Abstract: The invention relates to a method in a transmitting node for transmitting a modulated optical carrier signal over an optical channel in an optical communications network to a receiving node. The method enables full use of the polarization domain within a Poincaré sphere when modulating the optical carrier signal.

Abstract: The invention provides a method and system for measuring the length of a reflective resonator, by analyzing an electromagnetic spectrum emitted therefrom. The emitted spectrum is used for estimating a first cavity length. This estimation is thereafter improved, by first computing at least one interference number for the spectrum, adjust this value to e.g. an integer or half-integer depending on the configuration of the resonator, and thereafter re-calculating the length of the resonator using the adjusted value of the interference number. The above is an efficient way of improving the accuracy in the determination of a physical property of a resonator.

Abstract: The invention relates to a method in a transmitting node for transmitting a modulated optical carrier signal over an optical channel in an optical communications network to a receiving node. The method enables full use of the polarisation domain within a Poincaré sphere when modulating the optical carrier signal.

Abstract: The invention provides a method and system for measuring the length of a reflective resonator, by analyzing an electromagnetic spectrum emitted therefrom. The emitted spectrum is used for estimating a first cavity length. This estimation is thereafter improved, by first computing at least one interference number for the spectrum, adjust this value to e.g. an integer or half-integer depending on the configuration of the resonator, and thereafter re-calculating the length of the resonator using the adjusted value of the interference number. The above is an efficient way of improving the accuracy in the determination of a physical property of a resonator.

Abstract: The present invention relates to the encoding and decoding. respectively, of serial data, using block codes. Encoding of a serial bit stream of input data in groups of N bits, so-called words (O), to serial output data in groups of 2N bits, so-called code words (KO), is preferably carried out by a logic circuit in a manner such that N of the 2N bits in the code words (KO) are comprised of the N bits input data, unchanged or inverted, and remaining bits in the code words (KO) are determined so that, seen statistically, the code words (KO) will include approximately as many zeros as ones, such that each code word (KO) will be unique for each word (O), and such that at least one of the code words (KO) will remain unique even in bit stream shifting processes. Decoding includes further encoding in a similar logic circuit and comparison of the incoming code words with the code words encoded in the logic circuit, in a predetermined manner.

Abstract: The present invention relates to an optical duobinary transmitter system and method using optical intensity modulation. The system comprises an input terminal (51) arranged to receive a first binary signal, a driving circuit (53) connected to the input terminal and arranged to convert the first binary signal into a second and a third binary signal, a double electrode optical modulator (55) connected to the driving circuit in such a way that its upper and lower electrode may be driven by said second and third binary signal, respectively, said modulator being further arranged to modulate the amplitude and phase of an optical carrier according to the binary driving signals so as to provide an optical duobinary signal corresponding to said first binary signal and with a predetermined negative modulation chirp parameter, and an output terminal (57) connected to the optical modulator and arranged to feed an optical transmission line with the modulated optical duobinary signal.

Abstract: In a fiber-optical WDM-transmission system channel switching is used to achieve a high transmission capability and/or quality in spite of the polarization mode dispersion experienced by pulses propagating along an optical fiber. The WDM-channels having best transmission properties among the available WDM-channels are used to transmit high-priority traffic, the remaining channels being used for e.g. low-priority traffic. The high- and low-priority information arrives on input lines and is switched in a cross-connect element coupling the high-priority information to the best channels and the other information to the other channels, the channels being combined in a multiplexer to be injected in the transmission fiber.

Abstract: The present invention relates to the encoding and decoding respectively of serial data, using block codes. Encoding of a serial bit stream of input data in groups of N bits, so-called words (O), to serial output data in groups of 2N bits, so-called code words (KO), is preferably carried out by a logic circuit in a manner such that N of the 2N bits in the code words (KO) are comprised of the N bits input data, unchanged or inverted, and remaining bits in the code words (KO) are determined so that, seen statistically, the code words (KO) will include approximately as many zeros as ones, such that each code word (KO) will be unique for each word (O), and such that at least one of the code words (KO) will remain unique even in bit stream shifting processes. Decoding includes further encoding in a similar logic circuit and comparison of the incoming code words with the code words encoded in the logic circuit, in a predetermined manner.

Abstract: In transmission of optical signals in a dispersive medium, the signals are transmitted simultaneously in two modes in an optical fiber (15), which are orthogonal to each other, one of the signals being a non-chirped amplitude modulated signal modulated by an amplitude modulator (3), and the other signal is a phase modulated signal modulated by a phase modulator (5). The received signal is formed by the sum of the amplitude modulated contributions of the two signals. In an optical fiber system, two orthogonal modes of polarization in the same fiber can be chosen. In this manner it will be possible to transmit high bit rates and primarily over long distances.