Numerical modelling of near field optical data storage: Dissertation

Kari J. Kataja

Research output: ThesisDissertationCollection of Articles


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.
Original languageEnglish
QualificationDoctor Degree
Awarding Institution
  • University of Oulu
  • Kopola, Harri, Supervisor
  • Myllylä, Risto, Supervisor, External person
Award date8 Sept 2005
Place of PublicationEspoo
Print ISBNs951-38-6653-X
Electronic ISBNs951-38-6654-8
Publication statusPublished - 2005
MoE publication typeG5 Doctoral dissertation (article)


  • direct semiconductor laser readout system DSLR
  • super resolution technique SR
  • Finite Difference Time Domain method FDTD
  • numerical methods


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