Fig. 1. Comparison of working principle and SNR between TSIR and FTIR.

a Working principle of TSIR and FTIR. DFT dispersive Fourier-transform, FFT Fast-Fourier transform, BS beamsplitter, PD photodetector. b SNR dependence on the number of spectral elements, M (Blue: TSIR, Red: FTIR). P: average detection power, σ system’s overall noise equivalent power. c SNR dependence on measurement time, T (Blue: TSIR, Red: FTIR). The SNR is calculated for M = 1000 with typical values of P = 10 µW and σ =10 $\mathrm{pW}$ ${\mathrm{Hz}}^{-\frac{1}{2}}$. NEP noise-equivalent power