IN-SITU SMALL-SIGNAL GAIN OF SOLID-STATE LASERS DETERMINED FROM RELAXATION OSCILLATION FREQUENCY MEASUREMENTS

We present a simple, in situ technique to calculate the small-signal g ain of typical solid-state continuous-wave lasers, such as Nd:YAG and Nd:YLF lasers, by measuring the frequency of the relaxation oscillatio n noise peak. The laser's small-signal gain can be directly calculated from the frequency of the relaxation oscillation with knowledge of th e upper-state lifetime, the cavity round-trip time, and total losses, which are typically well-known values. When the laser is pumped many t imes above threshold the losses do not need to be known accurately. Th is technique is compared with the traditional method of changing outpu t couplers to establish its accuracy.