Abstract: A polycrystalline CVD synthetic diamond material is provided that has an average thermal conductivity at room temperature through a thickness of the polycrystalline CVD synthetic diamond material of between 1700 and 2400 Wm?1K?1, a thickness of at least 2.5 mm and a visible transmittance through the thickness of the polycrystalline CVD synthetic diamond of at least 25%. A wafer comprising the material is also provided, wherein at least 70% of a total area of the wafer has the properties of the polycrystalline CVD synthetic diamond material. A method for fabricating the wafer is also disclosed.

Abstract: A microwave plasma reactor for manufacturing synthetic diamond material via chemical vapour deposition includes a microwave generator configured to generate microwaves at a frequency f, a plasma chamber that defines a resonance cavity for supporting a microwave resonance mode, a microwave coupling configuration for feeding microwaves from the microwave generator into the plasma chamber, a gas flow system for feeding process gases into the plasma chamber and removing them therefrom, and a substrate holder disposed in the plasma chamber and having a supporting surface for supporting a substrate on which the synthetic diamond material is to be deposited in use. The resonance cavity is configured to have a height that supports a TM011 resonant mode at the frequency f and is further configured to have a diameter that satisfies the condition that a ratio of the resonance cavity height/the resonance cavity diameter is in the range 0.3 to 1.0.

Abstract: A heat sink comprising a heat spreader (2) made from synthetic diamond and having a front surface for mounting one or more components to be cooled like a laser disc (8) and a rear surface for direct fluid cooling (10). A plurality of ribs (4,7) is bonded to the rear surface of the heat spreader (2) to stiffen the heat spreader. Both the heat spreader and the plurality of ribs are formed of synthetic diamond material. The ribs (4,7) may be fixed to the heat spreader by braze bonds (6).

Abstract: A polycrystalline CVD synthetic diamond material is provided that has an average thermal conductivity at room temperature through a thickness of the polycrystalline CVD synthetic diamond material of between 1700 and 2400 Wm?1K?1, a thickness of at least 2.5 mm and a visible transmittance through the thickness of the polycrystalline CVD synthetic diamond of at least 25%. A wafer comprising the material is also provided, wherein at least 70% of a total area of the wafer has the properties of the polycrystalline CVD synthetic diamond material. A method for fabricating the wafer is also disclosed.

Abstract: A heat sink comprising a heat spreader (2) made from synthetic diamond and having a front surface for mounting one or more components to be cooled like a laser disc (8) and a rear surface for direct fluid cooling (10). A plurality of ribs (4,7) is bonded to the rear surface of the heat spreader (2) to stiffen the heat spreader. Both the heat spreader and the plurality of ribs are formed of synthetic diamond material. The ribs (4,7) may be fixed to the heat spreader by braze bonds (6).

Abstract: A microwave plasma reactor for manufacturing synthetic diamond material via chemical vapour deposition includes a microwave generator configured to generate microwaves at a frequency f, a plasma chamber that defines a resonance cavity for supporting a microwave resonance mode, a microwave coupling configuration for feeding microwaves from the microwave generator into the plasma chamber, a gas flow system for feeding process gases into the plasma chamber and removing them therefrom, and a substrate holder disposed in the plasma chamber and having a supporting surface for supporting a substrate on which the synthetic diamond material is to be deposited in use. The resonance cavity is configured to have a height that supports a TM011 resonant mode at the frequency f and is further configured to have a diameter that satisfies the condition that a ratio of the resonance cavity height/the resonance cavity diameter is in the range 0.3 to 1.0.

Abstract: A polycrystalline chemical vapor deposited (CVD) diamond wafer comprising: a largest linear dimension equal to or greater than 125 mm; a thickness equal to or greater than 200 ?m; and one or both of the following characteristics measured at room temperature (nominally 298 K) over at least a central area of the polycrystalline CVD diamond wafer, said central area being circular, centered on a central point of the polycrystalline CVD diamond wafer, and having a diameter of at least 70% of the largest linear dimension of the polycrystalline CVD diamond wafer: an absorption coefficient ?0.2 cm?1 at 10.6 ?m; and a dielectric loss coefficient at 145 GHz, of tan ??2×10?4.

