Abstract: A method of assembly is presented for a multi-wavelength optical monitor (MWOM) for use in fibre optic telecommunication networks. The method allows coarse optimisation to be used to align an input optical fibre and detector array relative to a wavelength division demultiplexing element. The detector array output data are transformed with a digital signal processor into relative intensities of the components of the spectrum or spectral parameters of telecommunication channels.

Abstract: An optical link is operative for transmitting a microwave signal in modulated optical form over an optical fiber. The optical link has a transmitter and a receiver. The transmitter splits and converts the microwave signal into two separate optical signals, each of which represents either the positive varying part of the microwave signal or the negative varying part of the microwave signal. The receiver combines the two separate optical signals and converts them back into the microwave signal.

Abstract: A pump laser diode for providing improved stability at various operating temperatures is disclosed. It includes a Fabry-Perot cavity formed by laser facets. Bragg Gratings or Fiber Bragg Gratings (FBG) in a pump module are provided, wherein the optical mirror losses are made to increase for wavelengths longer than the required emission wavelength, thus permitting the diode to be locked to an emission wavelength while operating at different temperatures. A stack of materials with different refractive indices is deposited on the back facet of the laser diode to achieve a change in optical mirror losses over longer wavelengths.

Abstract: A strain sensor comprises an optical waveguide having a plurality of reflecting structure (Bragg grating) along its length. Each structure reflects light at a different characteristic wavelength (&lgr;1 to &lgr;n+1) which changes in dependence on a change of physical length of at least part of the reflecting structure. The reflectivity of reflecting structures which reflect at characteristic wavelengths which are adjacent to each other (&lgr;1 and &lgr;2 or &lgr;n and &lgr;n+1) are configured to be different such that the intensity of light reflected from adjacent structures can be used to discriminate between them.

Abstract: An optoelectronic package includes a supporting structure with a surface, an opposed surface, and at least one side, at least one conductive interconnect extending through the supporting structure from the surface to the opposed surface of the supporting structure, wherein the at least one conductive interconnect is substantially flush with the opposed surface of the supporting structure.

Abstract: An electro-optic device is disclosed for altering the density of charge carriers within an integrated optical waveguide. The device includes a substrate, and an integrated optical waveguide extending across the substrate with two doped regions being provided such that an electrical signal can be applied across the doped regions to alter the density of charge carriers within the waveguide. The doped regions can each include a plurality of doped areas spaced apart from each other along the length of the waveguide.

Abstract: Semiconductor laser diodes, particularly high power ridge waveguide laser diodes, are often used in opto-electronics as so-called pump laser diodes for fiber amplifiers in optical communication lines. To provide the desired high power output and stability of such a laser diode and avoid degradation during use, the present invention concerns an improved design of such a device, the improvement in particular consisting of novel design of the ridge waveguide of the laser. Essentially the novel design consists in a segmented ridge waveguide having at least two straight segments, i.e. segments with constant, but different cross sections or widths, and at least one flared segment connecting the two different straight segments. A further improvement can be achieved by combining this approach with a laser diode design termed “unpumped end sections” and described in copending U.S. patent application Ser. No. 09/852,994, entitled “High Power Semiconductor Laser Diode”.

Abstract: Optical filter elements and optical systems comprise optically mismatched etalons and optically mismatched stacked, optically coupled etalons that are directly optically coupled, at least one of the etalons or stacked, optically coupled etalons comprising first and second selectively transparent thin film mirror coatings on opposite surfaces of a bulk optic. The optically mismatched etalons can be configured to selectively pass single passbands. The disclosed optical systems optionally comprise other devices optically coupled to the optically mismatched etalons and optionally mismatched stacked, optically coupled etalons.

Abstract: Semiconductor laser diodes, particularly high power AlGaAs-based ridge-waveguide laser diodes, are often used in opto-electronics as so-called pump laser diodes for fiber amplifiers in optical communication lines. To provide the desired high power output and stability of such a laser diode and avoid degradation during use, the present invention concerns an improved design of such a device, the improvement in particular significantly minimizing or avoiding (front) end section degradation of such a laser diode and significantly increasing long-term stability compared to prior art designs. This is achieved by establishing one or two “unpumped end sections” of the laser diode. One preferred way of providing such an unpumped end section at one of the laser facets (10, 12) is to insert an isolation layer (11, 13) of predetermined position, size, and shape between the laser diode's semiconductor material and the usually existing metallization (6).

Abstract: The invention relates to the stabilization of semiconductor laser diode sources as they are extensively used in the field of optical communication. Such lasers are mostly employed as so-called pump laser sources for fiber amplifiers, e.g. Erbium-doped fiber amplifiers, and are designed to provide a narrow-bandwidth optical radiation with a stable power output in a given frequency band. To improve the stability of such laser sources compared to prior art designs, a plurality of “external” cavities is provided. In the commonly employed optical fibers for conducting the laser beam, these cavities may be formed by a plurality of appropriately designed Bragg gratings. However, the cavities may as well be formed by other means reflecting a given amount of the energy back to the laser in a desired frequency band, thus effecting the stabilization of the laser's intensity and frequency.

