Abstract: Apparatus for processing an optical signal carrying symbols. Modulation conversion means converts the optical signal from a first format, wherein each symbol has a unique nominal phase, to a second format, wherein each symbol has a unique combination of nominal phase and nominal amplitude. The modulation conversion means includes a signal splitter for splitting the optical input signal into two optical partial signals, which are directed to respective optical paths. Delay elements cause a mutual temporal difference between the two optical partial signals, which are processed in at least one non-linear regenerator having at least two ports and a gain which depends on the combined signal power directed to the at least two ports. The apparatus directs the optical partial signals from the modulation conversion means to an internal or external photo detector stage in the second format.

Abstract: An optical data transmission system having a hub, an optical router, and a plurality of optically pumped sources at a curb location, and a plurality of optical network units (ONUs). The ONUs generate and transmit respective data modulated pumping light to the curb location where it is received by the optically pumped sources, which convert it into the wavelength channels having predefined wavelength ranges assigned to respective ONUs. The optical router routes the wavelength channels for transmission to the hub.

Abstract: A method and system for ensuring confidentiality of signal transmission in a point-to-multipoint data transmission network like Ethernet passive optical network, including at least one hub, at least one transmission medium and at least one station connected to the hub via the transmission medium. When an upstream signal is transmitted from a first station, the upstream signal is reflected by at least one disturbing reflector for producing a disturbing reflection. The disturbing reflection combines with a second reflection of the upstream signal and renders the second reflection undecodable by a second station.

Abstract: An optical signal regeneration technique includes receiving optical symbols in a phase-modulation format. The received symbols are converted to symbols in a phase/amplitude-modulation format. A first amplitude regeneration, which involves reduction of amplitude noise, is applied to a first symbol pair. A modulation format conversion is performed on the optical signal in the phase/amplitude modulation format after the first amplitude regeneration. A second amplitude regeneration is applied to a second symbol pair, wherein the first and second symbol pairs differ from one another in respect of at least one different feature, which is selected from a group that includes a different nominal phase value assigned to the symbols of the symbol pair and a different temporal distance between the symbols of a symbol pair.

Abstract: A method and system for ensuring confidentiality of signal transmission in a point-to-multipoint data transmission network like Ethernet passive optical network, including at least one hub, at least one transmission medium and at least one station connected to the hub via the transmission medium. When an upstream signal is transmitted from a first station, the upstream signal is reflected by at least one disturbing reflector for producing a disturbing reflection. The disturbing reflection combines with a second reflection of the upstream signal and renders the second reflection undecodable by a second station.

Abstract: A method and system for ensuring confidentiality of signal transmission in a point-to-multi point data transmission network like Ether net passive optical network, including at least one hub, at least one transmission medium and at least one station connected to the hub via the transmission medium. When an upstream signal is transmitted from a first station, the upstream signal is reflected by at least one disturbing reflector for producing a disturbing reflection. The disturbing reflection combines with a second reflection of the upstream signal and renders the second reflection undependable by a second station.

Abstract: A method for use in characterizing a digital imaging system (53) having an array of imaging elements (35), and in particular for measuring the modulation transfer function (sometimes called the spatial frequency response) even in directions (33) at large angles to both horizontal rows and vertical columns of the array of imaging elements (35), wherein at large angles compared to either horizontal rows or vertical columns of the array of imaging elements (35)—and even at angles other than for directions lying along a diagonal to the array of imaging elements—only non-interpolated readings of the imaging elements (35) are used in determining a supersampled characterization of the digital imaging system (53).

Abstract: The specification and drawings present a new method and apparatus for a rotary hinge for transmitting an optical signal (e.g., comprising data) bi-directionally or uni-directionally from one part to another in an electronic device, wherein these parts can rotate relative to each other using the rotary hinge. The optical signal can be transferred from one side to the other side of the hinge independently from light transmitted in the opposite direction. A sending guiding element (e.g., an optical fiber or a light guide) can rotate around a common rotation axis permanently attached to the side sending the optical signal and the emitted optical beam is directed towards the common rotation axis. The receiving guiding element, which collects the optical beam, is concentrically in the center (coinciding with the common rotation axis) of the receiving side and permanently attached to it.

Abstract: The specification and drawings present a new method and apparatus for a rotary hinge for transmitting an optical signal (e.g., comprising data) bi-directionally or uni-directionally from one part to another in an electronic device, wherein these parts can rotate relative to each other using the rotary hinge. The optical signal can be transferred from one side to the other side of the hinge independently from light transmitted in the opposite direction. A sending guiding element (e.g., an optical fiber or a light guide) can rotate around a common rotation axis permanently attached to the side sending the optical signal and the emitted optical beam is directed towards the common rotation axis. The receiving guiding element, which collects the optical beam, is concentrically in the centre (coinciding with the common rotation axis) of the receiving side and permanently attached to it.

Abstract: An optical keyboard having a plurality of keys formed on a sheet of transparent material used as light guide. Each key is a dome-shaped element such that the light beam launched into one end of the dome-shaped element spreads over at least part of the dome-shaped element and then converges at another end. The intensity of the re-focused light beam at the converging end can be sensed by a photosensor. When a key is pressed, the deformity on the dome-shaped element changes the focusing properties of the key and thus the sensed light intensity. The dome-shaped elements can be used as individual keys or as a group of keys arranged in a two-dimensional matrix.

Abstract: A method for use in characterizing a digital imaging system (53) having an array of imaging elements (35), and in particular for measuring the modulation transfer function (sometimes called the spatial frequency response) even in directions (33) at large angles to both horizontal rows and vertical columns of the array of imaging elements (35), wherein at large angles compared to either horizontal rows or vertical columns of the array of imaging elements (35)—and even at angles other than for directions lying along a diagonal to the array of imaging elements—only non-interpolated readings of the imaging elements (35) are used in determining a supersampled characterization of the digital imaging system (53).

