Device and method for measuring light extraction performance of laser gain medium

Abstract

The invention relates to the technical field of laser, and provides a device and a method for measuring the light extraction performance of a laser gain medium, and the device comprises a resonant cavity total reflection mirror, a grating, a wave band adjustable output coupling mirror group, a power measurement element and a data processing mechanism. The resonant cavity total reflective mirror and the grating are respectively positioned on two sides of the laser gain medium; the wave band adjustable output coupling mirror group is positioned on an emergent light path of the grating; the power measuring element is arranged on the transmission light path side of the wave band adjustable output coupling mirror group; and the data processing mechanism is connected with the power measuring element. According to the embodiment of the invention, dispersion is carried out on the laser output by the laser gain medium through the grating, the wavelength of the laser is adjusted through the band-adjustable output coupling mirror group, and the power measurement element measures the emission cross section corresponding to the target wavelength, so that direct measurement of the emission cross section of each wavelength during actual emission of the laser is realized; and the light extraction performance of the laser gain medium can be accurately obtained.

Description

Technical Field

[0001] The present invention relates to the field of laser technology, and in particular to a device and method for measuring the light emission performance of a laser gain medium. Background Art

[0002] Lasers, due to their ability to combine low noise, narrow linewidth, and excellent beam quality while achieving high-power output, are widely used in fundamental scientific research, including quantum information, cold atom physics, precision spectroscopy, precision measurement, laser processing, lidar, laser remote sensing, and optoelectronic countermeasures, as well as in industrial manufacturing, national defense, and security. The gain medium is the carrier that generates the oscillating laser and is one of the three key elements that make up a laser.

[0003] The choice of emission wavelength of the gain medium determines the output power, efficiency, linewidth range, etc. of the laser. Existing methods for measuring the output performance of gain media doped with active particles use a direct comparison of the gain medium's emission cross section, which is the degree of difficulty in simultaneously transitioning all upper energy levels of the active particles to lower energy levels. This can be specifically determined using formula (1).

[0004]

[0005] Where, σ em (λ) represents the emission cross section of the gain medium, I(λ) represents the fluorescence intensity, τ represents the measured upper level lifetime, c represents the speed of light, μ represents the refractive index, and λ represents the emission wavelength.

[0006] The aforementioned calculation of the gain medium's emission cross section is based on measurements taken when all upper energy levels of the activated particle simultaneously transition between lower energy levels. However, laser light often only has one or a few upper energy levels, making existing methods based on simultaneous transitions of all upper energy levels inaccurate. Summary of the Invention

[0007] The present invention provides a device and method for measuring the light emission performance of a laser gain medium, which are used to solve the defect of inaccurate measurement in the stimulated emission cross section measurement method in the prior art.

[0008] The present invention provides a device for measuring the light output performance of a laser gain medium, comprising a resonant cavity total reflection mirror, a grating, a band-adjustable output coupling mirror assembly, a power measurement element, a wavelength measurement element and a data processing mechanism;

[0009] The resonant cavity total reflection mirror and the grating are respectively located on both sides of the laser gain medium, and the grating is used to disperse the laser output by the laser gain medium;

[0010] The band-adjustable output coupling mirror assembly is located on the output light path of the grating, and is used to adjust the wavelength of the dispersed laser so that the band-adjustable output coupling mirror assembly outputs laser light of a target wavelength;

[0011] The wavelength measuring element is arranged on the transmission light path side of the band-adjustable output coupling mirror assembly, and the wavelength measuring element is used to monitor the wavelength of the laser output by the band-adjustable output coupling mirror assembly;

[0012] The power measuring element is arranged on the transmission light path side of the band-adjustable output coupling mirror assembly, and the power measuring element is used to measure the power of the laser of the target wavelength;

[0013] The data processing mechanism is connected to the power measuring element, and is used to determine the light extraction performance of the laser gain medium based on the power and the target wavelength.

[0014] According to an embodiment of the present invention, a device for measuring the light emission performance of a laser gain medium is provided, wherein the grating includes a blazed grating or a volume Bragg grating.

[0015] According to an embodiment of the present invention, a device for measuring the light output performance of a laser gain medium is provided, wherein the band-adjustable output coupling mirror assembly includes:

[0016] Mounting rack;

[0017] an aperture, the aperture being arranged on the mounting frame via a first adjustment component;

[0018] The aperture comprises a first aperture body and a second aperture body, and the first adjustment component is used to adjust the distance between the first aperture body and the second aperture body;

[0019] The output coupling mirror is arranged on the mounting frame.

[0020] According to an embodiment of the present invention, a device for measuring the light emission performance of a laser gain medium is provided. The first aperture body is made of a thermally expanding and contracting material. The first aperture body is provided with a temperature control line, and / or

[0021] The second aperture body is made of a thermally expanding and contracting material, and a temperature control line is arranged on the second aperture body.

[0022] According to an embodiment of the present invention, a device for measuring the light output performance of a laser gain medium further includes a pump source and a Q-switch module, wherein the pump source is used to control the frequency of the pump light and the Q-switch module is used to control the frequency of the loss change in the resonant cavity to control the frequency of the output pulsed laser;

[0023] The power measurement element is a photoelectric probe or a power meter, and the photoelectric probe is also used to measure the pulse width, peak power density and spot shape of the laser of the target wavelength.

[0024] According to an embodiment of the present invention, a device for measuring the light output performance of a laser gain medium is provided. A lens is arranged on the optical path between the grating and the band-adjustable output coupling mirror assembly, and the focal length of the lens is equal to the distance between the lens and the band-adjustable output coupling mirror assembly.

[0025] According to an embodiment of the present invention, a device for measuring the light output performance of a laser gain medium is provided. A spectroscopic element is provided on the transmission light path of the band-adjustable output coupling mirror group. The spectroscopic element is used to separate the light beam into a first light beam and a second light beam. The power measuring element is used to measure the power of the first light beam, and the wavelength measuring element is used to measure the wavelength of the second light beam.

