Coherent brillouin light time domain analysis sensing system based on single-sideband modulation detection light

Abstract

The invention discloses a coherent brillouin light time domain analysis sensing system based on single-sideband modulation detection light. In the device, sound and light intensity modulator external modulation optical carrier is driven by an electric pulse signal to generate pump light, and local light and detection light are obtained through two steps: 1) driving electro-optics intensity modulator external modulation same-frequency optical carriers working at linear work points by a 10-12GHz tunable microwave signal to generate two sidebands, and 2) filtering the upper sideband and reserving the lower sideband (the detection light) and the optical carrier (the local light). After interactions with the pump light in optical fibers, the detection light and the local light load brillouin gain spectrum information to a 10-12GHz high-frequency carrier wave through the photoelectric detection beat frequency to prevent baseband noise damage, and improve the signal to noise ratio of the whole device by utilizing coherent detection. The brillouin gain spectrum information is demodulated by a logarithmic detector, and then temperature information and strain information are further solved through a Lorentz fit on a brillouin gain spectrum.

Description

Technical field [0001] The invention relates to a coherent Brillouin optical time-domain analysis sensing device based on single-sideband modulation detection light, in particular to a Brillouin optical time-domain analysis sensor based on single-sideband modulation detection light and capable of coherent detection Analyze the sensing system. Background technique [0002] The use of Brillouin nonlinear effects in optical fibers for distributed optical fiber sensing has been extensively studied for decades. The core of this technology is that the Brillouin frequency shift of the optical fiber is linearly related to the temperature and deformation (stress) of the optical fiber. The temperature and stress sensing can be realized by solving the Brillouin frequency shift. In order to obtain the Brillouin frequency shift, pulsed pump light and continuous probe light will be injected separately from both ends of the fiber. The Brillouin gain range can be scanned by changing the frequen...

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Problems solved by technology

However, these methods are based on double-sideband modulation, which are sensitive to the dispersion and self-phase modulation effects of the fiber, which will cause phase-to-intensity conversion and power fading, thereby deteriorating the Brillouin gain spectrum and reducing system performance.

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