Device and method for generating columnar vector beams in optical fiber by utilizing electrically-controlled tunable optical grating

Abstract

The invention provides a device and a method for generating columnar vector beams in optical fiber by utilizing an electrically-controlled tunable optical grating. By means of the linear polarization characteristic of the electrically-controlled tunable optical grating, efficient coupling between a linear polarization vector basic mode in a fiber core and TM01 and TE01 modes can be realized, and a columnar vector light field with strict radial and angular polarization characteristics can be generated. Complete coupling between the linear polarization vector basic mode and the columnar vector light field can be realized by optimizing the refractive index modulation degree of the electrically-controlled tunable optical grating. Columnar vector light can be generated in different wavelength positions of the optical fiber conveniently by adjusting and modulating the period of the electrically-controlled tunable optical grating. The adopted device is simple and has high columnar vector light field generation efficiency, the generated columnar vector light beams have high mode purity, meanwhile, different radial and angular vector light fields can be conveniently converted, and the columnar vector light field can be generated in different wavelengths by adjusting radio-frequency signals.

Description

technical field [0001] The invention relates to the field of optoelectronic technology, in particular to a device and method for generating a columnar vector beam in an optical fiber by using an electrically controlled tunable grating. Background technique [0002] Cylindrical vector light field is a kind of light field whose polarization state is symmetrically distributed in space. There are three main types of cylindrical vector light beams: radial polarization, angular polarization and mixed polarization vector light field. Due to its unique electric field distribution, the cylindrical vector beam has important application value and research significance in engineering and scientific research fields. Taking the radial polarization vector light field as an example, in the case of high numerical aperture focusing, it has a strong longitudinal electric field component, which is used in laser micro-nano processing, second harmonic generation (SHG), super-resolution imaging, s...

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Problems solved by technology

This method needs to precisely adjust the angle between the spatial Gaussian beam and the fiber end face, so the coupling efficiency is relatively low, so the conversion efficiency of the columnar vector beam is very low, and it is easy to excite other modes in the fiber core, which will affect the columnar vector beam the purity of

2. Use squeezed gratings to realize the generation of cylindrical vector beams in optical fibers. Since the period of squeezed gratings cannot be adjusted accurately, there is a lack of convenient wavelength tunable characteristics.

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