Low-noise 569nm wavelength all-solid-state yellow-green laser and generation method

Abstract

A low-noise 569nm all-solid-state yellow-green laser generation method and device, wherein 1064nm stimulated emission fluorescence is generated by pumping Nd:YAG crystal with 808nm or 880nm semiconductor laser, and decomposed into e-linear polarization and o-linear polarization fluorescence by using double 45° cut LN crystal beam splitter. The e-linear polarization fluorescence oscillates and amplifies in the first resonant cavity to generate e-linear polarization 1064nm laser, while the o-linear polarization fluorescence oscillates and amplifies in the second resonant cavity to output o-linear polarization 1064nm laser. The o-linear polarization 1064nm laser continues to pump Cr:Mg2SiO4 crystal to generate o-linear polarization 1224nm fluorescence, which oscillates in the third resonant cavity to generate o-linear polarization 1224nm laser. The number of longitudinal modes of the two wavelength lasers is reduced by a pressure filter, thereby reducing mode competition and noise. Finally, the e-linear polarization 1064nm laser and the o-linear polarization 1224nm laser are nonlinearly sum-frequencyed in an LBO sum-frequency crystal to generate a 569nm yellow-green laser.

Description

Technical Field

[0001] The invention belongs to the technical field of all-solid-state lasers, and in particular relates to a low-noise 569nm wavelength all-solid-state yellow-green laser and a generation method thereof. Background Art

[0002] Low-noise yellow-green lasers with a wavelength of around 569nm have great application potential and market value in the fields of medicine and biomedicine, spectroscopy, industrial manufacturing, scientific research, display, etc. due to their unique characteristics. Low-noise yellow-green lasers can be used as excitation light sources in fluorescence microscopes to improve the contrast and resolution of images and help researchers observe the fine structures of cells and tissues. In optogenetics, yellow-green lasers can be used to activate or inhibit neuronal activity, while the low-noise characteristics can provide precise light irradiation, reduce interference signals, and improve the accuracy of experiments. In laser therapy, yellow-green lasers can be used in ophthalmic surgery (such as retinal repair surgery) and skin disease treatment (such as treatment of vascular lesions). In environmental monitoring and chemical analysis, the low-noise characteristics of yellow-green lasers help improve the sensitivity and accuracy of detection. In laser processing, yellow-green lasers can be used for precision laser cutting and welding, especially for processing some special materials such as metals and plastics, and the low-noise characteristics help improve processing quality. In precision measurement, such as gravitational wave detection and precision frequency measurement, low-noise yellow-green lasers can significantly improve the accuracy of measurements. In laser projection, low-noise yellow-green lasers can provide high-brightness and high-contrast images in laser projection displays, which are used in cinemas, stage performances and large display screens.

[0003] At present, the common method to obtain yellow-green laser is to use semiconductor laser to pump Nd:YAG crystal to generate 1112nm, 1116nm, 1123nm near-infrared laser, and then use nonlinear crystal to double the frequency of 1112nm, 1116nm, 1123nm, so as to obtain 556nm, 558nm, 561nm yellow-green laser respectively. However, since the stimulated emission cross sections of the three near-infrared lasers of 1112nm, 1116nm and 1123nm are similar and the wavelengths are very close to each other, it is usually difficult to suppress two of the spectral lines through optical coating so that the desired third spectral line can achieve single-wavelength laser oscillation in the resonant cavity. Therefore, in the same resonant cavity, multiple wavelengths of 1112nm, 1116nm and 1123nm often oscillate simultaneously and produce mode competition between each other, resulting in poor laser power stability and wavelength stability of the yellow-green laser and serious laser noise. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the disadvantages of the prior art and provide a low-noise 569nm wavelength all-solid-state yellow-green laser with good stability and a production method.

[0005] The technical solution adopted to solve the above technical problems is: a method for generating a low-noise 569nm wavelength all-solid-state yellow-green laser, comprising the following steps:

[0006] Step 1. Use a semiconductor laser pump source to generate a laser with a wavelength of 808 nm or 880 nm, and then expand, collimate and focus the laser to pump the first gain medium Nd: YAG crystal to generate non-polarized stimulated emission fluorescence with a wavelength of 1064 nm;

[0007] Step 2. decomposing the unpolarized stimulated emission fluorescence with a wavelength of 1064 nm into the non-coaxial e-linear polarized stimulated emission fluorescence with a wavelength of 1064 nm and the o-linear polarized stimulated emission fluorescence with a wavelength of 1064 nm;

[0008] Step 3. The e-linear polarized stimulated emission fluorescence with a wavelength of 1064 nm is independently oscillated and amplified in the first laser resonant cavity to generate a non-output e-linear polarized laser with a wavelength of 1064 nm;

[0009] Step 4. After the o-linear polarized stimulated emission fluorescence with a wavelength of 1064 nm is independently oscillated and amplified in the second laser resonant cavity, the o-linear polarized laser with a wavelength of 1064 nm is output through a second output mirror with a transmittance of 10%;

