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声光和电光器件可用于信号处理器件,如调制器、相关器和偏转器等许多领域内。这是由于大部分信号处理器都可用这两种类型的器件,故两种器件常常互相竞争。然而,可把这两种效应结合起来制成一种声-电-光器件。这样,就可克服它们各自本身可能存在的一些极限。这种器件可用体波器件或SAW来实现。SAW器件的结构可提供外加需要电场的各种各样的方法,例如,一种直流电压可施加到一种叉指换能器上。当光束通过换能器时,折射率的变化将以与等指换能器内发射的声波相同的方法使光衍射。唯一的区别就是光频内没有多普勒频移。如果现在一种声脉冲同时与光束相互作用,就可看到一种组合效应。电光互作用将影响受检脉冲的相位。在Y-切,Z传的LiNbO_3中,采用一种脉冲调制的55MHz的声信号和Y-偏振光,加5V电压在电光换能器上,就会迫使一阶衍射为零。加10V电压就会导致相位反相,因而产生负的脉冲。对于二阶衍射,其效应可增大受检脉冲的振幅。这种互作用为研制卷积器、相关器和调制器开辟了新的途径。用复合式电-光换能器可获得加权函数,卷积和相关间的唯一区别就是声波的方向不同。本文的目的是分析并阐明在SAW器件中的这一原理,并将讨论其不同于电光和声光器件的优越之处。
Acoustooptic and electro-optic devices are used in many areas of signal processing devices such as modulators, correlators, and deflectors. This is due to the fact that most signal processors are available with both types of devices, so the two devices often compete with each other. However, these two effects can be combined to make an acousto-electro-optic device. In this way, some of the limits that may exist for themselves may be overcome. This device can be body wave device or SAW to achieve. The structure of the SAW device can provide a wide variety of additional methods that require an electric field, for example, a DC voltage can be applied to an interdigital transducer. As the light beam passes through the transducer, the change in refractive index will diffract the light in the same way as an acoustic wave emitted in an equal-energy transducer. The only difference is that there is no Doppler shift in the optical frequency. If now an acoustic pulse interacts with the beam at the same time, you can see a combination effect. Electro-optical interaction will affect the phase of the pulse under examination. In Y-cut and Z-pass LiNbO_3, a pulse-modulated 55MHz acoustic signal and Y-polarized light are used. When 5V is applied to the electro-optical transducer, the first order diffraction is forced to zero. Add 10V voltage will lead to phase inversion, resulting in negative pulse. For second-order diffraction, the effect can increase the amplitude of the pulse under examination. This interaction opens up new avenues for the development of convolvers, correlators and modulators. Weighting functions are obtained with a hybrid electro-optical transducer. The only difference between convolution and correlation is the direction of the sound waves. The purpose of this paper is to analyze and clarify this principle in SAW devices and to discuss their advantages over electro-optic and acousto-optic devices.