[0026] The present invention further provides a method for measuring the light output performance of a laser gain medium, based on any of the above-mentioned devices for measuring the light output performance of a laser gain medium, the method comprising:

[0027] The laser output from the laser gain medium is dispersed by using a grating;

[0028] Adjusting the wavelength of the dispersed laser light by using a band-adjustable output coupling mirror assembly so that the band-adjustable output coupling mirror assembly outputs laser light of a target wavelength;

[0029] Measuring the power of the laser light of the target wavelength using a power measuring element;

[0030] A data processing mechanism is used to determine the light extraction performance of the laser gain medium based on the power and the target wavelength.

[0031] According to an embodiment of the present invention, a method for measuring the light extraction performance of a laser gain medium is provided, wherein the method uses a data processing mechanism to determine the light extraction performance of the laser gain medium based on the power and the target wavelength, including:

[0032] determining a photon number density based on the power and the target wavelength;

[0033] Based on the photon number density and the laser rate equation, an emission cross section is determined, where the emission cross section characterizes the light extraction performance of the laser gain medium.

[0034] The present invention also provides an electronic device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the method for measuring the light emission performance of any of the above-mentioned laser gain media is implemented.

[0035] The embodiments of the present invention provide a device and method for measuring the light extraction performance of a laser gain medium. A grating is used to disperse the laser light output by the laser gain medium. A band-tunable output coupling lens assembly is then used to adjust the laser wavelength, causing the band-tunable output coupling lens assembly to output laser light at a target wavelength. A power measurement element is used to measure the power of the laser light at the target wavelength output by the band-tunable output coupling lens assembly. Based on the target wavelength and its corresponding power, the light extraction performance of the laser gain medium is determined. This method, by adjusting the laser wavelength through the band-tunable output coupling lens assembly and measuring the emission cross section corresponding to each target wavelength through the power measurement element, enables direct measurement of the emission cross section of each wavelength during actual laser emission, thereby accurately determining the light extraction performance of the laser gain medium. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 Schematic diagram of the structure of a device for measuring the light output performance of a laser gain medium provided by an embodiment of the present invention;

[0038] Figure 2 1 is a schematic structural diagram of another device for measuring the light emission performance of a laser gain medium provided by an embodiment of the present invention;

[0039] Figure 3 The embodiment of the present invention provides a band-adjustable output coupling mirror assembly;

[0040] Figure 4 Schematic diagram of the relationship between the degenerate energy levels and emission wavelength of an Nd:YAG crystal, illustrating the relationship between the number of upper and lower energy levels and the emission cross section, provided by an embodiment of the present invention;

[0041] Figure 5 This is one of the flow charts of the method for measuring the light output performance of a laser gain medium provided in an embodiment of the present invention;

[0042] Figure 6 This is a second flow chart of a method for measuring the light output performance of a laser gain medium provided in an embodiment of the present invention;

[0043] Figure 7 It is a structural diagram of an electronic device provided by an embodiment of the present invention.

[0044] Reference numerals:

[0045] 1. Resonant cavity fully reflective mirror; 2. Laser crystal and pump module; 3. Grating; 4. Band-adjustable output coupling mirror assembly; 5. Laser optical path; 6. Highly reflective beam splitter prism; 7. Optical trash can; 8. Power measurement element; 9. Wavelength measurement element; 10. Data processing mechanism; 11. Gain fiber; 12. Semiconductor light emitting array coupling system; 13. Highly reflective beam splitter;

[0046] 41. Mirror frame base; 42. Mirror frame substrate; 43. First wave adjustment knob; 44. First aperture body; 45. Second wave adjustment knob; 46. Second aperture body; 47. Mirror frame; 48. Output coupling mirror; 49. Lens angle adjustment knob; 410. Lens fixing rod; 411. Temperature control line. DETAILED DESCRIPTION

[0047] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0048] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance.

[0049] In the description of the embodiments of the present invention, it should be noted that, unless otherwise specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; and direct connections or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of the present invention based on the specific circumstances.

[0050] In the embodiments of the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, a first feature being "above," "above," or "above" a second feature may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. A first feature being "below," "below," or "below" a second feature may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0051] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0052] The following combination Figure 1-Figure 4 A device for measuring the light emission performance of a laser gain medium according to an embodiment of the present invention is described.

[0053] The embodiment of the first aspect of the present invention provides a device for measuring the light emission performance of a laser gain medium, such as Figure 1 and Figure 2 As shown, the device for measuring the light output performance of the laser gain medium includes a resonant cavity total reflection mirror 1, a grating 3, a band-adjustable output coupling mirror group 4, a power measurement element 8, a wavelength measurement element 9 and a data processing mechanism 10.

[0054] Among them, the resonant cavity total reflection mirror 1 and the grating 3 are respectively located on both sides of the laser gain medium, the band-adjustable output coupling mirror group 4 is located on the output light path of the grating 3, the power measurement element 8 is arranged on the transmission light path side of the band-adjustable output coupling mirror group 4, and the data processing mechanism 10 is connected to the power measurement element 8 and the wavelength measurement element 9.

[0055] The grating 3 is used to disperse the laser light output by the laser gain medium; the band-tunable output coupling mirror group 4 is used to adjust the wavelength of the dispersed laser light so that the band-tunable output coupling mirror group 4 outputs laser light of a target wavelength; a wavelength measuring element is arranged on the transmission light path side of the band-tunable output coupling mirror group, and the wavelength measuring element is used to monitor the wavelength of the laser light output by the band-tunable output coupling mirror group so as to calibrate the wavelength of the laser light output by the band-tunable output coupling mirror group in real time; the power measuring element 8 is used to measure the power of the laser light of the target wavelength; and the data processing mechanism 10 is used to determine the light output performance of the laser gain medium based on the power and the target wavelength.

