Abstract: Planar waveguides having quantum dots and methods of manufacture of the planar waveguide are described.

Abstract: An optical sensor comprises at least one bundle comprising a plurality of optical fibers and a plurality of separate fluid-tight longitudinally extending ducts; and fluid connectors for introducing fluids selectively into at least some of said ducts. Test cells are formed (a) by array members with a pattern of holes or recesses applied to the end of the bundle, or sandwiched between the ends of two bundles or (b) within the fibers in cases where a duct overlaps with the optical field of the fiber. Usually others of the ducts serve to remove fluid from the test cells.

Abstract: An electro-optical device capable of modulating the amplitude or phase of an optical output in response to an electrical data or control signal, or of switching it, has reduced frequency-dependence and a better combination of operating voltage and bandwidth. It comprises a body of electro-optically active material, waveguides for passing light through the body, and electrodes for applying an electric field with a frequency in the microwave region to the body, and its transverse geometry is such as to maintain adequate phase velocity matching between optical and microwave frequencies. There is a discontinuity in either the body or at least one of the electrodes such that the direction of the electro-optic effect is reversed for a portion of the length of the device at or near its downstream end.

Abstract: A method of fabricating an indium phosphide-based vertical cavity surface emitting laser (VCSEL) having a high reflectivity distributed Bragg reflector (DBR) that is particularly adapted for emitting a light having a center wavelength of around 1.30 micrometers. The method includes the steps of selecting a specific operating wavelength, determining the photon energy corresponding to the selected operating wavelength, selecting a maximum operating temperature in degrees Centigrade, and fabricating at least half of the high index layers of the distributed Bragg reflector (DBR) of the VCSEL from AlGaInAs or other material that can be epitaxially grown on the InP substrate to have a band gap equal to or greater than the sum of the photon energy (in milli-electron volts) plus the sum of the maximum operating temperature plus 110 divided by 1.96.

Abstract: An integrated optical chip has a crystalline structure cut along parallel principal crystallographic planes and a thickness of less than 1.0 mm. An optical signal pathway is disposed generally longitudinally in one of the cut surfaces of the chip, and the chip is attached to a substrate material up to 1.0 mm thick and having similar coefficients of thermal expansion in that principal crystallographic plane. A grounding plane is disposed between the chip and substrate to provide an electrically conductive path between opposite lateral surfaces of the chip. A method of making the chip is also described.

Abstract: There is provided a two-stage optical regenerator for regenerating a data signal comprising a series of optical pulses. Each stage of the optical regenerator comprises a modulator for modulating a reference signal with an input signal, and an interferometer for causing the modulated reference signal to interfere with another version of the modulated reference signal delayed by less than one bit period of the data signal to regenerate the input signal. The input signal of the modulator of the first stage of the regenerator comprises the data signal, and the input signal of the modulator of the second stage of the regenerator comprises the output from the first stage of the regenerator.

Abstract: A method for splicing optical fibers includes securing a first optical fiber and a second optical fiber within an apparatus, stripping a coating from about the first optical fiber by a first laser beam generated from at least one laser, and stripping a coating from about the second optical fiber by the first laser beam. The method also includes cleaving an end of the first optical fiber via a second beam from the laser, and cleaving an end of the second optical fiber via the second laser beam. The method further includes splicing the ends of the optical fibers together via a third laser beam from the laser, thereby creating a fused connection between the first optical fiber and the second optical fiber, and removing the first and second optical fibers from within the apparatus.

Abstract: An optically-pumped mode-locked fiber ring laser for optical clock recovery of multiple wavelength division multiplexed optical signals actively mode-locks a plurality of outputs of the laser as a plurality of recovered clocks for a plurality of the multiple wavelength division multiplexed optical signals.

Abstract: Microlens arrays (105) having high focusing efficiencies are provided. The high focusing efficiencies are achieved by accurately producing the individual microlenses making up the array at high fill factors. Arrays of positive microlenses are produced by forming a master having a concave surface-relief pattern (101) in a positive photoresist (21) using direct laser writing. Through this approach, the problems associated with the convolution of a finite laser beam with a desired profile for a microlens are overcome. The microlens arrays of the invention have focusing efficiencies of at least 75%.

Abstract: A semiconductor ridge laser for coupling to a single-mode optical fiber has a ridge with a narrow parallel region, a diverging region, and then a wide parallel region that is adjacent to an output facet. A pump region for the laser may be less than the entire area of the ridge and have a “T” shape. Preferably, the ridge has a depth of about 350 to 550 nm and the narrow parallel region has a length of more than 0.4 times the overall length of the ridge. The wide parallel region at the output enables the laser to obtain low thermal resistance, which leads to a low operating temperature, a low power density in the laser cavity, and low astigmatism.

Abstract: Apparatus for recovering clock pulses of wavelength division multiplexed optical signals passed therethrough. The apparatus comprises an optically-pumped laser cavity defining a cavity length and comprising a nonlinear medium pumped at a wavelength selected to give efficient parametric amplification within said medium. The cavity length corresponds to an integer multiple of bit periods of at least one of the multiplexed optical signals. The optical signals copropagate through the medium with the pump radiation. The apparatus further comprises an optical path for recirculating a proportion of the output from the laser cavity back through the laser cavity. In this way, idler waves are generated symmetrically about the pump wavelength by four wave mixing with the at least one of the multiplexed optical signals and recirculated through the laser cavity to be amplified by parametric amplification in order to recover wavelength division multiplexed clock pulses.

