Department of Electronic Engineering, Okayama University of Science
Abstract
We have optically detected the electron-spin resonance of F center in the relaxed excited state (RES) from the changes observed in the magnetic circular polarization (MCP) under the condition of modulated circular polarization at the resonant microwave of 50 GHz. We have found a new ESR peak at g=1.995 for the slightly high concentration of F center. Under the non-resonant condition, that is without microwave and rf field, we have optically detected the hf signal. We have found three facts : (1) the hf signal intensity is decreased with an increase of the frequency of the modulation field superimposed on the static magnetic field ; (2) the spin-lattice relaxation time in the RES is an important factor for the occurrence of the hf signal ; (3) the hf signal intensity is independent of the excitation power, P, in the low power range. However, it is reduced with an increase in P of the high power pulse laser
