Slow and stopped light in dynamic Moiré gratings

Abstract

We investigate a theoretical model for a dynamic Moiré grating which is capable of producing slow and stopped light with improved performance when compared with a static Moiré grating. A Moiré grating superimposes two grating periods which creates a narrow slow light resonance between two band gaps. A Moiré grating can be made dynamic by varying its coupling strength in time. By increasing the coupling strength the reduction in group velocity in the slow light resonance can be improved by many orders of magnitude while still maintaining the wide bandwidth of the initial, weak grating. We show that for a pulse propagating through the grating this is a consequence of altering the pulse spectrum and therefore the grating can also perform bandwidth modulation. Finally we present a possible realization of the system via an electro-optic grating by applying a quasi-static electric field to a poled χ (2) nonlinear medium.

A dynamic and nonlinear time grating subdivision method for magnetic levitation ruler

“…Gao xu and et al proposed a method of constructing a linearized function curve by using the absolute values of two Moir é fringe signals output by grating sensors to add, subtract, multiply, and divide them, thereby obtaining position information based on linearized signals and proprietary dynamic compensation methods [4]. Based on the relationship between the subdivision error obtained by the grating sensor's output Moir é fringes electrical signal and the error parameters contained in the output Moir é fringes electrical signal, a signal compensation method is designed to convert the phase non orthogonal error of the two Moir é fringes electrical signals into amplitude coefficient unequal error [5]. From the perspective of amplitude subdivision method, many domestic and foreign scholars have started to study software subdivision algorithms, which linearize the collected Moir é fringes electrical signals through programming methods, namely electronic amplitude subdivision method [6].…”