CN109520637B - Temperature sensing demodulation device and demodulation method based on mode-locked fiber laser - Google Patents
Temperature sensing demodulation device and demodulation method based on mode-locked fiber laser Download PDFInfo
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Abstract
The invention discloses a temperature sensing demodulation device and a demodulation method based on a mode-locked fiber laser, wherein the mode-locked fiber laser comprises a laser resonant cavity, a temperature sensing fiber, an electro-optic modulator and a fiber coupler, the temperature sensing demodulation device comprises a photoelectric detector, a radio frequency band-pass filter, an electric power meter and a temperature demodulator, and the photoelectric detector is used for outputting a first electric signal; the radio frequency band-pass filter is used for filtering processing to output a second electric signal; the electric power meter is used for measuring the power of the second electric signal; the temperature demodulator is used for scanning the microwave signal frequency, acquiring the microwave signal frequency corresponding to the maximum power of the second electric signal and acquiring temperature change information induced by the temperature sensing optical fiber according to the microwave signal frequency corresponding to the maximum power and the microwave signal reference frequency transmitted by the microwave signal source; thereby realizing the remote temperature measurement for preventing electromagnetic interference; meanwhile, the manufacturing cost and the structural complexity of the temperature sensing equipment are reduced.
Description
Technical Field
The invention relates to the technical field of temperature sensing demodulation, in particular to a temperature sensing demodulation device and a temperature sensing demodulation method based on a mode-locked fiber laser.
Background
The optical fiber sensor has the characteristics of small volume, light weight, easy realization of remote and distributed measurement, explosion prevention, electric insulation, electromagnetic interference resistance and the like, thereby being widely applied to the field of remote measurement of temperature, stress and refractive index.
In the prior art, the structure of a michelson optical fiber interferometer and a mach-zehnder optical fiber interferometer is mostly adopted to measure the wavelength change in an interference spectrum, and then the change information of the temperature is judged according to the wavelength change in the interference spectrum; however, these measurement methods require high performance of the optical filter, which leads to an increase in implementation cost, and the structure thereof is complicated, and thus it is difficult to be popularized in practical use.
Disclosure of Invention
The present invention is directed to solving, at least to some extent, one of the technical problems in the art described above. Therefore, one objective of the present invention is to provide a temperature sensing demodulation apparatus based on a mode-locked fiber laser, which can realize the electromagnetic interference resistant remote temperature measurement, and has a large bandwidth and low loss; meanwhile, the manufacturing cost and the structural complexity of the temperature sensing equipment are reduced, and the mass production and the popularization of the demodulation technology of the optical fiber temperature sensor are facilitated.
The second purpose of the invention is to provide a temperature sensing demodulation method based on a mode-locked fiber laser.
In order to achieve the above object, a first embodiment of the present invention provides a temperature sensing demodulation apparatus based on a mode-locked fiber laser, the mode-locked fiber laser includes a laser resonant cavity, a temperature sensing fiber disposed in the laser resonant cavity, an electro-optic modulator for modulating an optical signal passing through the temperature sensing fiber according to a microwave signal emitted from a microwave signal source, and a fiber coupler, the temperature sensing fiber is configured to induce a temperature change to change an optical path of the laser resonant cavity, an electrical driving end of the electro-optic modulator is connected to the microwave signal source, a frequency of the microwave signal emitted from the microwave signal source is tunable in response to the optical path change of the laser resonant cavity, the mode-locked fiber laser forms a mode-locked laser according to the modulated optical signal and couples and outputs the mode-locked laser through the fiber coupler, and the temperature sensing demodulation apparatus includes a photodetector, a temperature sensor, and a temperature sensor, The temperature sensor comprises a radio frequency band-pass filter, an electric power meter and a temperature demodulator, wherein the input end of a photoelectric detector is connected with the first output end of an optical fiber coupler, the output end of the photoelectric detector is connected with the input end of the radio frequency band-pass filter, and the output end of the radio frequency band-pass filter is connected with the input end of the electric power meter; the photoelectric detector is used for performing photoelectric conversion on the mode-locked laser coupled and output by the optical fiber coupler so as to output a first electric signal; the radio frequency band-pass filter is used for filtering the first electric signal to output a second electric signal; the electric power meter is used for measuring the power of the second electric signal; the temperature demodulator is used for scanning the frequency of the microwave signal emitted by the microwave signal source, acquiring the frequency of the corresponding microwave signal according to the maximum power of the second electric signal measured by the electric power meter, and acquiring temperature change information induced by the temperature sensing optical fiber according to the frequency of the microwave signal corresponding to the maximum power and the reference frequency of the microwave signal emitted by the microwave signal source.
