Titanium carbide-based stress sensing multi-soliton state modulation fiber laser

Abstract

The embodiment of the invention discloses a stress sensing multi-soliton state modulation optical fiber laser based on titanium carbide, and belongs to the technical field of optical fiber communication and engineering measurement instruments and meters. The fiber laser comprises a laser pumping source, a wavelength division multiplexer, a gain fiber, a polarization independent isolator, an output coupler (8: 2), a three-ring polarization controller and a saturable absorber device based on titanium carbide, wherein the above devices are connected through a single-mode fiber. The invention has the following beneficial effects: (1) the microfiber is used as a stress sensor, and controllable periodic tuning of two key wavebands (1530, 1560) of the traditional soliton state is realized by changing the bending curvature of the microfiber; and (2) the controllable periodic tuning of two key wavebands (1530, 1560) of the bound state and the soliton state is realized by changing the power and the bending curvature of the microfibers. The invention verifies the application of stress sensing in wavelength tuning and soliton state switching of the fiber laser, and plays an important role in the fields of pulse dynamics, fiber sensing and the like.

Description

Technical Field

[0003] The present application relates to the field of optical fiber laser and optical fiber sensing technology, and in particular to a stress sensing multi-soliton state modulated optical fiber laser based on titanium carbide. Background Art

[0004] In the field of sensing, fiber optic sensors have attracted much attention due to their small size, light weight, and insusceptibility to external environmental influences. Researchers have used multimode optical fibers, polarization-maintaining optical fibers, photonic crystal fibers, and tapered optical fibers to achieve wavelength switching or tuning by taking advantage of their filtering effects at low pump powers. Among them, tapered optical fibers are particularly attractive sensors due to their low cost and simple design. Various spectral switching and tuning schemes are designed by changing the propagation of the physical size mutation field of the medium in the tapered optical fiber. At the same time, the design of the fiber optic sensing scheme must also make full use of the diversity of optical signals, such as spectral shape, wavelength position, and amplitude changes. In recent years, researchers have used saturable absorbers to generate ultrashort pulses with narrow pulse width and high repetition frequency in ultrafast fiber resonators, and the nonlinear effects in the cavity are used to induce various soliton morphologies in the pulses. These rich soliton phenomenon changes and switching just meet the visualization and diversification needs of fiber optic sensing. Therefore, the research on stress sensing in mode-locked fiber devices deserves in-depth discussion. Therefore, the present invention provides a low-cost and high-precision optical fiber laser, which can be used as a measurement method to observe underground soil conditions or perform multi-field related stress detection and phenomenon analysis by realizing periodic switching of multi-soliton states and adjustable wavelength. Summary of the invention

[0005] In order to solve the problems in the above-mentioned prior art, the present invention provides a stress-sensing multi-soliton state modulated fiber laser based on titanium carbide, which realizes the periodic switching of different soliton state wavelengths, the controllable periodic tuning of two key bands (1530 nanometers and 1560 nanometers) of the traditional soliton state, and the periodic switching of two key bands (1530 nanometers and 1560 nanometers) of the bound state soliton state.

[0006] Stress sensing multi-soliton state modulated fiber laser based on titanium carbide, the specific scheme is:

[0007] The laser includes a 980nm pump source, a (980nm / 1550nm) wavelength division multiplexer, a first optical fiber, an erbium-doped gain optical fiber, a second optical fiber, a polarization-independent isolator, a third optical fiber, a stress sensing modulator, a fourth optical fiber, a polarization controller, a fifth optical fiber, a titanium carbide saturable absorber, a sixth optical fiber, an optical coupler, a seventh optical fiber, and an eighth optical fiber.

[0008] Preferably, the 980nm pump source is guided and connected by the 980nm wavelength division multiplexer, the output end of the wavelength division multiplexer is connected to the erbium-doped gain fiber through the first optical fiber, the gain fiber is connected to the second optical fiber and then connected to the front end of the polarization-independent isolator, the rear end of the polarization-independent isolator is connected to the third optical fiber and connected to the front end of the stress sensing modulator, the rear end of the stress sensing modulator is connected to the fourth optical fiber and connected to the front end of the polarization controller, the rear end of the polarization controller is connected to the front end of the saturable absorber through the fifth optical fiber, the other end of the titanium carbide saturable absorber is connected to the rear end of the optical coupler through the sixth optical fiber, the 80% signal power end of the optical coupler is connected to the 1550nm port of the wavelength division multiplexer through the eighth optical fiber, and the 20% signal power end of the optical coupler is output outside the cavity through the seventh optical fiber.

