Application of titanium boride nanoparticles in fabricating an optical modulator

Abstract

The present invention belongs to the technical field of optical modulation, and specifically relates to the application of titanium boride nanoparticles in the fabrication of an optical modulator; the titanium boride nanoparticle optical modulator includes a light source module, a polarization controller, a coupler, a wavelength division multiplexer, a saturable absorber based on titanium boride nanoparticles, a gain fiber, and a detection module; the saturable absorber based on titanium boride nanoparticles is formed by combining titanium boride nanoparticles with a D-shaped fiber to obtain a saturable absorber composed of titanium boride nanoparticles and a D-shaped fiber; the optical modulator made based on the properties of titanium boride is a fully fiber-optic modulation device, and uses the self-properties of the saturable absorber of titanium boride nanoparticles to achieve the modulation effect, and can achieve Q-switched laser and mode-locked laser in the 1560 nm band, and mode-locked laser in the 2000 nm band. The titanium boride nanoparticle optical modulation device has strong stability, a wide application range, and can achieve the modulation of light in the near-infrared band.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical modulation, and particularly relates to the application of titanium boride nanoparticles in the fabrication of an optical modulator. Background Art

[0002] With the development of modern science and technology, an optical modulator is a key device for high-speed, short-distance optical communication and one of the most important integrated optical devices. In the process of optical emission, transmission, and reception of the overall optical communication, the optical modulator is used to control the intensity of light, and its role is very important.

[0003] In traditional modulation, the modulation process mainly uses laser as a carrier. Laser has excellent temporal coherence and spatial coherence. It is similar to radio waves, easy to modulate, and has an extremely high frequency, so it can carry a large amount of information. In addition, the laser beam has a small divergence angle and highly concentrated light energy, which can not only transmit over a long distance but also be easily encrypted. Among them, in traditional laser modulation, the most widely used is that laser modulation can be mainly divided into two categories: internal modulation and external modulation. External modulation means that the modulation signal is loaded after the laser is formed, that is, the modulator is placed outside the laser resonator, and a modulation signal voltage is applied to the modulator to cause a phase change in some physical properties of the modulator. When the laser passes through it, modulation is obtained. Therefore, external modulation does not change the parameters of the laser, but changes the parameters of the already output laser. Therefore, external modulation must introduce a driving signal for modulation, and it is relatively complex and costly. While internal modulation can achieve modulation without introducing an external drive. It means that the loaded modulation signal is carried out during the laser oscillation process, and the parameters of the oscillation are changed according to the law of the modulation signal, so as to achieve the purpose of changing the output characteristics of the laser to realize modulation. This internal modulation method is simple, economical, and easy to implement. The optical modulator involved in the present invention is internal modulation. By placing a modulation element and controlling the modulation element with a pump signal, the parameters of the resonator are changed, thereby changing the output characteristics of the laser and realizing the modulation effect. Therefore, fiber internal modulation has become a research hotspot in the modulator and has great research significance.

[0004] The optical modulator internally uses the characteristics of a saturable absorber to modulate the laser, thereby converting continuous light into pulsed light, and has a very wide application prospect. And seeking a saturable absorber with a large modulation depth and high stability has become a research hotspot for internal optical modulation. Its entire device is simple and easy to operate. By replacing saturable absorber materials with different concentrations, pulsed light output can be achieved in different wavelength bands, and both picosecond pulse widths and femtosecond pulses can be achieved. It has a wide research prospect and research value. It can be applied to industries such as laser fiber communication, industrial shipbuilding, automobile manufacturing, metal part cladding, military national defense security, medical device instruments, large infrastructure, and so on. Summary of the Invention

[0005] To overcome the above problems, the present invention provides an application of titanium boride nanoparticles in the fabrication of an optical modulator; the preparation of optical modulation using titanium boride as a saturable absorber is achieved by means of deposition on a D-type optical fiber; its application can achieve Q-switching laser and mode-locking laser in the 1560 nm band, and mode-locking laser in the 2000 nm band. It is an all-fiber modulation device that does not require introducing an external signal into the laser to generate pulses and has a strong non-linear saturable absorption ability, providing a new approach for novel fiber optical modulators.

