Extrait Annales des Télécommunications, tome 38, n° 1-2, janvier/février 1983
ABSTRACT
Des problèmes théoriques relatifs aux télécommunications optiques, aux capteurs, lasers et dispositifs d’imagerie ont été discutés de façon informelle par quarnte scientifiques au Colloque international sur la théorie des guides optiques. La réunion s’est tenue juste avant la Conférence européenne sur les communications optiques (ECOC, Cannes, sept. 1982) au Centre inter-régional d’enseignement sur les télécommunications (CIRET) à La Londe. Un rapport concis est présenté.
The paper provides simple expressions for the dopant concentrations that optimize the bandwidth of a fiber at a number of wavelengths. The solution is related to Olshanky’s multiple α profiles. Numerical application is made for germania, fluor and phosphorus doping at wavelengths where the losses are small. The effect of a free parameter on the fiber ∆ and its bandwidth is outlined.
IEE Proceedings H (Microwaves, Optics and Antennas), Volume 129, Issue 4, August 1982, p. 183 – 187
ABSTRACT
The whispering-gallery modes of cylindrical dielectric resonators of high permittivity (εr~38) are investigated. Axial-mode confinement is ensured by a slight increase in the rod diameter. The resonances for various azimuthal mode numbers and the two states of polarisation are identified experimentally. There is a good agreement between measured and calculated frequencies. The measured quality factor, of the order of 7000 at 6 GHz, is, for some resonances, limited only by the intrinsic loss of the dielectric material. The whispering-gallery mode of resonance enables designers to use comparatively larger-size dielectric resonators at millimetre-wavelengths with good frequency selection and low loss.
Electronics Letters, Volume 18, Issue 15, 22 July 1982, p. 660 – 661
ABSTRACT
Two-dimensional image transmission through a single multimode fibre has been performed using colour coding. The correspondence between image points and colours is achieved with the combination of dispersive prisms and fibre bundle convertors. The light source is an ordinary tungsten lamp. The reconstructed 10 × 10 image can be seen by the naked eye.
Electronics Letters, 18 march 1982, vol 18, n°6, 247-249
ABSTRACT
It is shown experimentally that short samples (about 1 m) of multimode optical fibres can be characterised by measuring the times of flight of tubular modes. There is fair agreement between measured and calculated values.
Electronics Letters, Volume 17, Issue 10, 14 May 1981, p. 339 – 341
ABSTRACT
The operation of graded-index fibres can be optimised in the neighbourhood of some wavelength whenever two dopants are available. Under the assumption that the index is a linear function of the dopant concentrations, a class of relations between dopants is found, which is related to that given by Olshansky.4 The case of a fibre doped with germanium and fluorine is treated.
J. Piasecki, B. Colombeau, M. Vampouille, C. Froehly et J. A. Arnaud
Applied Optics, Vol. 19, Issue 22, pp. 3749-3755 (15/11/1980)
ABSTRACT
A new technique for measuring the temporal transfer function of optical fibers is described. The method consists of placing the fiber under test in one arm of a Mach-Zehnder interferometer excited by a broadband source. The temporal impulse response is obtained from a holographic reconstruction. The method requires only short lengths of single-mode or multimode fibers (less than 1 m). We have measured a dispersion of 0.3 nsec/km.nm at 0.59 μm with a single-mode fiber, in good agreement with theory. The arrival times of the various modes of multimode fibers are resolved.
The clean propagation of tubular modes over more than 50 m of a multimode optical fibre has been observed. This observation opens the way to multichannel transmission through multimode optical fibres and provides a new fibre testing method.
Annals of Telecommunications Volume 35, Issue 1-2 , pp 61-73
01/03/1980
ABSTRACT
Une expression générale est obtenue qui décrit l’effet des microcourbures sur la transmission de fibres optiques multimodales. Cette expression est basée sur l’approximation des rayons paraxiaux.