No abstract

This review paper presents a discussion on dielectric substrate materials suitable for the preparation of YSa2C@-, thin-film based microwave integrated circuits. The requirements on the properties of the substrate materials are specified. They cover the properties crucial both for the preparation of high-quality YBa2Cu&-, films and for the design of microwave elements. The former includes mainly the lattice match, the match of thermal expansivities, chemical stability, and absence of twinning. The latter includes the relative dielectric permittivity (e) and the related tolerances, the microwave loss tangent, and the substrate area required for the accommodation of a microwave circuit.The properties of the currently available substrates suitable for YSM film epitaxy are discussed in view of these reauirements. The main attention is paid to the microwave properties. Current achievements and potential difficulties of the clystal growth technology in the preparation of the substrates are taken into account as well.

No abstract

No abstract

We examined the physical properties of infrared optical glasses composed of tellurium, germanium, selenium, sulfur and silicon. In particular, we measured optical, acoustic and photoelastic parameters of the following alloy compounds: germanium–selenium–tellurium (Ge–Se–Te), germanium–selenium–sulfur–tellurium (Ge–Se–S–Te), germanium–silicon–tellurium (Ge–Si–Te) and silicon–tellurium (Si–Te). Like single-crystal tellurium, the glasses demonstrate good acousto-optic (AO) diffraction efficiency and have reasonable optical transparency in a wide spectral region covering wavelengths from 1.5 to 20 μm. The optical, acoustic and photoelastic properties of the tellurium-based compounds were measured using infrared lamp sources of radiation as well as He–Ne and CO2 lasers. In this paper, we report on the optical, acoustic and photoelastic parameters of a selection of these compounds and discuss the advantages and disadvantages of using these glasses for AO device applications. We also present the measured characteristics of an AO cell fabricated in a Si20Te80 glass material which exhibited high optical uniformity and long-term chemical stability.