A broadband angle selective optical filter and its preparation method

Abstract

The invention discloses a broadband angle selection optical fiber and a preparation method thereof. The filter system comprises binary-phase diffraction gratings which achieves symmetric diffraction order distribution and volume Bragg gratings which correspond to the diffraction orders of the binary-phase diffraction gratings. The diffraction light orders of the binary-phase diffraction gratings are sequentially increased from the center to the two sides, the volume Bragg gratings are sequentially placed from the center to the two sides according to a grating period from low to high, and the central axis of the volume Bragg gratings and the central axis of the binary-phase diffraction gratings are symmetrically distributed. Rectangular grid bars are prepared on a grating substrate according to the duty ratio, the period and the grating layer thickness parameter of the gratings, and the binary-phase diffraction gratings are obtained. Gratings are prepared on silicate base photoinduced thermosensitive refractive index glass according to the number of the volume Bragg gratings and the corresponding period and thickness parameters. The broadband angle selection optical fiber has the broadband light input filtering effect, and is simple in structure and good in filtering consistency.

Description

technical field [0001] The invention relates to a grating-type broadband angle-selective optical filter device, which belongs to the technical field of laser optical system devices. Background technique [0002] In optical transmission, optical filters are used to select the desired wavelength from many wavelengths and block light waves other than this wavelength, and are widely used in various optical systems. For example, laser transmission is very sensitive to various spatial disturbances, and the diffraction caused by various disturbances entering the optical elements will reduce the spatial uniformity of the laser, thereby reducing the load capacity of the laser system. In the imaging optical system, the use of spatial optical filtering to process polychromatic signals can improve image quality, remove high-frequency noise and interference, and enhance image edges. [0003] The traditional "4f" spatial optical filtering system is mainly composed of metal pinholes, conv...

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Problems solved by technology

[0006] In the prior art, the document "Spatial Low-pass Filtering of Continuous Laser Beam by Transmission Volume Phase Grating" (Zheng Guangwei, He Yanlan et al., "Acta Optics Sinica", No. 4, 2009); Study on Diffraction Characteristics of Short Pulse Gaussian Beam" (Zheng Guangwei, Liu Li et al., "Acta Optics", No. 1, 2009); "Preparation of Volume Bragg Gratings for Realizing Spatial Filtering" (Zheng Haobin, He Yanlan et al., " Optoelectronic Engineering, No. 1, 2009) reported the diffraction characteristics of volume Bragg gratings for laser light and recorded volume Bragg gratings in photopolymers by holography to achieve two-dimensional spatial low-pass filtering of laser beams. The filter structure described The type meets the requirements of narrowband filtering, but does not support broadband laser output

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