CN204902858U - Measurement device for utilization is warbled fiber grating and is realized laser beat frequency - Google Patents
Measurement device for utilization is warbled fiber grating and is realized laser beat frequency Download PDFInfo
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- CN204902858U CN204902858U CN201520308294.4U CN201520308294U CN204902858U CN 204902858 U CN204902858 U CN 204902858U CN 201520308294 U CN201520308294 U CN 201520308294U CN 204902858 U CN204902858 U CN 204902858U
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Abstract
The utility model discloses a measurement device for utilization is warbled fiber grating and is realized laser beat frequency belongs to the measuring device technical field of temperature or stress. The technical scheme of the utility model main points do: a measurement device for utilization is warbled fiber grating and is realized laser beat frequency, includes the 980nm pump light source, loops through the fiber connection along light propagation direction and has wavelength devision multiplex, fiber grating, mixes bait optic fibre and the linearity fiber grating that warbles, fiber grating and the linearity fiber grating constitution fiber resonance cavity of warbling wherein, and fiber grating's dispersion measure is warbled more than 2000psnm to the linearity, and wavelength devision multiplex's the other end has connected gradually photoelectric detector and oscillograph through optic fibre. The utility model discloses low cost easily realizes having ultrastability and accuracy, has wide market prospect.
Description
Technical field
The utility model belongs to the measurement mechanism technical field of temperature or stress, is specifically related to a kind of measurement mechanism utilizing chirped fiber grating to realize laser beat frequency.
Background technology
In recent years, fiber grating is particularly noticeable in the applied research of sensing and the communications field, as sensing element, sensed convert information is the movement of response wave length by fiber grating, namely use Wavelength-encoding, be not thus subject to the impact of light source power fluctuation and system loss, stability is better; In addition, fiber grating has good reliability, electromagnetism interference and the feature such as anticorrosive, this be other sensing element incomparable.But the movement of how detection fiber grating response wave length, namely carrying out demodulation to Wavelength-encoding signal, is the key realizing optical fiber grating sensing.In general, it is the change of being measured bragg wavelength by the method for spectrum based on Fiber Bragg Grating FBG (FBG) sensor, when fiber grating contacts the change of some physical quantitys such as strain or temperature, corresponding change can be there is in bragg wavelength, but in order to detect and measure such change, although utilize the demodulation that the traditional optical instrument such as spectroanalysis instrument (OSA) or electric spectrum analyzer (ESA) can realize Wavelength-encoding, but this kind of instrument price is expensive, the cost of demodulating system is caused greatly to increase, and it is bulky, carry inconvenience, service condition is harsh, be unsuitable for rig-site utilization.Therefore, simplified solution adjusting system becomes the focus that people pay close attention to, and finding demodulation scheme practical and with low cost, is make fiber-optic grating sensor really move towards the practical matter of utmost importance that must solve.
Summary of the invention
The technical matters that the utility model solves there is provided a kind of easy to use and with low cost chirped fiber grating that utilizes and realizes the measurement mechanism of laser beat frequency.
The utility model adopts following technical scheme for solving the problems of the technologies described above, a kind of measurement mechanism utilizing chirped fiber grating to realize laser beat frequency, comprise 980nm pump light source, it is characterized in that: have wavelength-division multiplex, fiber grating, erbium-doped fiber and linear chirp optical fiber grating by Fiber connection successively along optical propagation direction, wherein fiber grating and linear chirp optical fiber grating form fiber resonance cavity, the dispersion measure of linear chirp optical fiber grating is at more than 2000ps/nm, and the other end of wavelength-division multiplex is connected with photodetector and oscillograph in turn by optical fiber.
The utility model realizes the demodulation of Wavelength-encoding signal by laser beat frequency technology, this measurement only needs just can be completed by common oscillograph, simultaneously, whole system is no longer pure optical design, but by optical conversion to electricity, also has reference value to the contact of optics and electricity from now on, this technical costs is cheap, be easy to realize, there is ultrastability and accuracy, there are wide market outlook.
Accompanying drawing explanation
Fig. 1 is model calling figure of the present utility model.
Drawing illustrates: 1,980nm pump light source, 2, optical fiber, 3, wavelength-division multiplex, 4, fiber grating, 5, erbium-doped fiber, 6, linear chirp optical fiber grating, 7, photodetector, 8, oscillograph.
Embodiment
Describe particular content of the present utility model by reference to the accompanying drawings in detail.A kind of measurement mechanism utilizing chirped fiber grating to realize laser beat frequency, comprise 980nm pump light source 1, wavelength-division multiplex 3, fiber grating 4, erbium-doped fiber 5 and linear chirp optical fiber grating 6 is connected with by optical fiber 2 successively along optical propagation direction, wherein fiber grating 4 and linear chirp optical fiber grating 6 form fiber resonance cavity, the dispersion measure of linear chirp optical fiber grating 6 is at more than 2000ps/nm, and the other end of wavelength-division multiplex 3 is connected with photodetector 7 and oscillograph 8 in turn by optical fiber 2.
