Measurements of gain profile in COIL using a tunable laser diode

A new method for small-signal gain measurements which uses a distributed feedback laser diode (DFB laser diode) as a probe laser has been developed. In this method, as the wavelength of the probe laser can be changed continuously, not only the small-signal gain but also the gain profile can be measured. Small-signal gain with the gain profile of a chemical oxygen iodine laser was measured by applying this method. Moreover, from the line width of the observed gain profile, the temperature of the laser medium was estimated.