[0006] An application of titanium boride nanoparticles in the preparation of a saturable absorber, and the application of titanium boride nanoparticles in the preparation of a saturable absorber for an optical modulator.

[0007] A saturable absorber based on titanium boride nanoparticles, which is a saturable absorber based on coating a D-type optical fiber with titanium boride nanoparticles.

[0008] A saturable absorber based on coating a D-type optical fiber with titanium boride nanoparticles is prepared by mixing titanium boride nanoparticles and deionized water in a ratio of 1 mg of titanium boride nanoparticles to 10 ml of deionized water, ultrasonically dispersing for 4 hours, coating the ultrasonically dispersed mixed solution on the surface of a D-type or tapered optical fiber, and naturally drying in a vacuum-sealed container. As the water evaporates, the titanium boride nanoparticle powder covers the surface of the D-type or tapered optical fiber to form the saturable absorber.

[0009] An application of titanium boride nanoparticles as an optical modulator.

[0010] An optical modulator based on titanium boride nanoparticles, comprising a light source module 1, a coupler 2, a detection module 3, a saturable absorber 4 based on titanium boride nanoparticles, a polarization controller 5, an isolator 6, a gain fiber 7, and a wavelength division multiplexer 8; wherein

[0011] The laser emitted by the light source module 1 is incident into the coupler 2. After being processed by the coupler 2, 10% of the light emitted from the coupler 2 is incident into the detection module 3, and the remaining 90% of the light is incident into the saturable absorber 4 based on titanium boride nanoparticles. Subsequently, the optical fiber exits from the saturable absorber 4 based on titanium boride nanoparticles and enters the polarization controller 5. The optical fiber with the polarization state adjusted by the polarization controller 5 exits from the polarization controller 5 and enters the isolator 6. The optical fiber isolated by the isolator 6 exits and enters the gain fiber 7. The gain fiber 7 amplifies the optical signal. The amplified optical fiber exits from the gain fiber 7 and enters the wavelength division multiplexer 8. The optical fiber exiting from the wavelength division multiplexer 8 is incident into the coupler 2 to form a ring cavity structure.

[0012] The light source module 1 is a pump light source, the polarization controller 5 is a linear polarization controller, the coupler 2 is a 10 dB optical coupler, the isolator 6 is a 1560 nm polarization-independent fiber optic isolator, the wavelength division multiplexer 8 is a 980 / 1560 nm wavelength division multiplexer, the gain fiber 7 is erbium-doped fiber, and the detection module 3 is a spectrometer or an oscilloscope.

[0013] A single-mode fiber SMF-28 is used to connect between the light source module 1 and the coupler 2, between the coupler 2 and the detection module 3, between the detection module 3 and the titanium boride nanoparticle-based saturable absorber 4, between the titanium boride nanoparticle-based saturable absorber 4 and the polarization controller 5, between the polarization controller 5 and the isolator 6, between the isolator 6 and the gain fiber 7, between the gain fiber 7 and the wavelength division multiplexer 8, and between the wavelength division multiplexer 8 and the coupler 2.

[0014] When the light source module 1 is a pump light source, specifically a 980 nm pump laser, the polarization controller 5 is a linear polarization controller, the coupler 2 is a 10 dB optical coupler, the isolator 6 is a 1560 nm polarization-independent fiber optic isolator, the wavelength division multiplexer 8 is a 980 / 1560 nm wavelength division multiplexer, and the gain fiber 7 is erbium-doped fiber, more specifically a 20 cm long erbium-doped silica fiber, a titanium boride nanoparticle-based optical modulator can achieve Q-switching laser and mode-locking laser in the 1560 nm band.

