Symmetrical Stubs Research Articles

Band-gap engineering in periodic acoustic stub tuners: Spectral gaps and transmission

A theoretical investigation on acoustic wave propagation in a periodically stubbed waveguide is reported. In general the waveguide segments and stubs are made of different materials. The acoustic wave in such a system has two independent polarizations: out-of-plane and in-plane modes. The band structure and transmission spectrum are studied for diverse geometries using a simple and efficient version of the transfer-matrix method. For the same material between the waveguide and symmetric stubs the width of some gaps can change, upon varying the stub length or width, by more than one order of magnitude. A further modulation can be achieved for different material between the stubs and the main waveguide or if the stubs are asymmetric. The gaps in the band structure of an infinitely long system correspond to those in the transmission spectrum of the same system but with finite number n of units. For n finite (i) there exist pseudogaps that gradually turn into complete gaps with increasing n and (ii) the introduction of defects gives rise to states in the gaps and leads to transmission resonances.

Ballistic spin transport through electronic stub tuners: Spin precession, selection, and square-wave transmission

Ballistic spin transport is studied through electronic tuners with double stubs attached to them. The spins precess due to the spin–orbit interaction. Injected polarized spins can exit the structure polarized in the opposite direction. A nearly square-wave spin transmission, with values 1 and 0, can be obtained using a periodic system of symmetric stubs and changing their length or width. The gaps in the transmission can be widened using asymmetric stubs. An additional modulation is obtained upon combining stub structures with different values of the spin–orbit strength.

Tunability of acoustic spectral gaps and transmission in periodically stubbed waveguides

A theoretical investigation is made of acoustic wave propagation in a periodically stubbed waveguide. In general the waveguide segments and stubs are made of different materials. The acoustic wave in such a system has two independent polarizations: out-of-plane and in-plane modes. The band structure and transmission spectrum is studied for diverse geometries using a simple and efficient version of the transfer-matrix method. For the same material between the waveguide and symmetric stubs the width of some gaps can change, upon varying the stub length or width, by more than one order of magnitude. A further modulation can be achieved for different material between the stubs and the main waveguide or if the stubs are asymmetric. The gaps in the band structure of an infinitely long system correspond to those in the transmission spectrum of the same system but with finite number n of units. For n finite (i) there exist pseudogaps that gradually turn into complete gaps with increasing n and (ii) the introduction of defects gives rise to states in the gaps and leads to transmission resonances.

LiNbO 3 resonant-type optical modulatorwith double-stub structure

A resonant-type LiNbO3 optical modulator with symmetric stubs and modulating electrodes was investigated. Modulation efficiency was enhanced by the resonance of the modulating electrode. The enhancement factor of the fabricated modulator was 3.41 at 10 GHz.

Generalized Scattering Matrix Method for Analysis of Cascaded and Offset Microstrip Step Discontinuities

Detailed algorithms are presented for characterizations of cascaded microstrip step discontinuities, symmetric stubs, and offset step. The analysis is based on the generalized scattering matrix techniques after the equivalent waveguide model is introduced for the microstrip line.