Study on magnetophotonic crystals for use in reflection-type magneto-optical spatial light modulators

Abstract

A magneto-optical spatial light modulator (MOSLM) is a real-time programmable device for modulating the amplitude and/or phase of two-dimensional optical signals at a high speed. Recently, we reported the development of the transmission-type MOSLM (T-MOSLM) based on a one-dimensional magnetophotonic crystal (MPC) with a high driving performance. However, further improvement of the T-MOSLM is required. The structure of the T-MOSLM has low optical efficiency due to weakening of transmittance through electrodes; furthermore, the fabrication of the driving electrodes is a very complicated process. In this study, we suggest a new design of the MPC for a reflection-type MOSLM (R-MOSLM). The idea of a reflection-type MPC (R-MPC) is to replace one of the Bragg mirrors with an aluminum reflection film. The structure is glass∕(Ta2O5∕SiO2)k∕Bi:YIG∕Al, where k is the repetition number. The approach of the optimal structure of the R-MPC was done by the calculation of the matrix approach method. In the calculation of the newly designed R-MPC, Kerr rotation of −10° was obtained. This result implied that the performance of the R-MOSLM using the MPC could be highly improved. According to the optimization of the calculation, the R-MPC was fabricated and its Kerr rotation was −2.2°. This means that Kerr rotation was enhanced by using the new design of the reflection-type MPC. In addition, surface reflection was the reason for the low reflectance and deterioration of Kerr rotation.