All-fiber visible light laser with switchable and tunable wavelength

Abstract

The invention provides a wavelength-switchable and tunable all-fiber visible light laser. The wavelength-switchable and tunable all-fiber visible light laser comprises a pump laser, a first dichroscope, a single-mode gain fiber, a second dichroscope and a coupling distance regulation and control device, pump light output by the pump laser is directly coupled into the single-mode gain optical fiber through the first dichroscope and is absorbed by the single-mode gain optical fiber to generate fluorescent light, and the fluorescent light is transmitted to the second dichroscope, is reflected back to the output end of the single-mode gain optical fiber through the second dichroscope and then is coupled back to the single-mode gain optical fiber. The fluorescence is reflected and amplified for multiple times to form laser which is output through the output optical fiber; and the second dichroscope is arranged on the coupling distance regulation and control device and is used for regulating and controlling the coupling distance between the output end of the single-mode gain optical fiber and the second dichroscope so as to realize laser wavelength switching and tuning. According to the invention, flexible switching among cyan light, orange light and red light can be realized, tuning of respective wavelength ranges can be realized, and the device has the characteristics of fast switching speed and wide tuning range.

Description

Technical Field

[0001] This invention relates to the field of visible light fiber laser technology, and more particularly to an all-fiber visible light laser with switchable and tunable wavelengths. Background Technology

[0002] Lasers in the visible light (390 nm – 780 nm) band show broad application prospects in fields such as optical communication, biomedical imaging, spectral analysis, and laser displays. Currently, methods for achieving visible light laser output mainly include: using nonlinear effects to achieve frequency conversion to generate visible light, and utilizing upconversion phenomena to generate visible light in fibers or crystals doped with rare ions. However, traditional visible light fiber lasers mostly only output a single wavelength, and there are many limitations in wavelength tuning, such as narrow tuning range, low tuning accuracy, slow response speed, and complex structure. These shortcomings seriously restrict the further application and development of visible light fiber lasers in related fields. Summary of the Invention

[0003] To address the technical problems existing in the prior art, this invention proposes a wavelength-switchable and tunable all-fiber visible light laser, which enables flexible switching of the output fiber laser wavelength between red, orange and cyan lasers, and achieves tunability within their respective small wavelength ranges.

[0004] To achieve the above technical objectives, the specific technical solution adopted by the present invention is as follows: A wavelength-switchable and tunable all-fiber visible laser includes a pump laser, a first dichroic mirror, a single-mode gain fiber, a second dichroic mirror, and a coupling distance control device. The pump light output from the pump laser is directly coupled into the single-mode gain fiber via the first dichroic mirror. After being absorbed by the single-mode gain fiber, fluorescence is generated. The fluorescence is transmitted to the second dichroic mirror, reflected back to the output end of the single-mode gain fiber, and then coupled back into the single-mode gain fiber. After being amplified by multiple reflections, the fluorescence forms a laser and is output through the output fiber. The second dichroic mirror is placed on the coupling distance control device. By adjusting the coupling distance between the single-mode gain fiber output end and the second dichroic mirror, laser wavelength switching and tuning can be achieved. The output pigtail of the pump laser is fused to the pigtail of the first dichroic mirror. The second dichroic mirror pigtail is fused to the output pigtail of the wavelength-switchable and tunable all-fiber visible laser. The first dichroic mirror is an optical fiber end-face dielectric film mirror with high transmittance for lasers with a wavelength of 443 nm and high reflectivity for lasers with wavelengths of 493 nm, 603 nm, and 635 nm. The second dichroic mirror is a fiber end-face dielectric film mirror with high reflectivity to lasers with wavelengths of 493 nm, 603 nm, and 635 nm.

[0005] Preferably, the coupling distance control device includes a connecting device and an electric displacement stage; The connecting device is used to fix the single-mode gain fiber output end and the output fiber input end; The electric displacement stage is connected to the output end of the single-mode gain fiber and the second dichroic mirror, respectively, and is used to adjust the coupling distance between the output end of the single-mode gain fiber and the second dichroic mirror.

[0006] Preferably, the connecting device is a sleeve or a V-groove; The electric displacement stage is a piezoelectric ceramic electric displacement stage or a stepper motor electric displacement stage.

