“FIVE-DIMENSIONAL OPTICAL RECORDING MEDIATED BY SURFACE PLASMONS IN GOLD

NANORODS” -ZIJLSTRA, CHON, GU

Presented by: Kyle Hershey

Jason Maldonis

WHAT DOES 5D MEAN?

Five Dimensions: 3x Spatial Dimensions Polarization Wavelength

SURFACE PLASMONS

Quantized electron oscillation at surface between dialectric and metal.

Can be excited by photons. Wavelength needed for excitation dependent on aspect ratio.

Can only be excited by photons at certain incident angles.Schematic representation of an electron

density wave propagating along a metal – dielectric interface. The charge density oscillations and associated electromagnetic fields are called surface plasmon-polaritonwaves. The exponential dependence of the electromagnetic field intensity on the distance away from the interface is shown on the right. These waves can be excited very efficiently with light in the visible range of the electromagnetic spectrum.

TWO PHOTON LUMINESCENCE (TPL)

Two photons used to excite molecules Then emit a single photon

http://www.ncl.ac.uk/bioimaging/techniques/2photon/

TPL WITH NANORODS

One of the photons can excite SPR, increasing the electric field around particle

Creates higher chance of emitting a photon

Since SPR depends on incident angle, we have polarization dependence in TPL

http://ej.iop.org/images/0957-4484/24/7/075201/Full/nano447839f2_online.jpg

WRITING DATA BY MELTING NANORODS Fempto second laser

pulse One of two polarizations One of three wavelengths If polarization and

wavelength matches nanorod’s orientation and aspect ratio then it melts

Melts only if laser is focused on that pixel (in 3D space)

EXPERIMENTAL RESULTS (WRITING)

“Pixels” are ~ 500nm x 500nm Notice selective reshaping

100 nm

100 nm

Befo

re

Aft

er

READING IN DATA

TPL has much higher angular dependence allowing for two distinct polarizations

Other polarizations and wavelengths are unaffected (d-f)

5D RESULTS

INFORMATION DENSITY RESULTS

Disclaimer: single write only

Best HD Normal HD 5D Nanorods

2D information density (Gbit /m2)

2.3 * 105 1.5 * 105 2.2 * 105

Layer spacing (m) 7.05 * 10-4 1.87 * 10-3 1.1 * 10-5

3D information density (Gbit /m3)

3.3 * 108 8.3 * 107 2.0 * 1010

REFERENCES

Five-dimensional optical recording mediated by surface plasmons in gold nanorods

Peter Zijlstra, James W. M. Chon, Min Gu

Surface plasmon effects on two photon luminescence of gold nanorods

Da-Shin Wang, Fu-Yin Hsu, Chii-Wann Lin

en.wikipedia.org/wiki/Memory_storage_density www.pctechguide.com/hard-disks/hard-disk-hard-drive-

construction www.techradar.com/us/news/computing-components/

storage/how-the-humble-hard-drive-is-made-667183