Abstract: An optical wireless local area network using line of sight optical links. The base station and terminal stations are provided with optical transceivers which include a transmitter array and detector array. The transmitter array consists of an array of resonant cavity light emitting diodes integrated using flip-chip technology with a CMOS driver circuit. The driver circuit includes constant bias, current peaking and charge extraction. The driver circuitry is compact and can be confined within a region underlying the corresponding light source. The detector array consists of an array of photo diodes, provided with sense circuitry consisting of a pre-amplifier and post-amplifier. The diodes and sense circuitry are also integrated using a flip-chip technique. The light emitter and the detector may include adaptive optical elements to steer and/or focus the light beams.

Abstract: An optical wireless local area network using line of sight optical links. The base station and terminal stations are provided with optical transceivers which include a transmitter array and detector array. The transmitter array consists of an array of resonant cavity light emitting diodes integrated using flip-chip technology with a CMOS driver circuit. The driver circuit includes constant bias, current peaking and charge extraction. The driver circuitry is compact and can be confined within a region underlying the corresponding light source. The detector array consists of an array of photo diodes, provided with sense circuitry consisting of a pre-amplifier and post-amplifier. The diodes and sense circuitry are also integrated using a flip-chip technique. The light emitter and the detector may include adaptive optical elements to steer and/or focus the light beams.

Abstract: The invention relates to the field of grating structures. The invention provides a longitudinal grating having an aperiodic structure, wherein the grating has a selected response characteristic and any repeated unit cell in the structure is significantly longer than a characteristic length associated with the selected response characteristic.

Abstract: An optical wireless local area network using line of sight optical links. The base station and terminal stations are provided with optical transceivers which include a transmitter array and detector array. The transmitter array consists of an array of resonant cavity light emitting diodes integrated using flip-chip technology with a CMOS driver circuit. The driver circuit includes constant bias, current peaking and charge extraction. The driver circuitry is compact and can be confined within a region underlying the corresponding light source. The detector array consists of an array of photo diodes, provided with sense circuitry consisting of a pre-amplifier and post-amplifier. The diodes and senses circuitry are also integrated using a flig-chip technique. The light emitter and the detector may include adaptive optical elements to steer and/or focus the light beams.

Abstract: An optical wireless local area network using line of sight optical links. The base station and terminal stations are provided with optical transceivers which include a transmitter array and detector array. The transmitter array consists of an array of resonant cavity light emitting diodes integrated using flip-chip technology with a CMOS driver circuit. The driver circuit includes constant bias, current peaking and charge extraction. The driver circuitry is compact and can be confined within a region underlying the corresponding light source. The detector array consists of an array of photo diodes, provided with sense circuitry consisting of a pre-amplifier and post-amplifier. The diodes and senses and the detector may include adaptive optical elements to steer and/or focus the light beams.

Abstract: A holographic filter for an optical communication system is configurable to provide signal power equalisation for a number of optical signals or signal channels in a wavelength division multiplexed system.

Abstract: A holographic filter for an optical communication system is configurable to provide signal power equalisation for a number of optical signals or signal channels in a wavelength division multiplexed system.

Abstract: A tunable optical wavelength selective filter is constituted by a dynamic holographic diffraction element (3) in combination with a fixed diffraction grating or hologram (2). The dynamic diffraction element (3) is preferably implemented as an electronically controlled image displayed on a pixelated spatial light modulator and in particular a spatial light modulating using photo-electronic integrated circuits fabricated using silicon VLSI technology and integrated with ferro-electric liquid crystals. Amongst other uses the filter can be implemented to form a digitally tunable laser.

Abstract: A polarisation independent optical switch is constituted by a light input (6), a diffractive and re-configurable liquid crystal device (8), a collimating lens (7) for distributing the input light over the liquid crystal device (8), a transform lens (9) receiving light from the liquid crystal device (8) and light output (6), wherein no polarisers are present between the light input and output. The diffractive and re-configurable liquid crystal device (8) may be formed as a liquid crystal spatial light modulator configured as a binary phase computer generated hologram with the holograms required to form broadcast, individual or multicast switching being re-generated using an iterative algorithm and then being recalled on demand. In one embodiment the switch has a folded configuration and includes a reflector (10) so that the light input and output are both on the same side of the liquid crystal device (8).