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

Digital storage in five dimensions In the cause of cramming more and more data onto optical storage devices, materials scientists have sought to add extra dimensions to recording media, literally. Now a group from Melbourne's Swinburne University of Technology has developed a five-dimensional optical recording technique with the potential to increase storage capacities by several orders of magnitude. The extra dimensions are the wavelength and polarization of light, which integrated with the familiar three spatial dimensions creates true five-dimensional recording within one volume. The result is a theoretical 1.6 terabytes capacity for a DVD-sized disk. The new system makes use of surface plasmon resonance (SPR)-mediated photothermal reshaping of a substrate of gold nanorods immersed in a polymer layer. Crosstalk-free readout is via two-photon luminescence. Immediate applications can be found in security patterning and multiplexed optical storage. By exploiting not only the three spatial dimensions but also other ways to record information, it is theoretically possible to store much more onto an optical device such as a DVD than has hitherto been possible. Here, a five-dimensional optical recording technique using polarization of light and its wavelength as the two additional dimensions, is demonstrated. The method consists of using a substrate of gold nanorods immersed in polymer. Multiplexed optical recording provides an unparalleled approach to increasing the information density beyond 10 12 bits per cm 3 (1 Tbit cm -3 ) by storing multiple, individually addressable patterns within the same recording volume. Although wavelength 1 , 2 , 3 , polarization 4 , 5 , 6 , 7 , 8 and spatial dimensions 9 , 10 , 11 , 12 , 13 have all been exploited for multiplexing, these approaches have never been integrated into a single technique that could ultimately increase the information capacity by orders of magnitude. The major hurdle is the lack of a suitable recording medium that is extremely selective in the domains of wavelength and polarization and in the three spatial domains, so as to provide orthogonality in all five dimensions. Here we show true five-dimensional optical recording by exploiting the unique properties of the longitudinal surface plasmon resonance (SPR) of gold nanorods. The longitudinal SPR exhibits an excellent wavelength and polarization sensitivity, whereas the distinct energy threshold required for the photothermal recording mechanism provides