Photoconductive semiconductor switches (PCSS) are needed for high-power microwave (HPM) applications due to their fast switching and high-voltage handling capabilities.  It consists of a wide bandgap material sandwiched between two electrodes, and a light source to control the flow of current between them.  There is a need then to maximize the utilization of light in the PCSS.


U.S. Patent No. 11,555,965 describes LLNL’s invention of “Illumination Frustums” for photoconductive switches to capture and “frustrate” the light from leaving the frustum.  LLNL researcher’s latest novel invention, “Twister Oven”, achieves this by encouraging laser light absorption in a photo conductor material.  Light enters the oven twisting and reflecting, making near normal incident multi-passes onto and into a photoconductive material.  The system is optimized to prevent light exiting the input port, minimizing losses at reflective surfaces.

  • Improved performance of photoconductive switches.
  • Increases light absorption in photoconductive switches.
  • Reduces photo conduction resistance
  • Frustum trapping illumination under photo conductor surface electrodes
Potential Applications
  • Power Electronics
  • Applications needing high voltage switches
Development Status

Current stage of technology development:  TRL 4 (Component and system validation in laboratory environment)

LLNL has filed for patent protection on this invention. Related patents:

U.S. Patent No. 11,555,965 Illumination frustums for photoconductive switches issued 1/17/2023

U.S. Patent No. 10,326,038 Three-Dimensional Co-Axial Linear Photonic System issued 6/18/2019

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