INFLUENCE OF LASER READ AND BIAS POWER LEVELS ON THE PERFORMANCE OF THERMOMAGNETOOPTIC RECORDING MEDIA

Read and bias power levels are capable of noticeably altering the response of thermomagnetooptic recording materials. The heating caused by the read power can decrease signal levels due to the temperature dependence of the polar Kerr rotation. Preheating caused by bias power levels also influences media sensitivity and responses during the writing process. Increased bias levels reduce the optimum recording power and increase the severity of mark length variations caused by write power fluctuations. Simple predictive expressions were derived to describe the influence of bias and read power levels during the mark formation and readout processes. The predicted results were in good qualitative and quantitative agreement with experimental observations. Key words: Thermomagnetooptic, Kerr rotation, laser heating, optical data storage, rare earth-transition metal alloys. © 1990 Optical Society of America.