According to the temperature sensing demodulation device based on the mode-locked fiber laser, the mode-locked fiber laser comprises a laser resonant cavity, a temperature sensing fiber, an electro-optic modulator and a fiber coupler, the temperature sensing fiber is arranged in the laser resonant cavity, the temperature sensing fiber induces temperature change to cause the optical path of the laser resonant cavity to change, the electric driving end of the electro-optic modulator is connected with a microwave signal source, the electro-optic modulator is used for modulating an optical signal passing through the temperature sensing fiber according to a microwave signal emitted by the microwave signal source, the frequency of the microwave signal emitted by the microwave signal source is tunable in response to the optical path change of the laser resonant cavity, the mode-locked fiber laser forms mode-locked laser according to the modulated optical signal and couples and outputs the mode-locked laser through the fiber coupler, and the temperature sensing demodulation device comprises a photoelectric detector, a radio frequency band-pass filter, a, The device comprises an electric power meter and a temperature demodulator, wherein the input end of a photoelectric detector is connected with the first output end of an optical fiber coupler, the output end of the photoelectric detector is connected with the input end of a radio frequency band-pass filter, and the output end of the radio frequency band-pass filter is connected with the input end of the electric power meter; the photoelectric detector is used for performing photoelectric conversion on the mode-locked laser coupled and output by the optical fiber coupler so as to output a first electric signal; the radio frequency band-pass filter is used for filtering the first electric signal to output a second electric signal; the electric power meter is used for measuring the power of the second electric signal; the temperature demodulator is used for scanning the frequency of the microwave signal emitted by the microwave signal source, acquiring the frequency of the corresponding microwave signal according to the maximum power of the second electric signal measured by the electric power meter, and acquiring temperature change information induced by the temperature sensing optical fiber according to the frequency of the microwave signal corresponding to the maximum power and the reference frequency of the microwave signal emitted by the microwave signal source; therefore, the electromagnetic interference prevention remote temperature measurement is realized, and the bandwidth is large and the loss is low; meanwhile, the manufacturing cost and the structural complexity of the temperature sensing equipment are reduced, and the mass production and the popularization of the demodulation technology of the optical fiber temperature sensor are facilitated.
In addition, the temperature sensing demodulation device based on the mode-locked fiber laser according to the above embodiment of the present invention may further have the following additional technical features:
optionally, the mode-locked fiber laser further includes an optical amplifier, an optical filter, and an optical isolator, an input end of the optical amplifier is connected to the second output end of the optical fiber coupler, an output end of the optical amplifier is connected to one end of the temperature sensing fiber, another end of the temperature sensing fiber is connected to an optical input end of the electro-optical modulator, an optical output end of the electro-optical modulator is connected to an input end of the optical filter, an output end of the optical filter is connected to an input end of the optical isolator, and an output end of the optical isolator is connected to an input end of the optical fiber coupler, wherein the emitted light is amplified by the optical amplifier and forms the mode-locked laser after passing through the temperature sensing fiber, the electro-optical modulator, the optical filter, the optical.
Optionally, the optical fiber coupler is a 90:10 optical fiber coupler, the first output end of the optical fiber coupler is a 10% output port, the second output end of the optical fiber coupler is a 90% output port, and the optical amplifier is an erbium-doped optical fiber amplifier.
Optionally, the temperature demodulator is further configured to set a reference temperature of the temperature sensing fiber, so as to obtain the reference frequency of the microwave signal according to the optical path of the laser resonant cavity corresponding to the reference temperature of the temperature sensing fiber.
Optionally, the temperature demodulator obtains the temperature variation information sensed by the temperature sensing optical fiber according to the following formula:
wherein, Δ f is the variation value of the frequency of the microwave signal, f2Frequency of microwave signal corresponding to maximum power, f1Is the reference frequency of the microwave signal, m is the order of the pass band, c is the speed of light in vacuum, L1Is the length of the temperature sensing fiber, L2The length of the laser resonant cavity minus the temperature sensing optical fiber is obtained, delta T is the temperature change quantity, n is the effective refractive index of the optical fiber, and zeta is the thermo-optic coefficient of the optical fiber.
In order to achieve the above object, a temperature sensing demodulation method based on a mode-locked fiber laser is provided in an embodiment of the second aspect of the present invention, the mode-locked fiber laser includes a laser cavity, a temperature sensing fiber, an electro-optical modulator and a fiber coupler, the temperature sensing fiber is disposed in the laser cavity, the temperature sensing optical fiber induces the optical path of the laser resonant cavity to change by sensing the temperature change, the electric drive end of the electro-optical modulator is connected with the microwave signal source, the electro-optical modulator is used for modulating the optical signal passing through the temperature sensing optical fiber according to the microwave signal emitted by the microwave signal source, the frequency of the microwave signal emitted by the microwave signal source can be tuned in response to the change of the optical path of the laser resonant cavity, the mode-locked fiber laser forms mode-locked laser according to the modulated optical signal, the mode-locked laser is coupled and output through the optical fiber coupler, and the temperature sensing demodulation method comprises the following steps: carrying out photoelectric conversion on the mode-locked laser coupled and output by the optical fiber coupler through a photoelectric detector so as to output a first electric signal; filtering the first electric signal through a radio frequency band-pass filter to output a second electric signal, and measuring the power of the second electric signal; and scanning the frequency of the microwave signal emitted by the microwave signal source, acquiring the frequency of the corresponding microwave signal according to the measured maximum power of the second electric signal, and acquiring the temperature change information induced by the temperature sensing optical fiber according to the frequency of the microwave signal corresponding to the maximum power and the reference frequency of the microwave signal emitted by the microwave signal source.
