Fig. 4.

Data preprocessing for the DRS-RL sensing. (a) response of the RL peak wavelength to the pump energy that is applied to the samples. The peak wavelength changes from blueshift to redshift at the lasing threshold determined by the peak intensity and FWHM, showing that the peak wavelength shift is a good indicator of the lasing threshold. (b) preprocessed data in the lasing regime. Different colors represent the samples with different OPs. (c) data cloud after the correction of the OPs effect. The data points are converged when dividing by $R_d$ , the value of which is calculated taking the arbitrary numbers of 8 and 2 for $k_1$ and $k_2$ .