Abstract: An optical waveguide device is proposed which comprises a substrate, thereupon a lower cladding layer, thereupon an upper cladding layer and between said cladding layers a waveguide element. The influence of the substrate on the stress-induced birefringence of the optical waveguide device is reduced by modification of the substrate from underneath the waveguide element.

Abstract: A singlemode lightwaveguide-coupling element is positioned between an initial waveguide section which there has a basic final width (W0f) and a final waveguide section which there has a basic initial width (Wn+1i) which is bigger than the basic final width (W0f). The lightwave directions of both waveguide sections are inclined at a predetermined total angle (&Dgr;&agr;) towards each other. Starting from the initial waveguide section, the lightwaveguide element comprises intermediate waveguide sections each of which at its end has a lightwave direction which is inclined towards the lightwave direction at its opposite end at an inclination angle (&Dgr;&agr;v), such that the sum of all inclination angles equals the predetermined total angle (&Dgr;&agr;).

Abstract: A singlemode lightwaveguide-coupling element is positioned between an initial waveguide section (10) which there has a basic final width (W0f) and a final waveguide section (30) which there has a basic initial width (Wn+1i) which is bigger than the basic final width (W0f). The lightwave directions of both waveguide sections are inclined at a predetermined total angle (&Dgr;&agr;) towards each other. Starting from the initial waveguide section, the lightwaveguide element comprises intermediate waveguide sections each of which at its end has a lightwave direction which is inclined towards the lightwave direction at its opposite end at an inclination angle (&Dgr;&agr;&ngr;), such that the sum of all inclination angles equals the predetermined total angle (&Dgr;&agr;).

Abstract: The present invention concerns optical memories. Such an optical memory (30) comprises a data line (31) which is optically coupled via a directional waveguide coupler (33) to a circular memory loop (32). In addition, it comprises a pump line (35), which is employed in order to couple a refresh signal into the loop (32). As in case of the data line, the pump line is coupled via a directional waveguide coupler (34) to the loop (32). The counter propagating refresh light pulse provides for an amplification of the light pulse circulating in the memory loop being doped with Erbium ions. The length L of the memory loop (32) is chosen such that the circulation frequency of the light pulse in said loop (32) is equal to the clock frequency of the optical memory (30). The memory provides for individual manipulation of each stored optical bit.