[0010] Step 5. The o-linear polarized laser with a wavelength of 1064 nm pumps the second gain medium Cr:Mg2SiO4 crystal to generate o-linear polarized stimulated emission fluorescence with a wavelength of 1224 nm and then generates o-linear polarized laser with no output at a wavelength of 1224 nm after independent oscillation and amplification in the third laser resonant cavity;

[0011] Step 6. Pass the non-output e-linear polarized laser generated in step 3 through a first pressure filter to generate a low-noise e-linear polarized laser with a wavelength of 1064 nm;

[0012] Step 7. Pass the non-output o-linear polarized laser generated in step 5 through a second pressure filter to generate a low-noise o-linear polarized laser with a wavelength of 1224 nm;

[0013] Step 8. After polarization beam combining the low-noise e-linear polarized laser with a wavelength of 1064nm and the low-noise o-linear polarized laser with a wavelength of 1224nm, the e-linear polarized laser and the o-linear polarized laser in the polarization beam combining state generate a low-noise yellow-green laser with a wavelength of 569nm through a nonlinear sum frequency process in a sum frequency crystal.

[0014] Preferably, the non-polarized stimulated emission fluorescence with a wavelength of 1064 nm in step 2 is decomposed into non-coaxial e-linear polarized stimulated emission fluorescence with a wavelength of 1064 nm and o-linear polarized stimulated emission fluorescence with a wavelength of 1064 nm by double 45° cutting of lithium niobate crystal.

[0015] Preferably, in step 6, the first pressure filter is a MgO: LN crystal, and both light-transmitting surfaces of the MgO: LN crystal are perpendicular to the laser incident light path. A voltage is applied to the MgO: LN crystal in a direction perpendicular to the light path, and the voltage value is adjusted so that the longitudinal mode in the e-linear polarized laser with a wavelength of 1064nm that satisfies a single round-trip phase difference of Aπ and A is an odd number has a transmittance of 100% through the MgO: LN crystal, and the longitudinal mode that does not satisfy the single round-trip phase difference of Aπ is suppressed by the first laser resonant cavity after passing through the MgO: LN crystal for multiple round trips.

[0016] Preferably, the second pressure filter in step 7 is a MgO: LN crystal, and the two light-transmitting surfaces of the MgO: LN crystal are perpendicular to the laser incident light path. A voltage is applied to the MgO: LN crystal in a direction perpendicular to the light path, and the voltage value is adjusted so that in the o-linearly polarized laser with a wavelength of 1224nm, the transmittance of the longitudinal mode that satisfies the single round-trip phase difference of Bπ and B is an even number through the MgO: LN crystal is 100%, and the longitudinal mode that does not satisfy the single round-trip phase difference of Bπ is suppressed by the second laser resonant cavity after passing through the MgO: LN crystal multiple times.

[0017] Preferably, in step 8, the low-noise e-linear polarized laser with a wavelength of 1064nm and the low-noise o-linear polarized laser with a wavelength of 1224nm are polarized and combined by a polarization beam combiner, and the angle between the incident surface of the polarization beam combiner and the low-noise e-linear polarized laser with a wavelength of 1064nm is 34°, and the angle between the incident surface of the polarization beam combiner and the low-noise o-linear polarized laser with a wavelength of 1224nm is 56°, so that the low-noise e-linear polarized laser with a wavelength of 1064nm passes through with a transmittance of 100%, and the low-noise o-linear polarized laser with a wavelength of 1224nm produces total reflection.

[0018] Preferably, the sum frequency crystal in step 8 is a type II angle phase matched LBO crystal, and the low noise e-linear polarized laser with a wavelength of 1064 nm and the low noise o-linear polarized laser with a wavelength of 1224 nm generate a low noise yellow-green laser with a wavelength of 569 nm in the sum frequency crystal according to the following formula:

[0019]

[0020] In the formula, 1064nm is the wavelength of the e-linearly polarized 1064nm laser, 1224nm is the wavelength of the o-linearly polarized 1224nm laser, 569nm is the wavelength of the low-noise yellow-green laser.

[0021] Preferably, the step 4 further comprises adjusting the phase of the output o-linear polarized laser with a wavelength of 1064 nm, so that the phase difference between the output o-linear polarized laser with a wavelength of 1064 nm and the e-linear polarized laser with a wavelength of 1064 nm is 2π.

