Abstract: Broadband optical switches based on adiabatic couplers having a pair of asymmetric waveguides with variable curvature sections include in a 2×2 configuration based on a Mach-Zehnder interferometer two such adiabatic couplers, and in a 1×2 or 2×1 configuration an adiabatic coupler and an Y-splitter. Each adiabatic coupler includes two waveguide branches of different but constant widths having curved sections with varying radii, separated over a coupling length by a changing spacing therebetween and blending in an asymmetric intersection area, and two symmetric branches. In the 2×2 switch, the two adiabatic couplers face each other with their respective symmetric branches, and are connected by the two identical arms along a main propagation axis in a mirror image. The utilization of the variable curvature adiabatic couplers in silica MZI switches on a silicon substrate provides switches with an exceptional broadband range (1.2-1.

Abstract: Ultra fast, compact wavelength-selective 2×2 optical switches based on polarization splitters and preferably electro-optical polarization converters, and switch matrices based on such switches. The switches and switch matrices are preferably implemented on electro-optical substrates using planar light-wave circuit technology. Switch designs include switches comprised of two polarization splitters and two polarization converters, and a switch comprised of one polarization splitter and two polarization converters. In a preferred embodiment, a switch comprises a TE-barring polarization splitter, a TM-barring polarization splitter, and two electro-optical wavelength-selective polarization converters connected in parallel between the TE- and TM-barring polarization splitters, and is implemented on an electro-optical substrate such as InP, GaAs, LiNbO3 or LiTaO3 using planar lightwave circuit technology.

Abstract: A method and system of operating a variable optical attenuator to provide a required total attenuation in a planar lightwave circuit. The method comprises providing a first Mach-Zehnder interferometer having a first and a second arm carrying signals in an arbitrary polarization state, providing a second Mach-Zehnder interferometer having a third and a fourth arm carrying signals in an arbitrary polarization state, the second Mach-Zehnder interferometer concatenated in tandem with the first Mach-Zehnder interferometer, and cooperatively operating the concatenated first and second Mach-Zehnder interferometers to obtain the required total attenuation and an effectively nil polarization dependent loss.

Abstract: A method for operating a planar lightwave circuit at a constant power consumption, comprises providing a matrix of integrated active elements, heating independently each active element with a separate heating power, and cooperatively operating the heating powers of the active elements to keep a sum of the operating heating powers constant in time independently on the dynamic operation of the element. The active element has two connecting configurations and is operative to have a phase change in a light beam passing through each of the connecting configurations, both connecting configurations being constantly heated. The active element is operable in both analog and digital modes with a constant power consumption.

Abstract: Broadband optical switches based on adiabatic couplers having a pair of asymmetric waveguides with variable curvature sections include in a 2×2 configuration based on a Mach-Zehnder interferometer two such adiabatic couplers, and in a 1×2 or 2×1 configuration an adiabatic coupler and an Y-splitter. Each adiabatic coupler includes two waveguide branches of different but constant widths having curved sections with varying radii, separated over a coupling length by a changing spacing therebetween and blending in an asymmetric intersection area, and two symmetric branches. In the 2×2 switch, the two adiabatic couplers face each other with their respective symmetric branches, and are connected by the two identical arms along a main propagation axis in a mirror image. The utilization of the variable curvature adiabatic couplers in silica MZI switches on a silicon substrate provides switches with an exceptional broadband range (1.2-1.

Abstract: A system for switching optical energy from a plurality of input waveguides to a plurality of output waveguides, while balancing power in the output waveguides, and a method for its use. The system is based on an optical switch matrix that includes, for each input waveguide and for each output waveguide, one or more attenuators that divert an adjustable portion of the optical energy, that enters via that input waveguide, to that output waveguide. Preferably, each input waveguide is coupled to each output waveguide via a pair of 2×2 mach-Zehnder interferometers, a first of which has an idle input port and a second of which has an idle output port. The system also includes a feedback mechanism that taps fixed portions of the power in either the input waveguides or the output waveguides, and adjusts the attenuators accordingly.

