We evaluate numerically the effect of shrinkage of photopolymer on the bit error rate or signal-to-noise ratio in a reflection-type holographic data storage system with angular multiplexing. In the evaluation, we use a simple model where the material is divided into layered structures and then the shrinkage rate is proportional to the intensity in each layer. We present the effectiveness of the proposed model from the experimental results in the recording of the plane waves both in a transmission-type hologram and a reflection-type one. Several kinds of shrinkage rates are used to evaluate the characteristics of angular multiplexing in the reflection-type holographic memory.

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We study gauge threshold corrections for systems of fractional branes at local orientifold singularities and compare with the general Kaplunovsky-Louis expression for locally supersymmetric N = 1 gauge theories. We focus on branes at orientifolds of the C 3 /Z 4 , C 3 /Z 6 and C 3 /Z ′ 6 singularities. We provide a CFT construction of these theories and compute the threshold corrections. Gauge coupling running undergoes two phases: one phase running from the bulk winding scale to the string scale, and a second phase running from the string scale to the infrared. The first phase is associated to the contribution of N = 2 sectors to the IR β functions and the second phase to the contribution of both N = 1 and N = 2 sectors. In contrast, naive application of the Kaplunovsky-Louis formula gives single running from the bulk winding mode scale. The discrepancy is resolved through 1-loop non-universality of the holomorphic gauge couplings at the singularity, induced by a 1-loop redefinition of the twisted blow-up moduli which couple differently to different gauge nodes. We also study the physics of anomalous and non-anomalous U(1)s and give a CFT description of how masses for non-anomalous U(1)s depend on the global properties of cycles.