[0022] A low-noise 569nm wavelength all-solid-state yellow-green laser, characterized in that it comprises a semiconductor laser pump source, a beam expansion and focusing structure, a first gain medium, and a beam splitter which are sequentially arranged along the optical path direction, wherein the output of the beam splitter is divided into two paths, one path is composed of a first pressure filter, a beam combiner, a sum frequency crystal, and a first output mirror which are sequentially arranged, and the other path is composed of a second output mirror, a second focusing mirror, a second gain medium, a first reflector, a second reflector, a second pressure filter, a beam combiner, a sum frequency crystal, and a first output mirror which are sequentially arranged;

[0023] The semiconductor laser pump source is used to generate laser light with a wavelength of 808 nm or 880 nm;

[0024] The beam expansion and focusing structure is used to shape the laser light with a wavelength of 808nm or 880nm into parallel light and focus it into the first gain medium;

[0025] The first gain medium is used to absorb the energy of the laser emitted by the semiconductor laser pump source and generate non-polarized stimulated emission fluorescence with a wavelength of 1064 nm by pumping;

[0026] The spectrometer is used to decompose the non-polarized stimulated emission fluorescence with a wavelength of 1064 nm into non-coaxial e-linear polarized stimulated emission fluorescence with a wavelength of 1064 nm and o-linear polarized stimulated emission fluorescence with a wavelength of 1064 nm;

[0027] The first pressure filter is used to receive e-linear polarized stimulated emission fluorescence with a wavelength of 1064 nm and generate low-noise e-linear polarized laser with a wavelength of 1064 nm;

[0028] The second output mirror is used to partially reflect and partially output the o-linearly polarized stimulated emission fluorescence with a wavelength of 1064 nm output by the beam splitter;

[0029] The second focusing mirror is used to focus the o-linearly polarized stimulated emission fluorescence with a wavelength of 1064 nm output by the second output mirror into the second gain medium;

[0030] The second gain medium is used to generate o-linear polarized stimulated emission fluorescence with a wavelength of 1224 nm;

[0031] The first reflector and the second reflector are used to totally reflect o-linearly polarized stimulated emission fluorescence with a wavelength of 1224 nm in sequence;

[0032] The second pressure filter is used to receive o-linear polarized stimulated emission fluorescence with a wavelength of 1224nm and generate low-noise o-linear polarized laser with a wavelength of 1224nm;

[0033] The beam combiner is used to allow 100% of the low-noise e-linear polarized laser with a wavelength of 1064 nm to pass through and to fully reflect the low-noise o-linear polarized laser with a wavelength of 1224 nm;

[0034] The sum frequency crystal is used to receive the low-noise o-linear polarized laser with a wavelength of 1224nm and the low-noise e-linear polarized laser with a wavelength of 1064nm which are totally reflected by the beam combiner, and generate a low-noise yellow-green laser with a wavelength of 569nm;

[0035] The first output mirror is used for the total reflection sum frequency crystal to output the remaining 1064nm low-noise e-linear polarized laser and 1224nm low-noise o-linear polarized laser that have not completed the sum frequency, and to output the 569nm low-noise yellow-green laser at the same time;

[0036] The first gain medium, the beam splitter, the first pressure filter, the beam combiner, the sum frequency crystal, and the first output mirror constitute a first resonant cavity, in which the e-linear polarized stimulated emission fluorescence with a wavelength of 1064 nm is oscillated and amplified to generate a non-output e-linear polarized laser with a wavelength of 1064 nm;

[0037] The first gain medium, the beam splitter, and the second output mirror constitute a second resonant cavity, in which the o-linear polarized stimulated emission fluorescence with a wavelength of 1064 nm is oscillated and amplified to generate a partial output of o-linear polarized laser light with a wavelength of 1064 nm;

[0038] The second gain medium, the first reflector, the second reflector, the second pressure filter, the beam combiner, the sum frequency crystal, and the first output mirror constitute a third resonant cavity, in which the o-linearly polarized stimulated emission fluorescence with a wavelength of 1224 nm is oscillated and amplified to generate a non-output o-linearly polarized laser with a wavelength of 1064 nm;

[0039] The first resonant cavity and the second resonant cavity share a first gain medium and a beam splitter, and the first resonant cavity and the third resonant cavity share a beam combiner, a sum frequency crystal, and a first output mirror.

[0040] Preferably, it also includes a pressurized phase controller, which is located between the second focusing mirror and the second gain medium and is used to phase-adjust the o-linear polarized laser with a wavelength of 1064nm, so that the phase difference between the o-linear polarized laser with a wavelength of 1224nm generated by the o-linear polarized laser pumping the second gain medium with a wavelength of 1064nm and the e-linear polarized laser with a wavelength of 1064nm is 2π.

[0041] Preferably, the beam expanding and focusing structure consists of a beam expanding mirror and a first focusing mirror which are sequentially arranged along the optical path.

[0042] The beneficial effects of the present invention are as follows:

[0043] The present invention uses a pressure filter to effectively reduce the number of longitudinal modes and mode competition of the laser, significantly reduce laser noise, and improve the coherence of the laser. By accurately controlling the phase matching in the frequency summing process, the energy conversion efficiency of the output yellow-green laser is ensured.

[0044] The present invention optimizes the energy conversion efficiency, effectively converts 1064nm and 1224nm lasers to 569nm yellow-green lasers, reduces energy loss during multiple frequency doubling processes compared to traditional frequency doubling conversion methods, and has higher energy conversion efficiency.