Abstract: An optical keyboard having a plurality of keys formed on a sheet of transparent material used as light guide. Each key is a dome-shaped element such that the light beam launched into one end of the dome-shaped element spreads over at least part of the dome-shaped element and then converges at another end. The intensity of the re-focused light beam at the converging end can be sensed by a photosensor. When a key is pressed, the deformity on the dome-shaped element changes the focusing properties of the key and thus the sensed light intensity. The dome-shaped elements can be used as individual keys or as a group of keys arranged in a two-dimensional matrix.

Abstract: A method and system for ensuring confidentiality of signal transmission in a point-to-multipoint data transmission network like Ethernet passive optical network, including at least one hub, at least one transmission medium and at least one station connected to the hub via the transmission medium. When an upstream signal is transmitted from a first station, the upstream signal is reflected by at least one disturbing reflector for producing a disturbing reflection. The disturbing reflection combines with a second reflection of the upstream signal and renders the second reflection undecodable by a second station.

Abstract: An optical fibre network comprises a hub, an optical router, and a plurality of optical network units (ONUs). In the downstream direction from the hub to the ONUs, the optical router receives channels having predefined wavelength ranges from a uni-directional input fibre and divides the channels so bi-directional input/output fibres receive at least one of the plurality of channels. In the upstream direction from the ONUs to the hub, the optical router receives the channels from the bi-directional input/output fibres, combines them, and outputs them to a uni-directional output fibre. For any particular channel, in the downstream direction it is routed to a first bi-directional input/output fibre and in the upstream it is routed from a second bi-directional input/output fibre different from the first bi-directional input/output fibre.

Abstract: An optical data transmission system (200) comprises a hub (202), an optical router (210) and a plurality of optically pumped sources (212) at a kerb location (208), and a plurality of ONUs (204). The ONUs generate and transmit respective data modulated pumping light to the kerb location where it is received by the optically pumped sources which convert it into the wavelength channels having predefined wavelength ranges assigned to respective ONUs. The optical router routes the wavelength channels for transmission to the hub.

Abstract: Interworking of optical protection in an optical network and IP-layer protection in the Internet is achieved by configuring optical links to form a part of a ring network and by arranging different protection types for different links. Each optical link is provided with an appropriate protection level corresponding to the nature of Internet traffic being transmitted over the link. The highest protection level is achieved with 1+1 protection. The optical layer can offer this protection for high priority Internet traffic that does not tolerate delay. The middle and the low protection level are achieved with 1:1 protection. The low protection level of a link does not guarantee uninterrupted transmission of the Internet traffic, in case of link failure caused by a fiber cut. Optical signaling at the optical layer takes care of protection wherein the IP-layer does not know when protection actions are carried out.

Abstract: The invention concerns an optical add/drop multiplexer for the node of a telecommunications system. In the telecommunications system wavelength multiplexing is used to transmit along an optical fiber a main system signal including several different signals. The signals are transmitted each with its own wavelength and of the signals it is possible to drop and to add desired chosen optical signals having different wavelengths (&lgr;1 . . . &lgr;N, (N>1). The add/drop multiplexer includes a group formed by direction selective organs and wavelength selective organs. Several such groups are connected to each other by connecting to each other gates of direction selective organs in the group. At least some of the other gates of the direction selective organs in the groups are used as gates of the add/drop multiplexer, so that the type of each gate to be used is chosen from a set including a unidirectional add gate, a unidirectional drop gate and a bi-directional add/drop gate.

Abstract: The invention relates to protection of an optical transmission connection. From the transmitting end of the connection, the same optical signal is transmitted along a first path and a second path to the receiving end, where the power level of the signal received from each path is monitored, and one of the paths is selected as the working path and the signal arriving from the said path is connected to the receiver, whereby the other path remains as a redundancy path. For the transmission connection to preserve an optimum performance also when the power level difference between the paths is varying, that path is at each time selected as the working path, where the received signal is considered at the moment in question to have the higher power level. The selection is always carried out when the power level difference between the signals reaches a predetermined threshold value, irrespective of the power level of the signal received at that time from the working path.

Abstract: The invention concerns an optical add/drop multiplexer for the node of a telecommunications system. In the telecommunications system wavelength multiplexing is used to transmit along an optical fiber a main system signal including several different signals. The signals are transmitted each with its own wavelength and of the signals it is possible to drop and to add desired chosen optical signals having different wavelengths (&lgr;1 . . . &lgr;N, (N>1). The add/drop multiplexer includes a group formed by direction selective organs and wavelength selective organs. Several such groups are connected to each other by connecting to each other gates of direction selective organs in the group. At least some of the other gates of the direction selective organs in the groups are used as gates of the add/drop multiplexer, so that the type of each gate to be used is chosen from a set including a unidirectional add gate, a unidirectional drop gate and a bi-directional add/drop gate.

Abstract: The invention relates to the implementation of multiplexing and demultiplexing of optical signals. The multiplexing and demultiplexing are carried out by using the same waveguide phased array component (WGA). On the first side, the component comprises at least an input port and an output port (IG, OG), and on its second side a first group of ports that constitute the demultiplexer function output ports, and a second group of ports that constitute the multiplexer function input ports. An optical input signal is applied to the input port, such an input signal comprising a number of signals each at its own wavelength, the input signal is demultiplexed in the component and the demultiplexed signals are coupled to ports of the first group. The signals to be multiplexed are applied to ports of the second group and the multiplexed signal is coupled to the output port (OG).