According to the temperature sensing demodulation method based on the mode locking fiber laser, the mode locking fiber laser comprises a laser resonant cavity, a temperature sensing fiber, an electro-optic modulator and a fiber coupler, the temperature sensing fiber is arranged in the laser resonant cavity, the temperature sensing fiber induces temperature change to cause the optical path of the laser resonant cavity to change, the electric driving end of the electro-optic modulator is connected with a microwave signal source, the electro-optic modulator is used for modulating an optical signal passing through the temperature sensing fiber according to a microwave signal emitted by the microwave signal source, the frequency of the microwave signal emitted by the microwave signal source can be tuned in response to the optical path change of the laser resonant cavity, the mode locking fiber laser forms mode locking laser according to the modulated optical signal, and the mode locking laser is coupled and output through the fiber coupler, and the temperature sensing demodulation method comprises the following steps: firstly, carrying out photoelectric conversion on mode-locked laser coupled and output by an optical fiber coupler through a photoelectric detector so as to output a first electric signal; then, filtering the first electric signal through a radio frequency band-pass filter to output a second electric signal, and measuring the power of the second electric signal; then, scanning the frequency of the microwave signal emitted by the microwave signal source, acquiring the frequency of the corresponding microwave signal according to the measured maximum power of the second electric signal, and acquiring temperature change information induced by the temperature sensing optical fiber according to the frequency of the microwave signal corresponding to the maximum power and the reference frequency of the microwave signal emitted by the microwave signal source; therefore, the electromagnetic interference prevention remote temperature measurement is realized, and the bandwidth is large and the loss is low; meanwhile, the manufacturing cost and the structural complexity of the temperature sensing equipment are reduced, and the mass production and the popularization of the demodulation technology of the optical fiber temperature sensor are facilitated.
In addition, the temperature sensing demodulation method based on the mode-locked fiber laser according to the above embodiment of the present invention may further have the following additional technical features:
optionally, the mode-locked fiber laser further includes an optical amplifier, an optical filter, and an optical isolator, an input end of the photodetector is connected to the first output end of the optical fiber coupler, an input end of the optical amplifier is connected to the second output end of the optical fiber coupler, an output end of the optical amplifier is connected to one end of the temperature sensing fiber, the other end of the temperature sensing fiber is connected to an optical input end of the electro-optical modulator, an optical output end of the electro-optical modulator is connected to an input end of the optical filter, an output end of the optical filter is connected to an input end of the optical isolator, and an output end of the optical isolator is connected to an input end of the optical fiber coupler, wherein the light emitted through the optical amplifier is amplified and passes through the temperature sensing fiber, the electro-optical modulator, the optical filter, the optical isolator, the temperature sensor, and the mode-locked laser is formed behind the optical isolator and the optical fiber coupler.
Optionally, the optical fiber coupler is a 90:10 optical fiber coupler, the first output end of the optical fiber coupler is a 10% output port, the second output end of the optical fiber coupler is a 90% output port, and the optical amplifier is an erbium-doped optical fiber amplifier.
Optionally, the method further comprises: and setting the reference temperature of the temperature sensing optical fiber so as to obtain the reference frequency of the microwave signal according to the optical path of the laser resonant cavity corresponding to the reference temperature of the temperature sensing optical fiber.
Optionally, the temperature change information sensed by the temperature sensing optical fiber is obtained according to the following formula:
wherein, Δ f is the variation value of the frequency of the microwave signal, f2Frequency of microwave signal corresponding to maximum power, f1Is the reference frequency of the microwave signal, m is the order of the pass band, c is the speed of light in vacuum, L1Is the length of the temperature sensing fiber, L2The length of the laser resonant cavity minus the temperature sensing optical fiber is obtained, delta T is the temperature change quantity, n is the effective refractive index of the optical fiber, and zeta is the thermo-optic coefficient of the optical fiber.
Drawings
FIG. 1 is a schematic structural diagram of a temperature sensing demodulation apparatus based on a mode-locked fiber laser according to an embodiment of the present invention;
fig. 2 is a schematic flow chart of a temperature sensing demodulation method based on a mode-locked fiber laser according to an embodiment of the invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
In the existing optical fiber temperature sensing device, the structure of a Michelson optical fiber interferometer and a Mach-Zehnder optical fiber interferometer is mostly adopted to measure the wavelength change in the interference spectrum, and then the change information of the temperature is judged through the change of the wavelength in the interference spectrum, the measurement mode has higher requirement on the performance of an optical filter, further the implementation cost is increased, and the structure is complex. The microwave signal frequency emitted by a microwave signal source responds to the change of the optical path of the laser resonant cavity and can be tuned, the mode-locked fiber laser forms mode-locked laser according to the modulated optical signal and couples and outputs the mode-locked laser through the fiber coupler, and the temperature sensing demodulation device comprises a photoelectric detector, a radio frequency band-pass filter, an electric power meter and a temperature demodulator, wherein the input end of the photoelectric detector is connected with the first output end of the fiber coupler, the output end of the photoelectric detector is connected with the input end of the radio frequency band-pass filter, and the output end of the radio frequency band-pass filter is connected with the input end of the electric power meter; the photoelectric detector is used for performing photoelectric conversion on the mode-locked laser coupled and output by the optical fiber coupler so as to output a first electric signal; the radio frequency band-pass filter is used for filtering the first electric signal to output a second electric signal; the electric power meter is used for measuring the power of the second electric signal; the temperature demodulator is used for scanning the frequency of the microwave signal emitted by the microwave signal source, acquiring the frequency of the corresponding microwave signal according to the maximum power of the second electric signal measured by the electric power meter, and acquiring temperature change information induced by the temperature sensing optical fiber according to the frequency of the microwave signal corresponding to the maximum power and the reference frequency of the microwave signal emitted by the microwave signal source; therefore, the electromagnetic interference prevention remote temperature measurement is realized, and the bandwidth is large and the loss is low; meanwhile, the manufacturing cost and the structural complexity of the temperature sensing equipment are reduced, and the mass production and the popularization of the demodulation technology of the optical fiber temperature sensor are facilitated.
