CN206321374U - A kind of fabry perot interferometer baroceptor based on optical fiber ring laser - Google Patents

Abstract

The utility model discloses a kind of Fabry-Perot interferometer baroceptor based on optical fiber ring laser, it is characterised in that：The fabry perot interferometer that one section of single-mode fiber with open fine interior bubble is constituted is fused in the optical fiber ring laser resonator being made up of pump laser, wavelength division multiplexer, Er-doped fiber, optical circulator, 1*2 types fiber coupler.On the one hand single-mode fiber with open fine interior bubble plays pneumatically-sensed effect, on the other hand as optical filter.Using when, embedded bubble single-mode fiber is placed in the chamber of different air pressure, utilize fiber spectrometer measure optical fiber ring laser output laser center wavelength, you can determine chamber in atmospheric pressure value.Using the modeling characteristic of laserresonator, with detectable signal is strong, signal to noise ratio is high, line width, high sensitivity the characteristics of, can be applied in all kinds of Practical Projects.

Description

A Fabry-Perot Interferometer Air Pressure Sensor Based on Fiber Ring Laser

technical field

The utility model belongs to the technical field of optical fiber sensing, in particular to a Fabry-Perot interferometer air pressure sensor based on an optical fiber ring laser.

Background technique

Air pressure is closely related to weather. The wind, cloud, rain, snow, and all kinds of weather on the earth's surface are all related to atmospheric movement, and the driving force for atmospheric movement is the imbalance and frequent changes in the distribution of atmospheric pressure. . Therefore, the study of barometric pressure sensors plays an important role in atmospheric detection and meteorological services.

The electronic air pressure sensor is greatly affected by the external environment such as temperature and magnetic field, and the manufacturing process is complicated and the cost is high, so its application range is greatly limited. Compared with traditional air pressure sensors, optical fiber air pressure sensors have the advantages of strong anti-electromagnetic interference, corrosion resistance, light weight, small size and easy remote monitoring.

Optical fiber air pressure sensors can be divided into two categories: one is sealed cavity optical fiber air pressure sensor, and the other is open cavity optical fiber air pressure sensor. For the sealed cavity fiber optic air pressure sensor, when the external pressure changes, the cavity length will also change accordingly. In order to effectively improve the air pressure sensitivity of the sealed cavity optical fiber air pressure sensor, the wall thickness of the sealed cavity must be reduced, but this method limits the detection range of the sensor, and because the cavity wall becomes very thin, the mechanical strength of the sensor is also reduced. will be bad. For the open-cavity optical fiber air pressure sensor, its detection principle is different from that of the sealed-cavity optical fiber air pressure sensor: it uses the characteristic that the refractive index changes when the gas pressure changes. Therefore, compared with the sealed-cavity fiber-optic pressure sensor, the open-cavity fiber-optic pressure sensor has a larger detection range. However, since they typically use broadband light sources, the probe signal, the specific resonance peak in the output spectrum, corresponds to a weak light intensity. On the other hand, the contrast of the interference spectrum output by the interferometer is low, usually 3-20dB, and the 3dB bandwidth (FWHM) of the resonance peak is large, about several nanometers to tens of nanometers, so it is difficult to accurately determine the center of the resonance peak wavelength, resulting in a large error in the measurement of the measured gas pressure. At the same time, these fiber optic interferometers are often sensitive to ambient temperature, which also increases the error of air pressure measurement to a certain extent.

Contents of the invention

In order to solve the above-mentioned deficiencies in the prior art, the utility model provides a Fabry-Perot interferometer air pressure sensor based on a fiber ring laser. connected to the ring laser. On the one hand, the optical fiber interferometer plays the role of air pressure sensing, and on the other hand, it acts as an optical filter, so that the central wavelength of the laser output laser is modulated by the air pressure. The pressure of the measured gas can be obtained by measuring the central wavelength of the laser output from the laser. The output laser of the laser has the characteristics of strong light and ultra-narrow line width, which provides a guarantee for the accurate determination of its central wavelength. On the other hand, since the length of the Fabry-Perot interferometer based on the open fiber bubble structure of the single-mode fiber is much smaller than the length of the laser resonator, the air pressure sensing measurement system is hardly affected by the temperature of the fiber interferometer, Has the advantage of being temperature insensitive.

The technical solution adopted in the utility model: a Fabry-Perot interferometer air pressure sensor based on a fiber optic ring laser, including a pump laser, a wavelength division multiplexer, an erbium-doped optical fiber, an optical circulator, and a Fabry-Perot interferometer. Perot interferometer, 1*2 fiber coupler, fiber optic spectrometer, characterized in that: the Fabry-Perot interferometer includes a single-mode fiber, one end of the single-mode fiber is a bevel, and there is a bubble inside, There is a small hole above the bubble, which connects the bubble with the outside, thus forming a Fabry-Perot interferometer; the two ports on one side of the wavelength division multiplexer are respectively connected to the pump laser and the erbium-doped fiber through the connecting fiber, The other end of the erbium-doped fiber is connected to one end of the optical circulator, the other end of the optical circulator is connected to the Fabry-Perot interferometer through the connecting fiber, and the third end of the optical circulator is connected to the 1*2 The other end of the 1*2 type fiber coupler is respectively connected to the fiber optic spectrometer and the wavelength division multiplexer through the connecting fiber.