[0015] When the light source module 1 is a pump light source, specifically a 1570 nm pump laser, the polarization controller 5 is a linear polarization controller, the coupler 2 is a 10 dB optical coupler, the isolator 6 is a 1980 nm polarization-independent fiber optic isolator, the wavelength division multiplexer 8 is a 1550 / 1980 nm wavelength division multiplexer, and the gain fiber 7 is thulium-doped fiber, more specifically a 20 cm long thulium-doped silica fiber, a titanium boride nanoparticle-based optical modulator can achieve mode-locking laser in the 2000 nm band.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] (1) Compared with traditional laser external modulators, it has strong stability, high sensitivity, simple structure, and anti-electromagnetic interference.

[0018] (2) It is an all-fiber optical modulator that combines the generation of an ultrafast laser with optical modulation, which is of great significance.

[0019] (3) It can be used as a laser for generating femtosecond and nanosecond pulses at different wavelengths, generating pulsed light in the near-infrared band, and expanding the application scope of the present invention.

[0020] (4) The D-shaped optical fiber can further increase the damage threshold of the longer nonlinear interaction length between the light guiding and the saturable absorber. In addition, the thickness and length of the titanium boride layer and the D-shaped region can be flexibly controlled to adjust the performance of the saturable absorber.

[0021] Accompanying drawings

[0022] Figure 1 Spectral diagram of Q-switching generated by titanium boride nanoparticles described in Embodiment 1 of the present invention at 1532 nm;

[0023] Figure 2 Spectral diagram of mode locking generated by titanium boride nanoparticles described in Embodiment 2 of the present invention at 1532 nm;

[0024] Figure 3 Spectral diagram of mode locking generated by titanium boride nanoparticles described in Embodiment 3 of the present invention at 1960 nm;

[0025] Figure 4 Schematic structural diagram of a titanium boride nanoparticle optical modulator described in the embodiments of the present invention;

[0026] Wherein: light source module 1, coupler 2, detection module 3, saturable absorber 4 based on titanium boride nanoparticles, polarization controller 5, isolator 6, gain fiber 7, wavelength division multiplexer 8. Detailed implementation manners

[0027] The present invention will be further described in detail below in conjunction with the embodiments. These implementation manners are only illustrative and do not limit the present invention.

[0028] A saturable absorber based on titanium boride nanoparticles is a saturable absorber in which titanium boride nanoparticles are coated on a D-shaped optical fiber. It is formed by combining titanium boride nanoparticles and a D-shaped optical fiber to obtain a saturable absorber composed of titanium boride nanoparticles and a D-shaped optical fiber. The specific preparation scheme is to mix 1 mg of titanium boride nanoparticles with 10 mL of deionized water and perform ultrasonic dispersion for 4 hours. Then, the ultrasonic-dispersed mixed solution is coated on the surface of the D-shaped optical fiber and naturally dried in a vacuum-sealed container. After the water evaporates, the titanium boride nanoparticle powder covers the surface of the D-shaped optical fiber, which is the saturable absorber.

[0029] The optical modulator is constructed based on the principle of the saturable absorber. At the same time, it can not only generate mode-locked pulses at different wavelengths, but also generate Q-switched pulses. The main way to realize the optical modulator is that the input continuous light generates laser light due to the introduction of a fixed phase relationship among different resonator in the laser mode to generate laser light. The relationship between these modes interferenceThe laser will generate a series of pulses. Depending on the extremely short duration, it can form a mode-locked laser or a Q-switched laser. The input continuous light is modulated to form pulsed light.

