Abstract: Devices, methods and techniques related to the use of a photoconductive semiconductor switch (PCSS) to drive a high-power laser diode for a wide range of pulse widths are disclosed. In one example aspect, a circuit for driving one or more laser diodes includes an input port configured to be coupled to a voltage input, one or more inductors that are configured to be in series with the one or more laser diodes, a photoconductive switch coupled with the one or more inductors, and an output port configured to be coupled to the one or more laser diodes.

Abstract: A product includes an elongated carbon-containing pillar having a bottom and a tip opposite the bottom. The width of the pillar measured 1 nm below the tip is less than 700 nm. A method includes masking a carbon-containing single crystal for defining masked regions and unmasked regions on the single crystal. The method also includes performing a plasma etch for removing portions of the unmasked regions of the single crystal, thereby defining a pillar in each unmasked region, and performing a chemical etch on the pillars at a temperature between 1200° C. and 1600° C. for selectively reducing a width of each pillar.

Abstract: An optically addressable light valve comprises a first transparent conductor layer, a layer of liquid crystal, and a photoconductor comprising an ultrawide band gap (UWBG) semiconductor. The liquid crystal is between the first transparent conductor layer and the semiconductor photoconductor. The optically addressable light valve is configured to apply a voltage across the liquid crystal and the UWBG semiconductor. A second transparent conductor may be formed in the UWBG semiconductor in some configurations, and the voltage may be applied across the first and second transparent conductor.

Abstract: A vacuum electronic device is configured to provide electrical current that is configured to be optically modulated by incident light. The vacuum electronic device comprises an optically gated field emission photocathode comprising photoconductive material, an anode comprising a conductive material, and a gap between said photocathode and said anode. The gap comprises vacuum. The anode and photocathode are configured to receive a voltage across the anode and photocathode, such that when said photocathode is illuminated with said light, electrons are emitted from the photocathode and travel through the gap.

Abstract: A high-voltage switch is adapted for use as a medium-voltage direct current circuit breaker, which provides a low-cost, small-footprint device to mitigate system faults. In one example, a method for operating a wideband optical device includes illuminating the wide bandgap optical device with a light within a first range of wavelengths and a first average intensity, allowing a current to propagate therethrough without substantial absorption of the current, illuminating the wide bandgap optical device with light within the first range of wavelengths and a second average intensity that is lower than the first average intensity to allow a sustained current flow though the wide bandgap optical device, and illuminating the wide bandgap optical device with light within a second range of wavelengths to stop or substantially restrict propagation of the current through the wide gap material.

Abstract: An optically addressable light valve comprises a first transparent conductor layer, a layer of liquid crystal, and a photoconductor comprising an ultrawide band gap (UWBG) semiconductor. The liquid crystal is between the first transparent conductor layer and the semiconductor photoconductor. The optically addressable light valve is configured to apply a voltage across the liquid crystal and the UWBG semiconductor. A second transparent conductor may be formed in the UWBG semiconductor in some configurations, and the voltage may be applied across the first and second transparent conductor.

Abstract: Devices, systems, and methods for illuminating a photoconductive switch are disclosed. The disclosed technology minimizes an amount of light that is reflected back into an input optical waveguide. The disclosed technology provides an illumination oven that delivers light from the input optical waveguide to the photoconductive switch. The illumination oven is configured to trap light and cause multiple reflection passes of the light therewithin. The illumination oven is configured to reduce opportunities for the light to escape via the input optical waveguide. In particular, the illumination oven includes a tipped or angled top end that directs light downward to the photoconductive switch. The input optical waveguide is coupled to the illumination oven at a lateral offset, which, along with the tipped top end, causes the light to rattle and chaotically flow within the illumination oven to be ultimately absorbed by the photoconductive switch or dissipate.

