Frequency modulation device based on microstructured fiber acousto-optic mode-locking effect

Abstract

The application discloses a frequency regulation device based on a micro-structured optical fiber acousto-optic mode-locking effect, which changes the gas concentration distribution mode in the air hole of the micro-structured optical fiber, changes the refractive index distribution mode of the micro-structured optical fiber, changes the acoustic field mode and the acoustic field resonance frequency of the micro-structured optical fiber, changes the gas pressure distribution mode in the air hole of the micro-structured optical fiber, changes the stress distribution mode of the micro-structured optical fiber, and changes the acoustic field mode and the acoustic field resonance frequency of the micro-structured optical fiber; and the application realizes the mode locking of the output pulse and the real-time regulation of the pulse frequency through the steps of acoustic field mode calling, inflation mode calling and loading inflation mode.

Description

Technical Field

[0001] This invention relates to the field of laser technology, and in particular to a frequency control device based on the acousto-optic mode-locking effect of microstructured optical fibers. Background Technology

[0002] Compared to solid-state lasers, fiber lasers offer advantages such as superior beam quality, higher efficiency, better heat dissipation, and more compact structure, leading to their widespread applications in communications, manufacturing, medical, laser printing, and military fields. Passively mode-locked fiber lasers, in particular, generate ultrashort pulses with high peak power, short duration, and high repetition frequency, making them suitable for optical frequency combs. Optical frequency combs exhibit extremely high stability and resolution in both the time and frequency domains and are now widely used in laser frequency measurement, precision spectral analysis, and precision distance measurement.

[0003] Passive harmonic mode-locked fiber lasers can generate ultra-short pulse sequences with extremely high repetition rates, and the repetition rate of the harmonic pulses is easily adjustable. Compared to fundamental frequency mode-locked pulsed lasers, they offer superior performance.

[0004] Mode-locked fiber lasers based on the acousto-optic effect utilize the GHz-level acousto-optic effect in microstructured optical fibers to increase the repetition frequency of the output pulsed laser. However, once the laser structure is fixed, controlling the laser pulse repetition frequency presents challenges.

[0005] Therefore, it is of great significance to construct an acousto-optic mode-locked fiber laser that is easy to control the repetition frequency of laser pulses. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the present invention provides a frequency control device based on the acousto-optic mode-locking effect of microstructured optical fiber, which aims to achieve mode locking of output pulse and real-time control of pulse frequency through steps such as sound field mode calling, inflation mode calling, and loading inflation mode, thereby improving the performance of optical frequency combs and other applications.

[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0008] The present invention provides a frequency control device based on the acousto-optic mode-locking effect of microstructured optical fiber, characterized in that it includes a pump source, a single-mode optical fiber, a wavelength division multiplexer, a gain medium, an isolator, a polarization controller, a frequency control module, and an output coupler.

[0009] The pump source is used to provide pump energy; the pump energy reaches the gain medium via the coupling of the wavelength division multiplexer and generates laser light in the gain medium;

[0010] After being transmitted unidirectionally through the isolator, the laser enters the polarization controller, where the polarization state of the laser is changed.

[0011] The frequency control module performs mode locking and frequency control on the laser after changing the polarization state, resulting in a mode-locked and frequency-controlled laser. Part of the laser is directly output through the output coupler, while another part of the laser is coupled through the wavelength division multiplexer and then re-enters the gain medium to enter the next cycle.

[0012] The frequency control device based on the acousto-optic mode-locking effect of microstructured optical fiber according to the present invention is characterized in that the frequency control module includes: microstructured optical fiber, air pump, air chamber and controller;

[0013] One end of the air chamber has multiple independently openable and closeable air inlets and outlets, and each air inlet and outlet is controlled by the controller. Each air inlet and outlet is connected to an air hole in the microstructure optical fiber.

