C1O) have been obtained from balloon measurements of atmospheric limb thermal emission at millimeter wavelengths. The C1O measurements, important for assessing the predicted depletion of stratospheric ozone by chlorine from industrial sources, are in close agreement with present theory, The predicted decrease of C1O at sunset was measured. A tentative value for the stratospheric abundance of hydrogen peroxide was also determined.
ABSTRACT
A technique is described for fitting collisional linewidths and shifts from experimental spectral data. The method involves convoluting a low-pressure reference spectrum with a Lorentz shape function and comparing the convoluted spectrum with higher pressure spectra. Several experimental examples are given. One advantage of the method is that no extra information is needed about the instrument response function or spectral modulation. In addition, the method is shown to be relatively insensitive to the presence of reflections in the sample cell.