Gain and dispersion focusing in a high gain laser

The transverse modes of a laser resonator containing a medium with a strong radial gain profile differ greatly from the modes of a similar resonator containing a low gain medium. Focusing and defocusing effects result from the gain profile and from the associated dispersion profile. The dispersion focusing causes an asymmetry in the power output as the laser is tuned across the gain line. The theory has been verified using a high gain 3.51-µ xenon laser

The Gaussian mode in optical resonators with a radial gain profile

The dependence of the parameters of the Gaussian mode in laser resonators on the properties of the medium in the cavity is studied. Experimental verification of the theoretical results is presented. It is found that the modes in a high-gain laser may differ widely from the usual free space resonator results. Also, resonator configurations which in free space are unstable may, with a suitable medium, support low-loss Gaussian modes

Spectral narrowing in high-gain lasers

The dependence of spectral narrowing in lasers on the line-broadening mechanism is investigated including the effects of saturation and distributed loss. It is found that in the unsaturated regime the narrowing is essentially independent of the resonance broadening mechanism and the narrowed line approaches a Gaussian. The onset of saturation slows or reverses the narrowing process. Experimental results have been obtained using a 3.51-μ xenon laser

The time behavior and spectra of relaxation oscillations in a high-gain laser

It is found that under appropriate conditions the high-gain 3.51-μ xenon laser may exhibit relaxation oscillations in the frequency range of 1 to 10 MHz. Experimental investigations have been conducted in both the time and frequency domains. Most of the observed features of these fluctuations are in good agreement with theoretical considerations

Human Factors Program for the Cooperative Pilot Warning Indicator System Final Report

Display devices for aircraft pilot warning system

The Phonology of Hiligaynon

There are 175 languages in the 7000+ islands that make up the Philippines. Hiligaynon is the fourth largest language spoken on the islands. The sound inventory of Hiligaynon has 22 phonemes, which include 17 consonants and 5 vowels. Contact with Spanish, English, and neighboring Filipino languages (mostly Cebuano, Tagolog, Kinaray-a, Aklanon) has influenced Hiligaynon resulting in many loanwords entering the lexical inventory of speakers of Hiligaynon. Although these loanwords contain sounds not native to Hiligaynon, most of them have assimilated to match the phonology of Hiligaynon. An example of this assimilation is seen in loanwords containing the labiodental fricatives [f] and [v] being pronounced with the biliabial stops [p] and [b] instead. This presentation identifies the phonology of modern Hiligaynon by briefly comparing key features of its sound system to that of other languages found in the Philippines. Morphophonemic rules will identify some of the word-formation processes that are influenced by the language’s phonology. The aim of this presentation is to clarify some of the phonological features of the language since an accurate description of the language is not yet available

Longitudinal modes in a high-gain laser

In lasers employing high-gain narrow-linewidth transitions the theory predicts major departures of the mode-splitting frequencies from their low-gain values as well as a new type of mode splitting. The first of these effects consisting of a reduction by a factor of 2.5 of the mode splitting in a xenon 3.51-µm laser is observed experimentally

Grazing Reflection of Gaussian Beams

The reflectivities of most surfaces are higher for grazing or near-90-deg angles of incidence than for more perpendicular or near-zero-deg angles. Grazing-incidence configurations are especially important in the development of lasers and optical systems that operate in the far-ultraviolet and soft-x-ray regions of the spectrum, where transparent or highly reflecting media are almost unknown. Analytical solutions of the paraxial wave equation are obtained for the grazing reflection and complex interference effects that take place when a Gaussian beam interacts at shallow angles with a reflecting surface

Fluttering Fountains: Annular Geometry

Under certain conditions of flow rate, height, and feedback, periodic or chaotic fluttering oscillations can be observed as the sheet of water from a dam or waterfall fountain descends through the air. Numerical and analytical interpretations of this phenomenon have recently been reported. The extension of these results to other fountain geometries is discussed here together with experimental observations on an annular waterfall fountain

Cylindrical laser resonators

A general class of cylindrical laser resonators is described in which the radiation propagates partially in the radial direction. There is a strong focusing of energy at the axis of such resonators. The low-loss cavity modes are related to ordinary gaussian beam modes. Two limiting forms are the disk laser and the tube laser, and some applications are considered