CN108759882B - Semiconductor laser mutual injection type distributed optical fiber sensing system and positioning method - Google Patents
Semiconductor laser mutual injection type distributed optical fiber sensing system and positioning method Download PDFInfo
- Publication number
- CN108759882B CN108759882B CN201810412141.2A CN201810412141A CN108759882B CN 108759882 B CN108759882 B CN 108759882B CN 201810412141 A CN201810412141 A CN 201810412141A CN 108759882 B CN108759882 B CN 108759882B
- Authority
- CN
- China
- Prior art keywords
- laser
- optical fiber
- electric signals
- sensing system
- semiconductor laser
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 239000013307 optical fiber Substances 0.000 title claims abstract description 48
- 239000004065 semiconductor Substances 0.000 title claims abstract description 24
- 238000002347 injection Methods 0.000 title claims abstract description 19
- 239000007924 injection Substances 0.000 title claims abstract description 19
- 238000000034 method Methods 0.000 title claims abstract description 14
- 230000010287 polarization Effects 0.000 claims abstract description 19
- 238000012545 processing Methods 0.000 claims abstract description 15
- 239000000835 fiber Substances 0.000 claims abstract description 13
- 230000003287 optical effect Effects 0.000 claims abstract description 7
- 230000001427 coherent effect Effects 0.000 claims description 2
- 230000008878 coupling Effects 0.000 claims description 2
- 238000010168 coupling process Methods 0.000 claims description 2
- 238000005859 coupling reaction Methods 0.000 claims description 2
- 230000035945 sensitivity Effects 0.000 abstract description 3
- 238000001514 detection method Methods 0.000 description 8
- 238000000253 optical time-domain reflectometry Methods 0.000 description 7
- 238000005516 engineering process Methods 0.000 description 6
- 238000012544 monitoring process Methods 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 230000036039 immunity Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000005312 nonlinear dynamic Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000009897 systematic effect Effects 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
- G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
- G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
- G01D5/35306—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement
- G01D5/35322—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement using interferometer with one loop with several directions of circulation of the light, e.g. Sagnac interferometer
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Length Measuring Devices By Optical Means (AREA)
- Optical Transform (AREA)
Abstract
The invention discloses a mutual injection type distributed optical fiber sensing system and a positioning method of a semiconductor laser. The fiber ring consists of a 2x2 coupler and a section of single-mode fiber, and half of the single-mode fiber is used as sensing fiber. Two polarization controllers are used to control the polarization state of the light injected into the two lasers. The built-in photoelectric detectors of the two lasers convert the optical signals of the system into electric signals to enter the data acquisition and processing unit. The positioning method comprises the step of positioning disturbance according to a relation curve of effective values of the difference of the two paths of output electric signals measured in advance and a disturbance position and the effective values of the difference of the two paths of electric signals measured at this time. The system has simple structure and signal processing, high sensitivity and good real-time property, and can detect and position various time-varying disturbances.
Description
Technical Field
The invention relates to a distributed optical fiber sensing system and a positioning method, in particular to a semiconductor laser mutual injection type distributed optical fiber sensing system and a positioning method, and belongs to the field of optical fiber sensing.
Background
The distributed optical fiber sensing system has the advantages of electromagnetic interference resistance, corrosion resistance, no power supply, high sensitivity, remote monitoring and the like, can realize full-automatic safety monitoring, and has wide application prospect in the aspects of perimeter security monitoring, leakage detection of oil and gas pipelines, structural health monitoring of large buildings and the like.