[0014] The other end of the air chamber is connected to the output coupler via the single-mode optical fiber;

[0015] The air pump is used to extract or fill gas into the air chamber;

[0016] The frequency modulation device based on the acousto-optic mode-locking effect of microstructured optical fiber described in this invention is also characterized in that the frequency modulation module performs mode locking and frequency modulation according to the following steps:

[0017] Step 1: Establish an inflation pattern database:

[0018] The air pump is used to fill the air chamber, and the controller controls the opening and closing combination of each air inlet and outlet of the air chamber, thereby loading different gas concentrations or gas pressures onto each air hole of the microstructure optical fiber, thus forming different gas concentration distribution patterns or gas pressure distribution patterns in the microstructure optical fiber, thereby establishing an air filling pattern database.

[0019] Step 2: Establish a sound field pattern database:

[0020] The refractive index distribution mode corresponding to the microstructured optical fiber under different gas concentration distribution modes is calculated, the stress distribution mode corresponding to the microstructured optical fiber under different gas pressure distribution modes is calculated, and the acoustic field mode and the resonant frequency corresponding to each refractive index distribution mode and stress distribution mode are calculated, thereby establishing an acoustic field mode database.

[0021] Step 3: Sound field mode activation:

[0022] Based on the desired pulse mode lock frequency, the sound field mode corresponding to the desired pulse mode lock frequency is called from the sound field mode database;

[0023] Step 4: Inflation Mode Activation:

[0024] Based on the sound field mode called in step 3, the corresponding inflation mode is called from the inflation mode database;

[0025] Step 5: Load inflation mode:

[0026] The air pump, air chamber and controller are used to apply the inflation mode called in step 4 to the microstructure optical fiber;

[0027] Step 6: Establish the desired pulse mode lock frequency:

[0028] Based on the inflation mode loaded in step 5, the desired acoustic field mode is formed in the microstructured optical fiber, and the desired pulse mode locking frequency under pulse mode locking is established based on the acousto-optic mode locking effect.

[0029] Step 7: Pulse mode lock frequency switching:

[0030] Based on the new desired pulse mode lock frequency, repeat steps 3 to 6 to establish the pulse mode lock frequency in the new sound field mode, so as to achieve the control of the pulse mode lock frequency.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] 1. This invention integrates frequency control devices into a single module, thereby achieving a compact structure for the frequency control device.

[0033] 2. This invention obtains a corresponding sound field mode database by calculating different inflation modes. By calling the database, the controller can change the corresponding inflation mode in real time to obtain the desired pulse lock frequency, while simultaneously switching the pulse lock frequency. Different needs require different pulse lock frequencies; this invention facilitates switching and adjusting the pulse lock frequency, expanding the application range of lasers.

[0034] 3. This invention can obtain the desired pulse frequency by calling an established database. Compared with mode-locked lasers based on nonlinear polarization rotation for switching pulse frequencies, it has higher stability and does not require adjustment of the laser structure. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the frequency control device based on the acousto-optic mode-locking effect of microstructured optical fiber according to the present invention;

[0036] Figure 2This is a schematic diagram illustrating the steps of using a frequency control module to achieve real-time frequency control in this invention.

[0037] The numbers in the diagram are: 1001-Pump source, 1002-Single-mode fiber, 1003-Coupler, 1004-Gas medium, 1005-Isolator, 1006-Polarization controller, 1007-Frequency control module, 1008-Output coupler, 2001-Microstructure fiber, 2002-Air pump, 2003-Air chamber, 2004-Controller. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0039] In this embodiment, a frequency modulation device based on the acousto-optic mode-locking effect of microstructured optical fibers, such as... Figure 1 As shown, it includes: a pump source 1001, a single-mode fiber 1001, a wavelength division multiplexer 1003, a gain medium 1004, an isolator 1005, a polarization controller 1006, a frequency control module 1007, and an output coupler 1008.

[0040] Pump source 1001 is used to provide pump energy; the pump energy is coupled to gain medium 1004 via wavelength division multiplexer 1003 and generates laser in gain medium 1004;

[0041] After the laser is transmitted unidirectionally through the isolator 1005, it enters the polarization controller 1006, where the polarization state of the laser is changed.

