A new method is proposed to increase the spectral resolving power of collinear acousto-optical filters by using optical feedback when the light leaving the region of its interaction with a periodic structure formed in the crystal by an acoustic wave returns to the input of the crystal, in which the diffraction process repeats itself many times. The light beam returned to the interaction region changes the boundary conditions of the parametric diffraction problem, because of which the amplitudes of the diffracted and passed light beams turn out to be strongly dependent on the feedback properties (similar to the processes occurring in a Fabry – Perot optical resonator). It is shown that such a combined acousto-optical Fabry – Perot filter with feedback is able to electronically tune the optical transmission wavelength and simultaneously has a higher spectral resolution than a conventional acousto-optical filter without feedback. It is also shown that the multiple radiation diffraction due to the feedback increases the diffraction efficiency with a comparatively small spatial change in the refractive index of the medium. Explicit analytical expressions for the instrumental functions of a combined acousto-optical Fabry – Perot filter are found and their properties are analysed. It is noted that a change in the feedback by any mechanism, i.e., by changing the returned wave phase or amplitude, leads to modulation of the measured signal, which makes it possible to create more precise methods of spectral measurements.

提出了一种新方法，当光离开其与晶体中由声波形成的周期性结构相互作用的区域返回晶体的输入时，通过使用光学反馈来提高共线声光滤波器的光谱分辨能力，其中衍射过程会重复多次。返回到相互作用区域的光束改变了参量衍射问题的边界条件，因此衍射和通过的光束的振幅强烈依赖于反馈特性（类似于发生在 Fabry –珀罗光学谐振器）。结果表明，这种带反馈的声光法布里-珀罗组合滤光片能够电子调谐光传输波长，同时比没有反馈的传统声光滤光片具有更高的光谱分辨率。还表明，由于反馈的多重辐射衍射提高了衍射效率，而介质折射率的空间变化相对较小。找到了组合声光法布里-珀罗滤波器的工具函数的显式解析表达式，并分析了它们的特性。值得注意的是，任何机制的反馈变化，即通过改变返回的波相位或幅度，都会导致测量信号的调制，这使得可以创建更精确的光谱测量方法。