Nois filtering method and device for Brillouin signal space frequency spectrum regulation and control

Abstract

The invention provides a noise filtering method and device for Brillouin signal space frequency spectrum regulation and control. The method includes: adding a phase image to the signal light to achieve target distribution presetting of the signal light intensity; loading spiral phase converters with different topological charges on the spectral surface of the first set of optical 4f imaging system, and regulating and controlling the frequency spectrum of the phase image; utilizing a second set of 4f imaging system to image the phase image frequency spectrum into a nonlinear medium, and introducing pump light from the other side of the amplification medium to enable the pump light to perform stimulated Brillouin amplification on the signal light frequency spectrum; adopting a second opticallens of the first set of optical 4f imaging system to carry out inverse Fourier transform and Fourier transform on the signal light spectrum and noise in the mixed light beam output from the nonlinear amplification medium respectively, so as to enable the amplified signal light intensity output through spatial spectrum regulation and control to be distributed at the edge position of the target phase image and to be separated from the noise spectrum focused at one point; and filtering out noise in the mixed light beams through a spatial filter, and obtaining pure amplified signal light.

Description

technical field [0001] The invention relates to the field of optics, in particular to a noise filtering method and device for Brillouin signal space spectrum regulation and filtering. Background technique [0002] Stimulated Brillouin amplification is a third-order nonlinear optical process based on photoacoustic interaction. It has important research value in the fields of laser physics and nonlinear optics. It has been widely used in high-energy laser generation and amplification, optical storage, Nonlinear optical microscopy imaging and distributed sensing, etc. However, as a common shortcoming based on the collinear amplification mechanism, in the Brillouin spectroscopy technique using the pump-probe method, under the condition of extremely weak incident signal light or high-power pump light, the backward stray light introduced by the pump light And spontaneous / stimulated Brillouin scattered light will become the inevitable background noise in weak signal measurement, h...

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Problems solved by technology

"High-speed stimulated Brillouin scattering spectroscopy at 780nm" published in "APL Photonics" Volume 1, Page 061301 in 2016 uses the ultra-narrow-band absorption spectrum characteristics of the thermal rubidium-85 atomic filter to suppress the stray light introduced by the pump light , but the preparation, storage and use of atomic filters are complex and costly, and atomic filters can only work for specific wavelengths

"Background-free Brillouin spectroscopy inscattering media at 780nm via stimulated Brillouin scattering" published in Volume 41, Issue 5 of "Optics Letters" in 2016 proposed a two-stage lock-in amplifier modulation technology, in which signal light and pump light are respectively loaded with modulations of different frequencies Signal, through the electrical signal demodulation technology, the Brillouin spectrum measurement without the stray light noise introduced by the pump light is realized, but this technology is not based on the optical field signal-noise separation based on all-optical regulation

"Orbital angular momentum mode division filtering for photon-phonon coupling" published on page 40526 of volume 7 of "Scientific Reports" in 2017 proposes to apply an orbital angular momentum mode label to the signal light to distinguish and extract the extremely weak amplified signal from the strong noise Light, the low-pass filter demodulation scheme adopted by this method has a large energy loss, and the evolution optical path required for mode demodulation is long

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