Method for making sub-wavelength rectangular single-cycle grating structure and even-number beam splitter

Abstract

The invention provides a method for making a sub-wavelength rectangular single-cycle grating structure. The method for making the sub-wavelength rectangular single-cycle grating structure is used for making the sub-wavelength rectangular single-cycle grating structure which can achieve even-number beam splitting. The method for making the sub-wavelength rectangular single-cycle grating structure comprises the following steps of S11, determining the wavelength of an incident wave and the refractive index of a material of a grating substrate, S13, building an evaluation function according to a target even-number beam splitting number, S15, carrying out optimization to obtain the ridge width, the groove width and the depth of the sub-wavelength rectangular single-cycle grating structure by using the rigorous coupled wave theory and a global optimization algorithm and combining the evaluation function, and S17, making the sub-wavelength rectangular single-cycle grating structure according to the ridge width, the groove width and the depth. According to the obtained sub-wavelength rectangular single-cycle grating structure, the ideal even-number beam splitting effect on different wavelengths of the incident waves can be achieved; meanwhile, the even-number beam splitter with the sub-wavelength rectangular single-cycle grating structure can effectively achieve even-number beam splitting, is of a periodic rectangular structure, and is easy to produce and copy and high in practicability.

Description

Technical field [0001] The invention relates to a diffractive optical device, in particular to a manufacturing method of a sub-wavelength rectangular single-period grating structure capable of realizing even beam splitting and an even beam splitter. Background technique [0002] The beam splitter is an important light splitting element in the optical system. In many technical fields such as optical fiber communication, optical computing, image processing, and optical disk storage, it is often necessary to use a beam splitter to convert a single signal into multiple signal outputs. The even beam splitter transforms an incident electromagnetic wave into an even beam output, that is, 1x2, 1x4, 1x6, etc. It has the advantages of symmetrical beam splitting effect and higher light energy utilization, making the even beam splitter useful in building optical systems important meaning. [0003] Ordinary grating design theory-scalar diffraction theory, due to its design limitations, cannot ...

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Problems solved by technology

[0003] Ordinary grating design theory - scalar diffraction theory, due to its design limitations, cannot produce the effect of high diffraction efficiency and even equal light intensity beam splitting

[0004] The Chinese patent with the notification number CN201107422Y proposes a Damman grating structure even-numbered beam splitter. Although it achieves low zero-order diffraction efficiency and better even-numbered beam splitting effect, it has a complex periodic rectangular structure and a relatively complicated structure. It is difficult to produce, which is not conducive to copying and application

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