Proc. SPIE. 5966, Seventh International Symposium on Optical Storage (ISOS 2005)
KEYWORDS: Beam splitters, Holograms, Holography, Data storage, Computer programming, Spatial light modulators, Very large scale integration, Error control coding, Volume holography, Holographic data storage systems
Volume holographic storage is currently the subject of widespread interest as a fast data readout, high-capacity digital data-storage technology. However, due to the effect of cross-talk noise, scattering noise, noise gratings formed during a multiple exposure schedule, it brings a lot of burst errors and random errors in the system. In general, row and column (RAC) array codes is based on single parity check codes, so it is weak to correct errors ability. In order to get the acceptable bit error rate (BER)(10<sup>-12</sup>). This paper presents multiblock strategy to solve the application of involving an entire page of data which may be as large as 1Mbits and We design VLSI implementations of multiblock RAC array coding encoder and decoder architecture for volume holographic storage. We analyze performance about hardware requirements and time delays associated with the multiblock RAC array code.
Block copolymers (BCPs), which self-assemble into spatially periodic one-dimensional (1D) ordered lamellar equilibrium structures, can be used as multilayer waveguide materials. In this article, the hybrid modal characteristics of three representative self-assembled BCPs multilayer stripe waveguides were studied with compact 2D finite-difference time-domain (2D-FDTD) method. By comparing our numerical results with those obtained by the N-layer waveguide formalism, it is found that on some occasions the two-dimensional (2D) formalism is a good choice to substitute for the three-dimensional (3D) modal analysis of multilayer waveguide . It is also been proved that if the sequence of the two different index layers is inverted in the structure, the modal analysis results change dramatically and the lamellar width is an important factor that influences the optical field distribution of the waveguide modes. An investigation about the triblock copolymer (tri-BCP) waveguide revealed that its field distribution layered more obviously for the particularity of tri-BCP waveguide core structure.
An effective way of constructing an AWG with a wide passband is to use a configuration with a parabolic horn as the input waveguide to a slab waveguide. This configuration provides good passband control ability and fabrication stability. However, the parabolic waveguide horn may induce chromatic dispersion (CD) in AWGs. In this paper, first the theory of broadening passband and origins of CD in AWG were analyzed, then the influences of the configuration parameters of parabolic horn to broaden spectrum of AWG were discussed through a beam propagation method (BPM) and numerical calculation. A good flat-top AWG was obtained by choosing rationally three parameters: exit width W, broadening coefficient α and length of multimode waveguide. And low CD was achieved through adjusting the length of multimode waveguide slightly.