The chaotic oscilloscope

In spite of its apparent simplicity, a system consisting of a high-frequency oscilloscope operated in the x–y mode and a photodiode, which detects the light emitted from the trace while feeding the signal back to the oscilloscope, exhibits extraordinary complex behavior. Scenarios involved are limit cycles evolving into chaos through the Feigenbaum bifurcation route and low-frequency relaxation oscillations that can be phaselocked to external signals. Regions of complete phase lock are observable in this case. Furthermore, the Feigenbaum oscillations can be superimposed upon the relaxation oscillations. The different scenarios will be illustrated and the underlying mechanisms discussed.