MECHANICAL LIGHT-MODULATOR FABRICATED ON A SILICON CHIP USING SIMOX TECHNOLOGY

This paper describes a light modulator fabricated on a silicon chip us ing SIMOX (separation by implantation of oxygen) technology. The modul ar consists of a double supported beam made of layers of silicon nitri de and mono-crystalline silicon, separated from a silicon substrate by the air gap. The voltage applied between the beam and the substrate b ends the beam and the thickness of the gap is reduced. This alters the interference pattern of light illuminating the modulator. Based on th is principle, light reflected by the device is modulated with the a.c. voltage signal which is driving the modulator beam. The modulator, wi th a beam 100 mum long, 5 mum wide and a total thickness of 0.43 mum, shows a 50% change in the reflected light intensity of the wavelength 514 nm, when biased with 20 V d.c. The fundamental resonant frequency of the modulator is 2.5 MHz.