Mathematical modeling of the parameters of an electro-optic modulator in the Mach–Zehnder interferometer configuration based on thin lithium niobate films

Abstract

Subject of study. An electro-optic modulator in a Mach–Zehnder interferometer configuration based on ridge waveguides made of a thin lithium niobate film was studied. Aim of study. The study aimed to mathematically model the parameters of an electro-optic modulator in a Mach–Zehnder interferometer configuration based on ridge waveguides made of a thin lithium niobate film. Method. The dependence of the optical losses introduced by a Y-branch splitter on the angle of the splitter was investigated using a beam propagation method based on the fast Fourier transform. Main results. The results of mathematical simulation of the parameters of the electro-optic modulator in the Mach–Zehnder interferometer configuration based on thin lithium niobate films were presented. The dependence of the optical losses, introduced by the Y-splitter, on the waveguide separation angle was obtained. Images of interference patterns occurring in the output waveguide were examined. A comparison revealed that the effectiveness of the proposed interferometer configuration was higher than that of the alternative solutions available in the literature. The novelty of the results is that the configuration of the electro-optic modulator investigated in this study was fabricated in the form of an integrated optical circuit based on ridge waveguides of thin-film lithium niobate. Such a solution enables a reduction in the dimensions of the final device and increases the sensitivity compared with that of existing analogs based on bulk electro-optic crystals. Additionally, owing to the use of a semiconductor substrate, an electronic circuit can possibly be integrated into the substrate, which enables the implementation of an electro-optic sensor system on a single chip. Practical significance. The method for interference pattern analysis proposed in this study provides information on the magnitude of the voltage applied to the arm of the interferometer and enables the development of requirements for its further modernization for increasing the accuracy of measurements and developing optoelectronic devices based on thin lithium niobate films, including integrated optical electric-field sensors.