SPECTRAL DEPENDENCE OF LIGHT-INDUCED MICROWAVE REFLECTION COEFFICIENT FROM OPTOELECTRONIC WAVE-GUIDE GRATINGS

After a short description of the method of operation of optoelectronic microwave filters, a detailed analysis of the spectral dependence of light-induced microwave reflection coefficient from an optoelectronically generated distributed Bragg reflection waveguide grating is reported. The theory is based on an improved stepped-impedance model utilizing a diffusion-controlled abrupt-profile approach of photoconductivity along with a conformal mapping technique for the quasi-static evaluation of the spectral performance of photoinduced wave attenuation, The validity of theory is clarified and the calculated results are compared with experimental results. As a useful result for future applications, an optimum excitation wavelength of about 825 nm for a fiber-optically controlled lab-tested 50 Ohm full-substrate silicon coplanar waveguide has been obtained.