[0056] It will be understood that the laser resonant cavity includes a laser gain medium. In this embodiment, a grating 3 is added to the resonant cavity to disperse the laser light within the cavity. A band-tunable output coupling mirror assembly 4 is arranged on the output optical path of the grating 3. The light beam dispersed by the grating 3 is incident on the band-tunable output coupling mirror assembly 4. The band-tunable output coupling mirror assembly 4 adjusts the laser light so that only the light beam with the target wavelength passes through the band-tunable output coupling mirror assembly 4. The power of the light beam with the target wavelength is then measured by a power measurement element 8 located on the transmission optical path side of the band-tunable output coupling mirror assembly 4. Ultimately, the band-tunable output coupling mirror assembly 4 adjusts the target wavelength, and the wavelength measurement element calibrates the wavelength of the laser light outputted by the band-tunable output coupling mirror assembly in real time, ensuring that the band-tunable output coupling mirror assembly outputs laser light with the target wavelength. Real-time monitoring of different target wavelengths and corresponding powers allows the light output performance of the laser gain medium when outputting laser light at different wavelengths to be determined.

[0057] It should be noted that the band-tunable output coupling mirror assembly 4 can select the target wavelength range of the output, and thus can directly measure the light output performance of lasers with different wavelengths, so that the measurement result is more accurate.

[0058] The device for measuring the light extraction performance of a laser gain medium provided in an embodiment of the present invention disperses the laser light output by the laser gain medium through a grating 3. The wavelength of the laser light is then adjusted by a band-tunable output coupling mirror assembly 4, causing the band-tunable output coupling mirror assembly 4 to output laser light of a target wavelength. The power of the laser light of the target wavelength output by the band-tunable output coupling mirror assembly 4 is measured by a power measurement element 8. Based on the target wavelength and its corresponding power, the light extraction performance of the laser gain medium is determined. It can be seen that the present invention achieves direct measurement of the emission cross section of each wavelength during actual laser emission by adjusting the laser wavelength by the band-tunable output coupling mirror assembly 4 and measuring the emission cross section corresponding to each target wavelength by the power measurement element 8, thereby enabling accurate determination of the light extraction performance of the laser gain medium.

[0059] Furthermore, the measuring device also includes a pump source and a Q-switch module, wherein the pump source is used to control the frequency of the pump light and the Q-switch module is used to control the frequency of the loss change in the resonant cavity to control the frequency of the output pulse laser.

[0060] It can be understood that the laser gain medium and the pump source are assembled into a whole. The shutdown characteristics of the pump source and the Q-switch module (not shown in the figure) are controlled by the power supply. The pump source is used to control the frequency of the pump light, and the Q-switch module is used to control the frequency of the loss change in the resonant cavity. The frequency of the output pulsed laser is then controlled by the pump source and the Q-switch module. The power measurement element uses a photoelectric probe.

[0061] When the Q-switch module starts working, the pump source and the Q-switch module work together to change the frequency of the pump light injected by the pump source into the laser gain medium and the frequency of the cavity loss change, thereby outputting a pulsed laser and controlling the frequency of the pulsed laser. In addition to being able to measure the power of the target wavelength laser through the photoelectric probe, it can also achieve real-time monitoring of the pulse width, peak power, and spot shape of the target wavelength laser, thereby obtaining more light output performance information such as the energy level lifetime and crystal uniformity of the laser gain medium when outputting lasers at different wavelengths. Of course, a power meter can also be used as the power measurement element.

[0062] According to an embodiment of the present invention, the resonant cavity total reflection mirror 1 and the grating 3 are respectively located on both sides of the laser gain medium. The angle between the grating 3 and the optical axis of the light beam emitted from the laser gain medium is an acute angle. The light beam emitted from the laser gain medium is reflected by the grating 3 to the band-adjustable output coupling mirror group 4. The laser light of a portion of the target wavelength dispersed by the grating 3 is transmitted and output through the band-adjustable output coupling mirror group 4, and the laser light of the remaining target wavelength returns to the grating 3 through the band-adjustable output coupling mirror group 4 and is reflected back into the resonant cavity again by the grating 3.

[0063] It should be noted here that the band-adjustable output coupling mirror group 4 acts as an output coupling mirror, and its returned light is reflected again by the grating 3 to undergo an inverse dispersion process, which can make the light field in the resonant cavity self-reproduced.

[0064] In one embodiment of the present invention, a spectrometer is provided on the transmission light path of the band-adjustable output coupling mirror group 4. The spectrometer is used to split the light beam into two paths. The power measuring element 8 is provided on one of the light beam sides, and the wavelength measuring element 9 is provided on the other light beam side. In this embodiment, the wavelength measuring element 9 is a spectrometer.

[0065] It can be understood that a spectrometer is arranged on the transmission light path of the band-adjustable output coupling mirror assembly 4 to split the light beam into two paths, namely a first light beam and a second light beam. A power measuring element 8 is arranged on the side of the first light path, and the power measuring element 8 is used to measure the power of the laser light of the target wavelength output by the band-adjustable output coupling mirror assembly 4; a spectrometer is arranged on the side of the second light path, and the spectrometer is used to measure the wavelength of the laser light output by the band-adjustable output coupling mirror assembly 4.

[0066] Furthermore, since the spectrometer is sensitive to power and easily damaged, in this embodiment, an optical trash can 7 is arranged on the second light beam output by the band-adjustable output coupling lens assembly 4, and the spectrometer is set on the side of the second light beam.

[0067] It is understandable that the laser light path 5 output by the band-adjustable output coupling lens group 4 is received by the optical trash can 7, and the wavelength of the scattered light is detected by a spectrometer on the side of the laser light path 5 to avoid damage to the spectrometer by the laser.

