Abstract: An optical device integrated on a planar substrate is disclosed, comprising a Y-branch attenuator optically coupled to a Mach-Zehnder modulator. The device also comprises means for reducing a crosstalk caused by unguided radiation between the Y-branch attenuator and the Mach-Zehnder modulator. In one embodiment, the reduction of the crosstalk is obtained by connecting the Mach-Zehnder modulator to one arm of the Y-branch attenuator. The invention also comprises a transmitting module including the integrated device.

Abstract: An optical device integrated on a planar substrate is disclosed, comprising a Y-branch attenuator optically coupled to a Mach-Zehnder modulator. The device also comprises means for reducing a crosstalk caused by unguided radiation between the Y-branch attenuator and the Mach-Zehnder modulator. In one embodiment, the reduction of the crosstalk is obtained by connecting the Mach-Zehnder modulator to one arm of the Y-branch attenuator. The invention also comprises a transmitting module including the integrated device.

Abstract: Active device assembly comprising a substrate having at least a planar surface on which a plurality of electrical contact pads are formed, a chip having a surface on which at least one optical waveguide and a plurality of electrodes are formed. Said chip surface is in a facing relationship with the planar surface of the substrate, and said electrical contact pads are in electrical contact to said electrodes. Said contact pads and said electrodes provide mechanical connection between said chip and said substrate and the coefficient of thermal expansion of the substrate is greater than or equal to the coefficient of thermal expansion of the chip in a length direction.

Abstract: An optical waveguide device comprises at least one Y-junction integrated on a planar substrate. The junction comprises a first (1), a second (3) and a third (4) optical waveguide extending on the said substrate, and a transition portion (2), in which the second and third waveguides branch from the first waveguide, comprising a truncation (5) of predetermined width. At the position of the truncation, the width of the first waveguide is less than the sum of widths of the second waveguide, the third waveguide and the truncation. The first optical waveguide extends into the transition portion up to the bifurcation with its width essentially constant.