At present, distributed optical fiber sensing systems mainly include two major types, namely Optical Time Domain Reflectometry (OTDR) type and interference type. The OTDR type technology is mature, only one sensing optical fiber needs to be laid, the use is convenient, but the detectable distance and the resolution of the system are limited, and the real-time performance is poor. Therefore, based on the conventional OTDR, various distributed optical fiber sensing technologies based on the OTDR structure, such as distributed optical fiber sensing technology based on brillouin scattering (BOTDR), Polarized Optical Time Domain Reflectometer (POTDR), and phase-sensitive optical time domain reflectometer (ϕ -OTDR), have been developed. The BOTDR sensing technology has a relatively simple structure, but has high requirements on a light source, and the sensing distance is limited. The POTDR sensing technology has high positioning accuracy, but has short sensing distance. The ϕ -OTDR sensing technology has great advantages in three aspects of long-distance detection, high-frequency response and accurate measurement, but requires a high-coherence light source and has poor anti-interference performance. The basic structure of the interference type distributed optical fiber sensing system mainly comprises a Mach-Zehnder (M-Z) interferometer and a Sagnac (Sagnac) interferometer. The M-Z interference type sensing system works in two directions, the mutual correlation positioning of output signals in two directions is utilized, the signal processing is simple, but the system is easily influenced by the environment due to the use of a double-arm structure. The Sagnac interference type sensing system uses a single light path, the immunity of the system to the slow change influence of the environment is enhanced, but the positioning can be realized by using a zero frequency method only by carrying out phase demodulation, and the positioning is only limited to the positioning of broadband disturbance signals.
In recent years, semiconductor laser mutual injection systems have received much attention. The invention provides a novel semiconductor laser mutual injection type distributed optical fiber sensing system and a positioning method by means of system design of the nonlinear dynamic characteristic of a semiconductor laser mutual injection system and a reflective optical fiber annular interferometer structure.
Disclosure of Invention
The invention aims to provide a semiconductor laser mutual injection type distributed optical fiber sensing system and a positioning method aiming at the defects in the prior art.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a mutual injection type distributed optical fiber sensing system of a semiconductor laser comprises a first laser, a first polarization controller, an optical fiber ring, a second polarization controller and a second laser which are sequentially connected, wherein the first laser and the second laser are respectively connected with a signal processing and collecting unit; the first polarization controller and the second polarization controller are used for controlling the polarization state of light injected into the first laser and the second laser; the built-in photoelectric detectors of the first laser and the second laser convert optical signals of the system into electric signals, the electric signals enter the signal processing and collecting unit, and the signal processing and collecting unit is used for determining the disturbance position according to a relation curve of effective values of differences of two paths of output electric signals measured in advance and the disturbance position and effective values of differences of two paths of electric signals measured at this time.
The optical fiber ring is composed of a 2x2 coupler and a section of single-mode optical fiber, two ends of the single-mode optical fiber are respectively connected with an II port of the coupler and an III port of the coupler, the length of the single-mode optical fiber is far larger than the coherent length of the two lasers, and half optical fibers of the single-mode optical fiber are used as sensing optical fibers.
The first laser and the second laser are both Distributed Feedback (DFB) semiconductor lasers, the frequency detuning of the first laser and the second laser is larger than 100GHz, and other parameters can be the same or different.
A positioning method of a semiconductor laser mutual injection type distributed optical fiber sensing system is used for the semiconductor laser mutual injection type distributed optical fiber sensing system and comprises the following steps:
step 1: determining whether disturbance occurs according to whether the waveform of any collected electric signal changes;
step 2: calculating the effective value of the difference of the two paths of electric signals;
and step 3: and determining the disturbance position according to a relation curve of the effective value of the difference of the two electric signals measured in advance and the disturbance position and the effective value of the difference of the two electric signals measured at this time.
By adopting the technical scheme, the invention has the following beneficial effects:
1. the invention uses the reflective ring interferometer as a detection structure and uses the semiconductor laser to nonlinearly amplify the interference signal, thereby improving the detection sensitivity of the system.
2. The invention utilizes the detection and positioning method based on the light intensity, so that the signal processing of the system is very simple, the real-time performance is enhanced, meanwhile, the detection of the system to the disturbance is not limited by the broadband disturbance any more, and the detection and positioning to the narrow-band disturbance can be realized.
3. The invention is based on the mutual injection system of the semiconductor laser, can utilize the detection and positioning method of the difference, make the systematic output not influenced by power fluctuation of the light source, the job stability is good.
Drawings
Fig. 1 is a structural view of embodiment 1 of the present invention.
Fig. 2 is a configuration diagram of an optical fiber ring in embodiment 1 of the present invention.
Fig. 3 is waveforms of two output signals collected from the electrical output ports of the first laser (upper) and the second laser (lower) in the absence of disturbance in embodiment 3 of the present invention.