[0068] In one embodiment of the present invention, grating 3 includes a blazed grating or a volume Bragg grating. For example, grating 3 can be a high damage threshold blazed grating, a volume Bragg grating, or other gratings. Where grating 3 is a high damage threshold blazed grating, the light energy is primarily concentrated in the first-order diffraction.

[0069] Furthermore, a lens (not shown in the figure) can be arranged on the optical path between the grating 3 and the band-adjustable output coupling mirror group 4. The focal length of the lens is approximately equal to the distance between the lens and the band-adjustable output coupling mirror group 4. The lens can collect more orders of diffraction light including the first-order diffraction, thereby reducing cavity loss.

[0070] It is understood that adding a lens between the aperture and grating 3 not only collects high-order diffracted light but also generates a Fourier transform, allowing for spatial separation of dispersion. Preferably, the focal length of the lens is equal to the distance between the lens and the band-adjustable output coupling mirror assembly 4. By cleverly positioning the output coupling mirror 48 and the lens, a 4f system is formed, meeting the requirements for intracavity light field self-reproduction.

[0071] In one embodiment of the present invention, the band-tunable output coupling mirror assembly 4 includes an aperture, which transmits light of a certain wavelength and intercepts light of other wavelengths, thereby enabling the band-tunable output coupling mirror assembly 4 to output laser light of a target wavelength.

[0072] It can be understood that the aperture intercepts light of other wavelengths, which is equivalent to the loss of these intercepted wavelengths of light in the cavity approaching infinity, and they cannot oscillate. By setting a detection device outside the cavity, the wavelength and output power of the output laser can be monitored in real time. The detection device here includes a spectrometer and a power measurement element 8. In this embodiment, a grating 3 is added to the intracavity optical path to disperse the light in the laser cavity, so that light of different wavelengths in the cavity is spatially separated. Then, an aperture is used to transmit light of a certain wavelength, and the laser power when the laser is output at this wavelength can be measured by the power measurement element 8. Based on the power and wavelength, the light output performance of the laser gain medium can be obtained.

[0073] It should be noted that by adjusting the aperture, the wavelength of the transmitted laser is adjusted, and the corresponding power is measured in real time by the power measuring element 8. Therefore, by adjusting the aperture, the light output performance of the laser gain medium when outputting lasers at different wavelengths can be obtained.

[0074] It should be noted that, during the process of adjusting the aperture, the wavelength of the laser output by the band-adjustable output coupling mirror assembly 4 is monitored in real time by a spectrometer.

[0075] The device for measuring the light emission performance of a laser gain medium provided in an embodiment of the present invention can achieve output laser power under the same resonant cavity, laser gain medium, pumping conditions, different wavelengths, and the same spectral width by adjusting the aperture. This device can invert the light emission performance of the laser gain medium at different wavelengths and more directly obtain the emission cross section of the laser gain medium when outputting laser light at different wavelengths.

[0076] The device for measuring the light emission performance of a laser gain medium provided by an embodiment of the present invention has the characteristics of simple structure and easy construction.

[0077] In one embodiment of the present invention, the band-adjustable output coupling mirror assembly 4 includes a mounting frame, an aperture and an output coupling mirror 48 disposed on the mounting frame.

[0078] It can be understood that the mounting frame has a first side and a second side, the diaphragm is set on the first side of the mounting frame through the first adjustment component, the output coupling mirror 48 is set on the second side of the mounting frame, and the diaphragm is arranged close to the grating 3.

[0079] It is understandable that the diaphragm is adjusted by the first adjustment component to adjust the wavelength of the transmitted laser light. That is, the center wavelength and wavelength range of the emitted laser light can be freely adjusted by the first adjustment component.

[0080] In this embodiment, Figure 3As shown, the aperture includes a first aperture body 44 and a second aperture body 46 that are spaced apart. The distance between the first aperture body 44 and the second aperture body 46 represents the wavelength of light transmitted through the aperture. The distance between the first aperture body 44 and the second aperture body 46 is adjusted by a first adjustment component to achieve adjustment of the wavelength of the laser transmitted through the aperture.

[0081] It should be noted that since the laser has been dispersed in space, the upper and lower limits of the emission wavelength range of the laser gain medium can be selected. The upper and lower limits respectively represent the upper and lower limits of the distance between the first aperture body 44 and the second aperture body 46. The distance between the first aperture body 44 and the second aperture body 46 can be adjusted between the upper and lower limits.

[0082] For example, the mounting frame includes a mirror frame base 41 and a mirror frame substrate 42, the mirror frame substrate 42 is vertically arranged on the mirror frame base 41, the first aperture body 44 and the second aperture body 46 are located on one side of the mirror frame substrate 42 and are supported on the mirror frame base 41, the first adjustment component includes a first wave adjustment knob 43 and a second wave adjustment knob 45, the first wave adjustment knob 43 passes through the mirror frame substrate 42 and is connected to the first aperture body 44, the second wave adjustment knob 45 passes through the mirror frame substrate 42 and is connected to the second aperture body 46, the first wave adjustment knob 43 can be used to make the first aperture body 44 close to or away from the side of the second aperture body 46, and the second wave adjustment knob 45 can be used to make the second aperture body 46 close to or away from the side of the first aperture body 44.

[0083] It should be noted that the distance between the first aperture body 44 and the second aperture body 46 can be adjusted by the first wave adjustment knob 43, the distance between the first aperture body 44 and the second aperture body 46 can be adjusted by the second wave adjustment knob 45, and the distance between the first aperture body 44 and the second aperture body 46 can be adjusted by the first wave adjustment knob 43 and the second wave adjustment knob 45. Of course, the first adjustment component can also adopt other adjustment mechanisms, such as an adjustment structure in which a slide groove and a slider cooperate.

