Abstract: A semiconductor phase modulator comprises a lower cladding layer, an active waveguide and an upper cladding layer, deposited successively on a substrate made of III-V material. The active waveguide comprises at least one first active layer having a first photoluminescence wavelength and one second active layer of compensation having a second photoluminescence wavelength. The operating wavelength of the modulator is higher than the first photoluminescence wavelength by a value ranging from 80 to 200 nm, and it is greater than the second photoluminescence wavelength by a value of over 300 nm.

Abstract: The demultiplexer comprises a diffraction space defined by a reception surface coupled to a grating. In order to obtain output waves of flattened spectral response, the input waveguide and the reception surface are dimensioned so that the input wave diffracts over said surface and presents a plurality of secondary lobes. The demultiplexer is particularly applicable to optical communications systems with wavelength multiplexing.

Abstract: Selection switches (C1, . . . , C3-4) enable an optical path (BC, C1, C2-1, C3-1, D1, B1) to be selected from a plurality of such paths predefined on a common substrate (PE), each of the switches belonging to a plurality of such paths for that purpose. Isolation switches (D1, . . . , DN) each belong to one such path only. The isolation switches are disposed at the ends of the paths so as to enable the selected path to be isolated from optical members (LEN) that are outside the selector and that are connected to the non-selected paths. In this way crosstalk is avoided. The invention applies in particular to backing up an optical link.

Abstract: An acoustic-optical device for optical filtering includes two successive acoustic-optical interaction segments separated by an intermediate polarizer and each modifying the polarization of light guided by it. The modification depends on the frequencies of the interacting optical and acoustic waves. The acoustic waves are supplied symmetrically to the two interaction segments from a common electro-optical transducer. The transmission spectrum of the optical filter is subject to apodization by coupling between an auxiliary acoustic waveguide including the transducer and a main acoustic waveguide including the optical waveguide. Applications of the device include fiber optic telecommunication systems.

Abstract: In a method for fixing a polarization-preserving optical fiber the fiber is illuminated transversely and orientation of the polarization-preserving plane of the fiber is monitored by direct visual examination of internal components of the fiber rendered visible by such illumination. The illumination is effected through the wall of a transparent ferrule holding the fiber. The method has applications in fiber optical telecommunications systems.

Abstract: High sensitivity interferential electro-optical modulator. The invention concerns an interferential electro-optical modulator. This modulator contains a Mach-Zehnder integrated interferometer in which each interferometer arm (24, 26) is overlapped by an electrode (40, 42), itself surrounded by two lateral electrodes (44, 46, 48, 50) to uniformize the electrical field crossing through each arm perpendicular to the face of the electro-optical crystall on which it is formed. Application to the detection of accoustic waves and low voltage measurement.