Abstract: An encoder for providing encrypted data for transmission via a transmission medium includes an encryption unit that is configured to encrypt data received at the encoder block by block and a processing unit. The processing unit is configured to randomly distribute an encrypted data block to a plurality of channels that are allocated to the transmission medium and to provide a sub-block, which includes part of the encrypted data block, to be transmitted via one of the channels, together with a channel identification allocated to the channel and a code value that is based on the encrypted data in the sub-block to be transmitted and the channel identification, for transmission via the allocated channel of the transmission medium.

Abstract: An encoder for providing encrypted data for transmission via a transmission medium includes an encryption unit that is configured to encrypt data received at the encoder block by block and a processing unit. The processing unit is configured to randomly distribute an encrypted data block to a plurality of channels that are allocated to the transmission medium and to provide a sub-block, which includes part of the encrypted data block, to be transmitted via one of the channels, together with a channel identification allocated to the channel and a code value that is based on the encrypted data in the sub-block to be transmitted and the channel identification, for transmission via the allocated channel of the transmission medium.

Abstract: A directional coupler comprising a first and a second optical waveguide extending at least partially parallel to one another is provided. The first and the second optical waveguide are arranged on a substrate in such a way that they extend in common plane running essentially parallel to the substrate. The first and the second optical waveguide are embedded in a polymer cladding. The first optical waveguide comprises a dielectric core and the second optical waveguide comprises a polymer core, or both the first and the second optical waveguide comprise a polymer core, wherein the cross section and/or the composition of the polymer cores is different.

Abstract: A tunealble optical grid-assisted add/drop filter for codirectional operational mode consisting of at least two waveguides composed of two different classes of material of different optical parameters. The thermal refractive index coefficient dn/dT, the electro-optic coefficient dn/dE or the dispersion dn/d&lgr; of the two materials differ from each other such that when the temperature, the electric field or the wavelength of or in the two waveguides is change, the result will be effects of different powers.

Abstract: The invention relates to a tuneable optical grid-assisted add/drop filter in codirectional mode of operation, which has the structure of a directional coupler filter with at least two adjacent waveguides having different refractive indices. The inventive filter must exhibit a spectral bandwidth of the filter transmission curve in the range from 50 GHz to 400 GHz for a high resolution in order to be tuneable and it must be producible in a more straightforward and more cost-effective manner, with dimensional tolerances higher than those of InP based add/drop filters. For that purpose, the material of the two waveguides is composed of two different classes of materials having different optical parameters.