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 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 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 fiber (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 fiber attachment means, the one or more optical fiber attachment means being arranged to receive one or more one optical fibers (42). The receiver is characterized in that radiation is guided from the one or more optical fibers (42) to the one or more detectors (32) by at least one hollow core optical waveguide (40) formed in a substrate.

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: 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 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 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: 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: 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: 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 method of micro-machining comprising providing a primary region of at least a first material which contacts a second material at at least one end portion thereof, the method comprising providing an infill material on to the second material, patterning and etching said infill material to form a hole through the infill material to the second material, depositing the first material on to said infill material so that the at least one portion of the first material contacts the second material through the hole. The method can be used to provide a track bridging suspended portions of micro-machined structures. Also a method of narrowing and sealing top portions of channels cut into a wafer is disclosed.

Abstract: A method of fabricating a micro-mechanical sensor (101) comprising the steps for forming an insulating layer (6) onto the surface of a first wafer (4) bonding a second wafer (2) to the insulating layer (6), patterning and subsequently etching either the first (4) or second wafer (6) such that channels (18,20) are created in either the first (2) or second (4) wafer terminating adjacent the insulating layer (6) and etching the insulating layer (6) to remove portions of the insulating layer (6) below the etched wafer such that those portions of the etched wafer below a predetermined cross section, suspended portions (22), become substantially freely suspended above the un-etched wafer. This method uses Silicon on Insulator technology. Also disclosed is a micro-mechanical gyroscope structure (101) allowing an anisotropic silicon to be used to fabricate a sensor functioning as if fabricated from isotropic silicon.

Abstract: A method of fabricating a micro-mechanical sensor (101) comprising the steps for forming an insulating layer (6) onto the surface of a first wafer (4) bonding a second wafer (2) to the insulating layer (6), patterning and subsequently etching either the first (4) or second wafer (6) such that channels (18,20) are created in either the first (2) or second (4) wafer terminating adjacent the insulating layer (6) and etching the insulating layer (6) to remove portions of the insulating layer (6) below the etched wafer such that those portions of the etched wafer below a predetermined cross section, suspended portions (22), become substantially freely suspended above the un-etched wafer. This method uses Silicon on Insulator technology. Also disclosed is a micro-mechanical gyroscope structure (101) allowing an anisotropic silicon to be used to fabricate a sensor functioning as if fabricated from isotropic silicon.

Abstract: A method of fabricating a micro-mechanical sensor (101) comprising the steps for forming an insulating layer (6) onto the surface of a first wafer (4) bonding a second wafer (2) to the insulating layer (6), patterning and subsequently etching either the first (4) or second wafer (6) such that channels (18, 20) are created in either the first (2) or second (4) wafer terminating adjacent the insulating layer (6) and etching the insulating layer (6) to remove portions of the insulating layer (6) below the etched wafer such that those portions of the etched wafer below a predetermined cross section, suspended portions (22), become substantially freely suspended above the un-etched wafer. This method uses Silicon on Insulator technology. Also disclosed is a micro-mechanical gyroscope structure (101) allowing an anisotropic silicon to be used to fabricate a sensor functioning as if fabricated from isotropic silicon.