In order to better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
In order to better understand the technical solution, the technical solution will be described in detail with reference to the drawings and the specific embodiments.
Fig. 1 is a schematic diagram of a temperature sensing demodulation apparatus based on a mode-locked fiber laser according to an embodiment of the present invention, and as shown in fig. 1, the temperature sensing demodulation apparatus based on a mode-locked fiber laser includes: the device comprises a mode-locked fiber laser 10, a microwave signal source 20 and a temperature sensing demodulation device 30.
The mode-locked fiber laser 10 includes a laser resonant cavity 11, a temperature sensing fiber 12, an electro-optical modulator 13, and a fiber coupler 14. The temperature sensing fiber 12 is arranged in the laser resonant cavity 11, the temperature sensing fiber 12 induces the optical path of the laser resonant cavity 11 to change by sensing the temperature change, the electric driving end of the electro-optical modulator 13 is connected with the microwave signal source 20, the electro-optical modulator 13 is used for modulating the optical signal passing through the temperature sensing fiber 12 according to the microwave signal emitted by the microwave signal source 20, the frequency of the microwave signal emitted by the microwave signal source 20 can be tuned in response to the change of the optical path of the laser resonant cavity 11, the mode-locked fiber laser 10 forms mode-locked laser according to the modulated optical signal, and the mode-locked laser is coupled and output through the fiber coupler 14.
That is, the temperature sensing fiber 12 is disposed in the laser resonator 11 to sense temperature changes through the temperature sensing fiber 12, so that the optical path of the laser resonator 11 can be changed according to the temperature changes, and an optical signal of the optical path corresponding to the temperature is output to the electro-optical modulator 13 through the temperature sensing fiber 12 according to the temperature changes; after receiving the optical signal output by the temperature sensing fiber 12, the electro-optical modulator 13 modulates the optical signal according to the microwave signal emitted by the microwave signal source 20 connected to the electric drive end thereof, so that the mode-locked fiber laser 10 forms mode-locked laser according to the modulated optical signal and couples and outputs the mode-locked laser through the fiber coupler 14; wherein, the frequency of the microwave signal emitted by the microwave signal source 20 is tunable in response to the optical path change of the laser resonant cavity 11.
In some embodiments, the mode-locked fiber laser 10 further includes an optical amplifier 15, an optical filter 16, and an optical isolator 17, an input of the optical amplifier 15 is connected to the second output of the fiber coupler 14, an output of the optical amplifier 15 is connected to one end of the temperature sensing fiber 12, another end of the temperature sensing fiber 12 is connected to an optical input of the electro-optical modulator 13, an optical output of the electro-optical modulator 13 is connected to an input of the optical filter 16, an output of the optical filter 16 is connected to an input of the optical isolator 17, and an output of the optical isolator 17 is connected to an input of the fiber coupler, wherein the light emitted through the optical amplifier 15 is amplified and passes through the temperature sensing fiber 12, the electro-optical modulator 13, the optical filter 16, the optical isolator 17, and the fiber coupler 14 to form the mode-locked laser.
The optical amplifier 15 may be selected in various ways, such as a fiber amplifier and a raman optical amplifier.
As an example, the optical amplifier 15 is an erbium-doped fiber amplifier to amplify light by the erbium-doped fiber amplifier.
The coupling ratio of the fiber coupler 14 may be various.
As an example, fiber coupler 14 is a 90:10 fiber coupler, the first output of fiber coupler 14 is a 10% output port, and the second output of fiber coupler 14 is a 90% output port.
That is, 10% of the output ports of the 90:10 optical fiber coupler are connected to the input terminal of the photodetector 31 to output the coupled mode-locked laser to the photodetector 31, and 90% of the output ports of the 10% 90:10 optical fiber coupler are connected to the input terminal of the optical amplifier 15 to receive the optical signal amplified by the optical amplifier 15 through the 90% of the output ports.
The temperature sensing demodulation device 30 comprises a photoelectric detector 31, a radio frequency band-pass filter 32, an electric power meter 33 and a temperature demodulator (not shown in the figure).