[0007] Preferably, the single-mode gain fiber is a single-mode rare-earth-doped fluoride fiber.

[0008] Preferably, in the single-mode rare-earth-doped fluoride optical fiber, the dopant ions are praseodymium, holmium, or dysprosium, and the concentration range of the dopant ions is 1000 ppm to 10000 ppm.

[0009] Preferably, the second dichroic mirror is an optical fiber end-face dielectric film mirror with a transmittance of 8.9% for laser with a wavelength of 493 nm, 45.5% for laser with a wavelength of 603 nm, and 80.4% for laser with a wavelength of 635 nm.

[0010] Preferably, the pump laser is a semiconductor laser with an output laser wavelength range of 440 nm to 455 nm.

[0011] Preferably, the output pigtail of the pump laser is a multimode fiber with a core diameter of 105 μm and a cladding diameter of 125 μm; The core diameter of the first dichroic mirror fiber is 105 μm and the cladding diameter is 125 μm.

[0012] Preferably, the second dichroic mirror pigtail is a multimode optical fiber with a core diameter of 105 μm and a cladding diameter of 125 μm; The output pigtail of the wavelength-switchable and tunable all-fiber visible laser is a multimode fiber with a core diameter of 105 μm and a cladding diameter of 125 μm.

[0013] Compared with the prior art, the beneficial technical effects of the present invention are as follows: This invention provides a wavelength-switchable and tunable all-fiber visible laser. By simply adjusting the coupling distance between the output end of the gain fiber and the second dichroic mirror, the output fiber laser wavelength can be flexibly switched between cyan, orange, and red light, and each wavelength range can be tunable. It features fast switching speed and wide tuning range, which greatly expands the application scenarios of visible fiber lasers.

[0014] The main structure of this invention consists of a pump laser, a first dichroic mirror, a gain fiber, and a second dichroic mirror, enabling all-fiber operation and a simple structure. Furthermore, this invention uses a coupling distance adjustment device to regulate the coupling distance between the output end of the gain fiber and the second dichroic mirror, making it easy to operate, cost-effective, and highly practical and economical. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0016] Figure 1 A structural diagram of a wavelength-switchable and tunable all-fiber visible laser provided for one embodiment; Figure 2 Rare-earth ion energy level diagram of a wavelength-switchable and tunable all-fiber visible laser provided as an embodiment; Figure 3 A gain fiber emission cross-section curve of a wavelength-switchable and tunable all-fiber visible laser provided as an embodiment; Figure 4 Transmittance curves of the first and second dichroic mirrors of a wavelength-switchable and tunable all-fiber visible laser provided as an embodiment; Figure 5 A detailed diagram of fiber end-face coupling of a wavelength-switchable and tunable all-fiber visible laser provided for one embodiment; Figure 6 A structural diagram of a coupling distance control device for a wavelength-switchable and tunable all-fiber visible laser is provided for one embodiment. Figure 7 The figure shows the total loss numerical simulation results of a wavelength-switchable and tunable all-fiber visible laser under different wavelengths and different coupling distances, as provided in one embodiment. Figure 8The output laser spectrum of a wavelength-switchable and tunable all-fiber visible laser is provided as an embodiment. Attached image captions: 1. Pump laser; 2. First dichroic mirror; 3. Single-mode gain fiber; 4. Second dichroic mirror; 5. Coupling distance control device; 6. End cap. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Reference Figure 1 One embodiment provides a wavelength-switchable and tunable all-fiber visible laser, including a pump laser 1, a first dichroic mirror 2, a single-mode gain fiber 3, a second dichroic mirror 4, and a coupling distance control device 5. The pump light output from the pump laser 1 is directly coupled into the single-mode gain fiber 3 via the first dichroic mirror 2. After being absorbed by the single-mode gain fiber 3, fluorescence is generated. The fluorescence is transmitted to the second dichroic mirror 4, reflected back to the output end of the single-mode gain fiber by the second dichroic mirror 4, and then coupled back into the single-mode gain fiber 3. After being amplified by multiple reflections, the fluorescence forms a laser and is output through the output fiber. The second dichroic mirror 4 is placed on the coupling distance control device 5. By adjusting the coupling distance between the single-mode gain fiber output end and the second dichroic mirror 4, laser wavelength switching and tuning can be achieved. The output pigtail of the pump laser 1 is fused to the pigtail of the first dichroic mirror 2; The second dichroic mirror pigtail is fused to the output pigtail of the wavelength-switchable and tunable all-fiber visible laser. The first dichroic mirror 2 is an optical fiber end-face dielectric film mirror with high transmittance for lasers with a wavelength of 443 nm and high reflectivity for lasers with wavelengths of 493 nm, 603 nm, and 635 nm. The second dichroic mirror 4 is a fiber end face dielectric film mirror with high reflectivity to lasers with wavelengths of 493 nm, 603 nm, and 635 nm.

