Abstract: A two-dimensional matrix of complex coupled (gain or loss coupled) semiconductor DFB lasers is disclosed. The matrix includes several parallel branches of series lasers, each series having a plurality of lasers which are grown on the same wafer. The parallel branches are combined at either one end or both ends with either an integrated on-chip optical combiner or an external coupler to obtain a single optical output port. Each laser in the series comprises a multiple quantum well active region and a complex coupled grating having corrugations along a cavity length direction formed by periodic etching grooves through either the active region or the lossy QW region. The depth of etching is defined so as to provide a substantial insensitivity of each laser to the external feedback and random facet variations and to thereby ensure no substantial interaction between lasers in the series.

Abstract: A method of patterning a brittle material, and particularly a semiconductor material, is provided comprising ion implantation induced selective area exfoliation. The method includes steps of masking the material, implanting unmasked regions of the material, with light ions of Hydrogen or Helium, and rapid thermal annealing at the temperature causing exfoliation of the material from the implanted regions. As a result, the material is patterned to a depth determined by the depth of ion implantation. The method allows patterning through crystalline or non-crystalline materials, or several layers of different materials at the same time. When the mask has straight sharp edges aligned parallel to natural cleavage planes of the semiconductor material, the exfoliation results in formation of high quality sidewall-facets of exfoliated material and of the remaining patterned material at the boundaries of exfoliated regions.

Abstract: A one dimensional series of complex coupled (gain or loss coupled) DFB semiconductor lasers is disclosed. Each laser comprises a multiple quantum well active region and a complex coupled grating having corrugations along a cavity length direction formed by periodically etching grooves through the active region. The grating has a period comprising a first section and a second section, wherein substantially all quantum wells are etched away from the second section providing no substantial photon generation in the second section. The depth of etching is defined so as to provide a substantial insensitivity of each laser to the external feedback and random facet variations and to ensure no substantial interaction between lasers in the series. The lasers in the series may further comprise means for tuning laser wavelengths around corresponding lasing modes and/or means for switching between the lasing modes.

Abstract: A passive method and packaging system for thermally controlling the temperature of electronic equipment within a housing are disclosed. The packaging system provides for two cooling steps, each of which uses a different passive cooling technology. Cooling by changing the phase of Phase Change Material, assists in controlling internal ambient temperatures by limiting the effects of short term localized thermal phenomena which would otherwise further increase internal temperatures. Cooling is also provided for by switching on a second passive cooling means, preferably a heat pipe, as the internal temperature of the housing increases above a predetermined temperature and to switch it off as the internal temperature drops below the predetermined temperature. Turning the second passive cooling means on and off provides respectively, a low or high thermal resistance path between the interior and exterior of the housing.

Abstract: A method of assembling an integrated circuit component onto a substrate by the use of a polymer adhesive having fluxing properties and a specified adhesive strength and temperature control volumetric change which is greater than that of a solder to be used between terminals of the component to terminals of the substrate. In the method the uncured polymer adhesive is located between the circuit component and the substrate and as the second component moves into its site position upon the substrate, the uncured polymer adhesive is compressed and is displaced outwardly from between the body of the component and the substrate. In the method, as an exterior force is required to displace the adhesive in this manner, glass microspheres are provided within the adhesive to limit the movement of the integrated circuit components towards the substrate.

Abstract: The invention provides a complex coupled distributed feedback (DFB) semiconductor laser device with energy band gap modulation. The device comprises an active region formed on a substrate, and a barrier region adjacent the active region, the energy band gap of the barrier region modulated along a cavity length direction to form a complex coupled grating. The modal gain is higher in the barrier region areas, having narrower energy band gap, due to higher material gain and higher optical confinement factor in these areas. Periodic modulation of the energy band gap of the barrier region produces gain (or loss) modulation and index modulation in the material of the active region, thus, gain coupling and index coupling mechanisms being provided. Methods of producing gain modulation in the DFB laser, and fabrication thereof are also provided.

Abstract: The invention relates to a passive liquid immersion cooling apparatus for electronic systems operating in thermally uncontrolled environments. The apparatus comprises an external shell, defining a chamber with a plurality of heat dissipating components disposed within the chamber and surrounded by the shell. The components are immersed into a low boiling point dielectric liquid partially filling the chamber. The shell has two portions, an upper portion of the shell adjacent the area above the liquid level which forms a vapor space, and a lower portion of the shell adjacent the liquid. The shell has an external heat transfer structure providing more efficient heat transfer from the upper part of the shell, for example, in the form of external fins extending outward from the shell, and an internal heat transfer structure in the form of internal fins extending inward from the shell and into the chamber. Preferably, the external fins extend along the upper portion of the shell only.

Abstract: A complex coupled (gain coupled or loss coupled) distributed feedback (DFB) semiconductor laser, having two sections axially distinct along a cavity length direction, and two excitation means for independent pumping of corresponding sections of the laser in a master and slave type of pumping control, is provided. An extended continuous wavelength tuning range of the laser is obtained by selectively activating a left Bragg mode or a right Bragg mode across the stop band of the laser as a dominant lasing mode by the master and slave type of current injection control into different sections of the laser to alternate gain coupling and loss coupling mechanisms of laser operation, and further tuning a wavelength around the activated Bragg mode. Methods of operating the laser, enhancing a tuning range, and fabricating thereof are provided.

Abstract: In methods and apparatus for controlling allocation of traffic channels in a telecommunications network having macrocells and microcells within the macrocells, a macrocell traffic channel is allocated in response to a request for a microcell traffic channel only when no suitable microcell traffic channel is available, a suitable macrocell traffic channel is available, and the requested microcell traffic channel is requested to implement a microcell to microcell handoff. Allocation of the macrocell traffic channel may further be conditional on a grade of service in the macrocell being deemed acceptable. The grade of service may be deemed acceptable when number of macrocell traffic channels assigned to each microcell is less than a predetermined maximum number of allowable macrocell traffic channels that can be assigned to each microcell (cutoff value) or when more than a threshold number of macrocell channels are available in the macrocell.