[0009] Preferably, the lengths of the first optical fiber, the gain optical fiber, the second optical fiber, the third optical fiber, the fourth optical fiber, the fifth optical fiber, the sixth optical fiber, the seventh optical fiber, and the eighth optical fiber are 2.5 m, 1 m, 1.7 m, 2.5 m, 1.15 m, 1.3 m, 2.3 m, 2.3 m, and 1.95 m, respectively.

[0010] Preferably, the gain optical fiber is a highly doped erbium-doped optical fiber;

[0011] Preferably, the saturable absorber is a titanium carbide film;

[0012] As a part of the titanium carbide-based stress-sensing multi-soliton state modulated fiber laser described in the embodiment of the present application, the output coupler has two output ends, and the optical power ratio is 80:20, of which 80% of the output ends are connected to the cavity and 20% of the output ends are used for signal data analysis.

[0013] As a part of the titanium carbide-based stress-sensing multi-soliton state modulated fiber laser described in the embodiment of the present application, the polarization-independent isolator can transmit pulses unidirectionally and generate stable mode-locked pulses by adjusting the pump power to 280mW output.

[0014] As a part of the titanium carbide-based stress-sensing multi-soliton state modulated fiber laser described in the embodiment of the present application, microfibers are used as stress-sensing modulators, and the periodic switching of wavelengths of different soliton states (traditional solitons, bound solitons) is achieved by changing the bending curvature of the microfibers.

[0015] As a part of the titanium carbide-based stress sensing multi-soliton state modulated fiber laser described in the embodiment of the present application, the stress sensing device is composed of a tapered microfiber made by flame brush technology, and the tapered area has a length of 3mm and a diameter of 30um.

[0016] The beneficial effects of the present invention are as follows: (1) By using the microfiber as a stress sensor and changing the bending curvature of the microfiber, the controllable periodic tuning of the two key bands (1530 nanometers and 1560 nanometers) of the traditional soliton state is achieved. (2) By using the microfiber as a stress sensor and changing the power, the polarization state of the optical fiber and the bending curvature of the microfiber, the controllable periodic tuning of the two key bands (1530 nanometers and 1560 nanometers) of the bound state soliton state is achieved.

[0017] The application embodiment will play an important role in the fields of ultrafast pulse dynamics, optical fiber sensing, etc. The sensor modulator has the potential in detecting soil cracks and underground landform analysis. Real-time observation is performed based on the real-time changes of the spectral center wavelength and soliton state. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more completely understand the technical solutions and the accompanying features in the embodiments of the present application, the following is a brief introduction to the drawings required for describing the embodiments. This figure is only for further understanding of this example, and for those skilled in the art, the schematic diagram does not constitute an improper limitation of this example.

[0019] Figure 1 It is a schematic diagram of the principle structure of a stress-sensing multi-soliton state modulated fiber laser based on titanium carbide provided in an embodiment of the present application;

[0020] Figure 2 This is a schematic diagram of a conventional soliton mode-locked spectrum of a stress-sensing multi-soliton state modulated fiber laser based on titanium carbide provided in an embodiment of the present application;

[0021] Figure 3 It is a schematic diagram of a stress sensing modulator of a titanium carbide-based stress sensing multi-soliton state modulated fiber laser provided in an embodiment of the present application;

[0022] Figure 4 The microfiber bending curvature of the titanium carbide stress sensing multi-soliton state modulated fiber laser provided in the embodiment of the present application is 0mm. -1 -0.171mm -1 The traditional soliton dual-band periodic modulation spectrum diagram;

[0023] Figure 5 The microfiber bending curvature of the titanium carbide stress sensing multi-soliton state modulated fiber laser provided in the embodiment of the present application is 0mm. -1 -0.181mm -1 The bound state soliton dual-band periodic modulation spectrum

[0024] The corresponding Chinese translation of the English words in the attached figure: SMF: single-mode fiber, Wavelength: wavelength, fundamental mode: fundamental mode, cladding mode: cladding mode, Evolution: evolution, state: stage, Frequency: frequency, Strain path: stress step, Intensity: intensity, nm: nanometer, curvature: mm -1 . DETAILED DESCRIPTION

[0025] In order to make the above-mentioned objects, features and advantages of the present invention more clearly understood, the specific implementation modes of the present invention are described in detail below in conjunction with the specification and the accompanying drawings.

