Signal quality improvement of holographic data storage by adaptive two-dimensional filter

In this paper, we examine whether the use of a two-dimensional finite impulse response (FIR) filter in two presently available recording/reproduction methods, the Off-axis method, results in an improvement in the signal quality. The linear minimum mean square error (LMMSE) method is first tested to examine its effectiveness in optimizing the coefficients of the FIR filter. Subsequently, the real-coded genetic algorithm (RCGA), which has the capability of searching a wide range of coefficients, is applied and the result obtained is compared with that for the LMMSE method to see if the coefficient evaluation leads to a local solution or the minimum solution. We also applied quadratic minimum mean-square-error (QMMSE) Equalizer as a nonlinear equalizer.