Magneto-Optic Spatial Light Modulators with Magnetophotonic Crystals Driven by PZT Films

Abstract

Spatial light modulator (SLM) is a real-time programmable device for modifying amplitude, phase or polarization of optical wave front by electrically controlled signals. Various types of SLMs with pixel arrays, such as a liquid crystal SLM, have been developed. Recently, SLMs have received much attention as a light modulator in holographic data storage which requires high speed SLMs for ensuring the high data transfer rate. In this field, the application of a magneto-optic SLM (MOSLM) is highly expected because of extremely fast pixel switching speed. The conventional MOSLM used a single crystal garnet with perpendicular magnetic anisotropy to switch as a binary depending on up and down magnetization. However, for an analog modulation in our concept, the direction of magnetization is gradually changed to in-plane direction, because the modulation is depending on the magnetization direction of the garnet film. A voltage driven MOSLM for analog modulation is developed using magnetostriction effect. Moreover, the MOSLM with a structure of a magnetophotonic crystal (MPC) is fabricated for the large enhancement of magneto-optical response. This report is about a current development of MOSLMs with magnetophonic crystal driven by a voltage. Key words: Magneto-optic spatial light modulator, Garnet, Magnetophotonic crystal, Magneto-optical response 1. Introduction Spatial light modulator (SLM) is a real-time micro-device for modulating the amplitude (or intensity), phase, or polarization of optical waves as a function of the spatial position across the wavefront. SLMs with liquid crystal or MEMS technology, such as DMD or GLV, are now commercially available, and are widely used as a key component in image projection systems. Recent needs of more sophisticated SLMs enabling ultra-high speed modulation of light have resulted from the renewed interests in holographic data storage or 3-dimensional display, which fields require high rate of data transfer. For such applications, SLMs based on the magneto-optical effect (Magneto-optic SLMs, MOSLMs) are to be a good candidate 1)-4). The reason is that MOSLMs provide magnetic visual images based on the Faraday effect, and the pixel switching takes place by the magnetization reversal being inherently very fast in the order of several nanoseconds. Non-volatility, robustness and radioactive resistance are also the main features of MOSLMs. In this paper, our historic researches of the MOSLM are reviewed and recent developments of the MOSLM are described in term of a structure of magnetophotonic crystals and driving of piezoelectric effect.