Abstract: An architecture of, and a method for realizing polarization-independent symmetric optical networks, in particular multi-substrate PLC-implemented networks. The architecture includes, in various embodiments, at least one PM fiber performing mid-span polarization conversion in an optical path between two bi-refringement elements. At least one, and preferably two identical PM fiber sections perform the conversion by appropriate connections of their fast and slow axes to the ordinary and extraordinary axes of the bi-refringent elements.

Abstract: The optical power in a waveguide of an optical circuit is monitored by mounting an optical sensor, such as a photodiode, laterally apart from the waveguide but sufficiently close to the waveguide to detect light emerging laterally from the waveguide, and by receiving signals from the sensor that are representative of the optical power. In a DWDM circuit, a bandpass filter is placed between the waveguide and the sensor for monitoring only one of the wavelengths carried by the waveguide. To minimize crosstalk, the monitored portions of the waveguides are isolated from each other, for example by trenches or by optically absorptive barriers. Suitably calibrated processing of signals from several sensors that monitor several waveguides eliminates crosstalk.

Abstract: A method for operating a planar lightwave circuit at a constant power consumption, comprises providing a matrix of integrated active elements, heating independently each active element with a separate heating power, and cooperatively operating the heating powers of the active elements to keep a sum of the operating heating powers constant in time independently on the dynamic operation of the element. The active element has two connecting configurations and is operative to have a phase change in a light beam passing through each of the connecting configurations, both connecting configurations being constantly heated. The active element is operable in both analog and digital modes with a constant power consumption.

Abstract: A protectively sealed package enclosing an optical component included in a light transmission system in which fiber-optics lines are connected to the component, the lines feeding through the package without breaking the seal. The package includes a tray to accommodate the optical component, a lid to close the tray, and a sealing unit formed of elastomeric material to define a loop and a jacket integral therewith. The sealing unit is sandwiched between the tray and the lid, the loop being seated on a ledge that runs along the rim of the tray and the jacket projecting outwardly therefrom. The jacket is provided with a duct through which extend the fiber-optics lines connected to the optical component, the duct being air-tight. When the lid is fastened to the tray it then compresses the loop therebetween to protectively seal the package.

Abstract: A method and system of operating a variable optical attenuator to provide a required total attenuation in a planar lightwave circuit.

Abstract: Ultra fast, compact wavelength-selective 2×2 optical switches based on polarization splitters and preferably electro-optical polarization converters, and switch matrices based on such switches. The switches and switch matrices are preferably implemented on electro-optical substrates using planar light-wave circuit technology. Switch designs include switches comprised of two polarization splitters and two polarization converters, and a switch comprised of one polarization splitter and two polarization converters. In a preferred embodiment, a switch comprises a TE-barring polarization splitter, a TM-barring polarization splitter, and two electro-optical wavelength-selective polarization converters connected in parallel between the TE- and TM-barring polarization splitters, and is implemented on an electro-optical substrate such as InP, GaAs, LiNbO3 or LiTaO3 using planar lightwave circuit technology.

Abstract: A broadband optical switch with high process tolerance designed and fabricated using Planar Lightwave Circuits (PLC) technology. A 2×2 configuration of the switch is based on a Mach-Zehnder interferometer (MZI) configuration that includes two 3 dB adiabatic couplers and two identical arms. Each adiabatic coupler is characterized by two straight branches having different widths, separated over a coupling length by a changing spacing therebetween and blending in a symmetric intersection area, which connect to two symmetric branches. The two adiabatic couplers are connected by the two arms with their symmetric branches facing each other along an optical propagation axis. Switch control is realized by changing an optical property of one or both of the MZI arms. Implementation in silica-on-silicon PLCs provides switches with an exceptional broadband range (1.2-1.7 &mgr;m), very high extinction ratios (>34 dB), low fabrication sensitivity and polarization independent operation.