Fig. 4 shows waveforms of two output signals collected from the electrical output ports of the first (upper) and second (lower) lasers when the distance between the disturbance point and the coupler is 120m in embodiment 3 of the present invention.
Fig. 5 is a relationship curve between the effective value of the difference between two output electrical signals and the disturbance position in embodiment 3 of the present invention.
Detailed Description
The following further describes a specific embodiment of the present invention with reference to the drawings.
Example 1:
as shown in fig. 1, a mutual injection distributed optical fiber sensing system of a semiconductor laser comprises a first laser, a first polarization controller, an optical fiber ring, a second polarization controller and a second laser which are connected in sequence, wherein the first laser and the second laser are respectively connected with a signal processing and collecting unit; the first polarization controller and the second polarization controller are used for controlling the polarization state of light injected into the first laser and the second laser; the built-in photoelectric detectors of the first laser and the second laser convert optical signals of the system into electric signals, the electric signals enter the signal processing and collecting unit, and the signal processing and collecting unit is used for determining the disturbance position according to a relation curve of effective values of differences of two paths of output electric signals measured in advance and the disturbance position and effective values of differences of two paths of electric signals measured at this time.
As shown in fig. 2, the optical fiber ring is composed of a 2x2 coupler and a single mode fiber, two ends of the single mode fiber are respectively connected to the II port of the coupler and the III port of the coupler, the length of the single mode fiber is much longer than the coherence length of the two lasers, and half of the single mode fiber is used as a sensing fiber.
The first laser and the second laser are both Distributed Feedback (DFB) semiconductor lasers, the frequency detuning of the first laser and the second laser is larger than 100GHz, and other parameters can be the same or different.
Example 2:
in this embodiment, the two semiconductor lasers are DFB laser modules of sanchuan sun super optical communication limited. The parameters are slightly different, the first output wavelength of the laser is 1528.308nm, and the output power is 1.232 mW. The output wavelength of the second laser is 1529.172nm, and the output power is 1.372 mW. The coupler is a 2x2 fiber coupler with a coupling ratio of 20/80. Both polarization controllers used a fiber extruder (PLC-001) from General Photonics, USA. The signal processing and collecting unit consists of a common microcomputer and a PicoScope 5203 digital oscilloscope of PICO company in England, the oscilloscope transmits the collected data to the computer, and the disturbance position is obtained by programming processing with Matlab software. All the optical fibers adopt G.652 standard single-mode optical fibers, wherein the optical fiber length of the optical fiber ring is 2.032 km.
Example 3:
a positioning method of a semiconductor laser mutual injection type distributed optical fiber sensing system comprises the following steps:
step 1: determining whether disturbance occurs according to whether the waveform of any collected electric signal changes;
step 2: calculating the effective value of the difference of the two paths of electric signals;
and step 3: and determining the disturbance position according to a relation curve of the effective value of the difference of the two electric signals measured in advance and the disturbance position and the effective value of the difference of the two electric signals measured at this time.
When there is no disturbance, the polarization controller is adjusted to make the light injected into the laser strongest, and the waveforms of the two signals collected by the oscilloscope are as shown in fig. 3. A piezoelectric ceramic (PZT) phase modulator is added between two sections of sensing optical fibers, a sinusoidal signal with the frequency of 26 kHz and the amplitude of 50 mVpp is generated by a signal generator (33250A) of Agilent company, and the PZT phase modulator is driven to simulate external disturbance. The sinusoidal signal works in burst mode, and the parameters are as follows: the period is 5ms, 1 cycle. The waveforms of two signals collected by the oscilloscope are shown in fig. 4, and the comparison with fig. 3 shows that the waveforms are obviously changed, so that the disturbance on the sensing optical fiber can be known. The relationship curve between the effective value of the difference between the two output signals and the disturbance position is shown in fig. 5. The effective value of the difference between the two output signals shown in fig. 4 is 0.498V, and according to the relationship curve shown in fig. 5, it can be known that the distance between the disturbance point and the coupler is 120 m.
