Time traces of the QDOGFET detector output responding to 500 photon bursts at 10 kHz. (a) The detector resets (beginning and end) plus the full illumination period (between arrows). (b) Magnifying the detail of the stair steps during illumination. (c) Detail of a single step, including parameters used in the detection analysis.
The square root of the noise spectral density for an amplified QDOGFET detector output. The SPS line is shown as a solid straight line. The line with SNR of 4.4 is shown as a dashed line. The weighting function for a measurement period of is shown as a dotted curve.
The histogram distribution of 5000 step amplitude signals for a measurement period of . The filled (open) circle data resulted from illumination with a mean number of photons per pulse of 0.65 (0).
All of the noise data presented in this figure were taken with the same QDOGFET bias conditions. The filled circles are signal-to-noise points resulting from the analysis of photon data (as explained in the text) for a series of different measurement frequencies. They are graphed with respect to the diagonal axis on the right. The data marked “with reset” and “no reset” are the square root of the noise spectral densities for the labeled electrical reset condition. The left axis applies to these noise spectra. The solid diagonal line with signal-to- is the SPS line from Eq. (9) .
Normalized noise spectra for the same QDOGFET operated at 4 and 77 K (as marked). The dashed line is the normalized SPS line and the spike at 10 kHz is the result of the calibrating gate modulation.
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