Studies Of Acousto-optic Modulate Device On SOI

Acousto-optic device, especially the device on SOI is of great significance in the field of integrated optics. Because the characteristic of the device is small volume, low drive power, easy integration, the device is widely used in the field of optic communication, optical sensing, optical information processing and so on, especially acousto-optic device driven by surface acoustic wave has attracted more and more attention because of its unique advantage. With the development of optical integrated technology, the miniaturization, integration and functionalization has become the development trends in the acousto-optic device.Based on the thought above, the purpose of the paper:the research of the Acousto-optic Modulate Device, we focus on the acousto-optic modulator on SOI in this paper, the details are presented as follows:1. Starting from the theory of the acoustic optic modulator, we introduce the piezoelectric effect what we used in the process of the SAW excitation, and discuss the design method of the IDT. we analysis the theory of the SAW and its exciting mechanism, After that, we describe the basic principle of acoustic optic effect.2. We introduce the principle of the Mach-Zehnder acousto-optic modulator. In this paper we propose an improved design scheme of Mach-Zehnder acoustic optic modulator. we first use COMSOL Multiphysics to simulate the acoustic frequency and the surface displacement of the excited SAW. Then we deduce the refractive index variations of all layers according to their acousto-optic effects. After that, we analyze the influences of different factors on the acousto-optic modulation efficiency, including the type and size of waveguide, the thickness of zinc oxide (ZnO) layer, and the area it covers, the number of electrodes, etc. These parameters are accordingly optimized to enhance the modulation efficiency. Modeling result based on COMSOL Multiphysics indicates that when the width of the strip waveguide is 6 μm, the ZnO layer covers only the area under the IDT and has a thickness of 2.2 μm, and the number of the electrodes is 50, the effective refractive index variation of the waveguide reaches 4.08* 10-4 provided that the amplitude of the driving voltage is 1 V. This value is 12% higher than that of the traditional structure. In order to make the modulation effect more obvious and test the parameters of loss, we design a ring resonator acousto-optic modulator3.The experiment design of the acoustic optic modulator on SOI is developed, we introduce the equipment used in the experiment, design the software of the lab test platform using labview and introduce the experimental process. In this experiment making the acoustic optic modulator requires alignment twice, sputtering twice and peeling twice. In the process of making the Mach-Zehnder acousto-optic modulator the L/H of the IDT is greater than 100, so we can’t make the IDT successfully. At the same time, in the process of making the ring resonator acousto-optic modulator, we can calculate the refractive index of ZnO is 1.72 by testing the spectral lines and obtain micro ring long after the loss of ZnO by fitting the experimental test results, the center frequency of the IDT is 230MHz.