Fig. 3

Threshold and operational lifetime performance of nanographene lasers. a Emission linewidth, defined as the full width at half maximum (FWHM), as a function of the pump energy density, E_pump, for the laser peaks associated with the TE₀ waveguide modes of devices 1^B, 2^C, and 3^B. Full lines are guides to the eye. The DFB threshold for each case, E_th-DFB, is defined as the E_pump at which the FWHM decays to half of its maximum value (E_th-DFB values in Table 2). b Log–Log plots of output intensity, I_out, as a function of the pump energy density, E_pump, for the same laser peaks shown in panel a). For each case, I_out is collected at the corresponding λ_DFB. Full lines are guides to the eye. c Evolution of the laser spectrum with E_pump for device 2^B. d DFB intensity, I_out^DFB, versus time, t, and versus the number of pump pulses (top and bottom axes, respectively) for the same laser peaks shown in panel a) within this figure. The operational lifetime (τ_1/2^DFB) for each case is defined as the time (or number of pump pulses), at which I_out^DFB decays to half of its initial value. Excitation was done at the same spot of the device in air under a moderate pump (MP, full lines) of (E_pump/ E_th-DFB) ≈ 4, or under an extreme pump (EP, dashed lines) of E_pump = 2 × 10⁴μJ cm⁻². Source data are provided as a Source Data file in the Institutional Repository of the University of Alicante [http://hdl.handle.net/10045/92007]