Nonlinear laser spectroscopy of solids and applications to computers

Summary form only given, as follows. Following a brief introduction to the physics of optical homogeneous line-widths in low-temperature soiids, two recem experimemal studies in our iab will be described. These experiments are aimed at spin flip rate measurements, since it appears that the main factors determining linewidths (dephasing times) are the spin flips of the host and /or dopant ions. In ruby these are the Al and Cr ions respectively. Using the Raman heterodyne technique we have observed Al nuclear dephasing in the frozen core and verified the concept proposed by Bloembergen some 40 years ago. An important realization is that such observations provide a new method for measurements of the Cr spin flip rate. The concentration dependence of this rate has been studied and found to agree with theory. In the second experiment, a pump-probe method has been used to study hole-burning in the frequency domain with ~1 kHz resolution. By varying the pump-probe delay, we have observed spectral diffusion which occurs in a time scale of ~100 usec for 0.0034 Wt% Cr203 ruby. This time is much shorter than the Cr-Cr spin flip time and suggests that Al-Al flips are responsible for the diffusion. Finally applications of hole-burning to optical processing and storage in the time and frequency domains will be discussed.