Abstract: Disclosed are non-linear transmission lines using ferromagnetic materials to generate ferromagnetic resonance oscillations. In one aspect, a non-linear transmission line apparatus is disclosed. The apparatus includes an outer conductor having a first side and a second internally facing side, and an inner conductor positioned internal to the non-linear transmission line apparatus. The apparatus further includes a ferromagnetic material surrounding the inner conductor, wherein the ferromagnetic material comprises nanoparticles of an ?-polymorph of iron oxide expressed as ?-Fe2O3. The apparatus also includes a first dielectric material positioned between the outer conductor and the inner conductor, the dielectric material in contact with both the ferromagnetic material and with the second internally facing side of the outer conductor, wherein the outer conductor, the inner conductor, the dielectric material and the ferromagnetic material form the nonlinear transmission line.

Abstract: Various devices, systems and methods such as photonductive semiconductor switches (PCSS) and optically addressable light valves (OALVs) include a photoconducting ?-Ga2O3 layer having a transition metal (TM) doped region formed by diffusion of transition metal into a ?-Ga2O3 substrate. The diffusion of the TM into the ?-Ga2O3 substrate provides for the controlled concentration and thickness of the doped TM region that is integrated into the bulk ?-Ga2O3 substrate.

Abstract: Devices, methods and techniques related to photoconductive switches using diamond are disclosed. In one example aspect, a photoconductive apparatus includes a diamond layer positioned to receive a light. The diamond layer is doped with nitrogen. The apparatus also includes a first electrode coupled to the diamond layer to provide a first electrical contact for the diamond layer, and a second electrode coupled to the diamond layer to provide a second electrical contact for the diamond layer and configured to reflect the light back to the diamond layer. The first electrode and the second electrode are configured to establish an electric field across the diamond layer in response to receiving the light.

Abstract: Devices, methods and techniques related to high voltage and high-power diamond transistors are disclosed. In one example aspect, a switch operable under high-voltage and high-power includes a P-type diamond layer doped with an acceptor material and an N-type diamond region doped with a donor material. The P-type diamond layer is at least partially embedded the N-type diamond region. The switch includes a layer comprising one or more apertures configured to allow illumination from a light source to pass through to reach the N-type diamond region, a source contact and a drain contact that are at least partially in contact with the P-type diamond layer; and a gate in contact with at least an area of the N-type diamond region.

Abstract: An optically addressable light valve comprises a first transparent conductor layer, a layer of liquid crystal, and a photoconductor comprising an ultrawide band gap (UWBG) semiconductor. The liquid crystal is between the first transparent conductor layer and the semiconductor photoconductor. The optically addressable light valve is configured to apply a voltage across the liquid crystal and the UWBG semiconductor. A second transparent conductor may be formed in the UWBG semiconductor in some configurations, and the voltage may be applied across the first and second transparent conductor.

Abstract: Devices, methods and techniques related to high voltage and high-power diamond transistors are disclosed. In one example aspect, a switch operable under high-voltage and high-power includes a P-type diamond layer doped with an acceptor material, a first N-type diamond layer doped with a donor material and in contact with one side of the P-type diamond layer, a light blocking layer comprising the one or more apertures configured to allow the light to enter the first N-type diamond layer, a source contact and a drain contact that are at least partially in contact with the P-type diamond layer, and the gate in contact with at least an area of the first N-type diamond layer that corresponds to one of the one or more apertures. The gate can be positioned on the backside of the substrate.

Abstract: A high-voltage switch, whose operation leverages the speed of electrons to generate the “on” time of the pulse in combination with the speed of light to generate the “off” time of the pulse, is described. In one example, the high-voltage switch includes a first electrode, a second electrode spaced apart from the first electrode, a region of non-absorbing material occupying a portion of the space between the first and second electrodes and allowing a laser pulse to propagate therethrough without substantial absorption, and a region of absorbing material occupying another portion of the space and producing a charged particle cloud upon receiving the laser pulse. The high-voltage switch remains “on” upon the charged particle cloud reaching an electrode and until it has been collected by the electrode, and where the high-voltage switch remains “off” subsequent to the collection and until another generated charged particle cloud reaches the electrode.