Claims (4)
1. The utility model provides a mutual injection type distribution optical fiber sensing system of semiconductor laser which characterized in that: the device comprises a first laser, a first polarization controller, an optical fiber ring, a second polarization controller and a second laser which are sequentially connected, wherein the first laser and the second laser are respectively connected with a signal processing and collecting unit; the first polarization controller and the second polarization controller are used for controlling the polarization state of light injected into the first laser and the second laser; the built-in photoelectric detectors of the first laser and the second laser convert optical signals of the system into electric signals, the electric signals enter the signal processing and collecting unit, and the signal processing and collecting unit is used for determining the disturbance position according to a relation curve of effective values of differences of the two paths of output electric signals measured in advance and the disturbance position and effective values of the differences of the two paths of output electric signals measured at this time.
2. The semiconductor laser co-injection distributed fiber sensing system of claim 1, wherein: the optical fiber ring is composed of a 2x2 coupler and a section of single-mode optical fiber, two ends of the single-mode optical fiber are respectively connected with a port II of the coupler and a port III of coupling output of the coupler, the length of the single-mode optical fiber is far larger than the coherent length of two lasers, and half optical fibers of the single-mode optical fiber are used as sensing optical fibers.
3. The semiconductor laser co-injection distributed fiber sensing system of claim 1, wherein: the first laser and the second laser are both distributed feedback semiconductor lasers, and the frequency detuning of the first laser and the second laser is larger than 100 GHz.
4. A method for positioning a semiconductor laser mutual injection type distributed optical fiber sensing system, which is used for the semiconductor laser mutual injection type distributed optical fiber sensing system as claimed in claim 1, and is characterized by comprising the following steps:
step 1: determining whether disturbance occurs according to whether the waveform of any collected electric signal changes;
step 2: calculating the effective value of the difference of the two paths of electric signals;
and step 3: and determining the disturbance position according to a relation curve of the effective value of the difference of the two electric signals measured in advance and the disturbance position and the effective value of the difference of the two electric signals measured at this time.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810412141.2A CN108759882B (en) | 2018-05-03 | 2018-05-03 | Semiconductor laser mutual injection type distributed optical fiber sensing system and positioning method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810412141.2A CN108759882B (en) | 2018-05-03 | 2018-05-03 | Semiconductor laser mutual injection type distributed optical fiber sensing system and positioning method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108759882A CN108759882A (en) | 2018-11-06 |
| CN108759882B true CN108759882B (en) | 2021-01-12 |
Family
ID=64009408
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810412141.2A Active CN108759882B (en) | 2018-05-03 | 2018-05-03 | Semiconductor laser mutual injection type distributed optical fiber sensing system and positioning method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108759882B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110146116B (en) * | 2019-06-19 | 2021-04-27 | 南昌航空大学 | Positioning method for Sagnac optical fiber sensing under multipoint disturbance |
| CN112525374B (en) * | 2020-12-10 | 2023-06-23 | 中红外激光研究院(江苏)有限公司 | Temperature sensor based on non-reciprocal optical fiber intracavity singular point effect |
| CN113488836B (en) * | 2021-06-23 | 2022-09-20 | 成都飞机工业（集团）有限责任公司 | Narrow linewidth light source |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6490045B1 (en) * | 1998-10-09 | 2002-12-03 | University Of Southhampton | Fibre optic sensor |
| CN101813238A (en) * | 2010-04-20 | 2010-08-25 | 上海大学 | Sagnac/Mach-Zehnder interferometer profile fiber sensing system and time domain positioning method thereof |
| CN103065407A (en) * | 2013-01-09 | 2013-04-24 | 新疆美特智能安全工程股份有限公司 | Optical fiber intelligent monitoring system and monitoring method based on phase signal carrier technology |
| CN104459676A (en) * | 2014-11-05 | 2015-03-25 | 上海大学 | System and method for simultaneously measuring lengths of two optical fibers |