Abstract: A microwave plasma reactor for manufacturing synthetic diamond material via chemical vapor deposition, the microwave plasma reactor comprising: a microwave generator configured to generate microwaves at a frequency f; a plasma chamber comprising a base, a top plate, and a side wall extending from said base to said top plate defining a resonance cavity for supporting a microwave resonance mode, wherein the resonance cavity has a central rotational axis of symmetry extending from the base to the top plate, and wherein the top plate is mounted across said central rotational axis of symmetry; a microwave coupling configuration for feeding microwaves from the microwave generator into the plasma chamber; a gas flow system for feeding process gases into the plasma chamber and removing them therefrom; and a substrate holder disposed in the plasma chamber and comprising a supporting surface for supporting a substrate on which the synthetic diamond material is to be deposited in use; wherein the resonance cavity is con

Abstract: A boron doped synthetic diamond material which has the following characteristics: a solvent window meeting one or both of the following criteria as measured by sweeping a potential of the boron doped synthetic diamond material with respect to a saturated calomel reference electrode in a solution containing only deionized water and 0.1M KNO3 as a supporting electrolyte at pH 6: the solvent window extends over a potential range of at least 4.1 V wherein end points of the potential range for the solvent window are defined when anodic and cathodic current density measured at the boron doped synthetic diamond material reaches 38 mA cm?2; and the solvent window extends over a potential range of at least 3.3 V wherein end points of the potential range for the solvent window are defined when anodic and cathodic current density measured at the boron doped synthetic diamond material reaches 0.

Abstract: A polycrystalline chemical vapour deposited (CVD) diamond wafer comprising: a largest linear dimension equal to or greater than 125 mm; a thickness equal to or greater than 200 ?m; and one or both of the following characteristics measured at room temperature (nominally 298 K) over at least a central area of the polycrystalline CVD diamond wafer, said central area being circular, centred on a central point of the polycrystalline CVD diamond wafer, and having a diameter of at least 70% of the largest linear dimension of the polycrystalline CVD diamond wafer: an absorption coefficient ?0.2 cm?1 at 10.6 ?m; and a dielectric loss coefficient at 145 GHz, of tan ??2×10?4.

Abstract: A polycrystalline chemical vapor deposited (CVD) diamond wafer comprising: a largest linear dimension equal to or greater than 125 mm; a thickness equal to or greater than 200 ?m; and one or both of the following characteristics measured at room temperature (nominally 298 K) over at least a central area of the polycrystalline CVD diamond wafer, said central area being circular, centered on a central point of the polycrystalline CVD diamond wafer, and having a diameter of at least 70% of the largest linear dimension of the polycrystalline CVD diamond wafer: an absorption coefficient ?0.2 cm?1 at 10.6 ?m; and a dielectric loss coefficient at 145 GHz, of tan ??2×10?4.

Abstract: The present disclosure relates to substrates for use in microwave plasma reactors. Certain substrates include a cylindrical disc of a carbide forming refractory metal having a flat growth surface on which CVD diamond is to be grown and a flat supporting surface opposed to said growth surface. The cylindrical disc may have a diameter of 80 mm or more. The growth surface may have a flatness variation no more than 100 mm The supporting surface may have a flatness variation no more than 100 mm.

Abstract: A polycrystalline chemical vapour deposited (CVD) diamond wafer comprising: a largest linear dimension equal to or greater than 70 mm; a thickness equal to or greater than 1.3 mm; and one or both of the following characteristics measured at room temperature (nominally 298 K) over at least a central area of the polycrystalline CVD diamond wafer, said central area being circular, centred on a central point of the polycrystalline CVD diamond wafer, and having a diameter of at least 70% of the largest linear dimension of the polycrystalline CVD diamond wafer: an absorption coefficient ?0.2 cm?1 at 10.6 ?m; and a dielectric loss coefficient at 145 GHz, of tan ??2×10?4.