[0030] The components of the titanium boride nanoparticle optical modulator include a light source module 1, a coupler 2, a detection module 3, a saturable absorber based on titanium boride nanoparticles 4, a polarization controller 5, an isolator 6, a gain fiber 7, and a wavelength division multiplexer 8. The light source module 1 is used to provide a pump light source, and the device used is a 980nm or 1570nm pump laser. The polarization controller 5 is used to adjust the polarization state in the optical path, and the polarization controller 5 used is a linear polarization controller 5. The coupler 2 uses a 10dB optical coupler 2, which has a good isolation effect on the input and output signals. A 1560nm / 1980nm polarization-independent optical fiber isolator 6 is selected. In order to ensure the unidirectional operation of the laser in the laser cavity, the wavelength division multiplexer 8 uses 980 / 1560nm and 1550 / 1980nm to form a branch, which is used to branch and export the generated pulse light. The D-type optical fiber deposited with titanium boride nanoparticles is used to realize mode locking or Q-switched laser. The D-type optical fiber is formed by cutting the cladding of the optical fiber along the axial direction to form an optical fiber structure with a D-type polished surface in cross section. The preparation method is to first deposit titanium boride particles on the D-type optical fiber and distribute a small amount of titanium boride nanoparticles in an aqueous solution. A stable suspension is obtained by continuous ultrasonic treatment and no precipitate is found within several hours. Then the solution is dropped on the D-type optical fiber and dried at room temperature to form a D-type optical fiber saturable absorber deposited with titanium boride nanoparticles. As the titanium boride nanoparticles are deposited on the D-type optical fiber, a D-type optical fiber deposited with titanium boride nanoparticles is formed.

[0031] like Figure 4As shown, the laser emitted by the light source module 1 is incident on the coupler 2. After being processed by the coupler 2, 10% of the light emitted from the coupler 2 is incident on the detection module 3 for spectral detection, and the remaining 90% of the light re-enters the loop to detect the spectral changes in the spectrometer, thereby achieving the modulation effect; it is incident on the saturable absorber 4 based on titanium boride nanoparticles. This part, as the saturable absorber, is the main part of the optical modulator. Subsequently, the optical fiber exits from the saturable absorber 4 based on titanium boride nanoparticles and enters the polarization controller 5. The optical fiber with the polarization state adjusted by the polarization controller 5 exits from the polarization controller 5 and enters the isolator 6. When the desired polarization state is reached, the mode-locked or Q-switched laser phenomenon can be observed in the detection module 3. The isolator 6 has a good isolation effect on the input and output light. The optical fiber isolated by the isolator 6 exits and enters the gain fiber 7. The gain fiber 7 amplifies the optical signal. The amplified optical fiber exits from the gain fiber 7 and enters the wavelength division multiplexer 8. The wavelength division multiplexer 8 combines or separates the light. Here, it mainly connects the light source and the coupler 2. The optical fiber exiting from the wavelength division multiplexer 8 is incident on the coupler 2 to form a ring cavity structure.

[0032] Since both the light source module 1 and the wavelength division multiplexer 8 need to be connected to the coupler 2, in order to prevent light from returning to the light source module 1, the fiber optic head of the light source module 1 uses an angled fiber optic head of single-mode fiber SMF-28.

[0033] When the light source module 1 is a pump light source, specifically a 980 nm pump laser, the polarization controller 5 is a linear polarization controller, the coupler 2 uses a 10 dB optical coupler, the isolator 6 is a 1560 nm polarization-independent fiber optic isolator, the wavelength division multiplexer 8 is a 980 / 1560 nm wavelength division multiplexer, and the gain fiber 7 is an erbium-doped fiber, more specifically a 20 cm long erbium-doped quartz fiber, an optical modulator based on titanium boride nanoparticles can achieve Q-switched laser and mode-locked laser in the 1560 nm band.

[0034] When the light source module 1 is a pump light source, specifically a 1570 nm pump laser, the polarization controller 5 is a linear polarization controller, the coupler 2 uses a 10 dB optical coupler, the isolator 6 is a 1980 nm polarization-independent fiber optic isolator, the wavelength division multiplexer 8 is a 1550 / 1980 nm wavelength division multiplexer, and the gain fiber 7 is a thulium-doped fiber, more specifically a 20 cm long thulium-doped quartz fiber, an optical modulator based on titanium boride nanoparticles can achieve mode-locked laser in the 2000 nm band.