Abstract: A wavelength dependent optical device comprising: at least two optical Ports (21, 22); a first series of polarisation modifying optical components (23, 25, 27, 28) placed between the two Ports and a first dielectric mirror (29); the first dielectric mirror (29) operating substantially in reflectance mode at a first predetermined wavelength range and substantially in transmission mode at a second predetermined wavelength range; at least one second polarisation modifying optical component (30) placed between the first dielectric mirror (29) and a second mirror (31); the second mirror (31) operating substantially in reflectance mode at the second predetermined wavelength range; wherein light emitted from the first Port (21) at the first predetermined wavelength range is transmitted to the second Port (22), and light emitted from the first Port (21) at the second predetermined wavelength range is transmitted away from the second Port (22).

Abstract: The invention relates to a clip for holding an optical fiber which is enclosed in a fiber support tube, with respect to an optical source. The clip provides a rigid front part and a flexible back part in one single structure. This specific structure allows fixing and precise adjustment of the optical fiber alignment in a fully automated process in relatively few steps. No parts matching and multiple part handling are required when this clip is used, and final fine adjustment can be achieved by laser hammering and/or re-bending. The support tube is laser welded to the clip.

Abstract: A semiconductor laser adapted for telecommunications applications. The opitical mode delivered by the laser has a high power output beam and a narrow far field, thus, enabling efficient coupling of the laser into small numerical aperture optical fibers. The laser is made up of a semiconductor heterostructure and one or more optical trap layers.

Abstract: A Mach-Zehnder Modulator (MZM) pulse generator is provided having an increased power output. Power carved from the output signal in creating the pulses is recycled back to the input of the pulse generator via a feedback arm. Careful design of the length of the feedback arm such that a feedback signal has a propagation time of (2n+1)T/2 to complete one loop (n being a non-negative integer and T being the pulse period) allows a 50% duty cycle to be obtained using a driving frequency of only one half of the pulse frequency.

Abstract: The invention features an edge-emitting semiconductor signal laser having an active region to produce laser light. There is provided a semiconductor pump laser monolithically integrated with the edge-emitting signal laser. The pump laser includes a photon emissive active region to provide photopumping of the active region of the edge-emitting signal laser, thereby providing optical excitation of the active region of the signal laser.

Abstract: An optical amplifier is provided from a body 21, at least part 25 of which is doped with a rare earth such as erbium. At least one waveguide 47 extends through the doped part of the body. Pump light 51 is input on a side face 35 of the body and is distributed in the body over the length of the waveguide 47. A reflective coating 57 may be provided away from the pump light input, including on the opposite face 37 to the pump light input, to multiply reflect pump light within the body 21 to distribute the pump light within the body. The body may be in the form of a slab.

Abstract: An optical device, such as an electro-absorption modulator, has a waveguide formed onto a base. Electrodes adjacent the waveguide are used to selectively apply an electric field to the device in order to control the passage of light through the device. To prevent overheating of the device in a region near the point of optical entry, the electrode, which acts as a thermal conduit to dissipate heat from the waveguide is extended over the region. To prevent undesirable electrical contact between the electrode and the region, the normally electrically conducting contact layer between the electrode and the waveguide is removed in that region and replaced by an isolation dielectric.

Abstract: A structure for doping of III-V compounds is provided. The structure is a multi-layered structure in which layers of dopant are alternated with layers of initially undoped III-V compound. Dopant diffuses from the layers of dopant into the layers of III-V compound. The structure does not facilitate the introduction of impurities into the III-V compound during the diffusion of the dopant.

Abstract: An arrangement of an integrated optical waveguide (1) relative to a V-groove (2) for receiving an optical fibre (5) which is to be optically coupled with an end of the waveguide (1) is described. A waveguide (1) is formed in a crystalline optical substrate (3), and a V-groove (2) formed therein beneath an elongate parallel sided window in the substrate with a centre line (2A) of the V-groove (2) aligned with an end (1A) of the waveguide (1). The parallel sides (2B, 2C) of the window at the end of the V-groove (2) aligned with the waveguide (1) terminate out of alignment with each other in a direction along the length of the V-groove whereby the V-groove undercuts a portion (3A) of the optically conducting layer (3) beneath said end of the waveguide (1). The end of the waveguide (1) therefore overhangs the end of the V-groove (2) to enable the end of an optical fibre (5) to be located in close proximity thereto.

Abstract: A compact source capable of generating continuously tunable high frequency microwave radiation and short optical pulses in the picosecond/sub-picosecond range is invented. It includes a laser structure having two lasers formed on the same substrate which simultaneously operate at different longitudinal modes. Each laser has a complex coupled (gain-coupled or loss-coupled) grating which is formed by deep etching through a multi-quantum well structure, either of the active medium or of the additional lossy quantum-well layers, thus ensuring no substantial interaction between lasers. The lasers have a common active medium and shared optical path and provide mutual light injection into each other which results in generation of a beat signal at a difference frequency of two lasers. The beat frequency is defined by spacing between the laser modes and may be continuously tuned by current injection and/or temperature variation. Thus, the beat signal provides a continuously tunable microwave radiation.