[0084] Furthermore, the band-adjustable output coupling mirror assembly 4 further includes a second adjusting component. The output coupling mirror 48 is disposed on the second side of the mounting frame through the second adjusting component. The second adjusting component is used to adjust the position of the output coupling mirror 48 .

[0085] It can be understood that the output coupling mirror 48 is located on the other side of the mirror frame substrate 42, that is, the output coupling mirror 48 and the aperture are arranged on both sides of the mirror frame substrate 42 respectively. Correspondingly, a light-transmitting window that cooperates with the aperture and the output coupling mirror 48 is provided on the mirror frame substrate 42.

[0086] It should be noted that the band-tunable output coupling mirror assembly 4 is positioned with the aperture side close to the grating 3 to control the resonant wavelength within the cavity. The output coupling mirror 48 and the aperture are placed together as a single component. The resonant cavity geometry is fixed, and only one aperture needs to be adjusted to measure and optimize the output power.

[0087] For example, the output coupling mirror 48 is disposed on the other side of the frame substrate 42 via a frame 47. The frame 47 is mounted on the frame substrate 42 via a lens angle adjustment knob 49 and a lens fixing rod 410. The output coupling mirror 48 is fixed to the frame 47. Adjusting the lens angle adjustment knob 49 can adjust the posture of the output coupling mirror 48, that is, adjust the angle of the output coupling mirror 48 in the optical path to optimize the optical path. In this embodiment, the frame 47 is mounted on the frame substrate 42 via two lens angle adjustment knobs 49 and two lens fixing rods 410. The two lens angle adjustment knobs 49 and the two lens fixing rods 410 are arranged in a rectangular shape, and the two lens angle adjustment knobs 49 are arranged diagonally. By adjusting the two lens angle adjustment knobs 49, the angle of the output coupling mirror 48 in the optical path can be adjusted.

[0088] In this embodiment, the output coupling mirror 48 transmits part of the light transmitted by the aperture to output for power and wavelength measurement, and the remaining light is reflected back to the grating 3 through the output coupling mirror 48 .

[0089] It should be noted that within the wavelength range with similar light output performance, the resonant cavity design of the present invention can also select the light output center wavelength and the light output wavelength range, because the resonant cavity structure does not change, the self-reproducing mode does not change, and there is almost no loss of beam energy and beam quality.

[0090] It can be understood that when the light returned by the output coupling mirror 48 is multiple, the grating 3 adopts a blazed grating, because the reflection of the blazed grating satisfies formula (6).

[0091] d(sinα+sinθ)=mλ (6)

[0092] Where α is the incident angle relative to the grating normal, and θ is the exit angle relative to the grating normal. j When there are multiple incident angles α, the corresponding exit angles θ are the same. j The return light path is reversible, then θ j becomes the incident angle, α becomes the exit angle, and the inverse dispersion process is completed. The light passing through the gain medium is no different from the light in the ordinary resonant cavity.

[0093] Preferably, the substrate of the output coupling mirror 48 should be a plane mirror to satisfy the inverse dispersion process.

[0094] Furthermore, the first aperture body 44 is made of a material that expands with heat and contracts with cold, and the first aperture body 44 is provided with a temperature control line 411 .

[0095] It can be understood that the first aperture body 44 is arranged with multiple temperature control lines 411 to form a temperature control line array, and the temperature of the first aperture body 44 is adjusted by the temperature control line array. Since the first aperture body 44 adopts a material that expands and contracts with heat, the distance between the first aperture body 44 and the second aperture body 46 can be precisely adjusted to precisely select the transmitted wavelength.

[0096] The second aperture body 46 may also be made of a thermally expanding and contracting material, and the second aperture body 46 is provided with a temperature control line 411 .

[0097] It should be noted that aperture adjustment requires high precision, and conventional mechanical adjustment cannot meet this precision requirement. In the embodiment of the present invention, the first aperture body 44 and the second aperture body 46 are made of a material that expands and contracts with heat, and temperature control wires 411 are arranged thereon. Based on the principle of thermal expansion and contraction, the aperture temperature is controlled to achieve precise wavelength selection.

[0098] In this embodiment, the temperature control line 411 on the first aperture body 44 and the second aperture body 46 can be connected to the wavelength detection module in the detector. When the center wavelength or spectral width of the output light deviates from the target wavelength, the center position and width of the gap between the two aperture bodies can be precisely adjusted by using the temperature control line to adjust the center wavelength and spectral width in real time, thereby forming self-feedback adjustment.

[0099] The following describes a method for measuring the light extraction performance of a laser gain medium provided by the present invention. The following method for measuring the light extraction performance of a laser gain medium and the above-described device for measuring the light extraction performance of a laser gain medium can be used for reference.

[0100] The embodiment of the second aspect of the present invention provides a method for measuring the light output performance of a laser gain medium, such as Figure 5 As shown, the method includes the following steps:

[0101] Step 100: Use the grating 3 to disperse the laser light outputted by the laser gain medium.

[0102] Step 200 : Using the band-tunable output coupling mirror assembly 4 to adjust the wavelength of the dispersed laser light, so that the band-tunable output coupling mirror assembly 4 outputs laser light of a target wavelength.

[0103] Step 300: Measure the power of the laser light of the target wavelength using the power measuring element 8.

[0104] Step 400: Determine the light output performance of the laser gain medium based on the power and the target wavelength using the data processing mechanism 10.

[0105] The method for measuring the light extraction performance of a laser gain medium provided in an embodiment of the present invention disperses the laser light output by the laser gain medium through a grating 3, then adjusts the laser wavelength through a band-tunable output coupling mirror assembly 4 so that the band-tunable output coupling mirror assembly 4 outputs laser light of a target wavelength. The power of the laser light of the target wavelength output by the band-tunable output coupling mirror assembly 4 is measured through a power measurement element 8, and the light extraction performance of the laser gain medium is determined based on the target wavelength and its corresponding power. It can be seen that the present invention achieves direct measurement of the emission cross section of each wavelength during actual laser emission by adjusting the laser wavelength through the band-tunable output coupling mirror assembly 4 and measuring the emission cross section corresponding to each target wavelength through the power measurement element 8, thereby accurately obtaining the light extraction performance of the laser gain medium.