[0026] Obviously, many specific details are set forth in the following description in order to fully understand the purpose, features and advantages of the present invention, but the present invention can also be implemented in other ways different from those described herein, and those skilled in the art can make similar explorations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0027] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0028] The terms "first", "second", etc. are for descriptive purposes only and should not be interpreted as a measure of relative weight or as an implicit indication of other technical parameters. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features.

[0029] Example 1

[0030] Reference Figure 1 , which is the first embodiment of the present invention, provides a stress-sensing multi-soliton state modulated fiber laser based on titanium carbide, and the device includes: a pump source 01, a wavelength division multiplexer 02, an erbium-doped gain fiber 03, a polarization-independent isolator 04, a stress-sensing modulator 05, a polarization controller 06, a titanium carbide saturable absorber 07, and an optical coupler 08.

[0031] The 980nm pump source 01 is connected to the 980nm entrance of the wavelength division multiplexer 02, the output end of the wavelength division multiplexer 02 is connected to the erbium-doped gain fiber 03 through the first optical fiber 021, the gain fiber 03 is connected to the second optical fiber 031 and then connected to the polarization-independent isolator 04, the polarization-independent isolator 04 outputs to the third optical fiber 041 and is connected to the microfiber stress sensing modulator 05 device, the output of the microfiber stress sensing modulator 05 is connected to one end of the fourth optical fiber 051, the other end of the fourth optical fiber 051 is connected to the polarization controller 06, the output from the polarization controller 06 is connected to the fifth optical fiber 061, the other end of the fifth optical fiber 061 is connected to the saturable absorber 07, the other end of the saturable absorber 07 is connected to the input end of the optical coupler 08 through the sixth optical fiber 071, the 80% signal power end of the optical coupler 08 is connected to the eighth optical fiber 091 and connected to the 1550nm input end of the wavelength division multiplexer, and the 20% signal power end of the optical coupler is connected to the signal analysis spectrometer through the seventh optical fiber 081.

[0032] The laser cavity length is 16.7 meters, the gain fiber 03 is 1 meter, and when titanium carbide is inserted into the saturable absorber 07, a stable self-starting mode-locked pulse is obtained under the condition of a pump power of 280mW. The corresponding output spectrum is Figure 2 As shown, the central wavelength is 1567.7nm and the 3dB spectral bandwidth is 3.2nm; Figure 2 We observe that the spectrum has obvious Kelly sidebands, which indicates that the mode locking is in the range of negative dispersion conventional solitons.

[0033] The stress sensing modulator 05 is moved from the bending curvature of 0mm -1 Schematic diagram as Figure 3 In this structure, the diameter of the tapered region is greatly reduced, and an air cladding surface is created. This design allows the fundamental mode and cladding mode to propagate simultaneously. When transitioning to the air cladding, both the fundamental mode and the cladding mode are excited and then recombine back to the fundamental mode. The tapered fiber has the function of a fiber filter interferometer, where the filter interference phenomenon depends on the phase difference between the modes passing through the tapered fiber. Tapered Microfiber 05 Bend Curvature from 0mm -1 To 0.171mm -1 When the central wavelength of the mode-locked pulse is tuned from 1530nm to 1555.2nm, the periodic change of the spectral width of the two cycles is shown as Figure 4

[0034] Increase the pump power to 300w, the curvature of the tapered microfiber 05 from 0mm -1 To 0.181mm -1 The wavelength shift is almost linearly related to the tuning. By adjusting the curvature of the bent cone filter to 0.181 mm-1, the mode-locked spectrum switching of bound state solitons at 1531 nm and 1555.5 nm can be achieved. Figure 5As shown, the wavelength interval is 23.2nm.

