Abstract: A multicast optical switch includes a free-space optical assembly of discrete splitters, cylindrical optics, and a linear array of reflective switching devices, such as microelectromechanical systems (MEMS) mirrors, to provide low-loss, high-performance multicast switching in a compact configuration. The assembly of optical splitters may include multiple planar lightwave circuit splitters or a multi-reflection beam splitter that includes a linear array of partially reflecting mirrors, each of a different reflectivity.

Abstract: Embodiments are directed to laser emitter modules, or subassemblies thereof, and methods and devices for making or using the modules. Some module embodiments are configured to provide hermetically sealed enclosures that are thermally stable during use, highly reliable in adverse environments, convenient and cost effective to manufacture or any combination of the foregoing.

Abstract: In a method of forming polycrystalline SiC grain material, low-density, gas-permeable and vapor-permeable bulk carbon is positioned at a first location inside of a graphite crucible and a mixture of elemental silicon and elemental carbon is positioned at a second location inside of the graphite crucible. Thereafter, the mixture and the bulk carbon are heated to a first temperature below the melting point of the elemental Si to remove adsorbed gas, moisture and/or volatiles from the mixture and the bulk carbon. Next, the mixture and the bulk carbon are heated to a second temperature that causes the elemental Si and the elemental C to react forming as-synthesized SiC inside of the crucible. The as-synthesized SiC and the bulk carbon are then heated in a way to cause the as-synthesized SiC to sublime and produce vapors that migrate into, condense on and react with the bulk carbon forming polycrystalline SiC material.

Abstract: In a physical vapor transport growth technique for silicon carbide a silicon carbide powder and a silicon carbide seed crystal are introduced into a physical vapor transport growth system and halosilane gas is introduced separately into the system. The source powder, the halosilane gas, and the seed crystal are heated in a manner that encourages physical vapor transport growth of silicon carbide on the seed crystal, as well as chemical transformations in the gas phase leading to reactions between halogen and chemical elements present in the growth system.

Abstract: A method of fabricating an SiC single crystal includes (a) physical vapor transport (PVT) growing a SiC single crystal on a seed crystal in the presence of a temperature gradient, wherein an early-to-grow portion of the SiC single crystal is at a lower temperature than a later-to-grow portion of the SiC single crystal. Once grown, the SiC single crystal is annealed in the presence of a reverse temperature gradient, wherein the later-to-grow portion of the SiC single crystal is at a lower temperature than the early-to-grow portion of the SiC single crystal.

Abstract: In a crystal growth method, an enclosed growth crucible is provided inside of a growth chamber. The growth crucible has polycrystalline source material and a seed crystal disposed in spaced relation therein. The interior of the growth crucible is heated whereupon a temperature gradient forms between the source material and the seed crystal. The temperature gradient is sufficient to cause the source material to sublimate and be transported to the seed crystal where it precipitates on the seed crystal. A gas mixture is caused to flow into the growth crucible and between the polycrystalline source material and an interior surface of the growth crucible. The gas mixture reacts with an unwanted element in the body of the growth crucible to form a gaseous byproduct which then flows through the body of the growth crucible to the exterior of the growth crucible.

Abstract: In the growth of a SiC boule, a growth guide is provided inside of a growth crucible that is charged with SiC source material at a bottom of the crucible and a SiC seed crystal at a top of the crucible. The growth guide has an inner layer that defines at least part of an opening in the growth guide and an outer layer that supports the inner layer in the crucible. The opening faces the source material with the seed crystal positioned at an end of the opening opposite the source material. The inner layer is formed from a first material having a higher thermal conductivity than the second, different material forming the outer layer. The source material is sublimation grown on the seed crystal in the growth crucible via the opening in the growth guide to thereby form the SiC boule on the seed crystal.

Abstract: In SiC sublimation crystal growth, a crucible is charged with SiC source material and SiC seed crystal in spaced relation and a baffle is disposed in the growth crucible around the seed crystal. A first side of the baffle in the growth crucible defines a growth zone where a SiC single crystal grows on the SiC seed crystal. A second side of the baffle in the growth crucible defines a vapor-capture trap around the SiC seed crystal. The growth crucible is heated to a SiC growth temperature whereupon the SiC source material sublimates and forms a vapor which is transported to the growth zone where the SiC crystal grows by precipitation of the vapor on the SiC seed crystal. A fraction of this vapor enters the vapor-capture trap where it is removed from the growth zone during growth of the SiC crystal.

Abstract: In a method of annealing a Cd1-xZnxTe sample/wafer, surface contamination is removed from the sample/wafer and the sample/wafer is then introduced into a chamber. The chamber is evacuated and Hydrogen or Deuterium gas is introduced into the evacuated chamber. The sample/wafer is heated to a suitable annealing temperature in the presence of the Hydrogen or Deuterium gas for a predetermined period of time.