[0045] The invention has the advantages of good coherence, low laser noise, narrow spectral line width, compact laser structure, high energy efficiency, low operating cost, etc., and has strong practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a schematic diagram of the structure of the low-noise 569nm wavelength all-solid-state yellow-green laser of the present invention.

[0047] Figure 2 It is a schematic flow chart of the method for generating low-noise 569nm wavelength all-solid-state yellow-green laser of the present invention.

[0048] Figure 3 It is a spectrum test chart of o-linear polarized laser with a wavelength of 1064nm according to an embodiment of the present invention.

[0049] Figure 4 1 is a schematic diagram of a curve showing a change in output power of an o-linearly polarized laser with a wavelength of 1064 nm as a function of pump current according to an embodiment of the present invention.

[0050] Figure 5 This is a spectrum test chart of a 569nm wavelength yellow-green laser according to an embodiment of the present invention.

[0051] Figure 6 It is a schematic diagram of a curve of a 569nm wavelength yellow-green laser output power varying with pump current according to an embodiment of the present invention.

[0052] Figure 7 It is a schematic diagram of a noise test curve of a yellow-green laser with a wavelength of 569 nm according to an embodiment of the present invention.

[0053] Wherein: 1. semiconductor laser pump source, 2. beam expander, 3. first focusing mirror 3, 4. first gain medium, 5. beam splitter, 6. first pressure filter, 7. beam combiner, 8. sum frequency crystal, 9. first output mirror, 10. second output mirror, 11. second focusing mirror, 12. pressure phase controller, 13. second gain medium, 14. first reflector, 15. second reflector, 16. second pressure filter. DETAILED DESCRIPTION

[0054] The present invention will be further described in detail below in conjunction with the accompanying drawings and examples, but the present invention is not limited to the following embodiments.

[0055] exist Figure 1 In the embodiment, the low-noise 569nm wavelength all-solid-state yellow-green laser comprises a semiconductor laser pump source 1, a beam expander 2, a first focusing mirror 3, a first gain medium 4, and a beam splitter 5 which are sequentially arranged along the optical path. The output of the beam splitter 5 is divided into two paths, one path is composed of a first boosting filter input, a beam combiner 7, a sum frequency crystal 8, and a first output mirror 9 which are sequentially arranged, and the other path is composed of a second output mirror 10, a second focusing mirror 11, a boosting phase controller 12, a second gain medium 13, a first reflector 14, a second reflector 15, a second boosting filter 16, a beam combiner 7, a sum frequency crystal 8, and a first output mirror 9 which are sequentially arranged.

[0056] A semiconductor laser pump source 1 is used to generate a laser with a wavelength of 808nm or 880nm; a beam expansion and focusing structure is used to shape the laser with a wavelength of 808nm or 880nm into parallel light and focus it into a first gain medium 4; the first gain medium 4 is a Nd: YAG crystal, which is used to absorb the energy of the laser emitted by the semiconductor laser pump source 1 and pump to generate non-polarized stimulated radiation fluorescence with a wavelength of 1064nm.

[0057] The beam splitter 5 is a double 45° cut lithium niobate crystal, and the unpolarized stimulated radiation fluorescence with a wavelength of 1064nm is incident perpendicularly to the incident surface of the double 45° cut lithium niobate crystal. Based on the natural birefringence characteristics of the double 45° cut lithium niobate crystal, the unpolarized stimulated radiation fluorescence with a wavelength of 1064nm is decomposed into non-coaxial e-linear polarized stimulated radiation fluorescence with a wavelength of 1064nm and o-linear polarized stimulated radiation fluorescence with a wavelength of 1064nm in the double 45° cut lithium niobate crystal. The e-linear polarized stimulated radiation fluorescence with a wavelength of 1064nm is transmitted perpendicularly from the output end face of the double 45° cut lithium niobate crystal and is parallel to the incident unpolarized stimulated radiation fluorescence with a wavelength of 1064nm. The o-linear polarized stimulated radiation fluorescence with a wavelength of 1064nm is transmitted from the output end face of the double 45° cut lithium niobate crystal at a certain refraction angle and forms a certain angle with the incident unpolarized stimulated radiation fluorescence with a wavelength of 1064nm.

[0058] The e-linear polarized stimulated emission fluorescence with a wavelength of 1064nm oscillates and amplifies in the first resonant cavity composed of the first gain medium 4, the beam splitter 5, the first pressure filter, the beam combiner 7, the sum frequency crystal 8, and the first output mirror 9, and generates the e-linear polarized laser with a wavelength of 1064nm without output. The first pressure filter is a MgO: LN crystal, and the two light-passing surfaces of the MgO: LN crystal are perpendicular to the laser incident light path. A voltage is applied to the MgO: LN crystal in a direction perpendicular to the light path. By adjusting the voltage value, the longitudinal mode of the e-linear polarized laser with a wavelength of 1064nm that satisfies the single round-trip phase difference of Aπ and A is an odd number has a transmittance of 100% through the MgO: LN crystal, and the longitudinal mode that does not satisfy the single round-trip phase difference of Aπ is suppressed by the first laser resonant cavity after passing through the MgO: LN crystal for multiple round trips. The first pressure filter reduces the number of longitudinal modes of the e-linear polarized laser with a wavelength of 1064 nm, which is beneficial to weakening the mode competition between the longitudinal modes and reducing the noise of the e-linear polarized laser with a wavelength of 1064 nm.

