Applied Optics, Vol. 8, Issue 8, August 1969, pp. 1687-1693
ABSTRACT
This paper considers the propagation and diffraction of coherent light beams through nonorthogonal optical systems such as sequences of astigmatic lenses oriented at oblique angles to each other. The fundamental (gaussian) mode has elliptical light spots in each beam cross section and ellipsoidal (or hyperboloidal) wavefronts near the axis. It is found that the orientation of the light spot differs from that of the wavefront, and changes continuously by as much as π radians as the beam propagates through free space. A theory of these general astigmatic beams is given and simple experimental observations are described. The coupling factor between two such beams is also given.
Applied Optics, Vol. 8, Number 9, page 1909-1917, 1969
ABSTRACT
A simple expression is given for the response of degenerate cavities suffering from arbitrary misalignments, and numerical results are presented. The method of resonance excitation is carried out analytically with the help of a complex ray representation of gaussian beams. It is first shown that the modulus and phase of such complex rays can be identified with, respectively, the beam radius and the phase of the on-axis field. This identification simplifies the calculation of the coupling factor between two gaussian beams, which is needed in deriving the expression for the response. For the case of conventional cavities, the results are in exact agreement with results derived from the Laguerre-Gauss or Hermite-Gauss mode theory. The case of degenerate cavities with large and possibly nonorthogonal misalignments, of interest in various nonresonant multipath systems, is also discussed.
Applied Optics, Vol. 8, Number 9, Issue 1, pp. 189-196 (1969)
ABSTRACT
An optical cavity is degenerate when an arbitrary ray retraces its own path after a single round trip. The condition for degeneracy is given for ring type cavities incorporating internal lenses, using geometrical optics methods. The simplest linear configurations require a spherical mirror or a corner cube, a thin lens, and a plane mirror. Planar rings with four plane mirrors require at least three thin focusing elements. A nonplanar ring is discussed which requires only two thin lenses. The alignment of degenerate cavities is, in general, as critical as the alignment of plane Fabry-Perot.
Quantum Electronics, IEEE Journal of (Volume:4 , Issue: 11 ), pages 893 – 899, Nov 1968
ABSTRACT
The amplification before detection of the carrier of a modulated optical signal by a narrow-band quantum amplifier enhances the signal-to-noise ratio, particularly when the signal wave-front is distorted. A further improvement is obtained by using a combination of wide-band and narrow-band quantum amplifiers. The practical application of these schemes requires a degenerate regenerative ring-type amplifier capable of amplifying arbitrary transverse field configurations. Experiments show that such an amplifier with a gain of 24 dB and a bandwidth of 1 MHz is feasible. The incident beam axis can be displaced by as much as ten times the beam-waist radius without losing more than 4 dB in gain. Frequency modulation may be converted into amplitude modulation by the phase shift introduced in the carrier.
Electron Devices Meeting, 1967 International (Volume:13 ), pages 26
ABSTRACT
This paper describes a family of crossed-field power-output noise generator tubes, which may be characterized as injected-beam forward-wave devices. They consist of a noisy gun, a drift space, and a crossed-field amplifier which amplifies the noise further and couples it to the external circuit. The frequency range, power, and efficiency are related closely to the crossed-field amplifier characteristics, and thus may be made to be broad-band, or to be narrow-band and tunable, depending on the slow-wave structure. The slow-wave structures used have been meander lines or lumped-constant structures, all supported on beryllia ceramics.
Annales de Radioelectricité, T. XXI, n°85, juillet 1966
ABSTRACT
Des nombreux dispositifs utlisent comme lignes à retard des systèmes multifilaires, c’est le cas des tubes à propagation d’onde et des masers à onde progressive. Des strctures complexes bi- ou tri- périodiques ont été déjà utilisées dans des tubes expérimentaux. Cet article expose une généralisation de la théorie des lignes à barreaux permettant de traiter le problème de la propagation d’ondes électromagnétiques dans un réseau de barreaux parallèles comportant des obstacles répartis périodiquement ; l’introduction d’une admittance caractéristique matricielle permet de traiter de façon simple le cas d’une disposition doublement périodique des barreaux.
La présence d’un champ magnétique parallèle à la surface d’une cathode provoque l’apparition d’un bruit supplémentaire très intense dans les tubes à vide (bruit anormal) ; l’auteur rappelle les connaissances acquises sur ce point : théories statiques et dynamiques des flux electroniques en champ électrique et magnétique roisés, et expériences sur le courant sole. Il présente ensuite des résultats expérimentaux nouveaux qui permettent de préciser la nature statistique du bruit anormal et les conditions dans lesquelles il se produit. Ces résultats expérimentaux ont été obtenus sur des optiques du type coaxial, où le champ magnéique est créé par un courant intense corculant dans une tige cylindrique. Il ne parait cependant pas possible de donner actuellement une théorie satisfaisante du phénomène étudié.