Wherein, the input end of the photoelectric detector 31 is connected with the first output end of the optical fiber coupler 14, the output end of the photoelectric detector 31 is connected with the input end of the radio frequency band-pass filter 32, and the output end of the radio frequency band-pass filter 32 is connected with the input end of the electric power meter 33.
That is, the input end of the photodetector 31 is connected to the first output end of the optical fiber coupler 14, so as to receive the mode-locked laser coupled and output by the optical fiber coupler 14, and perform photoelectric conversion on the received mode-locked laser to output a first electrical signal; then, the output end of the photodetector 31 is connected to the input end of the radio frequency band pass filter 32 to output the first electrical signal obtained after the photoelectric conversion to the radio frequency band pass filter 32, and the first electrical signal is subjected to filtering processing by the radio frequency band pass filter 32 to output a second electrical signal; then, the output terminal of the rf band-pass filter 32 is connected to the input terminal of the electric power meter 33 to output the second electric signal to the electric power meter 33, and the electric power meter 33 measures the power of the received second electric signal to obtain the power of the second electric signal.
As an example, after photoelectric conversion by the photodetector 31 to obtain a periodic first electrical signal output, the rf band-pass filter may be tuned to align with a filter pass band of a specified order, thereby outputting a specified second electrical signal.
The temperature demodulator is configured to scan a frequency of the microwave signal emitted by the microwave signal source 20, obtain a corresponding frequency of the microwave signal according to a maximum power of the second electrical signal measured by the wattmeter 33, and obtain temperature variation information induced by the temperature sensing fiber 12 according to the frequency of the microwave signal corresponding to the maximum power and a reference frequency of the microwave signal emitted by the microwave signal source 20.
That is, the temperature demodulator is configured to scan the frequency of the microwave signal emitted by the microwave signal source 20, and obtain the frequency of the microwave signal corresponding to the maximum power when the power of the second electrical signal measured by the wattmeter 33 is the maximum power; and calculating the temperature variation according to the microwave signal frequency corresponding to the maximum power and the reference frequency of the microwave signal emitted by the microwave signal source 20 to obtain the temperature variation information induced by the temperature sensing fiber 12.
In some embodiments, the temperature demodulator is further configured to set a reference temperature of the temperature sensing fiber 12, so as to obtain a reference frequency of the microwave signal according to the optical path length of the laser cavity 11 corresponding to the reference temperature of the temperature sensing fiber 12.
As an example, first, the reference temperature of the sensing fiber is set to T0Modulating a microwave signal emitted by a microwave signal source 20 onto an optical signal through an electro-optical modulator 13, wherein the frequency of the microwave signal is tunable corresponding to the change of the optical path of the laser resonant cavity 11, so that after the tunable microwave signal frequency is scanned, whether the output of the mode-locked laser is stable can be judged, and after the output of the mode-locked laser is stable, photoelectric conversion is performed through a photoelectric detector 31 to obtain periodic output; then, the rf band-pass filter 32 is tuned to align with the passband of the mth order filter, so that the power of the second signal measured by the wattmeter 33 is the maximum power, and at this time, the reference frequency f of the microwave signal can be obtained1The reference frequency f of the microwave signal1The formula is as follows:
f1＝mΔν＝mc/(nL)
wherein f is1The reference frequency of a microwave signal, m is the order of a passband, c is the speed of light in vacuum, n is the effective refractive index of an optical fiber, and L is the length of the whole laser resonant cavity; l is1Is the length of the temperature sensing fiber, L2The length of the laser cavity excluding the temperature sensing fiber,and, L ═ L1+L2。
In some embodiments, when the temperature sensing fiber 12 senses a temperature change, the temperature demodulator 34 obtains information about the temperature change sensed by the temperature sensing fiber 12 according to the following formula:
wherein, Δ f is the variation value of the frequency of the microwave signal, f2Frequency of microwave signal corresponding to maximum power, f1Is the reference frequency of the microwave signal, m is the order of the pass band, c is the speed of light in vacuum, L1Is the length of the temperature sensing fiber, L2The length of the laser resonant cavity minus the temperature sensing optical fiber is obtained, delta T is the temperature change quantity, n is the effective refractive index of the optical fiber, and zeta is the thermo-optic coefficient of the optical fiber.
