Abstract

The theory of the free induction decay (FID) after pulse saturation of finite duration is presented. The equations of the sudden modulation theory¹ are used for the determination of FID signal. It allows one to study the interaction between the field of laser radiation with the two-level system ensemble modeling impurity ions in solids. The environment influence inducing the frequency modulation of the two-level system is taken into account. Two models of spectral exchange are discussed: Markovian noncorrelated process and Markovian anticorrelated process (the model of "random-telegraph noise"). The first model assumes that the exchange takes place inside of the Lorentzian packets with their centers being evenly distributed in the broad spectral range. The two-level system frequency changes instantly and then remains constant up to the next jump. The distribution of the frequency value after the jump does not depend on the one before the jump. In the second model the two-level system frequency is a two-step random telegraph signal jumping between two states, a and −a. The jump process is characterized by the frequency 1/τ that the telegraph signal changes its state.

© 1994 IEEE