Abstract: In a physical vapor transport growth technique for silicon carbide a silicon carbide powder and a silicon carbide seed crystal are introduced into a physical vapor transport growth system and halosilane gas is introduced separately into the system. The source powder, the halosilane gas, and the seed crystal are heated in a manner that encourages physical vapor transport growth of silicon carbide on the seed crystal, as well as chemical transformations in the gas phase leading to reactions between halogen and chemical elements present in the growth system.

Abstract: A physical vapor transport system includes a growth chamber charged with source material and a seed crystal in spaced relation, and at least one capsule having at least one capillary extending between an interior thereof and an exterior thereof, wherein the interior of the capsule is charged with a dopant. Each capsule is installed in the growth chamber. Through a growth reaction carried out in the growth chamber following installation of each capsule therein, a crystal is formed on the seed crystal using the source material, wherein the formed crystal is doped with the dopant.

Abstract: A physical vapor transport growth system includes a growth chamber charged with SiC source material and a SiC seed crystal in spaced relation and an envelope that is at least partially gas-permeable disposed in the growth chamber. The envelope separates the growth chamber into a source compartment that includes the SiC source material and a crystallization compartment that includes the SiC seed crystal. The envelope is formed of a material that is reactive to vapor generated during sublimation growth of a SiC single crystal on the SiC seed crystal in the crystallization compartment to produce C-bearing vapor that acts as an additional source of C during the growth of the SiC single crystal on the SiC seed crystal.

Abstract: A sublimation-grown silicon carbide (SiC) single crystal boule includes a deep level dopant introduced into the SiC single crystal boule during sublimation-growth thereof such that in a continuous section of the boule that is not less than 50% of a continuous length of said boule, the deep level dopant concentration at the boule center varies by not more than 25% from the average concentration of the deep level dopant in the continuous section of the boule.

Abstract: In a method of annealing a Cd1?xZnxTe sample/wafer, surface contamination is removed from the sample/wafer and the sample/wafer is then introduced into a chamber. The chamber is evacuated and Hydrogen or Deuterium gas is introduced into the evacuated chamber. The sample/wafer is heated to a suitable annealing temperature in the presence of the Hydrogen or Deuterium gas for a predetermined period of time.

Abstract: A crystal is sublimation grown in a crucible by way of a temperature gradient in the presence of between 1 and 200 Torr of inert gas. The pressure of the inert gas is then increased to between 300 and 600 Torr, while the temperature gradient is maintained substantially constant. The temperature gradient is then reduced and the temperature in the crucible is increased sufficiently to anneal the crystal. Following cooling and removal from the crucible, the crystal is heated in the presence of oxygen in an enclosure to a temperature sufficient to remove unwanted material from the crystal. Following cooling and removal from the enclosure, the crystal surrounded by another instance of the source material is heated in a crucible in the presence 200 and 600 Torr of inert gas to a temperature sufficient to anneal the crystal.

Abstract: A method of fabricating an SiC single crystal includes (a) physical vapor transport (PVT) growing a SiC single crystal on a seed crystal in the presence of a temperature gradient, wherein an early-to-grow portion of the SiC single crystal is at a lower temperature than a later-to-grow portion of the SiC single crystal. Once grown, the SiC single crystal is annealed in the presence of a reverse temperature gradient, wherein the later-to-grow portion of the SiC single crystal is at a lower temperature than the early-to-grow portion of the SiC single crystal.

Abstract: In the growth of a SiC boule, a growth guide is provided inside of a growth crucible that is charged with SiC source material at a bottom of the crucible and a SiC seed crystal at a top of the crucible. The growth guide has an inner layer that defines at least part of an opening in the growth guide and an outer layer that supports the inner layer in the crucible. The opening faces the source material with the seed crystal positioned at an end of the opening opposite the source material. The inner layer is formed from a first material having a higher thermal conductivity than the second, different material forming the outer layer. The source material is sublimation grown on the seed crystal in the growth crucible via the opening in the growth guide to thereby form the SiC boule on the seed crystal.

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 physical vapor transport system includes a growth chamber charged with source material and a seed crystal in spaced relation, and at least one capsule having at least one capillary extending between an interior thereof and an exterior thereof, wherein the interior of the capsule is charged with a dopant. Each capsule is installed in the growth chamber. Through a growth reaction carried out in the growth chamber following installation of each capsule therein, a crystal is formed on the seed crystal using the source material, wherein the formed crystal is doped with the dopant.

Abstract: A radiation detection and counting system (2) includes a radiation detector element (5) for outputting a signal related to an energy of a radiation event received thereby and an amplifier (8) for amplifying the signal output by the detector element (5). A gain equalization circuit (10) adjusts the gain of the amplified output signal and a plurality of comparators (12) compare the gain adjusted amplified output signal to a like plurality of different valued threshold signals that are independently adjustable of each other A plurality of counters (20) is operative whereupon only the counter associated with the one comparator (12) that changes state in response to the peak of the gain adjusted amplified output signal exceeding the value of the trigger threshold signal thereof is incremented. A storage (24) stores the incremented value of each counter (20) accumulated over a sample time interval and data output logic circuit (26) transfers the stored accumulated counts out of the storage.