[0019] The second dichroic mirror 4 is connected to an end cap 6. After the fluorescence is amplified by multiple reflections, it forms a laser and is transmitted from the output end of the second dichroic mirror 4 to the output optical fiber, and then output through the end cap 6.

[0020] By adjusting the coupling distance between the output end of the single-mode gain fiber and the second dichroic mirror 4, the output fiber laser wavelength can be flexibly switched between cyan, orange and red light, and the wavelength range of each can be tunable.

[0021] In a preferred embodiment, the single-mode gain fiber 3 is a single-mode rare-earth-doped fluoride fiber. In the single-mode rare-earth-doped fluoride fiber, the dopant ions are praseodymium, holmium, or dysprosium, and the concentration of the dopant ions ranges from 1000 ppm to 10000 ppm.

[0022] The pump laser 1 is a semiconductor laser with an output laser wavelength range of 440 nm to 455 nm.

[0023] Reference Figure 2 In this embodiment, a single-mode praseodymium-doped fluoride fiber is selected as the single-mode gain fiber 3, and a 443 nm laser diode pump source is selected as the pump laser 1. The pump light generated by the 443 nm laser diode pump source is transmitted to the single-mode praseodymium-doped fluoride fiber through the first dichroic mirror 2. The 443 nm pump light causes the laser located at... 3 Pr at the H4 level 3+ Ions are excited to their ground state state through absorption. 3 P2 energy level, when Pr 3+ Ions from 3 When the P2 energy level undergoes transitions: transitions to... 3 The H4 energy level emits cyan light at 493 nm and transitions to [a higher energy level]. 3 The H6 energy level emits orange light at 603 nm, transitioning to... 3 The F2 energy level emits 635 nm red light.

[0024] Reference Figure 3 As can be seen, in this embodiment, the pump light generated by the 443nm laser diode pump source is transmitted to the single-mode praseodymium-doped fluoride fiber via the first dichroic mirror 2, exciting cyan light at 493nm, orange light at 603nm, and red light at 635nm. The emission cross-section of the red light is larger than that of the orange light, which is larger than that of the green light. Specifically, the emission cross-section of the single-mode gain fiber 3 at a wavelength of 493nm is... The emission cross section at a wavelength of 493 nm is The emission cross section at a wavelength of 493 nm is .

[0025] In a preferred embodiment, the second dichroic mirror 4 is a fiber end-face dielectric film mirror with a transmittance of 8.9% for laser light at a wavelength of 493 nm, 45.5% for laser light at a wavelength of 603 nm, and 80.4% for laser light at a wavelength of 635 nm. Since the emission cross-section of red light is larger than that of green light in the gain fiber 3, even at lower pump power, red light may reach the threshold first and begin oscillating, thereby suppressing the oscillation of orange and green light. Therefore, by setting the second dichroic mirror 4 to have a transmittance of 8.9% for laser light at a wavelength of 493 nm, 45.5% for laser light at a wavelength of 603 nm, and 80.4% for laser light at a wavelength of 635 nm, the transmittance of the second dichroic mirror 4 in the red light region is reduced, thereby ensuring that orange and green light can also oscillate stably within the cavity during coupling distance adjustment. By reducing the feedback of red light, the power distribution between red light and other wavelength modes can be effectively controlled, ensuring stable output of orange and green light.

[0026] In a preferred embodiment, the coupling distance control device 5 includes a connecting device and an electric displacement stage; The connecting device is used to fix the single-mode gain fiber output end and the output fiber input end; The electric displacement stage is connected to the output end of the single-mode gain fiber and the second dichroic mirror 4, respectively, and is used to adjust the coupling distance between the output end of the single-mode gain fiber and the second dichroic mirror 4.

