Photoconductive switch package configurations having a profiled resistive element
Methods, systems, and devices are disclosed for photoconductive switch package configurations. In some aspects, a photoconductive switch package includes of a wide bandgap photoconductive material (e.g., GaN, ZnO, diamond, AlN, SiC, BN, etc.), a source for energetic photons (e.g., a laser), a mechanism to couple the laser into the switch, and a mechanism for high voltage to enter and leave the switch package. In some implementations, the disclosed photoconductive switch packages can be configured as a three terminal device, e.g., similar to transistors, with one of the terminals being laser input or the voltage input to the laser system.
1. A photoconductive switch package, comprising:
a photoconductive switch including a wide bandgap photoconductive material;
a first electrode and a second electrode interfaced at a first surface and a second surface, respectively, of the photoconductive switch, wherein the first and second electrodes are electrically coupled with a voltage source; and
a profiled resistive element attached to the first and second electrodes and to the photoconductive switch at the opposing first and second surfaces, wherein the profiled resistive element is structured to include a lossy dielectric or resistive material having a tapered profile where a cross section spatially reduces in size along a vertical direction with respect to a horizontal direction,
wherein the photoconductive switch is optically coupled to a light source operable to emit energetic photons to the wide bandgap photoconductive material to cause an electrical signal to conduct between the first and second electrodes via the wide bandgap photoconductive material, and
wherein the electrical signal includes a high voltage at least 5 kV, and wherein the profiled resistive element is structured to provide a defined resistivity curve to allow for reduction of electric field stress concentrations on the photoconductive switch.
2. The photoconductive switch package of claim 1 , further comprising:
an encapsulation structure that surrounds the photoconductive switch and a portion of the first and second electrodes excluding two openings of the encapsulation structure on opposing sides of the photoconductive switch that at least partially expose the photoconductive switch and allow the light source to emit the light to the photoconductive switch.
3. The photoconductive switch package of claim 2 , wherein the encapsulation structure includes a dielectric material.
4. The photoconductive switch package of claim 3 , wherein the dielectric material includes epoxy.
5. The photoconductive switch package of claim 1 , wherein the high voltage is at least 25 kV.
6. The photoconductive switch package of claim 1 , wherein the wide bandgap photoconductive material includes at least one of GaN, ZnO, diamond, AlN, SiC, or BN.
7. The photoconductive switch package of claim 1 , wherein the light source includes a laser.
8. The photoconductive switch package of claim 7 , wherein photoconductive switch includes an antireflective coating on the surface of the photoconductive switch to which the laser is optically coupled.
9. The photoconductive switch package of claim 7 , wherein the photoconductive switch package is configured to receive the emitted light from the laser using an optical fiber feed aligned transversely with the photoconductive switch.
10. The photoconductive switch package of claim 9 , wherein the optical fiber feed includes a single module feed into a coax-to-waveguide adapter.
11. The photoconductive switch package of claim 1 , further comprising:
a high refection (HR) surface coating on a plurality of surfaces of the photoconductive switch to cause internal reflections of the emitted light within the wide bandgap photoconductive material.
12. The photoconductive switch package of claim 1 , wherein the photoconductive switch is structured a concave region on one or both of the first surface and the second surface, and wherein one or both of the first electrode and the second electrode are structured to include a convex terminal to interface with the concave region of the photoconductive switch.
13. The photoconductive switch package of claim 12 , wherein the convex terminal includes a contoured profile that conforms to one of a Rogowski, Bruce, Chang, Harrison, or Ernst profile.
14. The photoconductive switch package of claim 1 , wherein the first electrode is structured to include a hollow interior at a terminal end of the first electrode that electrically couples to the photoconductive switch, wherein the light source is optically coupled to the photoconductive switch through the hollow interior of the first electrode to axially feed the emitted light to the photoconductive switch.
15. The photoconductive switch package of claim 14 , further comprising:
an optical coupling component including an optically transmissive material located at the interface between the first electrode and the photoconductive switch.
16. The photoconductive switch package of claim 15 , wherein the optical coupling component includes silicon oxide (SiO2).
17. The photoconductive switch package of claim 15 , wherein the optical coupling component includes a diffusive element.
18. The photoconductive switch package of claim 15 , wherein the optical coupling component includes ITO coating structured to include a current mesh grid.
19. The photoconductive switch package of claim 1 , wherein one or both of the first electrode and the second electrode are structured to include at least one blunt terminal to interface with the photoconductive switch.
20. A photoconductive switch package, comprising:
a photoconductive switch including a wide bandgap photoconductive material;
a first electrode and a second electrode interfaced at a first surface and a second surface, respectively, of the photoconductive switch, wherein the first and second electrodes are electrically coupled with a voltage source;
a profiled resistive element attached to the first and second electrodes and to the photoconductive switch at the opposing first and second surfaces, wherein the profiled resistive element is structured to include a lossy dielectric or resistive material having a tapered profile where a cross section spatially reduces in size along a vertical direction with respect to a horizontal direction; and
a transparent and electrically conductive coating including indium tin oxide (ITO) or zinc oxide (ZnO) between the profiled resistive element and the photoconductive switch,
wherein the photoconductive switch is optically coupled to a light source operable to emit energetic photons to the wide bandgap photoconductive material to cause an electrical signal to conduct between the first and second electrodes via the wide bandgap photoconductive material.
21. The photoconductive switch package of claim 20 , wherein the transparent and electrically conductive coating is on external surfaces of the photoconductive switch.
22. A method for photoconductive switching, comprising:
providing a photoconductive switch including a wide bandgap photoconductive material between a first electrode and a second electrode interfaced at a first surface and a second surface, respectively, of the photoconductive switch, and a profiled resistive element attached to the first and second electrodes and to the photoconductive switch at the opposing first and second surfaces, wherein the profiled resistive element includes a lossy dielectric or resistive material having a tapered cross section spatially reducing in size along a vertical direction with respect to a horizontal direction;
applying, from a voltage source, a high voltage of at least 5 kV across the first and second electrodes;
emitting, from a light source, energetic photons to the wide bandgap photoconductive material to cause an electrical current to conduct between the first and second electrodes via the wide bandgap photoconductive material; and
reducing, at the profiled resistive element, electric field stress concentrations on the photoconductive switch.
23. The method of claim 22 , wherein the high voltage is at least 25 kV.
24. The method of claim 22 , wherein the wide bandgap photoconductive material includes at least one of GaN, ZnO, diamond, AlN, SiC, or BN.
25. The method of claim 22 , wherein the light source includes a laser.
26. The method of claim 22 , further comprising:
optically confining the energetic photons within the wide bandgap photoconductive material via a high refection (HR) surface coating on a plurality of surfaces of the photoconductive switch to cause internal reflections of the energetic photons within the wide bandgap photoconductive material.
27. The method of claim 22 , wherein the emitting includes transversely feeding the emitted energetic photons to the photoconductive switch one side of the photoconductive switch.
28. The method of claim 22 , wherein the emitting includes axially feeding the emitted energetic photons to the photoconductive switch via a hollow interior at a terminal end of the first electrode that electrically couples to the photoconductive switch.
29. The method of claim 28 , further comprising:
diffusing the axially fed energetic photons into the photoconductive switch.