| CN104729549A (en) * | 2015-03-26 | 2015-06-24 | 上海大学 | Two-way chaos ring laser distributed optical fiber sensing system and time difference positioning method thereof |
| CN106452570A (en) * | 2016-09-22 | 2017-02-22 | 北京交通大学 | Optical fiber fault detection system and detection method based on optical fiber phase mediation principle |
| CN107843248A (en) * | 2017-09-01 | 2018-03-27 | 长春理工大学 | Self-injection locking resonance type optical gyroscope and its method of work |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7679753B2 (en) * | 2007-06-26 | 2010-03-16 | Huang Hung-Chia | Passively biased fiber-optic gyroscope and current sensor |
-
2018
- 2018-05-03 CN CN201810412141.2A patent/CN108759882B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6490045B1 (en) * | 1998-10-09 | 2002-12-03 | University Of Southhampton | Fibre optic sensor |
| CN101813238A (en) * | 2010-04-20 | 2010-08-25 | 上海大学 | Sagnac/Mach-Zehnder interferometer profile fiber sensing system and time domain positioning method thereof |
| CN103065407A (en) * | 2013-01-09 | 2013-04-24 | 新疆美特智能安全工程股份有限公司 | Optical fiber intelligent monitoring system and monitoring method based on phase signal carrier technology |
| CN104459676A (en) * | 2014-11-05 | 2015-03-25 | 上海大学 | System and method for simultaneously measuring lengths of two optical fibers |
| CN104729549A (en) * | 2015-03-26 | 2015-06-24 | 上海大学 | Two-way chaos ring laser distributed optical fiber sensing system and time difference positioning method thereof |
| CN106452570A (en) * | 2016-09-22 | 2017-02-22 | 北京交通大学 | Optical fiber fault detection system and detection method based on optical fiber phase mediation principle |
| CN107843248A (en) * | 2017-09-01 | 2018-03-27 | 长春理工大学 | Self-injection locking resonance type optical gyroscope and its method of work |
Non-Patent Citations (1)
| Title |
|---|
| Interferometric distributed;SPAMMER SJ;《Applied Optics》;19961231;第35卷(第22期);第4522-4525页 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN108759882A (en) | 2018-11-06 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN108759882B (en) | Semiconductor laser mutual injection type distributed optical fiber sensing system and positioning method | |
| CN101975626B (en) | Brillouin scattering based distributive fiber sensing system | |
| Sun et al. | Distributed fiber-optic vibration sensor using a ring Mach-Zehnder interferometer | |
| CN103398801B (en) | A kind of optical fiber grating temperature measurement mechanism and measuring method | |
| CN103323215B (en) | A kind of light time domain reflection measuring apparatus and method | |
| CN107478352B (en) | Distributed sensing method and system based on Brillouin scattering and fused chaotic light signals | |
| CN102506913A (en) | Interference type optical fiber distribution disturbance sensor and disturbance location method thereof | |
| Tong et al. | High-speed Mach-Zehnder-OTDR distributed optical fiber vibration sensor using medium-coherence laser | |
| CN103591971A (en) | Positioning method and system of fiber grating | |
| CN112525238A (en) | Distributed optical fiber sensing system utilizing Mach-Zehnder interferometer filtering characteristics | |
| CN103217226A (en) | Passive homodyne demodulation device and passive homodyne demodulation method for fai-OTDR (optical time domain reflectometer) | |
| Wang et al. | Distributed acoustic sensor using broadband weak FBG array for large temperature tolerance | |
| Li et al. | Sagnac vibration sensing system with nested pulse method | |
| Wang et al. | Dual-wavelength Michelson interferometer employing time delay estimation for distributed disturbance location | |
| CN101324446B (en) | Destabilization sensing localization method | |
| CN101957238A (en) | Coherent phase detecting method based on Mach-Zehnder interferometer | |
| CN113834508B (en) | Distributed optical fiber sensing system based on mutual injection semiconductor laser and unbalanced Mach-Zehnder interferometer and positioning method thereof | |
| CN205912061U (en) | Optical fiber fault detecting system | |
| Tang et al. | Distributed acoustic sensors with wide frequency response based on UWFBG array utilizing dual-pulse detection | |
| Li et al. | Long-distance OFDR with high spatial resolution based on time division multiplexing | |
| Vasiljević-Toskić et al. | A simple fiber optic sensing system based on dual Sagnac interferometer for disturbance location detection | |
| CN103076160A (en) | Self-correlation-based system for optical time domain reflectometry (OTDR) system to measure single-mode optical fiber beat-length | |
| CN1888834B (en) | Optical fiber grating sensor wave length measuring system | |
| Zhen et al. | Low-coherence fiber differential interferometer with adjustable measurement range | |
| CN106017513A (en) | Measurement system based on optical coherent interference |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |