J. A. Arnaud, W. Mammel
Electronics Letters, Volume 12, Issue 1, 8 January 1976, pp. 6 – 8
In multimode circularly symmetric fibres whose index distribution is a stairlike approximation of an optimum profile, the modal dispersion increases as the number of steps decreases. For a fibre with Δn/n=0.02 and a core radius of 40 μm, numerical calculations based on wave optics show that the r.m.s. impulse response width at λ=1 μm increases from 0.075 ns/km for the smooth optimum profile to 0.23 ns/km for 40 steps of equal areas. Thus an important conclusion of the analysis is that one should avoid introducing steps in the refractive-index profile of fibres for optimum results.
LIEN VERS L’ARTICLE : DISPERSION IN OPTICAL FIBRES WITH STAIRLIKE REFRACTIVE-INDEX PROFILES
J. A. Arnaud
Rev. Sci. Instrum., Vol 47, n°1
We describe a tunable Fabry-Perot type filter which has application to radio astronomy in the frequency band 80-110 GHz. The filter causes image sideband suppression when used with a heterodyne spectral line receiver having an intermediate frequency of 4.75 GHz. The transmission loss in the signal sideband is about 0.4 dB, while the image sideband rejection is more than 15 dB ; there appears to be little if any problem with scattering or distortion of the antenna radiation pattern.
LIEN VERS L’ARTICLE : QUASI-OPTICAL BAND REJECTION FILTER AT 100 GHZ
J. A. Arnaud
Academic Press, (NY), , 1976
Beam and Fiber Optics discusses the concepts of wave and geometrical optics that are most relevant to a deeper understanding of beam optics. This book is organized into five chapters that provide the necessary algebraic details, particularly the laws of beam propagation through unaberrated optical systems.
The first chapter presents a broad view of the subject matter and a comparison between the laws of mechanics and the laws of optics. Chapter 2 explores the laws of propagation of Gaussian beams through freespace, unaberrated lenses, or lenslike media and resonators. The simplest configurations (two-dimensional with isotropic media) are first considered, but a few advanced problems are also treated. This chapter also discusses the use of Gaussian beams at millimeter wavelengths. In Chapter 3, various wave equations relevant to beam optics are given, and their relationship is examined. This text also emphasizes the importance of the Lorentz reciprocity theorem for problems of coupling between beams or fibers. The geometrical optics limit of wave equations is addressed in Chapter 4. This chapter also considers the propagation of optical pulses in dispersive inhomogeneous (graded-index) fibers based on the point of view of Hamiltonian optics. The final chapter is devoted to piecewise homogeneous dielectric waveguides, such as the dielectric slab and the dielectric rod. A method to evaluate the bending loss of open waveguides is described.
This book will be useful to students, professors, and research engineers in the field of electromagnetic communication.
LIEN VERS LE LIVRE : BEAM AND FIBER OPTICS
J. A. Arnaud
Am. J. Phys. 44, 1067 (1976)
The identification, medium refractive indexn = nonrelativistic particle velocityv, in the analogy of geometrical optics with nonrelativistic particle mechanics is physically correct and useful, but can easily be misinterpreted. The conditions under which the analogy holds are outlined. The significance of Descartes’s mechanical models is also discussed.
LIEN VERS L’ARTICLE : ANALOGY BETWEEN OPTICAL RAYS AND NONRELATIVISTIC PARTICLE TRAJECTORIES : A COMMENT