Extended Data Table 1 Experimental parameters and calculated quantum-noise limited signal to noise ratio

From: Near-ultraviolet photon-counting dual-comb spectroscopy

  1. L is the number of individual interferograms in the Tindiv time sequence. Ttot = TindivL is the total accumulation time in the entire recording. Nphot is the detected photon rate. In all experiments but that of Fig. 5, frep = 500 MHz, δfrep = 1.6 MHz. In Fig. 5, frep = 100 MHz, δfrep = −12.5 kHz. The sampling rate frep and the integration time per time bin is 1/frep. The experimental signal-to-noise ratio (SNR) is the inverse standard deviation of the normalized absorption baseline of the amplitude spectrum. The calculated SNR is calculated using Eq. 2. We attribute the slight mismatch between the measured and calculated by the rudimentary model that we use, which neglects additive noise sources and assumes that all comb lines have the same intensity. The calculated average power per comb is half the total power incident on the counter. The photon-counter efficiency is 25% in Figs. 3, 4, Extended Data Fig. 4 and 70% in Fig. 5.
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