[0042] The frequency control module 1007 performs mode locking and frequency control on the laser after changing the polarization state, resulting in a laser with mode locking and frequency control. Part of the laser is directly output through the output coupler 1008, while the other part of the laser is coupled through the wavelength division multiplexer 1003 and re-enters the gain medium 1004 to enter the next cycle.

[0043] In a specific implementation, the frequency control device 1007 includes: a microstructured optical fiber 2001, which provides an acoustic field mode and locks the pulse mode in the resonant cavity based on the acousto-optic mode-locking effect; an air pump 2002, which changes the gas concentration or gas pressure filled into the microstructured optical fiber; and an air chamber 2003, which is used to connect the microstructured optical fiber 2001 and the single-mode optical fiber 1002, and is connected to the air pump 2002.

[0044] By pumping gas into or out of the gas chamber 2003 using the air pump 2002, the gas concentration is changed, thereby altering the refractive index distribution of the air holes in the microstructured optical fiber, and consequently changing the acoustic mode resonant frequency of the microstructured optical fiber. Similarly, by pumping gas into or out of the gas chamber 2001, the gas pressure is changed, thereby altering the stress distribution of the air holes in the microstructured optical fiber, and consequently changing the acoustic mode resonant frequency of the microstructured optical fiber. Based on the acousto-optic mode-locking effect, different acoustic mode resonant frequencies correspond to different pulse mode locking frequencies.

[0045] The gas chamber 2003 has multiple independently controllable air inlets and outlets, controlled by a controller 2004, and connected to each air hole in the microstructured optical fiber 2001. Different gas concentrations or gas pressures can be applied to each air hole to form different gas concentration distribution patterns or gas pressure distribution patterns in the microstructured optical fiber, thereby forming a controllable refractive index distribution pattern or stress distribution pattern in the microstructured optical fiber.

[0046] In this embodiment, a frequency modulation method based on the acousto-optic mode-locking effect of microstructured optical fibers is as follows: Figure 2 As shown, it consists of seven steps, including:

[0047] Step 1: Establish an inflation pattern database:

[0048] The air pump 2002 is used to fill the air chamber 2003 with air. The controller 2004 controls the opening and closing combination of each air inlet and outlet of the air chamber 2003, thereby loading different gas concentrations or gas pressures onto each air hole of the microstructure optical fiber 2001, thus forming different gas concentration distribution patterns or gas pressure distribution patterns in the microstructure optical fiber 2001, thereby establishing an air filling pattern database.

[0049] Step 2: Establish a sound field pattern database:

[0050] The refractive index distribution mode of microstructured optical fiber 2001 under different gas concentration distribution modes is calculated, the stress distribution mode of microstructured optical fiber 2001 under different gas pressure distribution modes is calculated, and the acoustic field mode and the resonant frequency corresponding to each refractive index distribution mode and stress distribution mode are calculated, thereby establishing an acoustic field mode database.

[0051] Step 3: Sound field mode activation:

[0052] Based on the desired pulse mode lock frequency, call the sound field mode corresponding to the desired pulse mode lock frequency from the sound field mode database;

[0053] Step 4: Inflation Mode Activation:

[0054] Based on the sound field mode called in step 3, the corresponding inflation mode is called from the inflation mode database;

[0055] Step 5: Load inflation mode:

[0056] The inflation mode invoked in step 4 is applied to the microstructure optical fiber 2001 through the air pump 2002, air chamber 2003 and controller 2004.

[0057] Step 6: Establish the desired pulse mode lock frequency:

[0058] Based on the inflation mode loaded in step 5, the desired acoustic field mode is formed in the microstructure fiber 2001, and the desired pulse mode locking frequency under pulse mode locking is established based on the acousto-optic mode locking effect.