[0106] Furthermore, in step 300, the power measurement element can also measure information such as the pulse, peak power density, and spot shape of the laser light at the target wavelength. Correspondingly, in step 400, the data processing mechanism determines the light output performance of the laser gain medium based on the power, pulse, peak power density, spot shape, and target wavelength, thereby obtaining information such as the energy level lifetime and crystal uniformity of the laser gain medium.

[0107] In one embodiment of the present invention, Figure 6 As shown, step 400, using the data processing unit 10 to determine the light output performance of the laser gain medium based on the power and target wavelength laser, specifically includes the following steps:

[0108] Step 401: Determine the photon number density based on the power and target wavelength of the laser.

[0109] Step 402: Determine an emission cross section based on the photon number density and the laser rate equation. The emission cross section characterizes the light emission performance of the laser gain medium.

[0110] According to an embodiment of the present invention, the present invention uses a controlled variable method to compare the output laser power under the same resonant cavity, laser gain medium, pumping conditions, different wavelengths, and the same spectral width, and invert the light output performance of the laser gain medium at different wavelengths. This can more directly determine the performance of the laser gain medium when outputting laser light at different wavelengths.

[0111] This embodiment is based on the relationship between the photon number density and the emission cross section in the laser rate equation. By determining the photon number density, the emission cross section can be obtained, and thus the light emission performance of the laser gain medium can be obtained.

[0112] For example, the rate equation uses the rate equation of a typical three-level laser, and its expression is shown in formula (2).

[0113]

[0114] Where: n represents the number of energy level particles per unit volume of the gain medium, n tot represents the total number of doping particles per unit volume, c represents the speed of light, l represents the length of the laser gain medium, l′ represents the length of the resonant cavity, τ j represents the fluorescence decay time of the upper laser level, W p(i) represents the pumping rate; j represents the oscillation laser mode number, v j represents the frequency corresponding to the oscillating laser mode number j; represents the photon number density, represents the emission cross section, represents the decay time of the photon.

[0115] Among them, the frequency v j Obtained by formula (3).

[0116]

[0117] Where: j Represents the wavelength of each standing wave in the resonant cavity.

[0118] In theoretical analysis, the According to σ in formula (1) em (λ) is directly substituted into the equation. However, the physical conditions described by equations (1) and (2) are different. For a laser gain medium pumped by a specific wavelength, when all upper energy levels of the doped particles simultaneously undergo radiative transitions to all lower energy levels, equation (1) gives the emission cross section of each wavelength of the laser gain medium; when one or several upper energy levels of the doped particles undergo radiative transitions to one or several lower energy levels, equation (2) requires the emission cross section of several wavelengths of the laser gain medium to be substituted into the equation. Obviously, the equation (2) According to σ in formula (1) em (λ) is directly brought into the equation, and the evaluation of the light-emitting performance of the laser gain is obviously inaccurate.

[0119] For example, Figure 4 As shown, taking the Nd:YAG laser as an example, when the light emission band is around 1 micron, the Nd has 4 subdivided lower energy levels and 2 subdivided upper energy levels, and there are 8 permutations and combinations of transitions between the upper and lower energy levels. However, only one of these transitions occurs during actual laser emission. It is assumed that the transitions between these subdivided energy levels are completed transiently (the time for non-radiative transitions between energy levels is much shorter than the time for the doped particles to be stimulated to transition upward), thus giving the laser rate equation. If the emission cross section of each wavelength can be directly measured during actual laser emission, it will be more effective to evaluate the laser gain emission performance. Therefore, the present invention directly measures the emission cross section of each wavelength band (i.e., one or several intracavity standing wave wavelengths λj) during actual laser emission, thereby being able to accurately obtain the laser gain medium emission performance.

[0120] It is understandable that the wavelength of the output laser (corresponding to v j ) and optical power (corresponding to ) is used for real-time monitoring, so that the photon number density can be obtained based on the target wavelength and corresponding power of the output laser.

[0121] In a continuous laser, That is, we get formula (4).

[0122]

[0123] In formula (4), the decay time of the photon is The emission cross section can be obtained by inversely solving the parameters such as the diffraction efficiency of the grating and the output efficiency of the output coupling mirror. The other parameters are known, so the emission cross section can be obtained by combining formula (2) This allows the laser gain medium to directly measure its light output performance of lasers of different wavelengths, thereby ensuring the accuracy of the measurement results.

[0124] In a specific embodiment of the present invention, Figure 1 As shown, taking an Nd:YAG solid-state laser as an example, the laser gain medium of the Nd:YAG solid-state laser is a laser crystal, and the light output performance of the laser crystal in the 900-1200nm band is measured. The measuring device for the light output performance of the laser gain medium in this embodiment includes a resonant cavity total reflection mirror 1, a laser gain medium, a pump source, a Q-switch module, a grating 3, a band-adjustable output coupling mirror group 4, a power measurement element 8 and a data processing mechanism 10.

[0125] The resonant cavity total reflection mirror 1 is a full-detection band total reflection mirror. In this embodiment, the resonant cavity total reflection mirror 1 uses a silver mirror, and the laser crystal and the pump source are integrated into a laser crystal and pump module 2. The module is placed between the resonant cavity total reflection mirror 1 and the grating 3. In order to meet the heat dissipation requirements, the module has a water cooling function.

[0126] Grating 3 is located on the outgoing light path of the laser crystal. Grating 3 uses a high damage threshold blazed grating with a blazing wavelength of 1 micron and 100 lines / mm. In the 900-1200nm band, the single reflection efficiency can reach more than 60%.

