Numerical modelling of near field optical data storage
|Author:||Kataja, Kari J.|
Espoo : VTT Technical Research Centre of Finland,
|Publish Date:|| 2005-08-29
|Thesis type:||Doctoral Dissertation
|Defence Note:||Academic Dissertation to be presented with the assent of the Faculty of Technology, University of Oulu, for public discussion in the Auditorium YB210, Linnanmaa, on September 8th, 2005, at 12 o´clock noon.
In this thesis, two future generation optical data storage techniques are studied using numerical models. Direct semiconductor laser readout (DSLR) system employs external cavity configuration and super resolution (SR) technique an optically nonlinear material layer at the optical disc for recording and readout operation. Work with the DSLR system is focused on the studying and optimisation of the writing performance of the system, while work with the SR system has focused on explaining the physical phenomena responsible for SR readout and writing performance. Both techniques enable the writing and readout of the data marks smaller than the resolution limit of the conventional optical pickup head. Using SR technique 4x increase in the data density in comparison to DVD disk can be obtained. Because the studied structures are in the order of the wavelength, ray tracing and scalar methods cannot be used to model the system. But, the solution of Maxwell's vector equations is required in order to study these structures. Moreover, analytical solutions usually do not exist for such complex structures, thus the numerical methods have to be used. In this thesis the main modelling tool has been the Finite Difference Time Domain method.