Fig. 5

Characteristics of the CO-filled HCFGL. a The experimental layout for CO-filled HCFGL. b For different pump absorption lines, the relationship between MIR output power and pressure. c The measured output laser power at different CO gas pressures as a function of the incident pump power when pumped by the R(7) absorption line. d The variation of residual pump power and output power with CO pressure under the R(7) pump absorption line, and the pump power is fixed at 0.8 W. e The simulated population density distribution of the upper level along the longitudinal direction of the fiber at various pressures. f The simulated relationship between the output power, gas pressure, and fiber length. g The highest power generated by different pump absorption lines at their respective optimal pressures. h The measured output spectra of the CO-filled HCFGL pumped at different absorption lines. i For different pump absorption lines, the proportion of the P-branch output to the total output power (left y axis) and the respective powers of P branch and R branch (right y axis). j Typical output laser beam quality, where the inset shows the beam profile at the waist position