[0027] The connecting device is a sleeve or a V-groove; The electric displacement stage is a piezoelectric ceramic electric displacement stage or a stepper motor electric displacement stage.

[0028] Reference Figure 5 In one embodiment, the connecting device is a sleeve used to fix the output end of the single-mode gain fiber and the second dichroic mirror 4, so that the fluorescence generated by the single-mode gain fiber 3 can be directly coupled back to the single-mode gain fiber 3 after being reflected by the second dichroic mirror 4, and formed into laser output after multiple reflections and amplification. The fixing device has a simple structure and low cost.

[0029] Reference Figure 6 In one embodiment, the electric displacement stage is a piezoelectric ceramic electric displacement stage. By using the piezoelectric ceramic electric displacement stage to control the horizontal displacement of the second dichroic mirror 4, it is possible to achieve nanometer or even sub-nanometer level micro-displacement, improve the control accuracy of the coupling distance between the single-mode gain fiber output end and the second dichroic mirror 4, and achieve a better control effect. By adjusting the coupling distance, the coupling loss of different wavelength lasers can be changed, selectively suppressing or enhancing light of a specific wavelength, and realizing the switchability and tunability of the output laser wavelength.

[0030] Since the wavelength-switchable and tunable all-fiber visible laser has an all-fiber structure, adjusting the coupling distance between the single-mode gain fiber output end and the second dichroic mirror 4 is equivalent to adjusting the coupling loss in the process of the laser output from the gain fiber 3, reflected by the second dichroic mirror 4, and directly coupled back to the gain fiber 3. In the wavelength-switchable and tunable all-fiber visible laser, the second dichroic mirror 4 is a dielectric film mirror at the fiber end face, and the fiber is a single-mode gain fiber 3. Therefore, the above coupling loss can be compared with the coupling loss of a single-mode fiber.

[0031] Because the core size of single-mode fiber is very small and does not meet the geometric optics requirements, wave theory is used for analysis, and the coupling coefficient is determined. Calculated using modal field overlap:

[0032] in, It is the vacuum permittivity; The vacuum permeability; For pattern The light field distribution; For pattern The light field distribution; It is a conjugate operator; This refers to the overlapping area between the transmitting and receiving optical fibers. For single-mode fiber, the core only transmits the fundamental mode (LP). 01 ), connection loss for:

[0033] in, The coupling coefficient of the fundamental mode; Within a single-mode fiber, the mode field approximates a Gaussian function distribution. The beam waist is located at the fiber end face, and its optical field distribution is as follows:

[0034] in, The optical field distribution at the fiber end face; Let be the waist radius of the Gaussian beam. The numerical aperture of the optical fiber; The fiber core radius is... The wavelength is the vacuum wavelength.

[0035] Outside the optical fiber, at a distance from the end face of the optical fiber Light field distribution at for:

[0036] in, The wavenumber of the laser in the end face gap. The refractive index of the end face gap, The Rayleigh value of the Gaussian beam. For additional phase, Let be the radius of the Gaussian beam spot at point z. Let be the radius of curvature of the equiphase surface.

[0037] Based on the Gaussian approximation, the single-mode fiber connection loss is obtained. :

[0038] In the formula,

[0039]

[0040]

[0041]

[0042] in, This refers to the deviation of the fiber core. This refers to the fiber end face gap distance. The tilt angle of the fiber optic output end. The angle between the fiber tilt direction and the plane containing the fiber axis and lateral displacement. and The mode field radii of the transmitting and receiving optical fibers, respectively. Represents the refractive index of the fiber core.

[0043] When a laser beam propagates in a single-mode gain fiber 3, and is output from and reflected from the single-mode gain fiber 3 before being directly coupled back to the single-mode gain fiber 3, if the coupling distance is greater than the Rayleigh value, the laser spot radius will change. The amplitude of the laser beam increases rapidly, causing a mismatch between the spot radius and the mode field radius of the single-mode gain fiber 3 when coupling back to the single-mode gain fiber 3, thus resulting in coupling loss. Since the output end of the single-mode gain fiber is fixedly connected to the second dichroic mirror 4 via a connecting device, the axial deviation during laser coupling... , axis tilt angle Other parameters Coupling loss caused ( Since the coupling distance (gap distance between fiber end faces) remains basically unchanged, the coupling loss caused solely by the coupling distance is calculated. change:

[0044]

[0045]

[0046] in, V Let be the normalized propagation constant. This refers to the core radius of the receiving optical fiber.