The utility model in use, fiber grating (FBG) and linear chirp optical fiber grating (CFBG) form a fiber resonance cavity, then 980nm pump light source enters fiber resonance cavity by wavelength-division multiplex (WDM), the erbium-doped fiber of non-linear gain is provided with in fiber resonance cavity, pump light forms two mutually perpendicular polarized lights of polarization state through erbium-doped fiber, when pump light source reaches certain power, by the filtering of fiber grating, stable Laser output can be detected, connect photodetector, by oscillograph, laser beat frequency signal can be seen.In experiment, fiber grating (FBG) is narrow linewidth, antiradar reflectivity, and linear chirp optical fiber grating (CFBG) is that dispersive power is large, and delay variation is little, and fiber grating (FBG) is the same with the centre wavelength position of linear chirp optical fiber grating (CFBG).
The resonance frequency of laser cavity is:
In formula, q is the order of longitudinal mode, and c is light velocity of propagation in a vacuum, and n is the refractive index of medium, and L is that laserresonator chamber is long.
According to above formula, the frequency interval that can obtain adjacent longitudinal mode is:
The resonance frequency of laser cavity
, the frequency interval of adjacent longitudinal mode is all relevant with cavity length L.
At normal temperatures (namely temperature does not change), by regulating pump power, oscillograph can be seen a stable beat frequency phenomenon, and the beat frequency rate of laser is:
.
When acting on the temperature on fiber grating physical changes such as (or) stress and changing, corresponding change will be there is in bragg wavelength, corresponding wavelength location on linear chirp optical fiber grating also changes thereupon, because the dispersive power of linear chirp optical fiber grating is larger, the chamber long hair looks of fiber resonance cavity will be caused obvious change, reaction is exactly that the frequency of beat frequency significant change will occur on oscillograph, and now frequency is designated as:
.
Like this, by the frequency variation of the beat frequency of twice, the concrete variable quantity of Resonant Intake System can be calculated:
The variable quantity of L is:
The variable quantity of optical fiber grating Bragg wavelength when can calculate according to the chirp rate C of linear chirp optical fiber grating again:
The fiber grating reflection wavelength that temperature variation causes moves and can be expressed as
Wherein
for the thermo-optical coeffecient of optical fiber, optical fibre refractivity variation with temperature relation is described;
for the thermal expansivity of optical fiber, describe the pitch variation with temperature relation of grating, thus detect the variable quantity acting on physical factor on grating.Whole system achieves a conversion from optics to electricity, also for research is from now on laid a good foundation.
More than show and describe ultimate principle of the present utility model; principal character and advantage; under the prerequisite not departing from the utility model spirit and scope, the utility model also has various changes and modifications, and these changes and improvements all fall into claimed scope of the present utility model.
Claims (1)
1. the measurement mechanism utilizing chirped fiber grating to realize laser beat frequency, comprise 980nm pump light source, it is characterized in that: have wavelength-division multiplex, fiber grating, erbium-doped fiber and linear chirp optical fiber grating by Fiber connection successively along optical propagation direction, wherein fiber grating and linear chirp optical fiber grating form fiber resonance cavity, the dispersion measure of linear chirp optical fiber grating is at more than 2000ps/nm, and the other end of wavelength-division multiplex is connected with photodetector and oscillograph in turn by optical fiber.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520308294.4U CN204902858U (en) | 2015-05-14 | 2015-05-14 | Measurement device for utilization is warbled fiber grating and is realized laser beat frequency |
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| CN201520308294.4U CN204902858U (en) | 2015-05-14 | 2015-05-14 | Measurement device for utilization is warbled fiber grating and is realized laser beat frequency |
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| CN204902858U true CN204902858U (en) | 2015-12-23 |
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| CN201520308294.4U Expired - Fee Related CN204902858U (en) | 2015-05-14 | 2015-05-14 | Measurement device for utilization is warbled fiber grating and is realized laser beat frequency |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107024285A (en) * | 2017-04-28 | 2017-08-08 | 中国航空工业集团公司北京长城计量测试技术研究所 | A kind of full optical fiber laser frequency measuring equipment and method |
-
2015
- 2015-05-14 CN CN201520308294.4U patent/CN204902858U/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107024285A (en) * | 2017-04-28 | 2017-08-08 | 中国航空工业集团公司北京长城计量测试技术研究所 | A kind of full optical fiber laser frequency measuring equipment and method |
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| Date | Code | Title | Description |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20151223 Termination date: 20160514 |
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| CF01 | Termination of patent right due to non-payment of annual fee |