[0059] The o-linear polarized stimulated emission fluorescence with a wavelength of 1064 nm is oscillated and amplified in the second resonant cavity composed of the first gain medium 4, the beam splitter 5, and the second output mirror 10 to generate an output o-linear polarized laser with a wavelength of 1064 nm.

[0060] The incident surface of the second output mirror 10 is a concave surface, and the output surface is a flat surface. The radius of curvature of the incident surface is 1000 mm, and the surface of the incident surface is coated with a 1064 nm wavelength high reflection film (reflectivity R 1064nm =10.5%), the output surface is coated with a 1064nm wavelength high transmittance film (transmittance T 1064nm >99.8%). It is used to reflect 90% of the 1064nm wavelength o-linear polarized laser output by the beam splitter 5 and output 10%;

[0061] A second focusing mirror 11 is used to focus the o-linear polarized laser with a wavelength of 1064 nm output by the second output mirror 10 into the second gain medium 13;

[0062] The second gain medium 13 is a Cr: Mg2SiO4 crystal, which is used to generate o-linear polarized stimulated emission fluorescence with a wavelength of 1224nm under the pumping of an o-linear polarized laser with a wavelength of 1064nm;

[0063] The o-linearly polarized stimulated radiation fluorescence with a wavelength of 1224nm oscillates and amplifies in the third resonant cavity composed of the second gain medium 13, the first reflector 14, the second reflector 15, the second pressure filter 16, the combiner 7, the sum frequency crystal 8, and the first output mirror 9 to produce a non-output o-linearly polarized laser with a wavelength of 1224nm.

[0064] The pressurized phase controller 12 is located between the second focusing mirror 11 and the second gain medium 13, and is used to adjust the phase of the 1064nm o-linear polarized laser, so that the phase difference between the 1224nm o-linear polarized laser generated by the 1064nm o-linear polarized laser pumping the second gain medium and the 1064nm e-linear polarized laser is 2π, thereby improving the sum frequency efficiency of generating a low-noise 569nm wavelength yellow-green laser.

[0065] The first reflector 14 and the second reflector 15 are used to totally reflect the o-linear polarized stimulated emission fluorescence with a wavelength of 1224 nm in sequence, so as to ensure that the fluorescence oscillates multiple times in the third resonant cavity;

[0066] The second pressure filter 16 is a MgO: LN crystal, and both light-transmitting surfaces of the MgO: LN crystal are perpendicular to the laser incident light path. A voltage is applied to the MgO: LN crystal in a direction perpendicular to the light path. By adjusting the voltage value, the transmittance of the longitudinal mode in the 1224nm wavelength o-linearly polarized laser that satisfies the single round-trip phase difference of Bπ and B is an even number through the MgO: LN crystal is 100%, and the longitudinal mode that does not satisfy the single round-trip phase difference of Bπ is suppressed by the third resonant cavity after passing through the MgO: LN crystal for multiple round-trips.

[0067] The beam combiner 7 is a polarization beam combiner. The light-passing surface of the beam combiner 7 forms an angle of 34° with the optical path of the low-noise e-linear polarized laser with a wavelength of 1064nm, so that 100% of the low-noise e-linear polarized laser with a wavelength of 1064nm passes through. The light-passing surface of the beam combiner 7 forms an angle of 56° with the optical path of the low-noise o-linear polarized laser with a wavelength of 1224nm, so that the incident low-noise o-linear polarized laser with a wavelength of 1224nm is totally reflected.

[0068] The sum frequency crystal 8 is a type II angle phase matched LBO crystal, and the low noise e-linear polarized laser with a wavelength of 1064 nm and the low noise o-linear polarized laser with a wavelength of 1224 nm generate a low noise yellow-green laser with a wavelength of 569 nm in the sum frequency crystal 8 according to the following formula;

[0069]

[0070] In the formula, 1064nm is the wavelength of the e-linearly polarized laser, 1224nm is the wavelength of the o-linearly polarized laser, 569nm is the wavelength of the low-noise yellow-green laser.

[0071] The incident surface of the first output mirror 9 is a concave surface, and the output surface is a flat surface. The radius of curvature of the incident surface is 785 mm. The surface of the incident surface is coated with two wavelengths of 1064 nm and 1224 nm high reflection films (reflectivity R 1064nm >99.7%, reflectivity R 1224nm >99.7%) and 569nm wavelength high transmittance film (transmittance T 569nm >99.5%).

[0072] The first output mirror 9 is used for the total reflection sum frequency crystal 8 to output the remaining 1064nm low-noise e-linear polarized laser and 1224nm low-noise o-linear polarized laser which have not completed the sum frequency, and at the same time output the 569nm low-noise yellow-green laser.

[0073] The first resonant cavity and the second resonant cavity share the first gain medium 4 and the beam splitter 5 , and the first resonant cavity and the third resonant cavity share the beam combiner 7 , the sum frequency crystal 8 , and the first output mirror 9 .

[0074] exist Figure 2 The low-noise 569nm wavelength all-solid-state yellow-green laser generation method of this embodiment comprises the following steps:

[0075] Step 1. The 808nm or 880nm laser generated by the semiconductor laser pump source 1 is expanded, collimated and focused by the beam expander 2 and the first focusing mirror 3 in sequence, and then pumps the first gain medium 4Nd: YAG crystal to generate non-polarized stimulated emission fluorescence with a wavelength of 1064nm;

[0076] Step 2. The beam splitter 5 decomposes the unpolarized stimulated emission fluorescence with a wavelength of 1064 nm into non-coaxial e-linear polarized stimulated emission fluorescence with a wavelength of 1064 nm and o-linear polarized stimulated emission fluorescence with a wavelength of 1064 nm. The beam splitter 5 is a double 45° cut lithium niobate crystal.

[0077] Step 3. The e-linear polarized stimulated emission fluorescence with a wavelength of 1064 nm is independently oscillated and amplified in the first resonant cavity to generate a non-output e-linear polarized laser with a wavelength of 1064 nm;

[0078] Step 4. After the o-linear polarized stimulated emission fluorescence with a wavelength of 1064 nm is independently oscillated and amplified in the second resonant cavity, the o-linear polarized laser with a wavelength of 1064 nm is output through a second output mirror 10 with a transmittance of 10%, as shown in FIG. Figure 3 , 4 , the o-linear polarized laser with a wavelength of 1064 nm is phase-adjusted by the pressure phase controller 12 so that the phase difference between it and the e-linear polarized laser with a wavelength of 1064 nm is 2π;

[0079] Step 5. The 1064nm wavelength o-linearly polarized laser is focused by the second focusing mirror 11 to pump the second gain medium 13Cr:Mg2SiO4 crystal to generate 1224nm wavelength o-linearly polarized stimulated emission fluorescence and then independently oscillate and amplify in the third resonant cavity to generate 1224nm wavelength o-linearly polarized laser without output;

[0080] Step 6. Pass the non-output e-linear polarized laser generated in step 3 through the first pressure filter 6 to generate a low-noise e-linear polarized laser with a wavelength of 1064 nm;

[0081] Step 7. Pass the non-output o-linear polarized laser generated in step 5 through the second pressure filter 16 to generate a low-noise o-linear polarized laser with a wavelength of 1224 nm;

[0082] Step 8. After the low-noise e-linear polarized laser with a wavelength of 1064 nm and the low-noise o-linear polarized laser with a wavelength of 1224 nm are polarized and combined in the beam combiner 7, the low-noise e-linear polarized laser with a wavelength of 1064 nm and the low-noise o-linear polarized laser with a wavelength of 1224 nm in the polarization beam combining state are combined and combined to generate a low-noise yellow-green laser with a wavelength of 569 nm through a nonlinear sum frequency process in the sum frequency crystal 8, as shown in FIG. Figures 5 to 7 ;

[0083] Step 9. Adjust the voltage of the pressure phase controller 12 to implement phase adjustment on the 1064nm wavelength o-linear polarized laser, so that the phase difference between the 1064nm wavelength e-linear polarized laser and the 1224nm wavelength o-linear polarized laser participating in the sum frequency process is 2π, thereby improving the sum frequency efficiency of the low-noise 569nm wavelength yellow-green laser.