[0047] In one embodiment, the gain fiber 3 used It is 0.10. It is 2.5 μm.

[0048] At the same time, the loss effect of the end-face coating on lasers of different wavelengths also needs to be considered:

[0049] in, The Fresnel reflection loss is due to the gap between the end faces. T The transmittance of the material at the axis is denoted as .

[0050] The transmittance T of the end-face coating at different wavelengths λ is as follows: Table 1. Transmittance of end-face coatings at different wavelengths

[0051] In one embodiment, the emission cross-section of red light is larger than that of orange light, which is larger than that of green light. Since the emission cross-section σ is approximately positively correlated with the gain, the gain of red light is greater than that of orange light, which is greater than that of green light. Considering the gain-related parameter settings for different wavelengths, the following applies: Table 2 Gain-related parameters at different wavelengths

[0052] Therefore, the gain-dependent intrinsic loss of single-mode gain fiber 3 is set as ; In gain fiber 3, the dynamic fluctuation of loss at different wavelengths under varying coupling distances directly determines the selection of laser output wavelength. This loss includes coupling loss caused solely by the coupling distance. Fresnel reflection loss due to end face gap Gain-related intrinsic loss It can be calculated using the following formula:

[0053] Reference Figure 7 In one embodiment, by adjusting the coupling distance, the coupling loss of lasers of different wavelengths can be changed, and the total laser loss can be calculated. The corresponding numerical simulation results were obtained.

[0054] Specifically, when the coupling distance is relatively small, the total loss of cyan light is less than that of orange light, which in turn is less than that of red light. At this point, the laser emits cyan light, which conforms to... Figure 7 (a) Case I, the specific details are as follows: Figure 7 As shown in (b), with the increase of coupling distance, the total loss of cyan light increases faster than that of orange light, which in turn increases faster than that of red light. Therefore, the total loss of cyan light increases more rapidly. Consequently, at a certain coupling distance, the total loss of cyan light will be greater than that of orange light but less than that of red light. At this point, the total loss of orange light is the minimum, and the laser emits orange light, which conforms to... Figure 7 (a) Case II, the specific details are as follows: Figure 7 As shown in (c), with further increases in coupling distance, the total loss of cyan light increases faster than that of orange light, which in turn increases faster than that of red light, leading to a further increase in the total loss of both cyan and orange light. Therefore, at a certain coupling distance, the total loss of cyan light is greater than that of orange light, which is greater than that of red light. At this point, the total loss of red light is the minimum, and the laser emits red light, which aligns with... Figure 7 (a) Case III, the specific details are as follows: Figure 7 As shown in (d). Therefore, by adjusting the coupling distance, it is possible to selectively suppress or enhance light of a specific wavelength, thereby achieving switchable and tunable output laser wavelength. Under the simulation parameters set in this embodiment, the correspondence between the emission wavelength and the coupling distance is shown in the following table: Table 3. Correspondence between emission wavelength and coupling distance

[0055] Reference Figure 8 The coupling distance between the single-mode gain fiber output end and the second dichroic mirror 4 was gradually increased by adjusting the single-mode gain fiber output end, and the wavelength distribution of the laser output from the pigtail of the second dichroic mirror 4 was measured by a spectrometer. The wavelength switchable and tunable all-fiber visible laser can output three mutually switchable wavelengths, corresponding to 493 nm cyan light, 603 nm orange light and 635 nm red light respectively, and can achieve dual-wavelength operation, which is basically consistent with the simulation results.

