Noise properties of pulsed ruby laser amplifiers

The spontaneous emission noise properties of a pair of pulsed ruby laser amplifiers have been studied. Absorption and scattering loss measurements coupled with gain measurements as a function of pump time gave a measure of the inversion attained in the amplifiers. The high inversions reached enabled the authors to overcome the inherent noisiness of a 3-level system by having N
2
considerably larger than
(m_{2}/m_{1}) N_{1}
. Total spontaneous emission power was measured at gain saturation for each amplifier. Comparison of the observed with the theoretically expected spontaneous noise power gave good agreement.