Random Frequency Modulation Of Optical Coherent Transient Processes

Random frequency modulations exist in many systems, such as magnetic system and glasses at low temperature, dye-solution. Some experimental phenomena can not be understood within the frame of the conventional optical Bloch equations. To investigate this problem, first we introduce a general model to describe the system that is modulated by some stochastic processes, and also the method to solve it. Then we systematically investigate the optical dephasing mechanism of doped paramagnetic ions.By both analytical method and computer simulation, two kind of optical coherent transients have a self-consistent explanation. We prove that at high magnetic field, the optical dephasing will be well described if one only consider the nuclear spin flips of the host lattice and frozen core.At low magnetic field, the exact solution of the transient hole-burning shape has been obtained for systems with a noncorrelated spectral exchange. The THB shapes have been studied for various conditions. Because the phenomenal model can not give any practical dephasing mechanism, so considering the practical interaction in the paramagnetic ions doped systems, we present a general theory to describe the optical dephasing induced by indirect electronic flips. We suggest a new mechanism, the electronic spin controlling nuclear SFF mechanism, several photon echo experiments in ruby have a self-consistent explanation by the mechanism, and the spectral diffusion is also well explained. We believe that this mechanism is also suitable for other dilute paramagnetic ions doped systems.We have investigated the spectral diffusions of chromophores in low temperature glasses and doped paramagnetic ions at high field by pure frequency domain method. Although spectral diffusion behaviors in two domains are very different for a single modulator, but the final observed spectral diffusions will tend to show no difference due to the average over various time-scale dynamical processes.