Sensing method of optical-fiber Bragg grating laser device

A technology of optical fiber Bragg and sensing method, which is applied in the direction of instruments, scientific instruments, and optical devices, and can solve the problems of insufficient stability of the sensing system, low measurement accuracy, and easy interference of the fiber grating sensing signal.

Inactive Publication Date: 2010-08-04
NANJING UNIV
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  • Description
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Problems solved by technology

[0005] The problem to be solved by the present invention is: the fiber grating sensing signal is susceptible to interference, the measurement accuracy is not high, the sensing system is not stable enough, and the improved beat frequency signal of two polarized lights produced simultaneously by the erbium-ytterbium co-doped fiber grating laser is The detection method cannot realize the multiplexing of multiple sensors on one optical fiber

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  • Sensing method of optical-fiber Bragg grating laser device
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  • Sensing method of optical-fiber Bragg grating laser device

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specific Embodiment approach 1

[0065] Specific implementation mode one: as figure 2 As shown, two three-section fiber Bragg gratings 31 with an equivalent π phase shift interval and a length of 6.8 cm are written into the erbium-doped fiber 21, and the effective refractive index of the fiber core is 1.447. Through theoretical simulation, we can obtain the Fiber Bragg Grating theoretical transmission spectrum, such as image 3 shown. Here we can see that zero and even orders have no transmission peaks, so no lasing can be formed. There are two peaks in each odd-numbered transmission spectrum, and the depth of ±1 order is the deepest, that is, the energy is the highest, and they may form lasing. Due to the short-wavelength loss of the fiber, the -1 class is more likely to generate lasing than the +1 class. Through such analysis, we can know that our three-segment fiber grating structure can only generate stable two-wavelength laser light at the +1 order. The two laser wavelengths obtained are 1556.454nm ...

specific Embodiment approach 2

[0066] Specific implementation mode two: as Figure 5 As shown, this specific embodiment is an example of a demodulation device for a dual-wavelength fiber Bragg grating laser sensing method. The device consists of 980 or 1480nm pump light source 1, 980nm / 1550nm wavelength division multiplexer 2, sensor probe 3 is a dual-wavelength fiber Bragg grating laser, the fixed end of the micro-motion platform 4-1, and the adjustable end of the micro-motion platform 4-2 , an erbium-doped fiber amplifier 7, a high-frequency photodetector 5, and a spectrum analyzer 6. The light of the 980nm pump laser 1 is incident on the dual-wavelength fiber Bragg grating laser through the wavelength division multiplexer 2 to generate dual-wavelength laser light. The interference beat frequency signal of the two lasers is amplified by the fiber amplifier 7 , converted into an electrical signal by the high frequency photodetector 5 , and then detected by the spectrum analyzer 6 . The fiber grating lase...

specific Embodiment approach 3

[0067] Specific embodiment three: In order to avoid mode competition, the wavelength spacing of the dual-wavelength laser cannot be less than 40pm, so that the beat frequency signal of the sensor cannot be lower than 5GHz. In the second embodiment, the beat frequency of the dual-wavelength laser is 10.125GHz, which is High-speed photodetectors and spectrometers are required, and they require high prices and volumes, which are not convenient for cost-effectiveness and promotion of use. We can use the electro-optic modulator to reduce the beat frequency signal from high frequency to low frequency band, so that the sensor beat frequency signal can be detected by low frequency photodetector and spectrum analyzer. Such as Figure 7 Shown, the device of this specific embodiment consists of 980 pump light source 1, 980nm / 1550nm wavelength division multiplexer 2, sensing probe 3 is a dual-wavelength fiber Bragg grating laser, and the fixed end 4-1 of the micro-motion platform, the mic...

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Abstract

The invention relates to a sensing method with an optical-fiber Bragg grating laser device. An optical-fiber Bragg grating is used as a reflector of the resonant cavity, an active optical fiber capable of generating sufficient gains is added, and a double wavelength/multiple wavelength optical-fiber Bragg grating laser device is formed under the action of a pump light source and used as a sensor. When the outside strain, temperature and other physical quantities act on the sensing system, the beat signal frequency among the double wavelength or multiple wavelength laser can shift, and counter stress, temperature and other physical parameters can be measured precisely by detecting the beat signal frequency information. The invention has the advantages of simple manufacture, stable and reliable operation, stable measurement result and high precision, and is free from the interference of light intensity, polarization and other optical information quantities. The multipoint distribution sensing measurement can be realized in a frequency-division multiplexing mode. An electrooptical modulator is added before the spectrum analyzer starts detection so as to randomly adjust the beat signal frequency, thereby greatly reducing the spectral range of the spectrum analyzer and reducing the detection cost.

Description

technical field [0001] The invention belongs to the field of optoelectronic technology, relates to optical fiber sensing and other aspects, is related to optical fiber sensors, distributed feedback fiber lasers, fiber Bragg gratings, light intensity modulators, etc., and relates to the design and manufacture of complex distributed feedback fiber lasers, and the application of fiber grating sensors It is widely used in the measurement of various physical quantities such as strain, temperature and pressure. It is a sensing and measurement method for dual-wavelength / multi-wavelength fiber laser sensors to measure physical information such as strain and temperature. It is a sensor for fiber Bragg grating lasers. sense method. Background technique [0002] Due to the advantages of small size, light weight, strong anti-interference ability, wavelength coding, and easy multiplexing networking, fiber grating sensors have made rapid development of fiber grating sensors in recent year...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01K11/32G01B11/16G01K11/3206
Inventor 陈向飞刘盛春殷作为张亮高亮
Owner NANJING UNIV
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