Cd 00 NONLINEAR INTERACTION % P LASER BEAM WITH SOLIDS FINAL REPORT

This project deals with two types of nonlinear Interaction of Intense laser beam with dielectric medium. The first and extensively studied phenomenon Is the nonlinear dc polarization that Is caused by the second order nonlinear polarization. The quartz crystal is chosen as the dielectric medium. A quantitative relationship between the dc polarization and the Intensity of the propagating laser beam Is given. A convenient method of detecting dc polarization Is presented. With this technique the elements of the second order polarization coefficient can be determined experimentally. By considering a suitable detecting system wl;h a convenient configuration of the quartz crystal. It Is shown that the output voltage of the detector Is linearly proportional to the Intensity of the laser pulse. Thus, the possibility of using this principle to build a transmission type of meter for measuring power in high-power laser pulses is presented. Preliminary experimental results on the correlation between the spikings in the dc polarization and in the fundamental frequency of laser üscillatlon are presented. The second type of nonlinear polarization presented in this report is the initiation of a study on the generation of subharmonics at optical frequencies using high intensity laser sources. The physical mechanism that is utilized for this purpose is the nonlinear interaction of electromagnetic r