Figure 2
From: Adaptive sampling dual terahertz comb spectroscopy using dual free-running femtosecond lasers
(a) Experimental setup of adaptive-sampling-clock generator based on dual THz-comb-referenced spectrum analysers . BT-PCA1 and BT-PCA2, bowtie-shaped, low-temperature-grown, GaAs photoconductive antennas; Ls, objective lenses; PPLNs, periodically-poled-lithium-niobate crystals; THz-Ls, THz Teflon lenses; AMP, current preamplifier; FMs, frequency multipliers (frequency multiplication factor =N = 40); M, double-balanced mixer; LPF, low-pass filter. (b) Extraction of beat signal between dual THz comb modes based on dual THz-comb-referenced spectrum analysers. (c) Extracted beat signal between dual THz comb modes around 4 THz.
