Abstract: In a method and an apparatus for transmitting signals in an optical fiber, an amplitude modulator (1) is provided for amplitude modulating an optical carrier at high speed with signals to be transmitted. A suppressing means is provided to suppress at least part of one of the side bands of the modulated carrier to reduce the effect of group velocity dispersion in the optical fiber.

Abstract: An arrangement and a method route wavelength dependent optical signals including a number of wavelengths. The arrangement includes an optical Add-Drop multiplexing arrangement with input and output waveguides and a routing device with inputs and outputs. The routing device includes a splitting device with a number of inputs and a combining device with a number of outputs. One of the inputs and outputs, respectively, are used for a multi-wavelength input, whereas another input and another output, respectively, are used for an add/drop wavelength. The other inputs and outputs are used for looping back of the remaining wavelengths. Between the splitting and combining devices a number of branch waveguides are arranged, and both wavelength demultiplexing/multiplexing and switching are provided for by the routing device.

Abstract: The present invention relates to a wavelength selective switch. Said switch comprises at least one MMI waveguide, at least one Mach Zehnder waveguide, at least one phase control element and at least one Bragg grating, where said Mach Zehnder waveguide comprises said phase control element and said Bragg grating and is arranged in connection to at least one MMI waveguide. The invention further comprises a method for switching wavelength channels by using the above mentioned wavelength selective switch.