A method for generating red-edge band laser based on barium gallium selenide and potassium titanium oxyphosphate crystal

Abstract

The present invention proposes a method for generating a red-edge band laser based on barium gallium selenide and potassium titanyl phosphate crystals, and belongs to the field of red-edge band laser technology. The method uses a 1.06μm laser to pump a new nonlinear crystal BGSe. Under type I phase matching conditions, when the cutting angle of the BGSe crystal changes between 50.5°-56.9°, a 1.3-1.6μm near-infrared tunable laser output can be achieved. The output 1.3-1.6μm laser is pumped to a KTP crystal. Under type II phase matching conditions, when the KTP crystal changes between 58.4°-52.4°, a 670-760nm frequency-doubled laser output can be achieved. The method can obtain a higher wavelength tuning resolution, with an average tuning resolution of 14nm / °, and can obtain a red-edge band laser output that is at least better than 0.14nm.

Description

Technical Field

[0001] The invention belongs to the technical field of red edge band lasers, and in particular relates to a method for generating red edge band lasers based on barium gallium selenide and potassium titanyl phosphate crystals. Background Art

[0002] The red edge band is located between red light and near infrared light, with a wavelength range of approximately 670-760nm. In this band, the emissivity of vegetation changes rapidly, forming an obvious "red edge". The red edge band has important applications in agriculture and remote sensing. Due to the reflective characteristics of vegetation in this band, the red edge band can be used to monitor vegetation growth, health status, chlorophyll content and other information. In addition, it can also be used to distinguish different types of vegetation and land cover types, because different types of vegetation have different reflective characteristics in the red edge band. Therefore, the red edge band is widely used in agriculture, forestry, ecology and geography.

[0003] At present, the commonly used lasers for red edge band detection are mainly hyperspectral lidar (HSL) based on acousto-optic tunable filter (AOTF). HSL has a supercontinuum spectrum, and AOTF can select the corresponding filter band to achieve tunable laser output in the 670-760nm red edge band. However, this solution has two disadvantages. First, due to the limitations of the technical system, its tuning resolution is not high, about 2-6nm, and it is difficult to accurately align the required laser wavelength. Second, the laser utilization efficiency is not high. In the supercontinuum laser, only a small part of the laser energy of the specified wavelength can be output, and most of it is filtered out, so the output laser power is limited.

[0004] Another commonly used red-edge laser is the titanium sapphire laser, whose fluorescence spectrum covers 650-1030nm, but the highest transmittance is between 691-996nm, failing to cover the red-edge band of 670-690nm. In addition, titanium sapphire lasers have the disadvantages of being large in size, expensive, having low pump light conversion efficiency, being difficult to debug, and having high system maintenance costs.

[0005] The AOTF technology can be used to obtain tunable laser output in the 670-760nm band. Specifically, the acousto-optic tunable filter (AOTF) technology is used to perform spectral selection on the supercontinuum laser (SCL), achieving wavelength tuning in the range of 500-1000nm with a wavelength resolution of 10nm. The device was also used to measure the yellow and green leaves of four plants (aloe, dracaena, balata and dracaena) to evaluate its feasibility in agricultural applications. Although this scheme can achieve tunable laser output in the red edge band, the tuning resolution is not high, the output laser efficiency is not high, and the output laser energy (power) is limited.

[0006] The titanium sapphire laser can be used to obtain tunable laser output in the 720-884nm band. Specifically, the prism cavity and the Littman cavity are combined using a narrow linewidth titanium sapphire laser with wide wavelength tunability to achieve tunable output of 720-884nm. Although this solution can achieve wavelength tuning of part of the red edge band, it does not achieve the tuning range below 720nm and cannot cover the entire red edge band. Summary of the invention

[0007] Based on the above technical problems, the present invention proposes a method for generating red-edge laser based on barium gallium selenide and potassium titanyl phosphate crystals. The method uses a laser generating device to generate red-edge laser.

[0008] The laser generating device comprises the following components: a laser, a pinhole aperture D1, a telescope system, a pinhole aperture D2, an optical parametric oscillator, a plane mirror F1, a plane mirror F2, a KTP crystal, a plane mirror F3, and a spectrometer arranged in sequence along the optical transmission axis.

[0009] The optical parametric oscillator includes the following components: a plane mirror M1, a BGSe crystal located on a rotatable platform, and a plane mirror M2, which are sequentially arranged along the optical transmission axis.

[0010] The light transmission axis is located at the center of each of the above components.

[0011] The pulse laser output by the laser pump passes through the pinhole aperture D1, the telescope system, and the pinhole aperture D2 before reaching the optical parametric oscillator.

[0012] In the optical parametric oscillator, the pulse laser pumps the BGSe crystal after passing through the plane mirror M1, outputs near-infrared tunable laser under type I phase matching conditions, and the near-infrared tunable laser is output by the optical parametric oscillator after passing through the plane mirror M2.

[0013] The near-infrared tunable laser reaches the KTP crystal after passing through the plane mirrors F1 and F2. The near-infrared tunable laser pumps the KTP crystal, outputs frequency-doubled laser under type II phase matching conditions, and obtains red-edge laser after passing through the plane mirror F3.

[0014] The red edge laser light is captured by a spectrometer to determine the wavelength of the red edge laser light.

[0015] According to the above method: the laser is a Nd:YAG laser, and the wavelength of the output pulse laser is 1.06μm; the pinhole telescope D1 and the pinhole aperture D2 are used to adjust the transmission direction of the pulse laser so that the transmission direction of the pulse laser is perpendicular to the vertical direction of the optical parametric oscillator; the telescope system is used to adjust the spot radius of the pulse laser passing through the pinhole aperture D1.

