Fig. 2. PCDFB laser emission spectra at several operating temperatures, for pulsed optical pumping with a 200-pm-wide Gaussian stripe pumped at five times the lasing threshold. The spectra for Fabry-Perot lasers (no grating) from the same bar are also shown for comparison (dashed curve).was narrower than for any earlier antimonide mid-IR laser pumped far above threshold, apart from external cavity devices4 Fig. 2 illustrates PCDFB and Fabry-Perot spectra at several temperatures, where the Fabry-Perot linewidths range from 43 nm full width at half maximum (FWHM) at 180 K to 69 nm at 240 K, and the linewidths of a-DFB lasers fabricated from the same wafer' have similar values. At T = 180 K,