Abstract: In order to provide very fast tuning of an coherent optical receiver, an apparatus for use in optical telecommunications includes a coherent optical receiver with a converter stage adapted to convert a received optical signal to an electrical signal by down-converting the received optical signal in frequency using a local oscillator signal, an analog/digital converter stage adapted to sample the converted signal, a digital processor adapted to process the sampled signal to restore a transmitted data signal, and a wavelength selector adapted to select from a distribution network an unmodulated light signal at a configurable wavelength for use as the local oscillator signal. The distribution network is an optical bus system in the form of a fiber ring.

Abstract: A receiver for an OTDM/PDM pulse train (10) in which the pulses (12) have alternating polarizations (P1, P2) has a polarization insensitive optical switch (16; 161, 162, 163, 164) for isolating optical pulses (10?) within the pulse train (10), and a polarization selective element (17) for separating from the isolated pulses (10?) at least one component that has a single polarization. This allows to considerable relax the constraints posed on the switch since components in the isolated pulses that result from interchannel interference can, at least to a large extent, be eliminated by the subsequent polarization selective element (17).

Abstract: The invention shows a transmission system with a transmitter function, a transmitting fiber and a receiver function where the transmitter function comprising lightsources (1), modulators (2) and a multiplexer (3), and the receiver comprising at least a demultiplexer (5), filters and electrical receivers where the channels for left side filtering are modulated with modulators with a negative chirp and for right side filtering with modulators with positive chirp.

Abstract: The present invention discloses an electro-optical element and a method for generating an amplitude-modulated optical signal (24). The element comprises a semiconductor substrate (12), an electro-optical modulation structure arranged on the substrate (12), a first terminal (22) for supplying an optical signal (20) to be modulated, a second terminal (28) for supplying an electrical modulation signal, and a modulation area adapted for modulating the optical signal (20) with the electrical modulation signal (50). According to one aspect of the invention, a limiter (30) is provided for limiting the electrical modulation signal. The limiter (30) is arranged on the substrate (12) and is operatively connected between a second terminal (28) and the modulation area.

Abstract: A receiver for an OTDM/PDM pulse train (10) in which the pulses (12) have alternating polarizations (P1, P2) has a polarization insensitive optical switch (16; 161, 162, 163, 164) for isolating optical pulses (10′) within the pulse train (10), and a polarization selective element (17) for separating from the isolated pulses (10′) at least one component that has a single polarization. This allows to considerable relax the constraints posed on the switch since components in the isolated pulses that result from interchannel interference can, at least to a large extent, be eliminated by the subsequent polarization selective element (17).

Abstract: The invention refers to a fiber optical time division multiplexing device for modulating a laser carrier by some modulation signal, comprising at least one interferometrical unit The interferometrical unit comprises a first and a second optical path each one of said optical paths comprising one semiconductor optical amplifier, and one input port for some optical control signal. The interferometrical unit further comprises one input port for said laser carrier and one output port for some optical output signal, said carrier input port and said output port beeing common to both said optical paths. The laser carrier is split into two portions at the common carrier input port. One portion is travelling along the first optical path, while the other portion is travelling along the second optical path, both portions beeing individually amplified by the according SOA and beeing interferometrically reunified at the common output port.

Abstract: Summary A decision circuit for high data rates is disclosed comprising threshold detectors between which the data stream of the incoming signals is divided, a demultiplexer stage, and EXOR gates. Using the circuit, an eye monitor and a pseudoerror monitor can be constructed. Also disclosed is a transmission system using receivers incorporating the decision circuit according to the invention.

Abstract: The invention shows a transmission system with a transmitter function, a transmitting fiber and a receiver function where the transmitter function comprising lightsources (1), modulators (2) and a multiplexer (3), and the receiver comprising at least a demultiplexer (5), filters and electrical receivers where the channels for left side filtering are modulated with modulators with a negative chirp and for right side filtering with modulators with positive chirp.

Abstract: An integrated optoelectronic semiconductor component is presented, which can equally process light signals of any polarization direction. Such semiconductor components are used for digital optical telecommunications. The semiconductor component has active (A) and passive (B) waveguide sections, which comprise a number of semiconductor layers (SP) with so-called multiple quantum well structures. The semiconductor layers (SP) are deposited by a process known as selective area growth (SAG). A portion of the semiconductor layers has a lattice constant which is smaller than the lattice constant of a substrate (SUB). This creates a biaxial tensile strain in these layers. The tensile strain is optimized in the active waveguide sections (A) to attain polarization independence. Furthermore a process is described whereby such a semiconductor component can be manufactured.

Abstract: The invention concerns an optically controlled optical switching module (SM1), as well as a method of optically controlling an optical switching network, and an optical switching network. The optical switching module (SM1) is equipped with at least one optical switch (OCOSW), which is controlled through an optical control input (CONTR), which switches a useful optical signal. The optical switching module (SM1) furthermore has an optical pulse shaper (PW) that is connected to this control input (CONTR), which produces switching pulses that are suitable for the optical switch (OCOSW), from an optical control signal. The optical switching network contains at least one optical switching module (SM1). Control bits from an optical data packet are individually masked out in the optical switching network by means of optical switches (OSW), and the optical control signals corresponding to the respective control bits (CB1 to CB4) are fed to one of the optical pulse shapers (PW).