In summary, according to the temperature sensing demodulation apparatus based on the mode-locked fiber laser provided by the embodiment of the present invention, the mode-locked fiber laser includes a laser resonant cavity, a temperature sensing fiber, an electro-optical modulator and a fiber coupler, the temperature sensing fiber is disposed in the laser resonant cavity, the temperature sensing fiber induces a temperature change to change an optical path of the laser resonant cavity, an electrical driving end of the electro-optical modulator is connected to a microwave signal source, the electro-optical modulator is configured to modulate an optical signal passing through the temperature sensing fiber according to a microwave signal emitted by the microwave signal source, a frequency of the microwave signal emitted by the microwave signal source is tunable in response to the optical path change of the laser resonant cavity, the mode-locked fiber laser forms a mode-locked laser according to the modulated optical signal and couples and outputs the mode-locked laser through the fiber coupler, and the temperature sensing demodulation apparatus includes a photodetector, The temperature sensor comprises a radio frequency band-pass filter, an electric power meter and a temperature demodulator, wherein the input end of a photoelectric detector is connected with the first output end of an optical fiber coupler, the output end of the photoelectric detector is connected with the input end of the radio frequency band-pass filter, and the output end of the radio frequency band-pass filter is connected with the input end of the electric power meter; the photoelectric detector is used for performing photoelectric conversion on the mode-locked laser coupled and output by the optical fiber coupler so as to output a first electric signal; the radio frequency band-pass filter is used for filtering the first electric signal to output a second electric signal; the electric power meter is used for measuring the power of the second electric signal; the temperature demodulator is used for scanning the frequency of the microwave signal emitted by the microwave signal source, acquiring the frequency of the corresponding microwave signal according to the maximum power of the second electric signal measured by the electric power meter, and acquiring temperature change information induced by the temperature sensing optical fiber according to the frequency of the microwave signal corresponding to the maximum power and the reference frequency of the microwave signal emitted by the microwave signal source; therefore, the electromagnetic interference prevention remote temperature measurement is realized, and the bandwidth is large and the loss is low; meanwhile, the manufacturing cost and the structural complexity of the temperature sensing equipment are reduced, and the mass production and the popularization of the demodulation technology of the optical fiber temperature sensor are facilitated.
In order to implement the above embodiments, as shown in fig. 2, an embodiment of the present invention further provides a temperature sensing demodulation method based on a mode-locked fiber laser, where the mode-locked fiber laser includes a laser resonant cavity, a temperature sensing fiber, an electro-optical modulator and a fiber coupler, the temperature sensing fiber is disposed in the laser resonant cavity, the temperature sensing fiber induces a temperature change to change an optical path of the laser resonant cavity, an electrical driving end of the electro-optical modulator is connected to a microwave signal source, the electro-optical modulator is configured to modulate an optical signal passing through the temperature sensing fiber according to a microwave signal emitted by the microwave signal source, a frequency of the microwave signal emitted by the microwave signal source is tunable in response to the optical path change of the laser resonant cavity, the mode-locked fiber laser forms mode-locked laser according to the modulated optical signal and couples and outputs the mode-locked laser through the fiber coupler, the temperature sensing demodulation method comprises the following steps:
and S101, performing photoelectric conversion on the mode-locked laser coupled and output by the optical fiber coupler through the photoelectric detector to output a first electric signal.
That is, the mode-locked fiber laser outputs the mode-locked laser light to the photodetector after generating the mode-locked laser light, has photoelectrically converted the mode-locked laser light by the photodetector, and outputs the first electrical signal.
In some embodiments, the mode-locked fiber laser further comprises an optical amplifier, an optical filter, and an optical isolator, wherein an input of the photodetector is connected to a first output of the fiber coupler, an input of the optical amplifier is connected to a second output of the fiber coupler, an output of the optical amplifier is connected to one end of the temperature sensing fiber, another end of the temperature sensing fiber is connected to an optical input of the electro-optic modulator, an optical output of the electro-optic modulator is connected to an input of the optical filter, an output of the optical filter is connected to an input of the optical isolator, and an output of the optical isolator is connected to an input of the fiber coupler, wherein,
the light emitted by the light amplifier is amplified and passes through the temperature sensing optical fiber, the electro-optic modulator, the optical filter, the optical isolator and the optical fiber coupler to form the mode-locked laser.
As an example, the optical fiber coupler is a 90:10 optical fiber coupler, the first output end of the optical fiber coupler is a 10% output port, the second output end of the optical fiber coupler is a 90% output port, and the optical amplifier is an erbium-doped optical fiber amplifier.
S102, filtering the first electric signal through a radio frequency band-pass filter to output a second electric signal, and measuring the power of the second electric signal.
That is to say, after the photodetector photoelectrically converts the mode-locked laser and generates a first electrical signal, the first electrical signal is output to the rf bandpass filter, so that the first electrical signal is filtered by the rf bandpass filter to output a second electrical signal, and then the power of the second electrical signal is measured by the wattmeter to obtain the power of the second electrical signal.
S103, scanning the frequency of the microwave signal emitted by the microwave signal source, acquiring the corresponding frequency of the microwave signal according to the measured maximum power of the second electric signal, and acquiring the temperature change information induced by the temperature sensing optical fiber according to the frequency of the microwave signal corresponding to the maximum power and the reference frequency of the microwave signal emitted by the microwave signal source.
That is, the frequency of the microwave signal emitted by the microwave signal source is scanned, and when the power of the second electrical signal measured by the electrical power meter is the maximum power, the frequency of the microwave signal corresponding to the current maximum power is obtained, so as to obtain the temperature change information induced by the temperature sensing optical fiber according to the frequency of the microwave signal corresponding to the maximum power and the reference frequency of the microwave signal emitted by the microwave signal source.