[0035] The above is a detailed introduction to a stress-sensing multi-soliton modulated fiber laser based on titanium carbide provided in an embodiment of the present application. Specific examples are used in this article to explain in detail the phenomena and implementation methods of the present application. The description of the above embodiments is only used to help understand the purpose and advantages of the present application. At the same time, for technicians in this field, modifications or substitutions based on the scheme of the present application will cause corresponding changes in actual operation and use areas, which are all covered within the scope of the requirements of this specification.

Claims

1. A stress-sensing multi-soliton modulated fiber laser based on titanium carbide, characterized in that A 976-nanometer pump source is connected to one end of the input end of a wavelength division multiplexer, an output end of the wavelength division multiplexer is connected to one end of an erbium-doped gain fiber, the other end of the erbium-doped gain fiber is connected to a polarization-independent isolator, the other end of the polarization-independent isolator is connected to one end of a stress sensing modulation device, the other end of the stress sensing device is connected to a polarization controller, the polarization controller is connected to a saturable absorber and then connected to a coupler to output laser.

2. The titanium carbide-based stress sensing multi-soliton state modulated fiber laser according to claim 1, characterized in that The main cavity length of the resonant cavity is 16.7 meters. The interval between adjacent pulses observed by the oscilloscope is 81.3ns, and the interval between adjacent spectra observed by the spectrum analyzer is 12.3MHz.

3. The titanium carbide-based stress sensing multi-soliton state modulated fiber laser according to claim 1, characterized in that , the 976-nanometer pump source outputs laser after passing through a 980 / 1550-nanometer wavelength division multiplexer. The polarization-independent isolator enables the laser to be transmitted unidirectionally in the optical ring cavity, thereby increasing the service life of the fiber laser; the stress-sensing modulator affects the fiber mode by applying bending stress, thereby changing the central wavelength and realizing different soliton states; the polarization controller is used to adjust the polarization state of light during laser transmission; the saturable absorber composite film uses titanium carbide as a saturable absorber for pulse narrowing; an 80:20 fiber coupler (OC) is used to divide it into an 8:2 power optical path, and we extract 20% of the signal output outside the laser.

4. The titanium carbide-based stress sensing multi-soliton state modulated fiber laser according to claim 1, characterized in that The laser achieves mode locking by changing the polarization state through a pump source, a titanium carbide saturable absorber and a polarization controller to obtain a traditional mode-locked soliton state; the pulse output is observed through an oscilloscope, and the spectral changes of the frequency domain pulse are observed through a spectrometer; the pulse repetition frequency, pulse intensity and signal-to-noise ratio are observed through a spectrum analyzer.

5. The titanium carbide-based stress sensing multi-soliton state modulated fiber laser according to claim 1, characterized in that , a conical microfiber made by flame brush technology, the conical area length is 3mm and the diameter is 30um. The curvature of the microfiber is from 0mm -1 To 0.171mm -1 At this time, the conventional soliton wavelength can be observed by spectrometer to achieve periodic switching of 1530nm-1555.2nm, increasing the pump power and adjusting the curvature of the microfiber from 0mm -1 To 0.181mm -1 , bound state solitons can achieve wavelength tuning from 1530nm to 1555.2nm.

6. The titanium carbide-based stress sensing multi-soliton state modulated fiber laser according to claim 1, characterized in that ,The microfiber is placed between two optical fiber fixtures. The length of the sensitive section of the microfiber is constant at the bending angle. The curvature radius is deduced using the coupling angle of the center of circles with different diameters. The bending curvature is quantified by the bending degree of the microfiber.

7. The titanium carbide-based stress sensing multi-soliton state modulated fiber laser according to claim 1, characterized in that , the saturable absorber of titanium carbide, 1 gram of titanium carbide aluminum powder is gradually added to the hydrogen fluoride aqueous solution, and the mixture is magnetically stirred at 300 rpm for 24 hours at room temperature. Subsequently, the mixture is centrifuged at a speed of 4000 rpm, and the upper turbid suspension is discarded. The precipitate is repeatedly centrifuged and washed with deionized water until the pH value of the supernatant is close. The precipitate is dried at 60°C under vacuum conditions for 48 hours.

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