[0035] In the present invention, the D-shaped optical fiber for depositing titanium boride nanoparticles can also be replaced by various ways of realizing a saturable absorber, such as a titanium boride nanoparticle thin film, a tapered optical fiber coated with titanium boride nanoparticles, etc. A 20-cm-long erbium-doped or thulium-doped quartz optical fiber is used as the gain medium for laser generation. The detection module 3 is used to detect the central wavelength when mode locking occurs, so as to detect whether it is modulated. The selected detection module 3 is a spectrometer, which directly displays the optical intensity signal. An oscilloscope can also be used instead. Connect the above devices. At the cavity joints of each component, single-mode fiber SMF-28 is used for connection, and then it is welded by an optical fiber welding machine. This welding method can reduce the loss generated by the connection between each device and reduce the threshold power. In the self-built erbium-doped or thulium-doped laser, outside the D-shaped optical fiber deposited with titanium boride nanoparticles, by adjusting the polarization state of the polarizer, the spectral situation is observed.

[0036] Example 1 - A saturable absorber prepared by combining titanium boride nanoparticles with a D-shaped optical fiber and used for Q-switching laser output at 1.56 μm;

[0037] 1. Sample preparation

[0038] Mix 1 mg of titanium boride nanoparticles with 10 mL of deionized water and perform ultrasonic dispersion for 4 hours. Coat the ultrasonic-dispersed mixed solution on the surface of the D-shaped optical fiber and dry it naturally in a vacuum-sealed container. After the water evaporates, the titanium boride nanoparticle powder covers the surface of the D-shaped optical fiber, which is the saturable absorber 4 based on titanium boride nanoparticles.

[0039] 2. Conduct Q-switching test of the fiber laser

[0040] A saturable absorber 4 based on titanium boride nanoparticles provided in this Example 1 is used to self-build an erbium-doped fiber laser at 1560 nm. The optical modulator provided in this Example 1 mainly consists of 8 parts, namely: a light source module 1, a coupler 2, a detection module 3, a saturable absorber 4 based on titanium boride nanoparticles, a polarization controller 5, an isolator 6, a gain fiber 7, and a wavelength division multiplexer 8. Among them, the gain fiber 7 selects an erbium-doped fiber suitable for the 1530 - 1610 nm band, which meets the band range of Example 1. The light source module 1 is pumped by a 980-nm laser, amplified by a 20-cm-long erbium-doped fiber as the gain fiber 7, a polarization-independent isolator 6 at 1560 nm is selected, a polarization controller 5 with a linear polarization controller is selected, and the detection module 3 can be a spectrometer or an oscilloscope.

[0041] Among them, the light source module 1 is connected to the coupler 2 with a 980 nm semiconductor laser as the pumping light source, and the generated pulsed light is branched and exported. 90% of the light is circulated in the laser cavity, and 10% of the light is connected to the detection module 3 - spectrometer through the connection with the pulsed light output end. The optical fiber is combined with the saturable absorber 4 based on titanium boride nanoparticles, and after output, it is connected to a 10 dB polarization controller 5 at 1560 nm to change the polarization state of the optical path. In order to ensure the unidirectional operation of the laser in the laser cavity, an isolator 6 with 1560 nm polarization-independent optical fiber is added to block the reflected light, and then a gain fiber 7 is added to the optical path to amplify the optical signal. In the present invention, an erbium-doped silica fiber is selected as the gain fiber 7. Finally, it is connected to a 980 nm / 1560 nm wavelength division multiplexer 8 for branched export. The 980 nm branch is connected to the pump light source, and the 1560 nm branch forms a ring cavity structure to complete the entire device. Single-mode fiber SMF-28 is used to connect the joints of each component in the cavity of the entire experimental device, and then it is welded by an optical fiber welding machine. This welding method can reduce the loss generated by the connection between each device and reduce the threshold power.