Among them, the output wavelength of the pump laser can be 980nm, and the corresponding wavelength division multiplexer can use a 980/1550nm fiber wavelength division multiplexer; the end of the 1*2 fiber coupler with a smaller splitting ratio is connected to the optical fiber and the optical fiber The spectrometer is connected, and the end with a large splitting ratio is connected to the optical circulator through the connecting fiber; the diameter of the bubble inside the single-mode fiber is 30-40 μm, the distance between the slope and the bubble is 20-50 μm, and the slope of the slope is 5° ~10°, the diameter of the small hole is 5~30μm, the length of the erbium-doped fiber is 1~10m, and the connecting fiber can be G.652, G.653 and G.655 single-mode fiber.

The beneficial effects of the utility model are:

1. The preparation of the Fabry-Perot interferometer is based on ordinary G.652, G.653 or G.655 single-mode fiber, using a femtosecond laser to etch a small pit on the end face of the fiber, and then using fusion splicing technology to prepare a A Fabry-Perot interferometer with a bubble structure in the fiber; then the bubbles are broken down by a focused femtosecond laser beam to form an open Fabry-Perot interferometer, which has the advantages of convenient preparation and simple structure.

2. On the one hand, the Fabry-Perot interferometer plays the role of air pressure sensing, and on the other hand, it acts as an optical filter, so that the central wavelength of the laser output laser is modulated by the air pressure.

3. One end face of the single-mode optical fiber in the Fabry-Perot interferometer is inclined, which reduces the parasitic Fabry-Perot interference generated by the Fresnel reflection of the end face.

4. Connect the Fabry-Perot interferometer to the optical path of the resonant cavity of the fiber ring laser to form a pressure sensing measurement system based on the fiber ring laser. Since the laser output by the fiber laser has the characteristics of light intensity and ultra-narrow linewidth, it is conducive to the accurate determination of its central wavelength, which provides a guarantee for accurate measurement of the pressure of the gas to be measured, and finally can realize high-precision sensing and measurement of gas pressure .

Description of drawings

Below in conjunction with accompanying drawing and specific mode, the utility model is further described.

Fig. 1 is the application implementation schematic diagram of the Fabry-Perot interferometer air pressure sensor based on the fiber ring laser;

Fig. 2 is a schematic diagram of the air pressure sensing structure of a Fabry-Perot interferometer based on a single-mode fiber.

In the figure: 1. Pump laser, 2. Wavelength division multiplexer, 3. Erbium-doped fiber, 4. Optical circulator, 5. Fabry-Perot interferometer, 6.1*2 fiber coupler, 7. Fiber optic spectrometer, 8. Small hole, 9. Bubble, 10. Bevel.

detailed description

The two ports of the wavelength division multiplexer (2) are respectively connected with the pump laser (1) and the erbium-doped fiber (3) through the connecting fiber; the other end of the erbium-doped fiber (3) is connected with the optical circulator (4) One end is connected, the other end of the optical circulator (4) is connected to the Fabry-Perot interferometer (5) through the connecting fiber, and the third end of the optical circulator (4) is connected to the 1*2 type optical fiber through the connecting fiber The coupler (6) is connected; the other end of the 1*2 type fiber coupler (6) is connected with the fiber optic spectrometer (7) and the wavelength division multiplexer (2) respectively through the connecting fiber, as shown in Figure 1; The sensitive Fabry-Perot interferometer (5) is placed in different air pressure cavities for sensing and measurement. When placed in different air pressure environments, the refractive index in the bubble will be different, and finally the center of the laser output laser will be caused. The wavelength shifts. At the same time, the laser output by the fiber laser has the characteristics of strong light and ultra-narrow line width, which is conducive to the accurate determination of its central wavelength and the realization of high-precision measurement of gas pressure. It has the advantages of simple preparation, high sensitivity, wide measurement range and low cross-sensitivity.

Claims (2)

1. A Fabry-Perot interferometer air pressure sensor based on a fiber ring laser, including a pump laser, a wavelength division multiplexer, an erbium-doped optical fiber, an optical circulator, and a Fabry-Perot interferometer, 1* Type 2 fiber coupler and fiber optic spectrometer, characterized in that: the Fabry-Perot interferometer includes a single-mode fiber, one end of the single-mode fiber is an inclined plane, and there is a bubble inside, and there is a small hole above the bubble, Connect the bubble with the outside to form a Fabry-Perot interferometer; the two ports of the wavelength division multiplexer are respectively connected to the pump laser and the erbium-doped fiber through the connecting fiber, and the other end of the erbium-doped fiber is connected to the optical ring One end of the optical circulator is connected, the other end of the optical circulator is connected with the Fabry-Perot interferometer through the connecting fiber, the third end of the optical circulator is connected with the 1*2 fiber coupler through the connecting fiber, 1* The other end of the type 2 fiber coupler is respectively connected with the fiber optic spectrometer and the wavelength division multiplexer through the connecting fiber. 2. A kind of Fabry-Perot interferometer air pressure sensor based on fiber ring laser according to claim 1, characterized in that: the diameter of the bubble inside the single-mode fiber is 30-40 μm, and the distance between the inclined plane and the bubble is The diameter of the small hole is 20-50 μm, the inclination of the slope is 5°-10°, the diameter of the small hole is 5-30 μm, and the length of the erbium-doped optical fiber is 1-10 m.