High sensitivity intracavity stimulated emission pumping

Small optical gains have been measured by an intracavity laser technique. The iodine molecule is used to probe and calculate the different mechanisms occurring in the intracavity stimulated emission pumping technique. We observed and measured the gain of lines: R(15), P(13),P(17)(43-26). Absorption from nu'' = 6,7, and 8 was also obtained. We show that collision processes and random coincidences of the cavity modes govern the sensitivity of this technique.