Showing papers on "Guided wave testing published in 1971"

Optical Guided Wave Mode Conversion by an Acoustic Surface Wave

Abstract: The experimental observation of efficient (55%) mode conversion of thin‐film optical guided waves by a collinear interaction with a surface acoustic wave is reported. The effects of waveguide dispersion and finite geometry are discussed.

Optical Guided-Wave Focusing and Diffraction*

Abstract: One-dimensional focusing and diffraction techniques for thin-film optical waveguides are examined in terms of their effectiveness and fabrication requirements. Impetus for the study is derived from potential application of optical planar guided waves to analog signal-processing systems. Methods of altering modal-phase velocities to achieve ray deflection are investigated and include the use of substrate and film-embedded refractive-index discontinuities, multilayer films, thickness-profiled layers, and absorptive-material deposition on the guiding films. Thin-film lenses having f numbers as low as 2 to 3 may be fabricated by vacuum deposition of high-index materials, such as CeO2. Experimental results obtained with glass-sputtered films illustrating basic operation of thin-film lenses, gratings, and prisms are presented.

Ridge guides for acoustic surface waves

Abstract: A low-velocity flexural mode has been excited on acoustic-surface-wave topographic guides. With structures offering some hope of realisation at high frequencies, very strong confinement of the guided wave is obtained. Q factors in excess of 1000 have been observed on a ring resonator only ten wave lengths in diameter.

Low-loss modes in dielectric lined waveguide

Abstract: Recent studies of the heat loss characteristics of the normal modes in dielectric lined circular waveguide have shown that modes other than those of the circular electric type may have low loss over wide frequency bands. This unexpected behavior of the mode loss characteristics is explained by utilizing the well-known duality relationships between the electric and magnetic fields. Specifically, it is shown that the lowest loss modes are alternately circular electric and circular magnetic as frequency (or lining thickness) increases, with low loss occurring at frequencies and lining thickness where the wall impedance of the dielectric coated guide approximates a short circuit (or electric wall) for circular electric modes, and an open circuit (or magnetic wall) for circular magnetic modes. These findings will influence and aid in the selection and design of an appropriate waveguide(s) (employing the circular electric TE 01 mode) for the WTS millimeter wave transmission system which is presently under development; they may also influence the design of future guided wave systems.

Fast optical guided wave modulator and digital deflector

Abstract: An optical guided wave modulator and digital deflector is described having a piezoelectric substrate with an amorphous film waveguide thereon. An interdigital periodic electrode structure is connected to the amorphous film and to a source of d.c. voltage. The voltage produces fringing fields which generate a periodic strain in the piezoelectric substrate. The compressional strain in the piezoelectric substrate extends into the amorphous film to produce a periodic variation of index of refraction which functions as a grating at the Bragg angle which deflects an optical wave traveling in the amorphous film.

Two-Cavity Ring-Type Channel-Dropping Filters for a Millimeter-Wave Guided Wave Communication System (Correspondence)

Abstract: Newly developed two-cavity ring-type filters for a millmeter-wave communication system are described They are used in a five-channel transmit and receive multiplexer which operates in the 50-GHz frequency band The pulse response and interchannel crosstalk characteristics for 250-Mbit PCM-AM or PCM-PSK transmission were calculated and compared with experimental results