As an example, when the power of the second electrical signal measured by the electric power meter is the maximum power, the temperature change information induced by the temperature sensing fiber is obtained according to the following formula:
wherein, Δ f is the variation value of the frequency of the microwave signal, f2Frequency of microwave signal corresponding to maximum power, f1Is the reference frequency of the microwave signal, m is the order of the pass band, c is the speed of light in vacuum, L1Is the length of the temperature sensing fiber, L2The length of the laser resonant cavity minus the temperature sensing optical fiber is obtained, delta T is the temperature change quantity, n is the effective refractive index of the optical fiber, and zeta is the thermo-optic coefficient of the optical fiber.
In summary, according to the temperature sensing demodulation method based on the mode-locked fiber laser according to the embodiment of the invention, the mode-locked fiber laser includes a laser resonant cavity, a temperature sensing fiber, an electro-optical modulator and a fiber coupler, the temperature sensing fiber is disposed in the laser resonant cavity, the temperature sensing optical fiber induces the optical path of the laser resonant cavity to change by sensing the temperature change, the electric drive end of the electro-optical modulator is connected with the microwave signal source, the electro-optical modulator is used for modulating the optical signal passing through the temperature sensing optical fiber according to the microwave signal emitted by the microwave signal source, the frequency of the microwave signal emitted by the microwave signal source can be tuned in response to the change of the optical path of the laser resonant cavity, the mode-locked fiber laser forms mode-locked laser according to the modulated optical signal, the mode-locked laser is coupled and output through the optical fiber coupler, and the temperature sensing demodulation method comprises the following steps: firstly, carrying out photoelectric conversion on mode-locked laser coupled and output by an optical fiber coupler through a photoelectric detector so as to output a first electric signal; then, filtering the first electric signal through a radio frequency band-pass filter to output a second electric signal, and measuring the power of the second electric signal; then, scanning the frequency of the microwave signal emitted by the microwave signal source, acquiring the frequency of the corresponding microwave signal according to the measured maximum power of the second electric signal, and acquiring temperature change information induced by the temperature sensing optical fiber according to the frequency of the microwave signal corresponding to the maximum power and the reference frequency of the microwave signal emitted by the microwave signal source; therefore, the electromagnetic interference prevention remote temperature measurement is realized, and the bandwidth is large and the loss is low; meanwhile, the manufacturing cost and the structural complexity of the temperature sensing equipment are reduced, and the mass production and the popularization of the demodulation technology of the optical fiber temperature sensor are facilitated.
As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
It should be noted that in the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by one and the same item of hardware. The usage of the words first, second and third, etcetera do not indicate any ordering. These words may be interpreted as names.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
In the description of the present invention, it is to be understood that the terms "first", "second" and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above should not be understood to necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (10)
1. A temperature sensing demodulation device based on a mode locking fiber laser is characterized in that the mode locking fiber laser comprises a laser resonant cavity, a temperature sensing fiber, an electro-optic modulator and a fiber coupler, the temperature sensing fiber is arranged in the laser resonant cavity, the temperature sensing fiber induces the optical path of the laser resonant cavity to change by sensing temperature change, the electric driving end of the electro-optic modulator is connected with a microwave signal source, the electro-optic modulator is used for modulating an optical signal passing through the temperature sensing fiber according to the microwave signal emitted by the microwave signal source, the frequency of the microwave signal emitted by the microwave signal source can be tuned in response to the optical path change of the laser resonant cavity, the mode locking fiber laser forms mode locking laser according to the modulated optical signal and couples and outputs the mode locking laser through the fiber coupler, the temperature sensing demodulation device comprises a photoelectric detector, a radio frequency band-pass filter, an electric power meter and a temperature demodulator, wherein,
the input end of the photoelectric detector is connected with the first output end of the optical fiber coupler, the output end of the photoelectric detector is connected with the input end of the radio frequency band-pass filter, and the output end of the radio frequency band-pass filter is connected with the input end of the electric power meter;
the photoelectric detector is used for performing photoelectric conversion on the mode-locked laser coupled and output by the optical fiber coupler so as to output a first electric signal;
the radio frequency band-pass filter is used for filtering the first electric signal to output a second electric signal;
the electric power meter is used for measuring the power of the second electric signal;
the temperature demodulator is used for scanning the frequency of the microwave signal emitted by the microwave signal source, acquiring the frequency of the corresponding microwave signal according to the maximum power of the second electric signal measured by the electric power meter, and acquiring the temperature change information induced by the temperature sensing optical fiber according to the frequency of the microwave signal corresponding to the maximum power and the reference frequency of the microwave signal emitted by the microwave signal source.
2. The mode-locked fiber laser-based temperature sensing demodulation apparatus of claim 1, wherein the mode-locked fiber laser further comprises an optical amplifier, an optical filter and an optical isolator, wherein an input of the optical amplifier is connected to the second output of the fiber coupler, an output of the optical amplifier is connected to one end of the temperature sensing fiber, another end of the temperature sensing fiber is connected to an optical input of the electro-optical modulator, an optical output of the electro-optical modulator is connected to an input of the optical filter, an output of the optical filter is connected to an input of the optical isolator, and an output of the optical isolator is connected to an input of the fiber coupler, wherein the light emitted by the optical amplifier is amplified and passes through the temperature sensing fiber, the electro-optical modulator, the temperature sensing fiber, the electro-optical modulator, and the optical isolator, And the mode-locked laser is formed after the optical filter, the optical isolator and the optical fiber coupler.
