Abstract: An optical coupler is formed of a low index material and exhibits a mode field diameter suitable to provide efficient coupling between a free space optical signal (of large mode field diameter) and a single mode high index waveguide formed on an optical substrate. One embodiment comprises an antiresonant reflecting optical waveguide (ARROW) structure in conjunction with an embedded (high index) nanotaper coupling waveguide. Another embodiment utilizes a low index waveguide structure disposed in an overlapped arrangement with a high index nanotaper coupling waveguide. The low index waveguide itself includes a tapered region that overlies the nanotaper coupling waveguide to facilitate the transfer of the optical energy from the low index waveguide into an associated single mode high index waveguide. Methods of forming these devices using CMOS processes are also disclosed.

Abstract: An arrangement for providing optical crossovers between waveguides formed in an SOI-based structure utilize a patterned geometry in the SOI structure that is selected to reduce the effects of crosstalk in the area where the signals overlap. Preferably, the optical signals are fixed to propagate along orthogonal directions (or are of different wavelengths) to minimize the effects of crosstalk. The geometry of the SOI structure is patterned to include predetermined tapers and/or reflecting surfaces to direct/shape the propagating optical signals. The patterned waveguide regions within the optical crossover region may be formed to include overlying polysilicon segments to further shape the propagating beams and improve the coupling efficiency of the crossover arrangement.

Abstract: A plasma-based etching process is used to specifically shape the endface of an optical substrate supporting an optical waveguide into a contoured facet which will improve coupling efficiency between the waveguide and a free space optical signal. The ability to use standard photolithographic techniques to pattern and etch the optical endface facet allows for virtually any desired facet geometry to be formed—and replicated across the surface of a wafer for the entire group of assemblies being fabricated. A lens may be etched into the endface using a properly-defined photolithographic mask, with the focal point of the lens selected with respect to the parameters of the optical waveguide and the propagating free space signal. Alternatively, an angled facet may be formed along the endface, with the angle sufficient to re-direct reflected/scattered signals away from the optical axis.

Abstract: The surface silicon layer (SOI layer) of an SOI-based optical modulator is processed to exhibit a corrugated surface along the direction of optical signal propagation. The required dielectric layer (i.e., relatively thin “gate oxide”) is formed over the corrugated structure in a manner that preserves the corrugated topology. A second silicon layer, required to form the modulator structure, is then formed over the gate oxide in a manner that follows the corrugated topology, where the overlapping portion of the corrugated SOI layer, gate oxide and second silicon layer defines the active region of the modulator. The utilization of the corrugated active region increases the area over which optical field intensity will overlap with the free carrier modulation region, improving the modulator's efficiency.

Abstract: One or more nanotaper coupling waveguides formed within an optical substrate allows for straightforward, reproducible offset launch conditions to be achieved between an incoming signal and the core region of a multimode fiber (which may be disposed along an alignment fixture formed in the optical substrate), fiber array or other multimode waveguiding structure. Offset launching of a single mode signal into a multimode fiber couples the signal into favorable spatial modes which reduce the presence of differential mode dispersion along the fiber. This approach to providing single mode signal coupling into legacy multimode fiber is considered to be an improvement over the prior art which required the use of an interface element between a single mode fiber and multimode fiber, limiting the number of propagating signals and applications for the legacy multimode fiber. An optical switch may be used to select the specific nanotaper(s) for coupling into the multimode fiber.

Abstract: A silicon-based optical modulator structure includes one or more separate localized heating elements for changing the refractive index of an associated portion of the structure and thereby providing corrective adjustments to address unwanted variations in device performance. Heating is provided by thermo-optic devices such as, for example, silicon-based resistors, silicide resistors, forward-biased PN junctions, and the like, where any of these structures may easily be incorporated with a silicon-based optical modulator. The application of a DC voltage to any of these structures will generate heat, which then transfers into the waveguiding area. The increase in local temperature of the waveguiding area will, in turn, increase the refractive index of the waveguiding in the area.

Abstract: A silicon-insulator-silicon capacitive (SISCAP) optical modulator is configured to provide analog operation for applications which previously required the use of relatively large, power-consuming and expensive lithium niobate devices. An MZI-based SISCAP modulator (preferably a balanced arrangement with a SISCAP device on each arm) is responsive to an incoming high frequency electrical signal and is biased in a region where the capacitance of the device is essentially constant and the transform function of the MZI is linear.

Abstract: A silicon-based optical modulator structure includes one or more separate localized heating elements for changing the refractive index of an associated portion of the structure and thereby providing corrective adjustments to address unwanted variations in device performance. Heating is provided by thermo-optic devices such as, for example, silicon-based resistors, silicide resistors, forward-biased PN junctions, and the like, where any of these structures may easily be incorporated with a silicon-based optical modulator. The application of a DC voltage to any of these structures will generate heat, which then transfers into the waveguiding area. The increase in local temperature of the waveguiding area will, in turn, increase the refractive index of the waveguiding in the area. Control of the applied DC voltage results in controlling the refractive index.

Abstract: An electro-optic modulator arrangement for achieving switching speeds greater than 1 Gb/s utilizes pre-emphasis pulses to accelerate the change in refractive index of the optical waveguide used to form the electro-optic modulator. In one embodiment, a feedback loop may be added to use a portion of the modulated optical output signal to adjust the magnitude and duration of the pre-emphasis pulses, as well as the various reference levels used for modulated. For free carrier-based electro-optic modulators, including silicon-based electro-optic modulators, the pre-emphasis pulses are used to accelerate the movement of free carriers at the transitions between input signal data values.