[0042] As Figure 1 shown, an optical modulator with a central wavelength of 1560 nm is fabricated. The modulation depth of this saturable absorber based on titanium boride nanoparticles is 5.2%, the saturation intensity is 2.92 MW / cm2, and the unsaturated loss is 34%, showing good saturable absorber characteristics.

[0043] Example 2 - A saturable absorber prepared by combining titanium boride nanoparticles with a D-type optical fiber and its application in mode-locked laser output at 1.56 μm;

[0044] 1. Sample preparation

[0045] 1 mg of titanium boride nanoparticles is mixed with 10 mL of deionized water and ultrasonically dispersed for 4 hours. The ultrasonically dispersed mixed solution is coated on the surface of the D-type optical fiber and naturally dried in a vacuum-sealed container. After the water evaporates, the titanium boride nanoparticle powder covers the surface of the D-type optical fiber, which is the saturable absorber 4 based on titanium boride nanoparticles.

[0046] 2. Mode-locking test of the fiber laser

[0047] A saturable absorber 4 based on titanium boride nanoparticles provided in this Example 2 is used to self-build an erbium-doped fiber laser at 1560 nm. The optical modulator provided in this Example 2 is mainly composed of 8 parts, namely: light source module 1, coupler 2, detection module 3, saturable absorber 4 based on titanium boride nanoparticles, polarization controller 5, isolator 6, gain fiber 7, wavelength division multiplexer 8. Among them, the erbium-doped optical fiber belongs to the gain fiber 7, which is applicable to the 1530 - 1610 nm band and meets the band range of Example 2.

[0048] The light source module 1 is pumped by a 980 nm laser, amplified by a 20 cm erbium-doped fiber as the gain fiber 7, a 1560 nm polarization-independent isolator 6 is selected, and a polarization controller 5 with a linear polarization controller is selected. The detection module 3 can use a spectrometer or an oscilloscope.

[0049] Among them, the light source module 1 is connected to the coupler 2 with a 980 nm semiconductor laser as the pumping light source, and the generated pulsed light is branched and exported. 90% of the light is circulated in the laser cavity, and 10% of the light is connected to the detection module 3 - spectrometer through the pulsed light output end. The optical fiber is combined with the saturable absorber 4 based on titanium boride nanoparticles, and after output, it is connected to a 10 dB polarization controller 5 at 1560 nm to change the polarization state of the optical path. In order to ensure the unidirectional circulation of the laser in the laser cavity, a 1560 nm polarization-independent fiber isolator 6 is added to block the reflected light, and then a gain fiber 7 is added to the optical path to amplify the optical signal. The present invention selects erbium-doped quartz fiber as the gain fiber 7. Finally, it is connected to a 980 nm / 1560 nm wavelength division multiplexer 8 for branched export. The 980 nm branch is connected to the pump light source, and the 1560 nm branch forms a ring cavity structure to complete the entire device. Single-mode fiber SMF-28 is used to connect the joints of each component in the cavity of the entire experimental device, and then welded by an optical fiber welding machine. This welding method can reduce the loss generated by the connection between each device and reduce the threshold power.

[0050] The main difference from Example 1 is that the mode-locked laser generated in Example 2 is at the picosecond level, while the mode-locked laser generated in Example 1 is at the nanosecond level.

[0051] As Figure 2 shown, an optical modulator with a central wavelength of 1531 nm is fabricated. The modulation depth of this saturable absorber based on titanium boride nanoparticles is 2.2%, the saturation intensity is 2.67 MW / cm2, and the unsaturated loss is 58.4%, having good saturable absorber characteristics.

