is switched off). As is evident from the differences in the transmission in Fig. \[fano\](a), the probe beam experiences gain which is more than the total losses when interacting with atoms inside the cavity. The shift between blue and the red curve is due to lasing without any probe laser as we make sure that the cavity detuning is fixed on the red peak of the last graph in Fig. \[atnogrid\](a). In addition to gain, the blue trace also shows a Fano-like structure indicating interference between two or multiple probability amplitudes for emission [@miroshnichenko_fano_2010] which suppresses the lasing action. Fig. \[fano\](b) shows line narrowing even in the absence of Fano structure slightly away from the red peak of the last graph in Fig. \[atnogrid\](a). A similar experiment on the blue detuned peak attenuates and shows a tendency to broaden the transmitted light.

![Probe transmission spectra when atoms are present inside the cavity. For (a) and (b), the blue trace shows cavity probe transmission when driven atoms are present in the cavity, and the broken red trace is probe transmission curve without atoms.(a) This figure shows a gain and Fano-type structure in the presence of atoms. The cavity length is such 