1. From 4.7GB to 100 GB -- Theoretical study of the AgO x -type super-resolution near-field structure Ming-Yaw Ng and Wei-Chih Liu Department of Physics, NTNU

2. Outline Introduction Introduction Working mechanisms of the AgO x -type super-resolution near-field structure (Super- RENS) Working mechanisms of the AgO x -type super-resolution near-field structure (Super- RENS) Simulation results: Simulation results: random nanoparticles in AgO x layer random nanoparticles in AgO x layer periodic nanoparticles in AgO x layer periodic nanoparticles in AgO x layer frequency dependence of the AgO x –type Super-RENS frequency dependence of the AgO x –type Super-RENS Conclusions Conclusions

3. http://www.nano.gov

4. 1980 19902000 20052010 MB GB TB Advantages capacity >100 Giga Byte >20 DVD movies >100 部中國 25 史 >150 music CD CD/650MB Track Pitch=1.6  m Pit Length=0.83  m 7 CDs > 150 CDs 50 CDs HD-DVD/25GB Track Pitch=0.35  m Pit Length=0.2  m Super-RENS disk >100GB Pit Length < 0.1  m Comparison of optical disks DVD/4.7GB Track Pitch=0.74  m Pit Length=0.4  m

5. Near-field optical data storage systems (?) Far-field optical data storage systems (CD-R, CD-RW, DVD….) Mark size 200 nm100 nm50 nm1000 nm400 nm

8. 物理雙月刊（廿三卷二期） 2001 年 4 月 recording

9. ZnS-SiO 2 AgO x ZnS-SiO 2 10nm TEM image of cross-section of the AgO x -type Super-resolution near-field structure (Super-RENS) disk Silver nanoclusters W.-C. Liu, C.-Y. Wen, K.-H. Chen, W. C. Lin, and D. P. Tsai, Appl. Phys. Lett. 78, 685 (2001).

10. Mark size > λ Focusing laser beam NA = 0.6 marks Mark size < λ

11. Focusing laser beam NA = 0.6 Mark size < λ marks AgO x (15nm)

12. DVD disk substrate ZnS-SiO 2 (20 nm) AgO x (15 nm) Ge 2 Sb 2 Te 5 (15 nm) Recording mark Ag nanoclusters Focusing laser beam

13. TM mode Localized surface plasmon of the AgO x –type Super-RENS with silver nanoparticles TE mode

14. Far-field difference signals of the AgO x -type Super-RENS disks with random silver nanoparticles

15. Nonlinear optical response from random silver nanoparticles

16. Near-field images of AgO x -type Super-RENS disks with periodic silver nanoparticles Period = 150 nm

17. Far-field difference signals of the AgO x -type Super-RENS disk

18. Optical constant of bulk silver ‘Handbook of Optical Constants of Solids’, Ed. By Edward D. Palik, Academic Press, Inc., (1985) n = 0.14 k = 4.15 for λ= 650 nm n = 0.17 k = 1.95 for λ= 405 nm

19. Near-field images of the AgO x -type Super- RENS disks with silver nanoparticles

20. Far-field difference signals of the AgO x -type Super-RENS disk

22. Scattering efficiency of single silver nanoparticle

23. Conclusions Super-RENS was a multilayered structure, which could achieve resolution beyond optical diffraction limit. Super-RENS was a multilayered structure, which could achieve resolution beyond optical diffraction limit. The AgO x layer of the AgO x -type Super-RENS scattered the incident Gaussian beam and enhanced the localized surface plasmons. The AgO x layer of the AgO x -type Super-RENS scattered the incident Gaussian beam and enhanced the localized surface plasmons. The AgO x -type Super-RENS disks could transfer the evanescent light from sub-wavelength recording marks into propagation light. The AgO x -type Super-RENS disks could transfer the evanescent light from sub-wavelength recording marks into propagation light. The far-field signals of specific mark size could be controlled by periodic silver nanoparticles or nanoclusters. The far-field signals of specific mark size could be controlled by periodic silver nanoparticles or nanoclusters. The silver nanoparticles with highly scattering efficiency in AgO x layer of the AgO x – type Super-RENS disks have better resolution capability even though it is illuminated with incident light of longer wavelength The silver nanoparticles with highly scattering efficiency in AgO x layer of the AgO x – type Super-RENS disks have better resolution capability even though it is illuminated with incident light of longer wavelength