Herein the authors report on the demonstration of an 87% enhancement in cw laser power on the 1315 nm transition of atomic iodine via a 100% increase in the resonator mode volume. ${\text{O}}_2\left(a^1\Delta \right)$ is produced by a single rf-excited electric discharge sustained in an ${\text{O}}_2–\text{He}–\text{NO}$ gas mixture flowing through a rectangular geometry, and $\text{I}\left({{}^{2}P}_{1/2}\right)$ is then pumped using energy transferred from ${\text{O}}_2\left(a{}^1\Delta \right)$ . A total laser output power of 102.5 W was obtained using a Z-pass resonator configuration.