Fig. 1. Experimental materials and devices. (a) Structure of G-quadruplex; (b) experimental setup

Fig. 2. Spectrally integrated emission intensity as a function of the temperature. (a) Spectrally integrated emission intensity of the fluorescence from 555 nm to 620 nm as a function of the temperature with different concentrations of K⁺ solution at same pump energy density; (b) spectrally integrated emission intensity of the lasing from 580 nm to 620 nm as a function of the temperature with different concentrations of K⁺ solution at same pump energy density; (c) fluorescence spectra at different temperatures with 1 mmol/L concentration of K⁺ solution; (d) laser spectra at different temperatures with 1 mmol/L concentration of K⁺ solution

Fig. 3. Spectrally integrated emission intensity of lasing or the threshold of the lasing action as a function of the temperature. (a) Spectrally integrated emission intensity of the lasing from 580 nm to 620 nm as a function of the temperature with different concentrations of K⁺ solution at same pump energy density; (b) threshold of the lasing action from the acceptor as a function of the temperature with different concentrations of K⁺ solution