Abstract: An arrangement for providing optical crossovers between waveguides formed in an SOI-based structure utilize a patterned geometry in the SOI structure that is selected to reduce the effects of crosstalk in the area where the signals overlap. Preferably, the optical signals are fixed to propagate along orthogonal directions (or are of different wavelengths) to minimize the effects of crosstalk. The geometry of the SOI structure is patterned to include predetermined tapers and/or reflecting surfaces to direct/shape the propagating optical signals. The patterned waveguide regions within the optical crossover region may be formed to include overlying polysilicon segments to further shape the propagating beams and improve the coupling efficiency of the crossover arrangement.

Abstract: A photodetector integrated within a silicon-on-insulator (SOI) structure is formed directly upon an inverse nanotaper endface coupling region to reduce polarization sensitivity at the detector's input. The photodetector may be germanium-based PN (PIN) junction photodetector, a SiGe photodetector, a metal/silicon Schottky barrier photodetector, or any other suitable silicon-based photodetector. The inverse nanotaper photodetector may also be formed as an in-line monitoring device, converting only a portion of the in-coupled optical signal and allowing for the remainder to thereafter propagate along an associated optical waveguide.

Abstract: A silicon-based IR photodetector is formed within a silicon-on-insulator (SOI) structure by placing a metallic strip (preferably, a silicide) over a portion of an optical waveguide formed within a planar silicon surface layer (i.e., “planar SOI layer”) of the SOI structure, the planar SOI layer comprising a thickness of less than one micron. Room temperature operation of the photodetector is accomplished as a result of the relatively low dark current associated with the SOI-based structure and the ability to use a relatively small surface area silicide strip to collect the photocurrent. The planar SOI layer may be doped, and the geometry of the silicide strip may be modified, as desired, to achieve improved results over prior art silicon-based photodetectors.

Abstract: An improvement in the reliability and lifetime of SOI-based opto-electronic systems is provided through the use of a monolithic opto-electronic feedback arrangement that monitors one or more optical signals within the opto-electronic system and provides an electrical feedback signal to adjust the operation parameters of selected optical devices. For example, input signal coupling orientation may be controlled. Alternatively, the operation of an optical modulator, switch, filter, or attenuator may be under closed-loop feedback control by virtue of the inventive monolithic feedback arrangement. The feedback arrangement may also include a calibration/look-up table, coupled to the control electronics, to provide the baseline signals used to analyze the system's performance.

Abstract: Pyrrolopyrimidine derivatives of formula (I) are inhibitors of Spleen Tyrosine kinase (Syk) and therefore of potential therapeutic benefit in the treatment of diseases and conditions associated with inappropriate Syk activity, in particular in the treatment of inflammatory and allergic diseases.

Abstract: The surface silicon layer (SOI layer) of an SOI-based optical modulator is processed to exhibit a corrugated surface along the direction of optical signal propagation. The required dielectric layer (i.e., relatively thin “gate oxide”) is formed over the corrugated structure in a manner that preserves the corrugated topology. A second silicon layer, required to form the modulator structure, is then formed over the gate oxide in a manner that follows the corrugated topology, where the overlapping portion of the corrugated SOI layer, gate oxide and second silicon layer defines the active region of the modulator. The utilization of the corrugated active region increases the area over which optical field intensity will overlap with the free carrier modulation region, improving the modulator's efficiency.

Abstract: A silicon-based optical modulator structure includes one or more separate localized heating elements for changing the refractive index of an associated portion of the structure and thereby providing corrective adjustments to address unwanted variations in device performance. Heating is provided by thermo-optic devices such as, for example, silicon-based resistors, silicide resistors, forward-biased PN junctions, and the like, where any of these structures may easily be incorporated with a silicon-based optical modulator. The application of a DC voltage to any of these structures will generate heat, which then transfers into the waveguiding area. The increase in local temperature of the waveguiding area will, in turn, increase the refractive index of the waveguiding in the area.

Abstract: A low loss optical waveguiding structure for silicon-on-insulator (SOI)-based arrangements utilizes a tri-material configuration including a rib/strip waveguide formed of a material with a refractive index less than silicon, but greater than the refractive index of the underlying insulating material. In one arrangement, silicon nitride may be used. The index mismatch between the silicon surface layer (the SOI layer) and the rib/strip waveguide results in a majority of the optical energy remaining within the SOI layer, thus reducing scattering losses from the rib/strip structure (while the rib/strip allows for guiding along a desired signal path to be followed). Further, since silicon nitride is an amorphous material without a grain structure, this will also reduce scattering losses. Advantageously, the use of silicon nitride allows for conventional CMOS fabrication processes to be used in forming both passive and active devices.

Abstract: An SOI-based photonic bandgap (PBG) electro-optic device utilizes a patterned PBG structure to define a two-dimensional waveguide within an active waveguiding region of the SOI electro-optic device. The inclusion of the PBG columnar arrays within the SOI structure results in providing extremely tight lateral confinement of the optical mode within the waveguiding structure, thus significantly reducing the optical loss. By virtue of including the PBG structure, the associated electrical contacts may be placed in closer proximity to the active region without affecting the optical performance, thus increasing the switching speed of the electro-optic device. The overall device size, capacitance and resistance are also reduced as a consequence of using PBGs for lateral mode confinement.

Abstract: Compounds of formula (I): are inhibitors of p38 kinase and are useful in the treatment of conditions or disease states mediated by p38 kinase activity or mediated by cytokines produced by the activity of p38.

Abstract: The invention relates to compounds of formula (I) processes for their preparation, pharmaceutical compositions containing them and to their use in medicine, particularly use in the amelioration of a clinical condition for which a Factor Xa inhibitor is indicated.