Abstract: An apparatus, in accordance with one embodiment, includes a superjunction device having a voltage sustaining layer formed of a semiconductor material and a dopant in the voltage sustaining layer. The dopant is for distributing an electric field within the voltage sustaining layer. The dopant is more concentrated along a sidewall of the voltage sustaining layer than toward a center of the voltage sustaining layer, the sidewall extending at least a portion of the distance between a top surface and a bottom surface of a voltage sustaining layer. Methods of electric field-enhanced dopant diffusion to form a superjunction device are also presented.

Abstract: A photoconductive switch that uses materials that support negative differential mobility, whose operation leverages the pulse compression of a charge could to generate the “on” time of the pulse in combination with the speed of light to generate the “off” time of the pulse, is described. In one example, a method of operating a photoconductive switch, which includes two electrodes and a light absorbing material positioned therebetween, includes selecting a value for one or more parameters comprising a voltage for generation of an electric field, a spot size of a laser pulse, a temporal pulse width of the laser pulse, or an intensity of the laser pulse, wherein the selected value(s) for the one or more parameters enable the switch to operate in a region where the light absorbing material exhibits negative differential mobility, and illuminating the light absorbing material with the laser pulse to generate a charge cloud within the light absorbing material.

Abstract: Disclosed are apparatuses and methods of tuning a radio frequency circuit using stub tuners and photoconductive switches. In one aspect an electromagnetic stub tuner apparatus is disclosed. the apparatus includes a transmission line, and a photoconductive switch positioned along the length of the transmission line. The photoconductive switch is configured to turn on or turn off, wherein an impedance of the transmission line is changed when the photoconductive switch is turned on compared to when the photoconductive switch is turned off. In another aspect, a method of tuning a radio frequency circuit is disclosed. In yet another aspect, a method of producing a radio frequency tuning circuit is disclosed.

Abstract: Disclosed are non-linear transmission lines using ferromagnetic materials to generate ferromagnetic resonance oscillations. In one aspect, a non-linear transmission line apparatus is disclosed. The apparatus includes an outer conductor having a first side and a second internally facing side, and an inner conductor positioned internal to the non-linear transmission line apparatus. The apparatus further includes a ferromagnetic material surrounding the inner conductor, wherein the ferromagnetic material comprises nanoparticles of an ?-polymorph of iron oxide expressed as ?—Fe2O3. The apparatus also includes a first dielectric material positioned between the outer conductor and the inner conductor, the dielectric material in contact with both the ferromagnetic material and with the second internally facing side of the outer conductor, wherein the outer conductor, the inner conductor, the dielectric material and the ferromagnetic material form the nonlinear transmission line.

Abstract: In one general embodiment, a structure includes a first diode, comprising: a first layer having a first type of dopant, and a second layer above the first layer, the second layer having a second type of dopant that is opposite to the first type of dopant. A second diode is formed directly on the first diode. The second diode comprises a first layer having a third type of dopant and a second layer above the first layer of the second diode, the second layer of the second diode having a fourth type of dopant that is opposite to the third type of dopant. In another general embodiment, a process includes a repeated sequence of growing a first layer having a first type of electrically active dopant and growing a second layer having a second type of electrically active dopant that is opposite to the first type of dopant.

Abstract: Methods and devices for illuminating a photoconductive switch consisting of an optically actuated photoconductive material situated between two electrodes are described. Light from a light source is coupled to an optical fiber, which is attached to a frustum, the other side of which is proximate to the photoconductive switch. Light from the optical fiber enters the frustum, spreads out, and enters the photoconductive switch via the top-side electrode. Some of the light is absorbed, while the remaining light reflects off the bottom-side electrode, travels back through the photoconductive switch, and any unabsorbed light reenters the frustum. The geometry of the frustum is configured such that most of the light reflects back into the switch itself with only a negligible fraction escaping from the optical fiber, which advantageously results in near total utilization of the light.