Claims

1. A method for generating a low-noise 569nm wavelength all-solid-state yellow-green laser, characterized in that: The following steps are involved: Step 1. Use a semiconductor laser pump source to generate a laser with a wavelength of 808 nm or 880 nm, and then expand, collimate and focus the laser to pump the first gain medium Nd: YAG crystal to generate non-polarized stimulated emission fluorescence with a wavelength of 1064 nm; Step 2. decomposing the unpolarized stimulated emission fluorescence with a wavelength of 1064 nm into the non-coaxial e-linear polarized stimulated emission fluorescence with a wavelength of 1064 nm and the o-linear polarized stimulated emission fluorescence with a wavelength of 1064 nm; Step 3. The e-linear polarized stimulated emission fluorescence with a wavelength of 1064 nm is independently oscillated and amplified in the first laser resonant cavity to generate a non-output e-linear polarized laser with a wavelength of 1064 nm; Step 4. After the o-linear polarized stimulated emission fluorescence with a wavelength of 1064 nm is independently oscillated and amplified in the second laser resonant cavity, the o-linear polarized laser with a wavelength of 1064 nm is output through a second output mirror with a transmittance of 10%; Step 5. The o-linear polarized laser with a wavelength of 1064 nm pumps the second gain medium Cr:Mg2SiO4 crystal to generate o-linear polarized stimulated emission fluorescence with a wavelength of 1224 nm and then generates o-linear polarized laser with no output at a wavelength of 1224 nm after independent oscillation and amplification in the third laser resonant cavity; Step 6. Pass the non-output e-linear polarized laser generated in step 3 through a first pressure filter to generate a low-noise e-linear polarized laser with a wavelength of 1064 nm; Step 7. Pass the non-output o-linear polarized laser generated in step 5 through a second pressure filter to generate a low-noise o-linear polarized laser with a wavelength of 1224 nm; Step 8. After polarization beam combining the low-noise e-linear polarized laser with a wavelength of 1064nm and the low-noise o-linear polarized laser with a wavelength of 1224nm, the e-linear polarized laser and the o-linear polarized laser in the polarization beam combining state generate a low-noise yellow-green laser with a wavelength of 569nm through a nonlinear sum frequency process in a sum frequency crystal.

2. The method for generating a low-noise 569 nm wavelength all-solid-state yellow-green laser according to claim 1, characterized in that: In the step 2, the non-polarized stimulated emission fluorescence with a wavelength of 1064 nm is decomposed into non-coaxial e-linear polarized stimulated emission fluorescence with a wavelength of 1064 nm and o-linear polarized stimulated emission fluorescence with a wavelength of 1064 nm by double 45° cutting of the lithium niobate crystal.

3. The method for generating a low-noise 569 nm wavelength all-solid-state yellow-green laser according to claim 1, characterized in that: In step 6, the first pressure filter is a MgO: LN crystal, and both light-transmitting surfaces of the MgO: LN crystal are perpendicular to the laser incident light path. A voltage is applied to the MgO: LN crystal in a direction perpendicular to the light path, and the voltage value is adjusted so that the longitudinal mode of the e-linear polarized laser with a wavelength of 1064nm that satisfies a single round-trip phase difference of Aπ and A is an odd number has a transmittance of 100% through the MgO: LN crystal, and the longitudinal mode that does not satisfy the single round-trip phase difference of Aπ is suppressed by the first laser resonant cavity after passing through the MgO: LN crystal for multiple round-trips.

4. The method for generating a low-noise 569 nm wavelength all-solid-state yellow-green laser according to claim 1, characterized in that: In step 7, the second pressure filter is a MgO: LN crystal, and both light-transmitting surfaces of the MgO: LN crystal are perpendicular to the laser incident light path. A voltage is applied to the MgO: LN crystal in a direction perpendicular to the light path, and the voltage value is adjusted so that in the o-linearly polarized laser with a wavelength of 1224nm, the transmittance of the longitudinal mode that satisfies the single round-trip phase difference of Bπ and B is an even number through the MgO: LN crystal is 100%, and the longitudinal mode that does not satisfy the single round-trip phase difference of Bπ is suppressed by the second laser resonant cavity after passing through the MgO: LN crystal for multiple round-trips.

5. The method for generating a low-noise 569 nm wavelength all-solid-state yellow-green laser according to claim 1, characterized in that: In step 8, the low-noise e-linear polarized laser with a wavelength of 1064nm and the low-noise o-linear polarized laser with a wavelength of 1224nm are polarized and combined by a polarization beam combiner, and the angle between the incident surface of the polarization beam combiner and the low-noise e-linear polarized laser with a wavelength of 1064nm is 34°, and the angle between the incident surface of the polarization beam combiner and the low-noise o-linear polarized laser with a wavelength of 1224nm is 56°, so that the low-noise e-linear polarized laser with a wavelength of 1064nm passes through with a transmittance of 100%, and the low-noise o-linear polarized laser with a wavelength of 1224nm generates total reflection.

6. The method for generating a low-noise 569 nm wavelength all-solid-state yellow-green laser according to claim 1, characterized in that: In step 8, the sum frequency crystal is a type II angle phase matched LBO crystal, and the low noise e-linear polarized laser with a wavelength of 1064 nm and the low noise o-linear polarized laser with a wavelength of 1224 nm generate a low noise yellow-green laser with a wavelength of 569 nm in the sum frequency crystal according to the following formula; In the formula, 1064nm is the wavelength of the e-linearly polarized 1064nm laser, 1224nm is the wavelength of the o-linearly polarized 1224nm laser, 569nm is the wavelength of the low-noise yellow-green laser.

7. A method for generating a low-noise 569 nm wavelength all-solid-state yellow-green laser according to any one of claims 1 to 6, characterized in that: The step 4 also includes adjusting the phase of the output o-linear polarized laser with a wavelength of 1064 nm so that the phase difference between the output o-linear polarized laser with a wavelength of 1064 nm and the e-linear polarized laser with a wavelength of 1064 nm is 2π.

