Abstract: An optical switch is configured in a “dual-ganged” switch geometry to provide for the simultaneous switching of a selected transmit/receive pair of optical signal paths between a specific optical communication device and an optical communication network. A biaxially-symmetric signal redirection component may be used to direct the signals between the selected channel and the optical communication device. A specific waveguide (e.g., fiber) array topology within the dual-ganged switch (DGS) breaks the symmetry between the network transmit/receive arrays and a pair of transmit and receive signal paths associated with the communication device to improve isolation and minimize the possibility of cross-talk between non-selected waveguides in the transmit and receive arrays. The possibility of “hits” during switching between channels can be eliminated, and is controlled by dictating the process or switching steps used to rotate the biaxially-symmetric signal redirection element.

Abstract: A crucible has a first resistance heater is disposed in spaced relation above the top of the crucible and a second resistance heater with a first resistive section disposed in spaced relation beneath the bottom of the crucible and with a second resistive section disposed in spaced relation around the outside of the side of the crucible. The crucible is charged with a seed crystal at the top of an interior of the crucible and a source material in the interior of the crucible in spaced relation between the seed crystal and the bottom of the crucible. Electrical power of a sufficient extent is applied to the first and second resistance heaters to create in the interior of the crucible a temperature gradient of sufficient temperature to cause the source material to sublimate and condense on the seed crystal thereby forming a growing crystal.

Abstract: A light source assembly (300) for emitting depolarized light, and comprising: at least one light source (312) configured to emit substantially polarized light; and a light depolarizer (318) arranged to receive light from the light source and comprising a high birefringence optical fibre having a longitudinal core and orthogonal birefringent axes having an angular displacement around the core that varies along the length of the fibre, wherein light emitted from the depolarizer comprises a plurality of polarization states.

Abstract: A tunable multiport optical filter includes various types of arrays of optical ports. The tunable filter also includes a light dispersion element (e.g., a grating) and a reflective beam steering element (e.g., a tilting mirror). An optical signal exits an optical (input) port, is dispersed by the light dispersion element, reflects off the reflective beam steering element back to the light dispersion element, and on to another optical (output) port. The reflective beam steering element can be steered such that a wavelength portion of the dispersed optical signal can be coupled to the optical output port. For example, the input optical signal may be a wavelength division multiplexed signal carrying multiple channels on different wavelengths, and the tunable multiport optical filter directs one of the channels to the output optical port. Additionally, the tunable filter may be incorporated into a device acting as a wavelength reference.

Abstract: An arrangement for providing real-time, in-service OTDR measurements in an optical communication system utilizing distributed Raman amplification. One or more of the laser diodes used to provide the pump light necessary to create optical gain is modified to also generate short duration pulses that ride above or below the conventional pump light. These short duration pulses (which co-exist with the pump light within the optical fiber) are used in performing OTDR measurements, with a conventional processing system used to evaluate reflected pulses and create the actual OTDR measurements.

Abstract: A tunable multiport optical filter includes various types of arrays of optical ports. The tunable filter also includes a light dispersion element (e.g., a grating) and a reflective beam steering element (e.g., a tilting mirror). An optical signal exits an optical (input) port, is dispersed by the light dispersion element, reflects off the reflective beam steering element back to the light dispersion element, and on to another optical (output) port. The reflective beam steering element can be steered such that a wavelength portion of the dispersed optical signal can be coupled to the optical output port. For example, the input optical signal may be a wavelength division multiplexed signal carrying multiple channels on different wavelengths, and the tunable multiport optical filter directs one of the channels to the output optical port. Additionally, the tunable filter may be incorporated into a device act as a wavelength reference.

Abstract: In a crystal growth apparatus and method, polycrystalline source material and a seed crystal are introduced into a growth ambient comprised of a growth crucible disposed inside of a furnace chamber. In the presence of a first sublimation growth pressure, a single crystal is sublimation grown on the seed crystal via precipitation of sublimated source material on the seed crystal in the presence of a flow of a first gas that includes a reactive component that reacts with and removes donor and/or acceptor background impurities from the growth ambient during said sublimation growth. Then, in the presence of a second sublimation growth pressure, the single crystal is sublimation grown on the seed crystal via precipitation of sublimated source material on the seed crystal in the presence of a flow of a second gas that includes dopant vapors, but which does not include the reactive component.

Abstract: An optical amplifier assembly for determining a parameter of an optical fibre configured to amplify an optical signal being propagated therethrough, the assembly comprising: at least one amplifier pump light source assembly configured to transmit light at a plurality of wavelengths into the optical fibre; a receiver configured to receive light that has propagated through at least part of the optical fibre; and a processor configured to determine the parameter of the optical fibre based on the received light.

Abstract: An optical switch for performing high extinction ratio switching of an optical signal includes a beam polarizing element and one or more optical elements. The optical elements are configured to direct an optical signal along a first or second optical path based on the polarization state of the optical signal as it passes through the optical elements. The optical switch performs high extinction ratio switching of the optical signal by preventing unwanted optical energy from entering an output port by using an absorptive or reflective optical element or by directing the unwanted optical energy along a different optical path.

Abstract: In method of crystal growth, an interior of a crystal growth chamber (2) is heated to a first temperature in the presence of a first vacuum pressure whereupon at least one gas absorbed in a material (4) disposed inside the chamber is degassed therefrom. The interior of the chamber is then exposed to an inert gas at a second, higher temperature in the presence of a second vacuum pressure that is at a higher pressure than the first vacuum pressure. The inert gas pressure in the chamber is then reduced to a third vacuum pressure that is between the first and second vacuum pressures and the temperature inside the chamber is lowered to a third temperature that is between the first and second temperatures, whereupon source material (10) inside the chamber vaporizes and deposits on a seed crystal (12) inside the chamber.