Abstract: A method of fabricating a polycrystalline CVD synthetic diamond material having an average thermal conductivity at room temperature through a thickness of the polycrystalline CVD synthetic diamond material of at least 2000 Wm?1K?1, the method comprising: loading a refractory metal substrate into a CVD reactor; locating a refractory metal guard ring around a peripheral region of the refractory metal substrate, the refractory metal guard ring defining a gap between an edge of the refractory metal substrate and the refractory metal guard ring having a width 1.5 mm to 5.0 mm; introducing microwaves into the CVD reactor at a power such that the power density in terms of power per unit area of the refractory metal substrate is in a range 2.5 to 4.5 W mm?2; introducing process gas into the CVD reactor wherein the process gas within the CVD reactor comprises a nitrogen concentration in a range 600 ppb to 1500 ppb calculated as molecular nitrogen N2, a carbon containing gas concentration in a range 0.5% to 3.

Abstract: A microwave plasma reactor for manufacturing synthetic diamond material via chemical vapour deposition, the microwave plasma reactor comprising: a plasma chamber; a substrate holder disposed in the plasma chamber and comprising a supporting surface for supporting a substrate on which the synthetic diamond material is to be deposited in use; a microwave coupling configuration for feeding microwaves from a microwave generator into the plasma chamber; and a gas flow system for feeding process gases into the plasma chamber and removing them therefrom; wherein the microwave plasma reactor further comprises an electrically conductive plasma stabilizing annulus disposed around the substrate holder within the plasma chamber.

Abstract: A method of manufacturing an optical element, the method comprising: growing a first layer of single crystal diamond material via a chemical vapor deposition technique using a gas phase having a first nitrogen concentration; growing a second layer of single crystal diamond material over said first layer via a chemical vapor deposition technique using a gas phase having a second nitrogen concentration, wherein the second nitrogen concentration is lower than the first nitrogen concentration; forming an optical element from at least a portion of the second layer of single crystal diamond material; and forming an out-coupling structure at a surface of the optical element for increasing out-coupling of light.

Abstract: A method of fabricating a polycrystalline CVD synthetic diamond material having an average thermal conductivity at room temperature through a thickness of the polycrystalline CVD synthetic diamond material of at least 2000 Wm?1K?1, the method comprising: loading a refractory metal substrate into a CVD reactor; locating a refractory metal guard ring around a peripheral region of the refractory metal substrate, the refractory metal guard ring defining a gap between an edge of the refractory metal substrate and the refractory metal guard ring having a width 1.5 mm to 5.0 mm; introducing microwaves into the CVD reactor at a power such that the power density in terms of power per unit area of the refractory metal substrate is in a range 2.5 to 4.5 W mm?2; introducing process gas into the CVD reactor wherein the process gas within the CVD reactor comprises a nitrogen concentration in a range 600 ppb to 1500 ppb calculated as molecular nitrogen N2, a carbon containing gas concentration in a range 0.5% to 3.

Abstract: Single crystal diamond material produced using chemical vapour deposition (CVD), and particularly diamond material having properties suitable for use in optical applications such as lasers, is disclosed. In particular, a CVD single crystal diamond material having preferred characteristics of longest linear internal dimension, birefringence and absorption coefficient, when measured at room temperature, is disclosed. Uses of the diamond material, including in a Raman laser, and methods of producing the diamond are also disclosed.

Abstract: A boron doped synthetic diamond material which has the following characteristics: a solvent window meeting one or both of the following criteria as measured by sweeping a potential of the boron doped synthetic diamond material with respect to a saturated calomel reference electrode in a solution containing only deionised water and 0.1 M KNO3 as a supporting electrolyte at pH 6: the solvent window extends over a potential range of at least 4.1 V wherein end points of the potential range for the solvent window are defined when anodic and cathodic current density measured at the boron doped synthetic diamond material reaches 38 mA cm?2; and the solvent window extends over a potential range of at least 3.3 V wherein end points of the potential range for the solvent window are defined when anodic and cathodic current density measured at the boron doped synthetic diamond material reaches 0.

Abstract: The present disclosure relates to substrates for use in microwave plasma reactors. Certain substrates include a cylindrical disc of a carbide forming refractory metal having a flat growth surface on which CVD diamond is to be grown and a flat supporting surface opposed to said growth surface. The cylindrical disc may have a diameter of 80 mm or more. The growth surface may have a flatness variation no more than 100 mm The supporting surface may have a flatness variation no more than 100 mm.