8. A low-noise 569nm wavelength all-solid-state yellow-green laser for implementing the laser generation method of claim 7, characterized in that: It includes a semiconductor laser pump source, a beam expansion and focusing structure, a first gain medium, and a spectrometer arranged in sequence along the optical path. The output of the spectrometer is divided into two paths, one path is composed of a first pressure filter, a beam combiner, a sum frequency crystal, and a first output mirror arranged in sequence, and the other path is composed of a second output mirror, a second focusing mirror, a second gain medium, a first reflector, a second reflector, a second pressure filter, a beam combiner, a sum frequency crystal, and a first output mirror arranged in sequence; The semiconductor laser pump source is used to generate laser light with a wavelength of 808 nm or 880 nm; The beam expansion and focusing structure is used to shape the laser light with a wavelength of 808nm or 880nm into parallel light and focus it into the first gain medium; The first gain medium is used to absorb the energy of the laser emitted by the semiconductor laser pump source and generate non-polarized stimulated emission fluorescence with a wavelength of 1064 nm by pumping; The spectrometer is used to decompose the non-polarized stimulated emission fluorescence with a wavelength of 1064 nm into non-coaxial e-linear polarized stimulated emission fluorescence with a wavelength of 1064 nm and o-linear polarized stimulated emission fluorescence with a wavelength of 1064 nm; The first pressure filter is used to receive e-linear polarized stimulated emission fluorescence with a wavelength of 1064 nm and generate low-noise e-linear polarized laser with a wavelength of 1064 nm; The second output mirror is used to partially reflect and partially output the o-linearly polarized stimulated emission fluorescence with a wavelength of 1064 nm output by the beam splitter; The second focusing mirror is used to focus the o-linearly polarized stimulated emission fluorescence with a wavelength of 1064 nm output by the second output mirror into the second gain medium; The second gain medium is used to generate o-linear polarized stimulated emission fluorescence with a wavelength of 1224 nm; The first reflector and the second reflector are used to sequentially totally reflect o-linearly polarized stimulated emission fluorescence with a wavelength of 1224 nm; The second pressure filter is used to receive o-linear polarized stimulated emission fluorescence with a wavelength of 1224 nm and generate low-noise o-linear polarized laser with a wavelength of 1224 nm; The beam combiner is used to allow 100% of the low-noise e-linear polarized laser with a wavelength of 1064 nm to pass through and to fully reflect the low-noise o-linear polarized laser with a wavelength of 1224 nm; The sum frequency crystal is used to receive the low-noise o-linear polarized laser with a wavelength of 1224nm and the low-noise e-linear polarized laser with a wavelength of 1064nm which are totally reflected by the beam combiner, and generate a low-noise yellow-green laser with a wavelength of 569nm; The first output mirror is used for the total reflection sum frequency crystal to output the remaining 1064nm low-noise e-linear polarized laser and 1224nm low-noise o-linear polarized laser that have not completed the sum frequency, and to output the 569nm low-noise yellow-green laser at the same time; The first gain medium, the beam splitter, the first pressure filter, the beam combiner, the sum frequency crystal, and the first output mirror constitute a first resonant cavity, in which the e-linear polarized stimulated emission fluorescence with a wavelength of 1064 nm is oscillated and amplified to generate a non-output e-linear polarized laser with a wavelength of 1064 nm; The first gain medium, the beam splitter, and the second output mirror constitute a second resonant cavity, in which the o-linear polarized stimulated emission fluorescence with a wavelength of 1064 nm is oscillated and amplified to generate a partial output of o-linear polarized laser light with a wavelength of 1064 nm; The second gain medium, the first reflector, the second reflector, the second pressure filter, the beam combiner, the sum frequency crystal, and the first output mirror constitute a third resonant cavity, in which the o-linearly polarized stimulated emission fluorescence with a wavelength of 1224 nm is oscillated and amplified to generate a non-output o-linearly polarized laser with a wavelength of 1064 nm; The first resonant cavity and the second resonant cavity share a first gain medium and a beam splitter, and the first resonant cavity and the third resonant cavity share a beam combiner, a sum frequency crystal, and a first output mirror.

9. The low-noise 569nm wavelength all-solid-state yellow-green laser according to claim 8, characterized in that: It also includes a pressurized phase controller, which is located between the second focusing mirror and the second gain medium and is used to adjust the phase of the 1064nm o-linear polarized laser so that the phase difference between the 1224nm o-linear polarized laser generated by pumping the second gain medium with the 1064nm o-linear polarized laser and the 1064nm e-linear polarized laser is 2π.

10. The low-noise 569nm wavelength all-solid-state yellow-green laser according to claim 8, characterized in that: The beam expanding and focusing structure is composed of a beam expanding mirror and a first focusing mirror which are sequentially arranged along the optical path.

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