Showing papers on "Radiation mode published in 1969"

Excitation and Scattering of Modes on a Dielectric or Optical Fiber

Abstract: A technique similar to that of Kirchhoff is used to obtain an analytic expression for mode Iaunching on a semi-infinite rod. The approximation is quasi-optical and only valid for small angles of incidence /spl theta/. When /spl theta/ = 0 only HE/sub 1M/ modes are excited; however, for /spl theta/<<1 many modes can be launched. The effect on HE/sub 11/ mode propagation of small imperfections in a dielectric waveguide is analyzed. At the frequency of interest for optical communication (cutoff for the TM/sub 01/ mode) the radiated power is 160 times larger than that scattered into the HE/sub 11/ mode.

Mode conversion caused by diameter changes of a round dielectric waveguide

Abstract: This paper presents the theory of mode conversion and radiation losses of the lowest order circular electric mode in a dielectric rod (fiber) waveguide and its confirmation by a microwave experiment. The theoretical results were obtained from a theory whose detailed development has been presented in an earlier paper. The microwave experiment was carried out at approximately 50 GHz. The optical fiber with imperfect walls was simulated by a teflon rod of 1 cm diameter and 1 m length with a periodically corrugated wall. Mode conversion was observed in excellent agreement with theory. The observed radiation losses are somewhat less than the prediction of the perturbation theory, but the agreement is quite good. The direction and width of the far-field radiation pattern was observed in agreement with theory.

Scattering due to irregularities on dielectric or optical fibres

Abstract: The effect on mode propagation of small (with respect to wave-length) irregularities or imperfections in a dielectric waveguide is analysed. Asymptotically, for large frequencies, the power which is scattered in the form of radiation (not guided) has an ω2 behaviour, and that scattered into the modes obeys a 1/ω2 relationship. At the frequency of paramount interest for optical communication (cutoff for TM01 mode), the radiated power is 22dB larger than the power scattered into the HE11 mode.

Nonlinear Interaction of a Microwave Field with a Plasma Slab in a Waveguide

Abstract: The nonlinear interaction of the dominant TE(10) waveguide mode of a fundamental frequency with a plasma slab in an infinitely long rectangular waveguide is analyzed utilizing an approximate technique. Explicit expressions for the first three harmonic components of the electron density and current density in the plasma are given. General expressions for the nonlinearly generated second‐harmonic electric fields are derived. Numerical results show that the second‐harmonic power generated in the TM(11) wave‐guide mode is more than ten times that generated in the TE(11) waveguide mode.

On edge diffraction rays of an open-ended waveguide

Abstract: Two main results are reported in the development of a system of rays diffracted at the edges of an open-ended parallel-plate waveguide which take care of the coupling effect between the two plates of the waveguide automatically. As an example, the application of such rays to the problem of radiation from an open-ended waveguide recovers the exact solution obtainable by the Wiener-Hopf technique.