Sparks as sub-nanosecond, broadband light switches

We evaluate spark micro-discharges as the working element of laser switches that can operate on sub-nanosecond timescales, function over a broad range of wavelengths, and handle high laser power. Sparks were generated in room temperature argon at 11-51 bar and xenon at 3-11.6 bar. A continuous 405 nm wavelength laser light was focused through the spark gap, and its transmission was recorded by a high-speed photodiode. We demonstrate that the transition to opacity at the higher pressures is faster than our detection circuit's 90%-10% fall time of 400 ps, indicating that the true fall time is 100 ps or shorter. The challenges to be overcome to improve device reliability are identified.