[0052] Example 3 - A saturable absorber prepared by combining titanium boride nanoparticles with a D-type fiber and used for mode-locked laser output at 2 μm;

[0053] 1. Sample preparation

[0054] 1 mg of titanium boride nanoparticles is mixed with 10 mL of deionized water and ultrasonically dispersed for 4 hours. The ultrasonically dispersed mixed solution is coated on the surface of the D-type fiber and naturally dried in a vacuum-sealed container. After the water evaporates, the titanium boride nanoparticle powder covers the surface of the D-type fiber to obtain the saturable absorber 4 based on titanium boride nanoparticles.

[0055] 2. Conduct mode-locking test of the fiber laser

[0056] A self-built thulium-doped fiber laser at 1960 nm using a saturable absorber 4 based on titanium boride nanoparticles provided in this Example 3. The fiber laser, i.e., the optical modulator, provided in this Example 2 mainly consists of 8 parts, namely: a light source module 1, a coupler 2, a detection module 3, a saturable absorber 4 based on titanium boride nanoparticles, a polarization controller 5, an isolator 6, a gain fiber 7, and a wavelength division multiplexer 8. Among them, the gain fiber 7 is selected as a thulium-doped fiber, applicable to the 1600 nm - 2200 nm band, which conforms to the band range of Example 3.

[0057] The light source module 1 is provided with pump light by a high-power light source laser and accesses a 2μm ring cavity, which is amplified by a 20 cm thulium-doped gain fiber 7. A 1980 nm polarization-independent isolator 6 is selected. By adjusting the polarization state of the linear polarization controller 5, it accesses the coupler 2. Finally, the detection module 3 can use a spectrometer 3 or an oscilloscope.

[0058] Among them, the light source module 1 is connected to the coupler 2 with a high-power semiconductor laser as the pumping light source, and the generated pulsed light is branched and exported. 90% of the part operates in the laser cavity, and 10% of the part is connected to the detection module 3 - spectrometer through the connection with the pulsed light output end. The optical fiber is combined with the saturable absorber 4 based on titanium boride nanoparticles, and after output, it accesses a 1980 nm 10 dB polarization controller 5 to change the polarization state of the optical path. In order to ensure the unidirectional operation of the laser in the laser cavity, a 1980 nm polarization-independent fiber isolator 6 is added for connection to block the reflected light. Then, a gain fiber 7 is added to the optical path to amplify the optical signal. In this invention, a thulium-doped quartz fiber is selected as the gain fiber 7. Finally, it is connected to a 1550 nm / 1980 nm wavelength division multiplexer 8 for branched export. The 1550 nm branch accesses the pump light source, and the 1980 nm branch forms a ring cavity structure to complete the entire device. In the entire experimental device, single-mode fiber SMF-28 is used to connect the joints of each component in the cavity, and then it is welded by a fiber welding machine. This welding method can reduce the loss generated by the connection between each device and reduce the threshold power.

[0059] As Figure 3 shown, an optical modulator with a central wavelength of 1921 nm is fabricated. Different from Examples 1 and 2, the selected gain fiber 7 is a thulium-doped fiber for amplification. The modulation depth of this optical modulator is 2.2%, the saturation intensity is 5.34 MW / cm2, and the unsaturated loss is 58.3%, having good saturable absorber characteristics.

Claims

1. Application of titanium boride nanoparticles in preparing a saturable absorber, characterized in that the application of titanium boride nanoparticles in preparing a saturable absorber for an optical modulator.

2. A saturable absorber based on titanium boride nanoparticles, characterized in that it is a saturable absorber based on titanium boride nanoparticles coated on a D-shaped optical fiber.

3. A saturable absorber based on titanium boride nanoparticles according to claim 2, characterized in that a saturable absorber based on titanium boride nanoparticles coated on a D-shaped optical fiber is prepared by mixing titanium boride nanoparticles and deionized water in a ratio of 1 mg of titanium boride nanoparticles to 10 ml of deionized water, ultrasonically dispersing for 4 hours, coating the ultrasonically dispersed mixed solution on the surface of a D-shaped or tapered optical fiber, and naturally drying in a vacuum-sealed container. After the water evaporates, the titanium boride nanoparticle powder covers the surface of the D-shaped or tapered optical fiber to form the saturable absorber.