[0059] Step 7: Pulse mode lock frequency switching:

[0060] Based on the new desired pulse mode lock frequency, repeat steps 3 to 6 to establish the pulse mode lock frequency in the new sound field mode, so as to achieve the control of the pulse mode lock frequency.

[0061] Figure 1 The embodiment shown is a ring cavity structure. The present invention is not limited to a ring cavity structure, and can also be applied to other structures such as linear cavities and composite cavities.

Claims

1. A frequency control device based on the acousto-optic mode-locking effect of microstructured optical fibers, characterized in that, It includes a pump source (1001), a single-mode fiber (1002), a wavelength division multiplexer (1003), a gain medium (1004), an isolator (1005), a polarization controller (1006), a frequency control module (1007), and an output coupler (1008). The pump source (1001) is used to provide pump energy; the pump energy is coupled to the gain medium (1004) via the wavelength division multiplexer (1003) and generates laser light in the gain medium (1004); After being transmitted unidirectionally through the isolator (1005), the laser enters the polarization controller (1006), and the polarization state of the laser is changed in the polarization controller (1006). The frequency control module (1007) performs mode locking and frequency control on the laser after changing the polarization state to obtain a laser with mode locking and frequency control. Part of the laser is directly output through the output coupler (1008), and another part of the laser is coupled through the wavelength division multiplexer (1003) and re-enters the gain medium (1004) to enter the next cycle.

2. The frequency modulation device based on the acousto-optic mode-locking effect of microstructured optical fiber as described in claim 1, characterized in that, The frequency control module (1007) includes: a microstructure optical fiber (2001), an air pump (2002), an air chamber (2003), and a controller (2004); One end of the air chamber (2003) has multiple independently openable and closeable air inlets and outlets, and each air inlet and outlet is controlled by the controller (2004). Each air inlet and outlet is connected to an air hole in the microstructure optical fiber (2001). The other end of the air chamber (2003) is connected to the output coupler (1008) via the single-mode optical fiber (1002); The air pump (2002) is used to extract or fill gas into the air chamber (2003).

3. The frequency modulation device based on the acousto-optic mode-locking effect of microstructured optical fiber as described in claim 2, characterized in that, The frequency control module (1007) performs mode locking and frequency control according to the following steps: Step 1: Establish an inflation pattern database: The air pump (2002) is used to inflate the air chamber (2003), and the controller (2004) controls the opening and closing combination of each air inlet and outlet of the air chamber (2003), thereby loading different gas concentrations or gas pressures onto each air hole of the microstructure optical fiber (2001), thereby forming different gas concentration distribution patterns or gas pressure distribution patterns in the microstructure optical fiber (2001), and thus establishing an inflation pattern database. Step 2: Establish a sound field pattern database: The refractive index distribution mode of the microstructured optical fiber (2001) under different gas concentration distribution modes is calculated, the stress distribution mode of the microstructured optical fiber (2001) under different gas pressure distribution modes is calculated, and the acoustic field mode and the resonant frequency corresponding to each refractive index distribution mode and stress distribution mode are calculated, thereby establishing an acoustic field mode database. Step 3: Sound field mode activation: Based on the desired pulse mode lock frequency, the sound field mode corresponding to the desired pulse mode lock frequency is called from the sound field mode database; Step 4: Inflation Mode Activation: Based on the sound field mode called in step 3, the corresponding inflation mode is called from the inflation mode database; Step 5: Load inflation mode: The air pump (2002), air chamber (2003), and controller (2004) apply the inflation mode invoked in step 4 to the microstructure optical fiber (2001); Step 6: Establish the desired pulse mode lock frequency: Based on the inflation mode loaded in step 5, the desired acoustic field mode is formed in the microstructure optical fiber (2001), and the desired pulse mode locking frequency under pulse mode locking is established based on the acousto-optic mode locking effect. Step 7: Pulse mode lock frequency switching: Based on the new desired pulse mode lock frequency, repeat steps 3 to 6 to establish the pulse mode lock frequency in the new sound field mode, so as to achieve the control of the pulse mode lock frequency.

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