The Time-resolution Limit of Photodetection Using Single-frequency Oscillations Excited by Secondary Electrons

Analytical estimates for the limiting temporal resolution of the photoreceiving system based on the spectral analysis of the interference signal from single-frequency decayed oscillations excited by the secondary electron train are given. It is shown that the resolution limit is defined by the r.m.s. fluctuations of the photoemission time and time-jitter of the secondary electron packets divided by the square root of the number of photoelectrons within the resolution cell at arbitrary intensities, and does not depend on the time-broadening of the electron packets excited by individual photoelectrons. Numerical estimates show the possibility of obtaining resolutions of the order of 10 −12 -10 −14 s. The achieving of such resolutions is due to the interference of a great number of oscillations with phase differences smaller than π giving a resultant signal of very small phase variance. The product of the limiting resolution interval and the square root of the signal energy is a constant, depending on the device fluctuation parameters. It is shown that the resolution limit may be achieved in the low frequency range, while the resolution of the Fourier method is limited by the maximum attainable frequency. The estimates show the possibility of realizing a new type of photoreceiving device with the following main advantages-high resolution (better than 1 ps for a standard gating technique), use of the full signal energy at arbitrary intensities and a sensitivity close to that of the photon detectors.