3. The mode-locked fiber laser-based temperature sensing demodulation device according to claim 2, wherein the fiber coupler is a 90:10 fiber coupler, the first output end of the fiber coupler is a 10% output port, the second output end of the fiber coupler is a 90% output port, and the optical amplifier is an erbium-doped fiber amplifier.
4. The mode-locked fiber laser-based temperature sensing demodulation device according to any one of claims 1-3, wherein the temperature demodulator is further configured to set a reference temperature of the temperature sensing fiber, so as to obtain the reference frequency of the microwave signal according to the optical path length of the laser cavity corresponding to the reference temperature of the temperature sensing fiber.
5. The mode-locked fiber laser-based temperature sensing demodulation device according to claim 4, wherein the temperature demodulator obtains the temperature variation information sensed by the temperature sensing fiber according to the following formula:
wherein, Δ f is the variation value of the frequency of the microwave signal, f2Frequency of microwave signal corresponding to maximum power, f1Is the reference frequency of the microwave signal, m is the order of the pass band, c is the speed of light in vacuum, L1Is the length of the temperature sensing fiber, L2The length of the laser resonant cavity minus the temperature sensing optical fiber is obtained, delta T is the temperature change quantity, n is the effective refractive index of the optical fiber, and zeta is the thermo-optic coefficient of the optical fiber.
6. A temperature sensing demodulation method based on a mode locking fiber laser is characterized in that the mode locking fiber laser comprises a laser resonant cavity, a temperature sensing fiber, an electro-optic modulator and a fiber coupler, the temperature sensing fiber is arranged in the laser resonant cavity, the temperature sensing fiber induces the optical path of the laser resonant cavity to change by sensing temperature change, the electric driving end of the electro-optic modulator is connected with a microwave signal source, the electro-optic modulator is used for modulating an optical signal passing through the temperature sensing fiber according to the microwave signal emitted by the microwave signal source, the frequency of the microwave signal emitted by the microwave signal source can be tuned in response to the optical path change of the laser resonant cavity, the mode locking fiber laser forms mode locking laser according to the modulated optical signal and couples and outputs the mode locking laser through the fiber coupler, the temperature sensing demodulation method comprises the following steps:
performing photoelectric conversion on the mode-locked laser coupled and output by the optical fiber coupler through a photoelectric detector to output a first electric signal;
filtering the first electric signal through a radio frequency band-pass filter to output a second electric signal, and measuring the power of the second electric signal;
and scanning the frequency of the microwave signal emitted by the microwave signal source, acquiring the corresponding frequency of the microwave signal according to the measured maximum power of the second electric signal, and acquiring the temperature change information induced by the temperature sensing optical fiber according to the frequency of the microwave signal corresponding to the maximum power and the reference frequency of the microwave signal emitted by the microwave signal source.
7. The method of claim 6, wherein the mode-locked fiber laser further comprises an optical amplifier, an optical filter, and an optical isolator, wherein an input of the photodetector is connected to a first output of the fiber coupler, an input of the optical amplifier is connected to a second output of the fiber coupler, an output of the optical amplifier is connected to one end of the temperature sensing fiber, another end of the temperature sensing fiber is connected to an optical input of the electro-optical modulator, an optical output of the electro-optical modulator is connected to an input of the optical filter, an output of the optical filter is connected to an input of the optical isolator, and an output of the optical isolator is connected to an input of the fiber coupler, wherein,
the light emitted by the light amplifier is amplified and passes through the temperature sensing optical fiber, the electro-optic modulator, the optical filter, the optical isolator and the optical fiber coupler to form the mode-locked laser.
8. The method of claim 7, wherein the fiber coupler is a 90:10 fiber coupler, the first output port of the fiber coupler is a 10% output port, the second output port of the fiber coupler is a 90% output port, and the optical amplifier is an erbium-doped fiber amplifier.
9. The mode-locked fiber laser-based temperature sensing demodulation method according to any one of claims 6 to 8, further comprising:
and setting the reference temperature of the temperature sensing optical fiber so as to obtain the reference frequency of the microwave signal according to the optical path of the laser resonant cavity corresponding to the reference temperature of the temperature sensing optical fiber.
10. The mode-locked fiber laser-based temperature sensing demodulation method according to claim 9, wherein the temperature change information induced by the temperature sensing fiber is obtained according to the following formula:
wherein, Δ f is the variation value of the frequency of the microwave signal, f2Frequency of microwave signal corresponding to maximum power, f1Is the reference frequency of the microwave signal, m is the order of the pass band, c is the speed of light in vacuum, L1Is the length of the temperature sensing fiber, L2The length of the laser resonant cavity minus the temperature sensing optical fiber is obtained, delta T is the temperature change quantity, n is the effective refractive index of the optical fiber, and zeta is the thermo-optic coefficient of the optical fiber.
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