Pulse Sharpening and Gain Saturation in Traveling-Wave Masers

This paper presents earlier considerations concerning the gain process in traveling-wave masers in cases where the signal energy, over an appropriate period of time, is comparable to the energy stored in the maser material. The results were communicated several years ago in reports with limited circulation. 1 - 2 3 The studies were prompted originally by the development of microwave masers, in particular the ruby comb-structure traveling-wave maser. 4 Here gain saturation is of interest primarily in a negative sense: it is a condition that should be avoided in system applications. The maser may handle input signals up to some typical saturation limit which depends 011 the tolerable gain compression, the signal duty ratio, and the low-power gain. Thus the situation of drastic gain reduction due to saturation is largely of academic interest. It may be used, however, as a check on the theoretical understanding of the maser gain process. 3 It should be added that even with drastically compressed gain the maser is still a linear amplifier in the sense that it does * This work was supported in p a r t by the U.S. Army Signal Corps under contracts No. DA 36-039 SC-73224 and SC-85357. 625