Abstract: A photonic light circuit device is described that comprises a semiconductor substrate (220) and two or more optical components (226, 228, 236, 240) wherein one or more hollow core optical waveguides (230, 232, 224) are formed in the semiconductor substrate to optically link said two or more optical components. The PLC may comprise a lid portion (44) and a base portion (42). The PLC can be adapted to receive optical components (8: 608) or optical components may be formed monolithically therein. Coating with a reflective layer is also described.

Abstract: A device for detecting infrared radiation is described that comprises a resonator element (36; 72; 96; 120) fixably attached to a supporting frame (32;130). The supporting frame (32;130) is arranged to absorb infrared radiation received by the device. The resonator element (36; 72; 96; 120) has a resonant property, such as resonant frequency, that varies with temperature. The device may comprise a plurality of detection elements (70), each detection element comprising a resonator element (72) fixably attached to a supporting frame. A thermal detector array device may also be provided.

Abstract: An optical amplifier is described that comprises at least two sections of amplifying optical fibre and pumping means for optically pumping the amplifying optical fibre. Optical fibre support means, for example a channel or channels in a substrate, are also provided to hold the two or more sections of amplifying optical fibre substantially straight during use. The optical fibre support means also includes a means for coupling light between the at least two sections of amplifying optical fibre. The at least one amplifying optical fibre may comprise an Erbium doped core to provide an erbium doped fibre amplifier (EDFA).

Abstract: A retro-reflective identification tag capable of modulating an optical signal whereby to support bi-directional communication with an associated remote optical interrogation device. The tag comprises a MOEMS modulating layer over a retro-reflective substrate, giving the tag a wide angle of effective operation. The tag modulator may optionally be switched on only responsive to detection of a precursor beam from the interrogation system in order to save power. The interrogation device may make use of multiple optical wavelengths for communicating with the tag.

Abstract: An optical routing device is described that comprises a semiconductor substrate (52) having at least one optical input (4), a plurality of optical outputs (6,8) and an array of MEMS moveable reflective elements (58;102). The array of moveable reflective elements (58;102) are configurable such that light can be selectively routed from any one optical input (4) to any one of two or more of said plurality of optical outputs (6,8). Light selectively routed from any one optical input to any one of two or more of said plurality of optical outputs (6,8) is guided within a hollow core waveguide (54). In one embodiment, a cross-connect optical matrix switch is described.

Abstract: A variable optical attenuator (VOA) device (20; 40; 50; 90) is described that comprises a first optical waveguide (24; 52; 80; 94; 120; 140) and a second optical waveguide (26; 42; 54; 82; 96; 122; 142). A moveable reflective element (28; 84; 106; 124; 144), such as a micro-electro mechanical system (MEMS) based component, is provided that has a controllable orientation with respect to at least one of said first and second optical waveguides. The first and second waveguides are formed as hollow core optical waveguides.

Abstract: Optical circuits for optical amplifier input and output stages are described. The input stage circuit (42) comprises a first optical waveguide (46) for carrying a signal beam to be amplified, a second optical waveguide (62) for carrying a pump beam, a beam combining means (58) optically coupled to the first and second optical waveguides (46, 62) for producing a combined signal/pump beam, and means for optically coupling the combined signal/pump beam into an amplifying optical fibre (63). The output stage circuit (44) comprises a first output optical waveguide (64), an optical fibre attachment means arranged to receive an amplifying optical fibre (63) and an optical fibre attachment means arranged to receive an output optical fibre (76) wherein light from the amplifying optical fibre (63) is optically coupled to the output optical fibre (76) via the first output optical waveguide (64).

Abstract: An optical wavelength division multiplexer/demultiplexer device is described that comprises a substrate having a plurality of wavelength selecting filters. The filters are arranged to provide conversion between a combined beam comprising a plurality of wavelength channels and a plurality of separate beams each comprising a subset of said plurality of wavelength channels. Hollow core waveguides are formed in said substrate to guide light between the wavelength selecting filters. An add/drop multiplexer is also described.

Abstract: A transmitter apparatus (2) is described that comprises one or more lasers (4), modulation means (10) to intensity modulate radiation output by each of said one or more lasers (4), and output means for outputting the modulated radiation produced by the modulation means into, for example, an optical fibre (22). The apparatus comprises hollow core optical waveguides (20) formed in a substrate (18) which, in use, guide radiation from the one or more lasers (4) to the modulation means (10) and from the modulation means (10) to the output means. An associated receiver apparatus (30) is also described that comprises one or more detectors (32) and one or more optical fibre attachment means, the one or more optical fibre attachment means being arranged to receive one or more one optical fibres (42). The receiver is characterised in that radiation is guided from the one or more optical fibres (42) to the one or more detectors (32) by at least one hollow core optical waveguide (40) formed in a substrate.

Abstract: A variable optical attenuator device is described that comprises a first optical input, a first optical output, a first optical path between the first optical input and the first optical output, and means for moving a shutter across said first optical path. A hollow core waveguide is provided to substantially guide light along the first optical path of the device. The device may also be used to provide an analogue beam splitting or switch function in telecommunication systems and the like.

Abstract: A hollow core multi-mode interference (MMI) device is described that comprises a multi-mode waveguide (10, 14) optically coupled to at least two fundamental mode waveguides (8, 12, 16). The device is characterised in that it comprises a means for varying the internal cross-sectional dimensions of a portion of one or more of said at least two fundamental mode waveguides. In particular, the side wall of a fundamental mode waveguide having a substantially square cross-section can be moved using micro-electro mechanical systems (MEMS). Various optical routing devices incorporating such MMI devices are described.

Abstract: A MEMS incorporating a sensing element and a JFET electrically connected to the sensing element is fabricated by the steps of: forming a first layer of electrically insulating barrier material on a surface of a substrate; patterning the first layer so as to expose a first region of the substrate; doping by ion implantation the first region of the substrate to form a well region of the JFET; forming a second layer of barrier material on the surface of both the first layer and the first region of the substrate; patterning the barrier material so as to expose a part of the first region of the substrate; doping by ion implantation the exposed part of the first region of the substrate to form source and drain contact areas of the JFET; patterning the barrier material so as to expose a second region of the substrate; and doping by ion implantation the second region of the substrate to form gate and substrate contact areas of the JFET in a single implantion step.

Abstract: A micro-electromechanical system (MEMS) comprises a substrate incorporating an oscillatory ring, forcing electrodes for driving the ring into resonance, and sensing electrodes providing an electrical output signal dependent on oscillation of the ring as a result of such forcing and any externally applied force. A positive feedback circuit is provided for feeding back a signal dependent on the output signal of the sensing electrodes to the forcing electrodes in order to sustain oscillation of the ring. The use of positive feedback to drive the forcing electrodes in order to sustain oscillation of the ring is highly advantageous in such an application since it produces a system which exhibits very low phase noise of a magnitude considerably less than the phase noise experienced in use of a phase-lock loop circuit to sustain oscillation.

Abstract: A multi-mode interference (MMI) device, comprising a hollow core multi-mode waveguide optically coupled to at least one hollow core input waveguide, is described in which the internal surfaces of the hollow core waveguides carry a reflective coating. The coating may be a low refractive index material at the wavelength of operation, such as a metal, or a multiple layer dielectric stack. Resonators and optical amplifiers using such (MMI) devices are also described.