Multiplexed optical storage

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1 Multiplexed optical storage Peter Török Blackett Laboratory Photonics Group Page 1

2 Talk outline Introduction to our simulation tools BluRay results High density ODS by multiplexing - experimental results - theoretical results Predictions for storage density 1 TB Page 2

3 Optical data storage system Page 3

4 High aperture optical data storage Laser Collimator lens Anamorphic prisms Quarter waveplate Head assembly Page 4

5 High aperture focusing NA=0.3 NA=0.6 Experiment NA=0.85 NA=1.0 Page 5

6 The power of this method Page 6

7 Measuring the lens Page 7

8 Measuring the lens Clutter Drive electronics Clutter CCD Diffuser Imaging lens Reference mirror Spherical mirror Page 8

9 Measuring the lens Page 9

10 Focusing through stratified media Interfaces 1. Air - polycarbonate 2. Polycarbonate protection top 3. Protection top active layer The sample introduces spherical aberration and angle dependent transmittance (Fresnel transmittance) The solution is given as a set of integrals (not too complicated) Page 10

11 ODS optical layout Page 11

12 Illumination Page 12

13 Specimen-light interaction FDTD method used to compute light scattering from sample Extract scattered field Introduce field Typical track with illumination spot FDTD result: electric field distribution Page 13 DVD Blu-Ray data

14 Analytic continuation Outpropagating field to plane and considering re-emitting dipoles Page 14 DVD Blu-Ray data

15 Modelling the detection After summing all dipoles the field at the detector is given by: Outpropagated field Field in detector plane Page 15 DVD Blu-Ray data

16 BD Numerical simulations results Page 16

17 BD simulations Numerical results Scalar simulations Vectorial simulations detector signal scanning position Page 17 Scalar traces are courtesy of Dr Sjoerd Stallinga, Philips Research

18 High density ODS - future Non-volumetric methods Super-RENS MAMMOS SIL? Volumetric data storage Holographic (collinear and non-collinear) 2-photon, etc. Page 18

19 High density ODS - Multiplexing Previously suggested methods: Gray scale levels Mirror orientation (recently US 6,879,556, but before many) SLAM results: Nanoparticle surface plasmon excitation Polarisation multiplexing Page 19

20 High density ODS - Multiplexing Previously suggested methods: Gray scale levels Mirror orientation SLAM results: Nanoparticle surface plasmon excitation Polarisation multiplexing Page 20

21 High density ODS - Multiplexing Work on multiplexing: Static tester built Simulation tool constructed Static simulations are performed Dynamic simulations are performed Page 21

Multiplexing: discriminating M levels log 2 M bits How many levels can be discriminated?

22 High density ODS - Multiplexing Task: determination of the orientation of edge with respect to polarisation 0 Edge 0 to input polarisation Max Edge 45 to input polarisation Multiplexing: discriminating M levels log 2 M bits How many levels can be discriminated? How closely packed can neighbouring data points be? Page 22 With contributions from IMT, Univ. of Neuchâtel

grid 50 µm 50 µm 10 µm by 2.5 µm 20 µm-long by 5 µm-wide trenches 50 µm 50 µm 50 µm 50 µm 5 µm by 1.25 µm 2 µm by 0.5 µm 1 µm by 0.25 µm 0.

23 Polarisation Multiplexing θ Code: 3 tracks of random numbers between 0 and 45 Upper track: 40, 27, 19, 08, 32, 24, 02, 36, 09, 30, 04, 20 Centre track: 20, 24, 23, 11, 39, 01, 37, 30, 09, 22, 34, 05 Lower track: 15, 03, 40, 33, 13, 11, 21, 39, 18, 30, 14, 20 y 25 µm by 25 µm grid 50 µm 50 µm 10 µm by 2.5 µm 20 µm-long by 5 µm-wide trenches 50 µm 50 µm 50 µm 50 µm 5 µm by 1.25 µm 2 µm by 0.5 µm 1 µm by 0.25 µm 0.5 µm by µm 0.25 µm by µm x Page 23 Images courtesy of IMT, University of Neuchâtel Mask manufactured by Applied Optics Group, TUD

Polarisation Multiplexing Noise tests with static tester: Page 24 83 signal levels

24 Polarisation Multiplexing Noise tests with static tester: Page signal levels distinguishable between 0 and x improvement Data courtesy of IMT, University of Neuchâtel

25 Numerical results Page 25

26 Numerical results Page 26

27 Numerical results Page 27

28 Limitations of the technique Primarily memory either 1GB (36 CPUs, each) or 16GB (dual CPU each) Page 28

29 Limitations of the technique 36x(360x360x30 cell) = 36x(18λx18λx1.5λ) 1x(360x360x480 cell) = 1x(18λx18λx24λ) Page 29

30 Storage density projections Number of distinguishable levels should be between 80 and 100 for angles between 0 and 45 Segmented detector permits removal of angle ambiguity possible states, or times standard binary capacity For CD surface with CD pit density, this is 6 GB, DVD: 38 GB, BD: 216 GB ( 1TB/disk) Page 30

31 Acknowledgements Research Groups participating in some parts of the research: Imperial College London: Ben Eastley, Peter Munro, Peter Török Aristotle University of Thessaloniki: Emmanouil Kriezis IMT, University of Neuchâtel Martin Salt, Carsten Rockstuhl, Hans Peter Herzig Applied Optics Group, TUD Arthur van de Nes, Mandeep Singh, Silvania Pereira, Joseph Braat Plasmon Data Systems Ltd. Andrew Pauza Page 31

32 Acknowledgements Research group: Peter Munro (Postdoctoral researcher) Ed Grace (Postdoctoral Fellow) Alexandros Gogornas (PhD student) Ben Eastley (PhD student) Mike Homer (PhD student) Rami Saab (Summer student) Remi Derville (EUREKA student) Matt Warren (MSci and UROP student) Carlos Macias Romeo (PhD student) Nasim Bolorsaz (PhD student) Gung-Hsuan Ho (PhD student) Page 32

33 Acknowledgements Page 33

FDTD Analysis of Readout Characteristics in a near-field MAMMOS recording system. Matthew Manfredonia Paul Nutter & David Wright

FDTD Analysis of Readout Characteristics in a near-field MAMMOS recording system Matthew Manfredonia Paul Nutter & David Wright Electronic & Information Storage Systems Research Group School of Computer