Fig. 2: Experimental results of the microring electro-optic (EO) dual-comb spectrometer.
From: Thin-film lithium-niobate electro-optic platform for spectrally tailored dual-comb spectroscopy
a The setup for dual-comb spectroscopy for the acetylene gas cell at near atmospheric pressure with two EO-Comb sources (CW: Continuous-wave laser, AOFS: Acousto-optic frequency shifter; BS: Beam splitter). b Apodized dual-comb spectrum (f1 = 191.55 THz and δfrep1 = 40 MHz) with the measurement time of 95 s. 19,000 interferograms (5 ms each) are acquired and processed, and the amplitude spectra are averaged. The two EO combs are driven with microwave frequencies with fRF1 = 10.45 GHz and fRF2-fRF1 = 0.1 MHz. The signal-to-noise ratio (SNR) of the center comb line is 8 × 105, and the average SNR of 160 comb lines is 1 × 105. c An unapodized individual comb line, near 41 MHz in (a), is shown featuring a cardinal sine instrumental line shape. d The evolution of the SNR of three selected comb lines from (a) at 40 MHz, 42 MHz, and 44 MHz over the measurement time. Their linear fitted slopes (black line) are 0.46, 0.49, and 0.54, respectively, indicating that SNR increases with the square root of the measurement time. e The reconfigurability of the microring EO dual-comb system. The interferogram refresh rate (fRF2-fRF1) is varied on demand at 0.800, 0.200, 0.100, and 0.001 MHz.
