We used sapphire dielectric resonator technique with copper cylindrical shield and two endplates replaced by HTS layers for very accurate surface resistance measurements of laser-ablated YBCO films, The resonant system using the TEoll mode has resonant frequency of about 18.1 GHz and parasitic losses Q factor of about 120,000. It allows 10 mm X 10 mm samples to be measured with sensitivity of +30 p a . Individual samples can be measured with somewhat lower accuracy. Using larger HTS samples, one can reduce parasitic losses of the system to an unsignificant level. The exact formulas presented further below for the resonant system allow for avoiding calibration procedures during the evaluation of the surface resistance value.

Electrically controlled Kerr effect in magnetophotonic crystals based on nematic liquid crystals J. Appl. Phys.The encapsulation of liquid crystals in a polymer matrix produces a material with interesting and potentially useful optical properties. The earliest efforts generated a dispersed phase whose dimensions were comparable to optical wavelengths and therefore afforded materials which were highly scattering. These materials have already been found useful for display applications. We have found that when these materials are fabricated so that the dimensions of the dispersed phase are substantially smaller than the incident radiation wavelengths, the material is far less scattering. de Kerr measurements on these liquid-crystal composites yield quite large values, ranging as high as 30000 times CS 2 This activity is shown to be a strong function of the liquidcrystal loading and the temperature. 4253 J.

We demonstrate the first polyimide guest/host system which exhibits stable electro-optic response after parallel-plate poling. Such systems are based on a class of polyimides which, once cured, possess a clear glass transition in their dielectric relaxation spectra, characteristic of thermoplasticity. After doping with compatible nonlinear optical molecules the polyimide host system can first be thermally imidized (cured) and then poled with an electric field. High glass transition temperatures are achieved leading to excellent thermal stability of the poled electro-optic response.

We describe a novel technique for the fabrication of electro-optic (EO) waveguides in integrated optic device structures employing organic EO materials. The technique combines the poling and waveguide formation steps by utilizing patterned poling electrodes and the induced birefringence associated with the poling process. Several prototype waveguide devices fabricated using this procedure are reported.

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