Ascom Tech Ltd.

Ascom Tech Ag

Rainer Battig

Paul Vogel

Olivier Anthamatten

The reflection modulator (11), serving the purpose of modulating a light beam emerging from an optical fiber (42) and re-entering the same, is essentially based on a microstructural Fabry and Perot interferometer. The interferometer is formed by two parallel reflecting layers (18, 20) which are electrically conductive, electrically insulated from each other, and connected to electric terminals (28, 30), and an air gap (19) which is comprised between them. A mechanical excursion of one (20) of the two reflecting layers can thus be produced by an electric wanted signal (NS). The reflecting layers (18, 20) are disposed on a base block (14) of monocrystalline silicon having two parallel main surfaces (15, 16) each of which is covered by two passivating coatings (25, 35, 26, 36). The base block (14) is provided with a recess on one (16) of the main surfaces. An optical fiber (42) is fastened in said recess by means of an adhesive (44) in such a manner that the fiber end is completely enclosed by said adhesive. Thereby and by the structure of the associated coatings (26, 36), a minimal reflection is obtained. On the other main surface (15), the combination of the corresponding coatings (25, 35) and of the fixed reflecting layer (18) result in semipermeability to the light beam emerging from the optical fiber (42) and passing through the base block (14). After its modulation in the Fabry and Perot interferometer, the light beam returns to the optical fiber (42) in the reverse direction. (FIG. 1).

Optical reflection modulator

A light modulator useful for modulating a diverging light beam exiting from an optical fiber. In one embodiment, the modulator has a focusing lens and two flat partial mirrors. The lens collimates the light, one half of which respectively strikes each of the partial mirrors orthogonally. These mirrors reflect the light back onto itself causing, depending on the relationship between the wavelength of the incident light and the differences in path lengths, varying degrees of constructive or destructive interference. The difference in path length can be varied electrically if the partial mirrors are embodied as etched semiconductor foils which are controllably displaced in an electrostatic field set up between the foils and a substrate electrode.

Light modulator

A light modulator for modulating a light beam which emerges in the shape of a cone from an optical fiber. The modulator has a mirror which can be brought into at least two different states. In the one of these states, the light diverges in such a way that only a small portion returns back into the fiber. In the other of these states, however, more of the light returns back into the fiber. In one embodiment, the mirror is embodied as an etched semiconductor foil and is deformed by the force of a variable electrostatic field between the foil and an electrode which has been placed on a substrate.

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Berne, Switzerland

Rainer Battig