Abstract: Routers for trunk telecommunication systems currently operate at 2.5 Gb/s. Next generation routers will be required to switch 128 input data streams into 128 output data streams, each data stream being at a data rate of 10 Gb/s. Current routers employ massively parallel electronic switches to route data at 1.25 Gb/s. Such technology is reaching its limit and a new approach to high-speed switching is required. The present invention provides an apparatus and method for enabling such high-speed switching by providing a data compression apparatus which comprises a pulsed chirped laser (226) coupled to a modulator (218, 220), the modulator (218, 220) being coupled to a compressor (228, 230). A chirped laser pulse having the duration of a data packet is modulated with data received on an input channel and then passed through the compressor (228, 230) in order to generate a compressed modulated data pulse for high speed switching.

Abstract: In a method for coupling an electromagnetic signal between an electromagnetic signal source and an electromagnetic waveguide, wherein, in use, there is relative movement between the source and the waveguide, at each side where the source is launched into the waveguide, the properties of the waveguide are modified to permit the signal to be coupled into the waveguide, and the signal is launched into the waveguide at each site. At each site, the modification is reversed after launching the signal, so that the signal launched into the waveguide propagates along the waveguide. The process is repeated for each launch site along the waveguide. An electromagnetic coupler operates according to this method.

Abstract: An acoustically activated marketing for displaying predefined information in response to predefined data being received. The device is obtained from a retailer and worn as a badge while at the cinema or while listening to the radio or TV. When a specific advertisement is broadcast, the badge interprets part of the sound track and activates the display on the badge. The displayed information may be an advertisement or a message. The predefined data may be broadcast by a commercial broadcasting means, such as a television or radio.

Abstract: Methods and apparatus are provided for forming an image (68) of a scene (18) comprising a source of emitted or reflected light. The scene is illuminated (54) and a first image corresponding to the illuminated scene is recorded. Illumination is ceased, and a second image of the emitted or reflected light, corresponding to the non-illuminated scene, is recorded. The second image is used to generate a marker in the first image, said marker indicating the position of the emitted or reflected light.

Abstract: A system for controlling the demultiplexing process in an optical backplane device has application to optical switching in high-speed digital communication routers and switches. In demultiplexing, a selected compressed data packet is extracted from a multiplexed stream of compressed packets by a modulator and decompressed. The modulator is controlled by a control signal. An error in the timing of the modulator control signal corresponds to a characteristic distortion in the decompressed signal. By monitoring the effect of timing errors on decompressed signals, steps can be taken to correct the timing errors by controlling delays in either the optical or the electronic parts of the switching device. The timing of modulator control pulses is thus continuously adjusted to minimize timing errors. Instead of monitoring just decompressed signals, calibration pulse trains of known value and suitable form can be inserted.

Abstract: A pulse shaping apparatus for shaping an input optical pulse into an output optical pulse having substantially constant optical power, includes a modulator that acts upon the input optical pulse in response to a control signal. A sampling unit samples a portion of the input or output pulse and generates a sample signal that corresponds to the optical power of the input or output optical pulse. In a preferred embodiment, the sampling unit includes a power splitter that splits off sample portion of the input or output pulse, and directs the sample portion to the photodetector which generates the sample signal. Processing of the sample signal may be performed in either an analog or digital form.

Abstract: In the field of Acousto-Optic processors, it is desirable to sample and multiplex a large quantity of time varying data generated by a photodiode array. However, current multiplexers cannot sample at a high enough rate in order to process all of the data generated in real time, resulting in a reduced sampling bandwidth and therefore a loss of information. A data filtering apparatus and method of filtering a plurality of data signals overcomes this problem by providing a channel selection logic unit which instructs a multiplexer to only sample data generated which is above a predetermined threshold value, thereby omitting to sample data which is of little information value.

Abstract: A data compression device comprises at least two pulse generating devices (212, 222); a delay element (211, 221), modulating means (214, 224) and pulse compression element (215, 225) associated with each pulse generating device; and control means (240); whereby each modulated, compressed, pulse is multiplexed onto an optical fibre. The compression may be applied in the time domain or the spatial domain.

Abstract: There is provided a pulse shaping apparatus for shaping an input optical pulse (500) into an output optical pulse having substantially constant optical power (100, in FIG. 1). The apparatus includes a modulator, which acts upon the input optical pulse (500) under the control of a control signal, and a sampling means, which takes a sample of the incoming optical pulse for further processing. In a feedback configuration, the modulator acts on the incoming pulse under the control of an error signal, the incoming pulse is then sampled, the sample processed and the error signal generated from the processed sample. In a feed-forward configuration, the incoming pulse is sampled first, the sample processed and the modulator acts on the incoming pulse under the control of an error signal resulting from the processing steps.

Abstract: Routers for trunk telecommunication systems currently operate at 2.5 Gb/s. Next generation routers will be requires to switch 128 input data streams into 128 output data streams, each data stream being at a data rate of 10 Gb/s. Current routers employ massively parallel electronic switches to route data at 1.25 Gb/s. Such technology is reaching its limit and a new approach to high-speed switching is required. The present invention provides an apparatus and method for enabling such high-speed switching by providing a data compression apparatus which comprises a pulsed chirped laser (226) coupled to a modulator (218, 220), the modulator (218, 220) being coupled to a multiplexer (232) and a compressor (228). A chirped laser pulse having the duration of a data packet is modulated with data received on an input channel and then passed through the multiplexer (232) and the compressor (228) in order to generate a compressed modulated data pulse for high speed switching.

Abstract: There is provided an system for controlling the demultiplexing process in an optical backplane device (100). The system has application to optical switching in high-speed digital communication routers and switches. In demultiplexing, a selected compressed data packet (120) is extracted from a multiplexed stream of compressed packets by a modulator (102) and decompressed (104). The modulator (102) is controlled by a control signal (112). An error in the timing of the modulator control signal (112) corresponds to a characteristic distortion in the decompressed signal (116). By monitoring the effect of timing errors on decompressed signals (116), steps can be taken to correct the timing errors by controlling delays in either the optical or the electronic parts of the switching device. The timing of modulator control pulses (112) is thus continuously adjusted to minimise timing errors. Instead of monitoring just decompressed signals (116), calibration pulse trains of known value and suitable form can be inserted.

Abstract: Described herein is an integrated optical device (400) having an input path (402) and an output path (420). A waveguide (430) including a Bragg grating is located in the output path (42). A plurality of control elements are located along the waveguide (430) for providing local adjustment of the Bragg grating to compensate for manufacturing errors. The control elements are conveniently thermo-optic elements, for example, resistive elements whose temperature can be changed by supplying current to them.