Abstract: Apparatus for generating of a comb having a large number optical teeth and comprises an optical loop (3) including an optical amplifier (5) a frequency shifter (4) and an optical filter (6). A signal from a laser (9) is partially coupled into the loop by a coupler (7) such that a part of it is output at output port (10). The signal in the loop (the feedback signal) is amplified by the amplifier (5) and frequency shifted by the frequency shifter (4) and is then partially coupled out of the loop by coupler (7). The part coupled out of the loop (the output signal) exits via output port (10). This process is repeated to produce the desired number of output signals exiting via output port (10). The signal from the laser (9) may be continuous or pulsed.

Abstract: Shocks or sudden stresses caused by attempts to tap into an optical fiber network are detected by monitoring the "speckle pattern" produced by intermodal interference at the output of a multimode fiber. The fiber is a single mode optical fiber communication link through which a monitoring beam having a wavelength at which the fiber supports multiple propagation modes is also transmitted.

Abstract: An optical fiber (1) has an endface (2) which has been coated with a metal oxide coating (5) such that the light guiding core region (4) of the endface (2) is at least partially bounded by the coating (5) while being uncoated itself. The core region (4) has a different reflectivity than that of the boundary region (3). The fiber may be used in a system for aligning a fiber with an optical device (20).

Abstract: In a coherent optical system, a transmitter or transceiver having an optical source which feeds a single coherent wave to both a modulator and a bi-direction amplifier. The modulator generates a modulated information signal and the amplifier generates an unmodulated, amplified reference signal. A coupling means combines the modulated and amplified signals for transmission to a remote detector. The detector uses the amplified signal as the reference optical signal in a homodyne or heterodyne system.

Abstract: A micromechanical cantilever beam (1) for use in an optical switch or other radiation deflector assembly includes a beam portion (2) comprising two parallel arms (5,6) hinged at one end to a supporting substrate (4) and at the other end to a load portion (3) which provides the major proportion of the total mass of the cantilever beam. The beam is deflected by the application of an electrostatic potential between electrodes on opposing surfaces (8,9) of the load portion and the supporting substrate respectively. The structure has improved switching performance in operation.

Abstract: A hermetically sealed package (20) for an optical device (7) has a wall (21) which is formed partly by a positioning device (1) soldered to the wall (21). The positioning device (1) allows a fibre (4) to be aligned with the optical device (7) on either side of a transmissive window (3).

Abstract: An optical network comprises a plurality of transmitting (T.sub.n) and receiving (R.sub.n) terminals; and cross-coupling means (2), the transmitting (T.sub.n) and receiving (R.sub.n) terminals being optically coupled with the cross-coupling means whereby modulated carrier signals transmitted from each transmitting terminal (T.sub.n) are fed to each receiving terminal (R.sub.n) via the cross-coupling means (2). A plurality of first sources (4, 7) of optical signals are grouped together remotely from and optical coupled with the transmitting (T.sub.n) and receiving (R.sub.n) terminals to supply carrier signals and tuning signals to the transmitting and receiving terminals respectively.

Abstract: An optical component such as a laser chip is mounted on a substrate. The chip is mounted on a bridge positioned on the substrate locator in the form of depending legs provided on the bridge so that the bridge is located in the vertical direction relatively to the substrate and hence the laser chip is also located. Finally, the chip is secured to the substrate by, for example, soldering.

Abstract: The mounting of a movable member such as an optical mirror (3) by bridges (4-7) between a pair of supports (1, 2). The support (1, 2) bridges (4-7) and mirror (3) are integrally formed from a silicon substrate. A pair of electrically conductive paths (8, 9) are formed by doping or metallizing portions of the assembly so that by passing controlled currents through the paths, thermal expansion of parts of the paths will cause deflection of the mirror (3). The assembly is particularly useful for deflecting optical beams.

Abstract: The wavelength selection device comprises a substrate (1); and a deflectable wavelength selection member constituted by a diffraction grating (10) provided by a torsion member (6) mounted to the substrate (1). A pair of electrode (4,5) are responsive to a control current to cause the torsion member (6) to deflect whereby radiation centered on a predetermined wavelength is selected from radiation having a number of wavelengths impinging on the selection member (10) by setting the selection member (10) at a predetermined angle to the incoming radiation.

Abstract: A radiation deflector assembly, primarily for deflecting optical radiation, includes three waveguides mounted in V-shaped grooves (2,3,4) of a substrate (1) which are substantially coplanar. A cantilevered beam (6) integral with the substrate (1) is positioned in a cavity (5) of the substrate such that when the beam (6) is in a first position radiation passes between optical waveguides in two of the grooves (2,3) and when the beam is in a second position optical radiation passes between optical waveguides in another two of the grooves (2,4). Control electrodes (8,9) are responsive to control signals to generate a suitable electrostatic field for moving the beam (6) between the two positions.

Abstract: A method of mounting an optical component such as a laser chip on a substrate. The method involves mounting the chip on a bridge and positioning the bridge on the substrate. Depending legs are provided on the bridge so that the bridge is located in the vertical direction relatively to the substrate and hence the laser chip is also located. Finally, the chip is secured to the substrate by, for example, soldering.

Abstract: An optical interconnection system for integrated circuits has an optical source that is split into at least two parts. One part is modulated and the other part is transmitted to a detector and input on the local oscillator signal in homodyne detection. A single source may be split many ways to provide a plurality of beams for modulating and a plurality of local oscillator inputs to separate detectors. Both inter and intra wafer connections are described.

Abstract: A method of positioning an optical component such as a laser diode (36) in alignment with an optical waveguide (30) comprises forming an elongate V-shaped groove (29) and a depression (31) in a substrate (28). A laser diode (3) is then mounted in the depression (31) and is accurately located therein. An optical fibre (30) is mounted in the groove (29). The relative positions of the depression (31) and the waveguide (30) are such that in use an optical beam may be coupled between the optical component and the waveguide.