[0056] In one embodiment, the output pigtail of the pump laser is a multimode fiber with a core diameter of 105 μm and a cladding diameter of 125 μm; the first dichroic mirror pigtail has a core diameter of 105 μm and a cladding diameter of 125 μm; the output pigtail of the pump laser is fused to the first dichroic mirror pigtail; the second dichroic mirror pigtail is a multimode fiber with a core diameter of 105 μm and a cladding diameter of 125 μm; the output pigtail of the wavelength-switchable and tunable all-fiber visible light laser is a multimode fiber with a core diameter of 105 μm and a cladding diameter of 125 μm.

[0057] Matters not covered in this invention are common knowledge.

[0058] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0059] The embodiments described above are merely examples of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A wavelength-switchable and tunable all-fiber visible light laser, characterized in that, It includes a pump laser, a first dichroic mirror, a single-mode gain fiber, a second dichroic mirror, and a coupling distance control device; The pump light output from the pump laser is directly coupled into the single-mode gain fiber via the first dichroic mirror. After being absorbed by the single-mode gain fiber, fluorescence is generated. The fluorescence is transmitted to the second dichroic mirror, reflected back to the output end of the single-mode gain fiber, and then coupled back into the single-mode gain fiber. After being amplified by multiple reflections, the fluorescence forms a laser and is output through the output fiber. The second dichroic mirror is placed on the coupling distance control device. By adjusting the coupling distance between the single-mode gain fiber output end and the second dichroic mirror, laser wavelength switching and tuning can be achieved. The output pigtail of the pump laser is fused to the pigtail of the first dichroic mirror. The second dichroic mirror pigtail is fused to the output pigtail of the wavelength-switchable and tunable all-fiber visible laser. The first dichroic mirror is an optical fiber end-face dielectric film mirror with high transmittance for lasers with a wavelength of 443 nm and high reflectivity for lasers with wavelengths of 493 nm, 603 nm, and 635 nm. The second dichroic mirror is a fiber end-face dielectric film mirror with high reflectivity to lasers with wavelengths of 493 nm, 603 nm, and 635 nm.

2. The wavelength-switchable and tunable all-fiber visible laser as described in claim 1, characterized in that, The coupling distance control device includes a connecting device and an electric displacement stage; The connecting device is used to fix the single-mode gain fiber output end and the output fiber input end; The electric displacement stage is connected to the output end of the single-mode gain fiber and the second dichroic mirror, respectively, and is used to adjust the coupling distance between the output end of the single-mode gain fiber and the second dichroic mirror.

3. The wavelength-switchable and tunable all-fiber visible light laser as described in claim 2, characterized in that, The connecting device is a sleeve or a V-groove; The electric displacement stage is a piezoelectric ceramic electric displacement stage or a stepper motor electric displacement stage.

4. The wavelength-switchable and tunable all-fiber visible light laser as described in claim 1, characterized in that, The single-mode gain fiber is a single-mode rare-earth-doped fluoride fiber.

5. The wavelength-switchable and tunable all-fiber visible laser as described in claim 4, characterized in that, In the single-mode rare-earth-doped fluoride optical fiber, the doping ions are praseodymium, holmium, or dysprosium, and the concentration range of the doping ions is 1000 ppm-10000 ppm.

6. The wavelength-switchable and tunable all-fiber visible laser as described in claim 1, characterized in that, The second dichroic mirror is an optical fiber end-face dielectric film mirror with a transmittance of 8.9% for laser with a wavelength of 493 nm, 45.5% for laser with a wavelength of 603 nm, and 80.4% for laser with a wavelength of 635 nm.

7. The wavelength-switchable and tunable all-fiber visible laser as described in claim 1, characterized in that, The pump laser is a semiconductor laser with an output laser wavelength range of 440 nm to 455 nm.

8. The wavelength-switchable and tunable all-fiber visible light laser as described in claim 1, characterized in that, The output pigtail of the pump laser is a multimode fiber with a core diameter of 105 μm and a cladding diameter of 125 μm; The core diameter of the first dichroic mirror fiber is 105 μm and the cladding diameter is 125 μm.

9. The wavelength-switchable and tunable all-fiber visible laser as described in claim 1, characterized in that, The second dichroic mirror pigtail is a multimode optical fiber with a core diameter of 105 μm and a cladding diameter of 125 μm; The output pigtail of the wavelength-switchable and tunable all-fiber visible laser is a multimode fiber with a core diameter of 105 μm and a cladding diameter of 125 μm.

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