Abstract: A connector assembly for connecting and aligning an active optical component with an optical waveguide is provided. The assembly comprises: (i) a waveguide chip having an optical waveguide embedded beneath a cladding layer and a cavity for accommodating the active optical component comprising at least one wall extending from the surface of the cladding layer through the waveguide; and (ii) a second chip for carrying the active optical component. The waveguide chip comprises a locating stop and the second chip has first and second reference regions formed thereon, the first reference region being adapted to locate the active optical component, and the second reference region being adapted to engage the surface of the cladding layer and the locating stop of the waveguide chip when the waveguide chip and second chip are connected together with the active optical component located within the cavity in order to provide alignment of the waveguide with the active optical component.

Abstract: Self-aligned aperture masks are produced using a positive-acting photoresist (18) which is developed with a liquid developer. The apertures (30) of the mask have lower levels of inter-aperture variability than masks produced using mechanical transfer of toner particles (FIGS. 4-5 and 7-8), both for the apertures of a given mask and between masks.

Abstract: The invention relates to an optical assembly for opto-electronic packages comprising an optical fibre secured on the underside of an elongated support member in optical alignment with an opto-electronic device, wherein said support member is affixed to an aligning member, which in turn is affixed, e.g., by laser welding, to a welding platform. In a preferred embodiment, the elongated support member is a planar parallelepiped. In a further preferred embodiment, the elongated support member is a parallelepiped with an axially extended slot, in which the optical fibre is secured with its longitudinal axis substantially parallel to the axially extended slot.

Abstract: Screens for use with image-forming illumination (53,54) are provided, as well as methods for producing such screens. The screens include an array of lenses (51), a substrate, and a layer of light-absorbing material (55) in which apertures are formed using aperture-forming illumination (52) which passes through the lenses (51). The optical properties of the lenses (51) and the thickness of the substrate are selected so as to maximize the light-blocking area of the layer of light-absorbing material (55) while allowing long-wavelength image-forming illumination (54) to pass through the apertures substantially unimpeded. The array of lenses can be an array of randomized, anamorphic microlenses.

Abstract: Optical pumping unit comprising a first pump source adapted to emit a first pump radiation at wavelength &lgr;p1; a second pump source adapted to emit a second pump radiation at wavelength &lgr;p2, with wavelength &lgr;p2 different from wavelength &lgr;p1; and a common coupling section comprising a first and a second port connected to the first and second pump source for respectively receiving the first and the second pump radiation; a third port for a signal radiation at wavelength &lgr;s; a fourth port, wherein the coupling section is adapted to combine, in the fourth port, the signal radiation and the first and second pump radiation through a reversal of the direction of propagation of the first pump radiation from the first port to the fourth port.

Abstract: An optical selector for an asynchronous transfer mode (ATM) optical network, the said selector being capable of selecting ATM cells of bits having a frequency of arrival f less than or equal to a predetermined frequency (PCR), the said optical selector comprising: an input having a first device capable of blocking the entry of bits; an output having a second device capable of permitting the outflow of bits; an ATM cell recognition unit constructed in such a way that it recognizes the headers of ATM cells and connected to the said input and to the said output for the transit of bits from the said input to the said output; and an optical decision unit connected operationally to the said first device, to the said second device and the said ATM cell recognition unit.

Abstract: An optical device comprises an input for an input optical impulse and an optical beam splitting element for supplying, from the input optical impulse, a first pair and a second pair of optical impulses. Also included is a first optical delay element to delay, by a predetermined time, at least one of the first pair of optical impulses and a second optical delay element to delay, by a predetermined time, at least one of the second pair of optical impulses. A first optical processing element supplies a first output optical signal to a first output when commanded by the first pair of optical impulses and a second optical processing element supplies a second output optical signal to a second output when commanded by the second pair of optical impulses.

Abstract: A method is disclosed for operating a computer system to reduce the size of an image, which comprises the following steps. First, data representing an image, a size of the image, and a desired size of a corresponding compressed image is received by the system. If processing of the image is finished, then data representing the compressed image is emitted, otherwise the image is partitioned into at least one strip to omit and a plurality of subimages, each represented by data representing the subimage, a size of the subimage, and a desired size for a corresponding compressed subimage. Then the above steps are repeated for each subimage.

Abstract: A handwritten character recognizer having an input cluster buffer and a point buffer with dynamic and static stroke feature extraction and segment analysis by conical boundaries for identification of stroke segments dynamic stroke feature extractor static stroke feature extractor. A stroke recognizer compares single copies of idealized stroke representations with hierarchically approximated multiple scaled topological representations of a current stroke, followed by stroke proportion discrimination comparing a selected topological representation of the current stroke with boundaries defined by linear combinations of features of direct and reversed ideal stroke prototypes to provide a stroke identification. A cluster recognizer maintains a time ordered current stroke buffer and previous stroke buffer and constructs a per stroke area of influence list. The time ordered buffers are scanned to generate a spatially ordered window buffer.