[0127] For example, wavelength λ j =1000nm, the reflection efficiency R=65%, and the output coupling loss S of the ordinary cavity corresponding to each round-trip optical path in the cavity is calculated by the following formula (5).

[0128] S=1-R 2 T (5)

[0129] Where R represents the reflection efficiency and T represents the transmittance.

[0130] The output coupling mirror in the band-adjustable output coupling mirror assembly is coated with a film layer with a transmittance T>17% in the range of 900-1200 nm.

[0131] Based on formula (5), the corresponding common cavity output coupling loss S is calculated to be approximately 1-65%×65%×(1-17%)>65%.

[0132] The band-adjustable output coupling lens assembly 4 includes a mounting frame, an aperture, and an output coupling mirror 48. The aperture is set on the first side of the mounting frame through a first adjustment component, and the output coupling mirror 48 is set on the second side of the mounting frame. The aperture includes a first aperture body 44 and a second aperture body 46 that are spaced apart. The first adjustment component includes a first wave adjustment knob 43 and a second wave adjustment knob 45.

[0133] By adjusting the first wave adjustment knob 43 and the second wave adjustment knob 45, the first aperture body 44 and the second aperture body 46 can be moved towards or away from each other, so that the band-adjustable output coupling mirror group 4 outputs laser light of the target wavelength; the output coupling mirror 48 is set on the other side of the mirror frame substrate 42 through the mirror frame 47, and the mirror frame 47 is set on the mirror frame substrate 42 through the lens angle adjustment knob 49 and the lens fixing rod 410. The output coupling mirror 48 is fixed on the mirror frame 47. The angle of the output coupling mirror 48 can be adjusted by adjusting the two lens angle adjustment knobs 49 to optimize the optical path; and the temperature can be adjusted based on the temperature control line 411 to precisely adjust the distance between the first aperture body 44 and the second aperture body 46, so as to precisely select the wavelength of the light transmitted by the aperture.

[0134] When placing the band-adjustable output coupling mirror assembly 4, the aperture side is close to the grating 3 to control the resonant wavelength in the cavity.

[0135] A spectroscopic element is provided in the transmission light path of the band-adjustable output coupling mirror assembly 4. The spectroscopic element adopts a high-reflection spectroscopic prism 6. The high-reflection spectroscopic prism 6 is coated with a high-reflection film in the 900-1200nm band on one side of the resonant cavity (the first side, i.e., the incident surface) with a reflectivity greater than 99%. The other side of the laser light path 5 (the second side, i.e., the exit surface) is coated with a high-transmittance film in the 900-1200nm band with a transmittance greater than 95%.

[0136] Since the spectrometer is sensitive to power and easily damaged, an optical trash can 7 is arranged on the transmission light path of the highly reflective beam splitter 6. The optical trash can 7 is used to connect the laser light path 5, and a spectrometer is used on the side of the laser light path 5 to detect the wavelength of the scattered light.

[0137] The power measuring element 8 is a photoelectric probe, which is arranged on the reflected light path of the high-reflection beam splitter 6. The photoelectric probe monitors the light power output from the resonant cavity, and an attenuation plate is arranged in front of the photoelectric probe.

[0138] The distance between the first aperture body 44 and the second aperture body 46 is adjusted by the first adjustment component and the temperature control line 411 so that the wavelength monitored by the spectrometer reaches the target wavelength, and the photoelectric probe obtains the power of the laser of the target wavelength in real time.

[0139] The data processing mechanism 10 is connected to the spectrometer and the photoelectric probe respectively. The photon number density is obtained based on the target wavelength and the power (output light power) corresponding to the target wavelength. The emission cross section corresponding to the target wavelength is calculated based on formula (4). The distance between the first aperture body 44 and the second aperture body 46 is adjusted by the first adjustment component and the temperature control line 411 to adjust the wavelength of the laser light, thereby accurately measuring the light output performance of the laser gain medium outputting lasers of different wavelengths.

[0140] When the Q switch starts working, the photoelectric probe can also monitor the power, pulse width, peak power, and spot shape of lasers with different target wavelengths in real time, thereby obtaining more light output performance information such as the energy level lifetime and crystal uniformity of the laser gain medium when outputting lasers at different wavelengths.

[0141] In another specific embodiment of the present invention, Figure 2 As shown, taking a Ho-doped fiber laser as an example, the laser gain medium of the Ho-doped fiber laser is a gain fiber 11, and the light output performance of the gain fiber core in the band around 2.1 μm is measured. The measuring device for the light output performance of the laser gain medium in this embodiment includes a resonant cavity total reflection mirror 1, a gain fiber 11, a grating 3, a band-adjustable output coupling mirror group 4, a power measurement element 8, and a data processing mechanism 10.

[0142] The gain fiber 11 adopts a double-cladding structure, with the inner layer being the gain fiber core and the outer layer being the pump light channel. The pump light is introduced into the pump light channel through the semiconductor light emitting array coupling system 12 .

[0143] The resonant cavity total reflection mirror 1 is a total reflection mirror for the entire detection band, and the output coupling mirror 48 in the band-adjustable output coupling mirror group 4 is coated with a 2.1 μm T=5% transmittance film.

[0144] Grating 3 uses a high damage threshold volume Bragg grating with a central wavelength λ of 2.1μm and a diffraction efficiency of 99%. By controlling the temperature of the volume Bragg grating, the central wavelength λ can be improved to λ±dλ (dλ is very small, but the diffraction efficiency of this central wavelength is still very high).

[0145] The spectroscopic element adopts a high-reflection spectrometer 13, which is coated with a 2.1μm high-transmittance film on one side of the resonant cavity with a transmittance of 99% and a 2.1μm high-transmittance film on the other side of the laser light path 5 with a transmittance of 99%.

