In this paper we present a new type of fiber-integrated all optical modulator. The operation principle of the proposed device is based upon plasma dispersion effect in silicon, which enables control of the optical properties of silicon at wavelength of 1550nm by modifying the concentration of free charges either by applying external electrical field or by using illumination in spectral range that is being absorbed by this semiconductor. The concentration of the generated free charge carriers affects the real and the imaginary part of the refractive index of the semi-conductor i.e. yields controllable absorption and refraction effects over the information carrier wavelength of 1550nm.

In this paper we present two types of devices. In the first we fabricate a silicon fiber having a silica clad. The fabrication process involves special tapering rig based upon uniform heating process obtained by CO2 laser that is directed towards a pre-form positioned in the focal spot of an ellipsoidal mirror. The uniformly heated pre-form is drawn into a fiber by computer controllable motors. The second device includes a silicon strip acting as waveguide and which is coupled to regular single mode fibers at its input and output edges. The silicon strip is composed from differently doped silicon layers acting as the core and the cladding of the guided light.

In both cases, the proposed devices are to be incorporated as in-line modulators which are an integral part of any optics communication system.