Abstract: An optoelectronic device has at least a first facet (S), a first waveguide (2) and a second waveguide (3). The waveguides are substantially coincident at the first facet (6), such that light travelling along the first waveguide (2) is reflected into the second waveguide (3) by the first facet (6). The first facet (6) is formed by precision cleaving. Preferably an etch feature is incorporated in the same mask level as that to define the waveguide core.

Abstract: An optoelectronic device has at least a first facet (S), a first waveguide (2) and a second waveguide (3). The waveguides are substantially coincident at the first facet (6), such that light travelling along the first waveguide (2) is reflected into the second waveguide (3) by the first facet (6). The first facet (6) is formed by precision cleaving. Preferably an etch feature is incorporated in the same mask level as that to define the waveguide core.

Abstract: A semiconductor optical amplifier has the materials and dimensions of its waveguide chosen to obtain, at an intended working wavelength (say the C band), a confinement factor of less than 0.06 for the most confined mode and mode field diameters in the range from about 3 to about 4 &mgr;m for the fundamental TE and TM modes, based on a 1/e mode field boundary, whereby the semiconductor optical amplifier can be readily coupled to a tensed optical fiber without requiring a mode expander or additional optics.

Abstract: An optical monomode guided-wave device, especially an electroabsorption modulator, having an active region with a mode size small compared with that of an optical fibre is integrated with at least one passive spot size adjuster which has an optical core that tapers simultaneously from a width and height substantially equal to those of the active region adjacent to that region to a width large compared with the width of the active region and a thickness substantially smaller than the thickness of the active region at a position remote from that region. Usually—unless the device includes its own light source—there will be two spot size adjusters, respectively at the inlet and outlet of the device.

Abstract: An optical device package includes an optical device held in optically coupled relationship with an optical fibre by a ceramic ferrule. The optical device is mounted on a heatsink, the heatsink being mounted on the ferrule. The optical device is accurately mounted in relation to the rim of the ferrule such that insertion of the optical fibre into the ferrule brings the optical fibre into optically coupled relationship with the optical device without the need for active alignment techniques. The optical device, in use, is encapsulated in silicon sealant to seal the device form the effects of humidity.

Abstract: A semiconductor device, preferably a laser device such as a signal generator, a signal amplifier or a signal detector e.g. a distributed feedback laser, which is implemented in III/V semiconductors. Such devices often require a barrier layer to encourage current flow to pass through the localised p/n-interface and this invention provides the barrier layer in the form of a layer of hole trapping semiconductor material located between and in contact with two p-type layers. III/V semiconductors contain at least one of indium, gallium and aluminum and at least one of phosphorus and arsenic but the preferred devices are laser devices implemented in various types of indium phosphide except for the active zone wherein photons are generated. The active zone is preferably formed of ternary and/or quaternary semiconductors. In the preferred structures the barrier layer is formed of chromium doped indium phosphide which is located between two layers of p-type indium phosphide.