4. An optical modulator prepared using the saturable absorber based on titanium boride nanoparticles according to any one of claims 2-3, characterized in that it includes a light source module (1), a coupler (2), a detection module (3), a saturable absorber based on titanium boride nanoparticles (4), a polarization controller (5), an isolator (6), a gain fiber (7), and a wavelength division multiplexer (8); wherein the laser emitted by the light source module (1) is incident into the coupler (2). After being processed by the coupler (2), 10% of the light emitted from the coupler (2) is incident into the detection module (3), and the remaining 90% of the light is incident into the saturable absorber based on titanium boride nanoparticles (4). Subsequently, the optical fiber exits from the saturable absorber based on titanium boride nanoparticles (4) and enters the polarization controller (5). The optical fiber with the polarization state adjusted by the polarization controller (5) exits from the polarization controller (5) and enters the isolator (6). The optical fiber isolated by the isolator (6) exits and enters the gain fiber (7). The gain fiber (7) amplifies the optical signal. The amplified optical fiber exits from the gain fiber (7) and enters the wavelength division multiplexer (8). The optical fiber exiting from the wavelength division multiplexer (8) is incident into the coupler (2) to form a ring cavity structure.

5. An optical modulator prepared using the saturable absorber based on titanium boride nanoparticles according to claim 4, characterized in that the light source module (1) is a pump light source, the polarization controller (5) is a linear polarization controller, the coupler (2) is a 10 dB optical coupler, the isolator (6) is a 1560 nm polarization-independent fiber isolator, the wavelength division multiplexer (8) is a 980 / 1560 nm wavelength division multiplexer, the gain fiber (7) is an erbium-doped fiber, and the detection module (3) is a spectrometer or an oscilloscope.

6. An optical modulator prepared using the saturable absorber based on titanium boride nanoparticles according to claim 5, characterized in that A single-mode fiber SMF-28 is used to connect between the light source module (1) and the coupler (2), between the coupler (2) and the detection module (3), between the detection module (3) and the saturable absorber based on titanium boride nanoparticles (4), between the saturable absorber based on titanium boride nanoparticles (4) and the polarization controller (5), between the polarization controller (5) and the isolator (6), between the isolator (6) and the gain fiber (7), between the gain fiber (7) and the wavelength division multiplexer (8), and between the wavelength division multiplexer (8) and the coupler (2).

7. The optical modulator prepared from the saturable absorber based on titanium boride nanoparticles according to claim 4, characterized in that when the light source module (1) is a pump light source, specifically a 980 nm pump laser, the polarization controller (5) is a linear polarization controller, the coupler (2) is a 10 dB optical coupler, the isolator (6) is a 1560 nm polarization-independent fiber isolator, the wavelength division multiplexer (8) is a 980 / 1560 nm wavelength division multiplexer, and the gain fiber (7) is a 20 cm long erbium-doped quartz fiber, an optical modulator based on titanium boride nanoparticles can achieve Q-switching laser and mode-locking laser in the 1560 nm band.

8. The optical modulator prepared from the saturable absorber based on titanium boride nanoparticles according to claim 4, characterized in that when the light source module (1) is a 1570 nm pump laser, the polarization controller (5) is a linear polarization controller, the coupler (2) is a 10 dB optical coupler, the isolator (6) is a 1980 nm polarization-independent fiber isolator, the wavelength division multiplexer (8) is a 1550 / 1980 nm wavelength division multiplexer, and the gain fiber (7) is a 20 cm long thulium-doped quartz fiber, an optical modulator based on titanium boride nanoparticles can achieve mode-locking laser in the 2000 nm band.

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