Abstract: A light source package is disclosed for a Raman amplifier node having a primary optical fiber for carrying an optical signal and a secondary optical fiber for carrying the optical signal when the signal is rerouted from the primary optical fiber. The light source package includes a primary light source for emitting light into the primary optical fiber when the optical signal is carried by the primary optical fiber to induce Raman gain of the optical signal, and a secondary light source for emitting light into the secondary optical fiber when the optical signal is carried by the secondary optical fiber to induce Raman gain of the optical signal.

Abstract: A reconfigurable optical device including input and output ports, and add or drop ports, has a high degree of flexibility such that any wavelength channel from any optical signal introduced through the add ports may be added to any of the optical signals transmitted through the output ports. In addition, any wavelength channel from any optical signal received through the inputs ports may be dropped through any of the drop ports. Furthermore, the optical device is configurable to allow the same wavelength channel from two different optical signals supplied respectively through any two inputs ports to be simultaneously directed to two different drop ports.

Abstract: In a crystal growth method, a seed crystal 8 and a source material 4 are provided in spaced relation inside of a growth crucible 6. Starting conditions for the growth of a crystal 14 in the growth crucible 6 are then established therein. The starting conditions include: a suitable gas inside the growth crucible 6, a suitable pressure of the gas inside the growth crucible 6, and a suitable temperature in the growth crucible 6 that causes the source material 4 to sublimate and be transported via a temperature gradient in the growth crucible 6 to the seed crystal 8 where the sublimated source material precipitates. During growth of the crystal 14 inside the growth crucible 6, at least one of the following growth conditions are intermittently changed inside the growth crucible 6 a plurality of times: the gas in the growth crucible 6, the pressure of the gas in the growth crucible 6, and the temperature in the growth crucible 6.

Abstract: A method of operating a production optical amplifier comprises determining a training data set of amplified spontaneous emission (ASE) values of a training optical amplifier over a plurality of training operating conditions, determining a production data set of ASE values of the production optical amplifier over a plurality of production operating conditions, the plurality of production operating conditions corresponding to a sub-set of the plurality of training operating conditions, determining an adjusted data set of adjusted ASE values produced by extrapolation from the production data set so that the adjusted data set is provided over a plurality of operating conditions corresponding to the plurality of training operating conditions, determining, for each of a plurality of operating conditions, a dynamic ASE tilt factor from the training data set and the adjusted ASE data set so determined, determining a larger data set of ASE values over a wider set of operating conditions than either the training data s

Abstract: A physical vapor deposition method of growing a crystal includes providing a seed crystal and a source material in spaced relation inside of a growth crucible that is at least in-part gas permeable to an unwanted gas. The growth chamber is heated whereupon the source material sublimates and is transported via a temperature gradient in the growth chamber to the seed crystal where the sublimated source material precipitates. Concurrent with heating the growth chamber, a purging gas is caused to flow inside or outside of the growth crucible in a manner whereupon the unwanted gas flows from the inside to the outside of the growth crucible via the gas permeable part thereof.

Abstract: Disclosed is a method and apparatus for simultaneously polishing both surfaces of an optical substrate. An upper platen and a lower platen, each covered with a polishing pad material and at least one carrier having an aperture for holding the optical substrate between the platens are provided. The location of the aperture of the carrier is set such that the center of the optical substrate is offset from the center of the carrier and at least a portion of the outer perimeter of the optical substrate extends outwardly beyond at least a portion of at least one of the outer perimeter and the inner perimeter of the platens. The platens are rotated with respect to the carrier, and the carrier is rotated with respect to the platens to polish the optical substrate. The location of the aperture of the carrier is adjustable.

Abstract: Disclosed is a system and method for patterning internal and/or external doubly-curved surfaces by use of a light source, three-dimensional scanning optics, computer controller, and a multi-axis robot. The system is capable of digitally receiving shape, location, and pattern data of a three-dimensional doubly-curved surface and applying said pattern over large areas with high precision in a seamless fashion.

Abstract: A sublimation grown SiC single crystal includes vanadium dopant incorporated into the SiC single crystal structure via introduction of a gaseous vanadium compound into a growth environment of the SiC single crystal during growth of the SiC single crystal.

Abstract: Fiber-optic communications systems are provided for optical communications networks. Fiber-optic communications links may be provided that use spans of transmission fiber to carry optical data signals on wavelength-division-multiplexing channels at different wavelengths between nodes. An apparatus and method are disclosed to use one optical light source per node to perform OTDR and LCV to satisfy safety concerns and accelerate the verification of the integrity of optical fiber links, before the application of high Raman laser powered light sources to a fiber link. A system using only one receiver per node is also disclosed.

Abstract: A method and system of forming large-diameter SiC single crystals suitable for fabricating high crystal quality SiC substrates of 100, 125, 150 and 200 mm in diameter are described. The SiC single crystals are grown by a seeded sublimation technique in the presence of a shallow radial temperature gradient. During SiC sublimation growth, a flux of SiC bearing vapors filtered from carbon particulates is substantially restricted to a central area of the surface of the seed crystal by a separation plate disposed between the seed crystal and a source of the SiC bearing vapors. The separation plate includes a first, substantially vapor-permeable part surrounded by a second, substantially non vapor-permeable part. The grown crystals have a flat or slightly convex growth interface. Large-diameter SiC wafers fabricated from the grown crystals exhibit low lattice curvature and low densities of crystal defects, such as stacking faults, inclusions, micropipes and dislocations.