Liquid crystal ferroelectric electro-optical phase modulators which are insensitive to polarization

摘要

The modulator is formed by a smectic chiral ferroelectric C* liquid crystal cell (CL), crossed by the light signal which is transmitted by the said fibre. The cell (CL) is provided with transparent walls and transparent command electrodes (5 to 7). The liquid crystal (CL) , used in half-wave mode, is of the SSFLC (surface stabilized ferroelectric liquid crystal) type, having a wide tile angle . theta., which is as close as possible to 45°, in such a way that the said modulator is insensitive to polarisation. The modulator may be connected to two parallel fibres (A2, A3; B2, B3), pertaining to the intermediary part of a Mach-Zehnder coupler between the two 3 dB couplers, and when it is provided in order to modulate the light signal transmitted by either one of the two fibres.