Abstract: A safety shutter module adapted to fit onto a standard fiber-optics connector which terminates a transmission line conveying light signals of high intensity to be received by an adapter when it is coupled to the connector. When decoupled, these light signals leak from the front end of the connector and are radiated therefrom. This radiation is hazardous to the eyes of individuals exposed thereto. The module is composed of a cap that fits onto the connector and is provided with a visor that projects beyond the front end, the visor having a hinged shutter plate that depends therefrom to block the radiation. But when the adapter is plugged into the connector, it then acts to swing the shutter plate upwardly against the visor to admit the adapter and unblock the connector.

Abstract: A system for switching optical energy from a plurality of input waveguides to a plurality of output waveguides, while balancing power in the output waveguides, and a method for its use. The system is based on an optical switch matrix that includes, for each input waveguide and for each output waveguide, one or more attenuators that divert an adjustable portion of the optical energy, that enters via that input waveguide, to that output waveguide. Preferably, each input waveguide is coupled to each output waveguide via a pair of 2×2 mach-Zehnder interferometers, a first of which has an idle input port and a second of which has an idle output port. The system also includes a feedback mechanism that taps fixed portions of the power in either the input waveguides or the output waveguides, and adjusts the attenuators accordingly.

Abstract: A system for switching optical energy from a plurality of input waveguides to a plurality of output waveguides, while balancing power in the output waveguides, and a method for its use. The system is based on an optical switch matrix that includes, for each input waveguide and for each output waveguide, one or more attenuators that divert an adjustable portion of the optical energy, that enters via that input waveguide, to that output waveguide. Preferably, each input waveguide is coupled to each output waveguide via a pair of 2×2 Mach-Zehnder interferometers, a first of which has an idle input port and a second of which has an idle output port. The system also includes a feedback mechanism that taps fixed portions of the power in either the input waveguides or the output waveguides, and adjusts the attenuators accordingly.

Abstract: An optical add/drop multiplexer (OADM) system with reduced crosstalk, and a method to reduce the system crosstalk in an OADM system are provided. The reduction of system crosstalk is achieved by the replacement of at least one of the common wavelength-independent switches in the drop switch or switch array, with at least one wavelength-dependent switch.

Abstract: An optical switch array in which a plurality of input waveguides is coupled to a plurality of output waveguides. All but one of the output waveguides is coupled to each of the input waveguides by a switching element such as a 1×2 switch. A combining mechanism couples all the input waveguides to each of the output waveguides. In one preferred embodiment, one of the input waveguides continues directly into the output waveguide that is not coupled to input waveguides by switching elements, and each combining mechanism includes, for each of the other input waveguides, a coupling element such as a y-junction combiner. The switching elements are connected to the corresponding combining mechanisms by intermediate waveguides. Intermediate waveguides intersect input waveguides as required to allow the array to be fabricated as a planar integrated device.

Abstract: An optical switch matrix connects N input waveguides to M output waveguides via M rows of switch sets. Each row of switch sets includes a first switch set that has one input port and two output ports, N−2 intermediate switch sets that have two input ports and two output ports, and a last switch set that has two input ports and one or two output ports. One output port of each first or intermediate switch set is optically coupled to an input port of a succeeding switch set in the same row, and the other output port is optically coupled to an input port of a respective switch set in a cyclically succeeding row, by intermediate waveguides that do not cross each other. The only exceptions are the intermediate waveguides that connect the last row to the first row. These intermediate waveguides may cross other waveguides.

Abstract: An optical switch array in which at least three input waveguides are coupled to at least three output waveguides. Each of the output waveguides is coupled in the same order to each of the input waveguides by a switching element such as a 1×2 switch, via an intermediate waveguide and a combining mechanism that includes a coupling element such as a y-junction combiner. For compactness, the switching elements that couple to the same output waveguide are mutually displaced along the input waveguides. Optionally, each of the input waveguides is coupled to an auxiliary waveguide, which in turn is coupled to further output waveguides.