[0146] Since the optical output power of the fiber laser is relatively low, a spectrometer can be used to directly connect to the laser light path 5 , and the spectrometer is set on the reflected light path of the high-reflection beam splitter 13 .

[0147] The power measuring element 8 is a power meter, which is arranged on the transmission light path of the high-reflection beam splitter 13 .

[0148] The data processing mechanism 10 is connected to the spectrometer and the power meter respectively. The photon number density is obtained based on the target wavelength and the power (output power) corresponding to the target wavelength. The emission cross section corresponding to the target wavelength is calculated based on formula (4). The distance between the first aperture body 44 and the second aperture body 46 is adjusted by the first adjustment component and the temperature control line 411 to adjust the wavelength of the laser light output, thereby accurately measuring the light output performance of the gain fiber core outputting lasers of different wavelengths.

[0149] Figure 7 The physical structure diagram of the electronic device provided by the embodiment of the present invention is illustrated as follows. Figure 7 As shown, the electronic device may include: a processor 710, a communications interface 720, a memory 730, and a communication bus 740, wherein the processor 710, the communications interface 720, and the memory 730 communicate with each other via the communication bus 740. The processor 710 may call the logic instructions in the memory 730 to execute the method for measuring the light output performance of the laser gain medium as described in any of the above embodiments.

[0150] In addition, the logic instructions in the above-mentioned memory 730 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when sold or used as an independent product. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0151] On the other hand, the present invention also provides a computer program product, which includes a computer program. The computer program can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the method for measuring the light output performance of the laser gain medium as in any of the above embodiments.

[0152] On the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to perform the method for measuring the light output performance of a laser gain medium as described in any of the above embodiments.

[0153] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A device for measuring the light output performance of a laser gain medium, characterized in that: It includes a resonant cavity full reflection mirror, a grating, a band-adjustable output coupling mirror group, a power measurement element, a wavelength measurement element and a data processing mechanism; The resonant cavity total reflection mirror and the grating are respectively located on both sides of the laser gain medium, and the grating is used to disperse the laser output by the laser gain medium; The band-adjustable output coupling mirror assembly is located on the output light path of the grating, and is used to adjust the wavelength of the dispersed laser so that the band-adjustable output coupling mirror assembly outputs laser light of a target wavelength; The wavelength measuring element is arranged on the transmission light path side of the band-adjustable output coupling mirror assembly, and the wavelength measuring element is used to monitor the wavelength of the laser output by the band-adjustable output coupling mirror assembly; The power measuring element is arranged on the transmission light path side of the band-adjustable output coupling mirror assembly, and the power measuring element is used to measure the power of the laser of the target wavelength; The data processing mechanism is connected to the power measuring element, and is used to determine the light extraction performance of the laser gain medium based on the power and the target wavelength.

2. The device for measuring the light emission performance of a laser gain medium according to claim 1, wherein: The grating includes a blazed grating or a volume Bragg grating.

3. The device for measuring the light output performance of a laser gain medium according to claim 1, wherein: The band-adjustable output coupling mirror assembly includes: Mounting rack; an aperture, the aperture being arranged on the mounting frame via a first adjustment component; The aperture comprises a first aperture body and a second aperture body, and the first adjustment component is used to adjust the distance between the first aperture body and the second aperture body; The output coupling mirror is arranged on the mounting frame.

4. The device for measuring the light emission performance of a laser gain medium according to claim 3, wherein: The first aperture body is made of a thermally expanding and contracting material, the first aperture body is provided with a temperature control line, and / or, The second aperture body is made of a thermally expanding and contracting material, and a temperature control line is arranged on the second aperture body.

5. The device for measuring the light output performance of a laser gain medium according to claim 1, wherein: It also includes a pump source and a Q-switch module, wherein the pump source is used to control the frequency of the pump light and the Q-switch module is used to control the frequency of the loss change in the resonant cavity to control the frequency of the output pulse laser; The power measurement element is a photoelectric probe or a power meter, and the photoelectric probe is also used to measure the pulse width, peak power density and spot shape of the laser of the target wavelength.

6. The device for measuring the light emission performance of a laser gain medium according to any one of claims 1 to 5, characterized in that: A lens is arranged on the optical path between the grating and the waveband-adjustable output coupling mirror assembly, and the focal length of the lens is equal to the distance between the lens and the waveband-adjustable output coupling mirror assembly.

7. The device for measuring the light emission performance of a laser gain medium according to any one of claims 1 to 5, characterized in that: A spectroscopic element is provided on the transmission light path of the band-adjustable output coupling mirror assembly, and the spectroscopic element is used to separate the light beam into a first light beam and a second light beam. The power measuring element is used to measure the power of the first light beam, and the wavelength measuring element is used to measure the wavelength of the second light beam.

8. A method for measuring the light output performance of a laser gain medium, characterized in that: The device for measuring the light emission performance of a laser gain medium according to any one of claims 1 to 7, wherein the method comprises: The laser output from the laser gain medium is dispersed by using a grating; Adjusting the wavelength of the dispersed laser light by using a band-adjustable output coupling mirror assembly so that the band-adjustable output coupling mirror assembly outputs laser light of a target wavelength; Measuring the power of the laser light of the target wavelength using a power measuring element; A data processing mechanism is used to determine the light extraction performance of the laser gain medium based on the power and the target wavelength.

9. The method for measuring the light output performance of a laser gain medium according to claim 8, wherein: The determining the light output performance of the laser gain medium based on the power and the target wavelength by using a data processing mechanism includes: determining a photon number density based on the power and the target wavelength; Based on the photon number density and the laser rate equation, an emission cross section is determined, where the emission cross section characterizes the light extraction performance of the laser gain medium.

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the method for measuring the light output performance of the laser gain medium according to any one of claims 1 to 9 is implemented.

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