ABSTRACT
One of the fundamental achievements of today’s information society is providing storage and processing of ever-increasing amounts of data that is based on basic research in physics in combination with fundamental technology developments over the last four decades. As no low-cost universal memory that is suited for all kinds of applications exists, digital data storage is separated mainly into three di˜erent lines:
1. ›e digital versatile disk (DVD) and the compact disk (CD) are nonvolatile storage media based on an optical write and read-out process using laser light at wavelengths of 650 and 780 nm, respectively. ›e newest representative of optical data storage is the Blu-ray disk, using a laser wavelength at 405 nm with a maximum capacity of up to 50 GB disk−1.
