Subwavelength aperiodic reflective structures in media are shown by FDTD modeling to be capable of separating the interacting focused laser beam into four separate beam paths upon reflection/diffraction. This was not an apparent result predictable from known classical closed-form theory on the topic. The exit pupil intensity fields for these subwavelength structures show both spatial frequency content as well as significantly differing positional distributions within that field. These FDTD modeling results demonstrates that information can be extracted from the reflected intensity distributions of subwavelength-sized optical ROM media structures.
Exploring optical multilevel information storage using
subwavelength-sized media structures
Advanced R&D, Iomega Corporation, 1821 West Iomega Way, Roy, Utah 84067
Phone: 801-332-4662 Email: firstname.lastname@example.org
Abstract: Can complex 3-D subwavelength-sized structures molded in plastic optical ROM media
be interrogated by a diffraction-limited focused spot for the retrieval of multilevel information?
Finite-difference time-domain (FDTD) methods are used to examine the reflected intensity fields
from such structures. The results presented show that such information retrieval is possible.
2003 Optical Society of America
OCIS codes: (050.0050) Diffraction and gratings, (210.0210) Optical data storage, (260.0260) Physical optics
The general goal behind the data storage concept explored in this paper is the following: the creation of
subwavelength media structures whose property, upon reflection/diffraction of a focused laser spot, is the creation of
multiple beam paths, each of whose irradiance pattern’s centroid position in the lens aperture changes predictably
and measurably for the storage of multilevel encoded information.
The author introduced this concept for storing information in subwavelength-sized topographic media features at
this conference last year . That paper used geometrical optical arguments for conceiving a high capacity and high
transfer rate ROM optical memory system that encoded multilevel information using an array of lithographically
fabricated micro-mirrors. A 2x2 array of these mirrors was termed an AO-DVD “optical data element” (ODE). Each
ODE is the size of the far-field optical drive’s laser stylus spot. For the particular example discussed, each ODE had
a square dimension of 780 nm. A DVD track width has this dimension. Leveraging this equivalent track size, an
explanation as to how a DVD/AO-DVD cross-compatible system might be implemented was provided. Each of the
four micro-mirrors in the ODE has both a tilt