Majid L Riaziat

Coplanar Waveguides Used in 2-18 GHz Distributed Amplifier

This paper describes the use of coplanar waveguide as an alternative transmission medium in a monolithic distributed amplifier. The coplanar waveguide layout substantially reduces coupling effects between adjacent lines, and eliminates the need for via holes and substrate thinning, leading to higher fabrication yields. The resulting device reported here is a compact (1.3 x 1.5mm) low noise distributed amplifier on a thick GaAs substrate (15 mil), with a gain of 6.0 +- 0.5dB over the frequency range of 2 - 18GHz.

Optical wavelength shifting by traveling-wave electrooptic modulation

Optical wavelength shifting of 1.054-nm laser pulses in excess of +or- 10 wavenumbers (+or- 300 GHz) was demonstrated. The wavelength shifter consists of synchronous microwave and optical waveguides fabricated monolithically on LiNbO/sub 3/. An optical pulse experiences a constant refractive index gradient that travels with the pulse and causes the wavelength shift.<<ETX>>

Electrooptic sampling measurement of dispersion characteristics of slot line and coplanar waveguide (coupled slot line) even and odd modes

The application of an electrooptic sampling technique for the characterization of propagating modes of uniplanar guiding structures on GaAs is described. The characteristics of slotline and even and odd modes of coplanar waveguides (CPW) on semi-insulating GaAs substrate are investigated. The potential distribution over the cross section of each was measured. The guide wavelength for each guide was directly obtained from standing-wave measurements by electrooptic sampling, and the dispersion characteristics of CPW modes and slotline were measured from 15 to 40 GHz.<<ETX>>

Internal Microwave Propagation and Distortion Characteristics of Travelling-Wave Amplifiers Studied by Electro-Optic Sampling

The internal signal propagation and saturation characteristics of two monolithic microwave travelling-wave amplifiers (TWA) are measured by electro-optic sampling. Gate and drainline responses are compared with theory and simulation, leading to revisions in the FET models. Drain voltage frequency dependence and harmonic current propagation together lead to more complex saturation behavior than is discussed in the literature.