[0016] According to the above method: the plane mirror M1 and the plane mirror M2 transmit the pump light and the signal light, and reflect the idler light, and the plane mirror M1 and the plane mirror M2 are perpendicular to the transmission direction of the pulse laser; in the optical parametric oscillator, the pulse laser is used as the pump light to pump the BGSe crystal after passing through the plane mirror M1, and is decomposed into signal light and idler light, the signal light is transmitted by the plane mirror M2, and the idler light is reflected by the plane mirror M2; the near-infrared tunable laser output by the optical parametric oscillator is the signal light, the residual pump light and the idler light.

[0017] According to the above method: under type I phase matching conditions, when the cutting angle of the BGSe crystal varies between 50.5° and 56.9°, the near-infrared tunable laser with a wavelength range of 1.3-1.6 μm is output.

[0018] According to the above method: the plane mirror F1 and the plane mirror F2 transmit signal light and reflect pump light and idler light; the plane mirror F1, the plane mirror F2 and the plane mirror F3 have an angle with the transmission direction of the pulsed laser, and the angle ranges from 85° to 89°, so as to prevent the laser reflected by the plane mirror F1, the plane mirror F2 and the plane mirror F3 from damaging the various components configured on the optical transmission axis.

[0019] According to the above method: after the near-infrared tunable laser output by the optical parametric oscillator passes through the plane mirror F1 and the plane mirror F2, only the signal light reaches the KTP crystal, and under the type II phase matching condition, when the KTP crystal changes between 58.4° and 52.4°, the output frequency-doubled laser with a wavelength range of 670-760nm is output; the plane mirror F3 transmits the red-edge laser and reflects the signal light, and the frequency-doubled laser obtains the red-edge laser after passing through the plane mirror F3.

[0020] According to the above method: the cutting angle range of the BGSe crystal is (53.7°, 0°), it is tuned within the range of (50.5°, 56.9°), and an anti-reflection film is plated in the corresponding bands of the pump light with a wavelength of 1.06μm, the signal light with a wavelength of 1.3-1.6μm, and the idler light with a wavelength of 3.1-5.9μm.

[0021] According to the above method: the cutting angle range of the KTP crystal is (55.4°, 0°), it is tuned in the range of (52.4°, 58.4)°, and an anti-reflection film is plated in the corresponding bands of the signal light with a wavelength of 1.3-1.6 μm and the red edge laser with a wavelength of 670-760 nm.

[0022] The technical solution proposed by the present invention first uses a 1.06μm laser to pump a BaGa4Se7 (BGSe) crystal to generate a 1340-1520nm laser, and then multiplies the generated 1340-1520nm laser to 670-760nm through a KTiOPO4 (KTP) crystal. The laser generating device proposed by the present invention has a wide tunable range, high tuning accuracy, simple structure, and is fully solidified, and has broad application prospects in the fields of agriculture, remote sensing, and earth monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 is a schematic diagram of components of a laser generating device according to an embodiment of the present invention;

[0025] Figure 2 is the phase matching curve of BGSe crystal;

[0026] Figure 3 is the phase matching curve of KTP crystal. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0028] BGSe:BaGa 4 Se 7 , barium gallium selenide, a mid-to-far infrared nonlinear crystal.

[0029] KTP:KTiOPO 4 , potassium titanyl phosphate, a mid-infrared nonlinear crystal.

[0030] OPO: optical parametric oscillator, composed of nonlinear crystal and optical resonant cavity, can achieve large-range continuous tuning of output wavelength.

[0031] The present invention provides a method for generating red-edge laser based on barium gallium selenide and potassium titanyl phosphate crystals. The method uses a laser generating device to generate red-edge laser.

[0032] The laser generating device (such as Figure 1 The optical parametric oscillator (OPO) is a device that is configured in sequence along the optical transmission axis. The device includes the following components: a laser, a pinhole aperture D1, a telescope system, a pinhole aperture D2, an optical parametric oscillator, a plane mirror F1, a plane mirror F2, a KTP crystal, a plane mirror F3, and a spectrometer.

[0033] The optical parametric oscillator includes the following components: a plane mirror M1, a BGSe crystal located on a rotatable platform, and a plane mirror M2, which are sequentially arranged along the optical transmission axis.

[0034] The light transmission axis is located at the center of each of the above components.

[0035] The pulse laser output by the laser pump passes through the pinhole aperture D1, the telescope system, and the pinhole aperture D2 before reaching the optical parametric oscillator.

[0036] In the optical parametric oscillator, the pulse laser pumps the BGSe crystal after passing through the plane mirror M1, outputs near-infrared tunable laser under type I phase matching conditions, and the near-infrared tunable laser is output by the optical parametric oscillator after passing through the plane mirror M2.

[0037] The near-infrared tunable laser reaches the KTP crystal after passing through the plane mirrors F1 and F2. The near-infrared tunable laser pumps the KTP crystal, outputs frequency-doubled laser under type II phase matching conditions, and obtains red-edge laser after passing through the plane mirror F3.

[0038] The red edge laser light is captured by a spectrometer to determine the wavelength of the red edge laser light.

[0039] According to the above method: the laser is a Nd:YAG laser, and the wavelength of the output pulse laser is 1.06μm; the pinhole telescope D1 and the pinhole aperture D2 are used to adjust the transmission direction of the pulse laser so that the transmission direction of the pulse laser is perpendicular to the vertical direction of the optical parametric oscillator; the telescope system is used to adjust the spot radius of the pulse laser passing through the pinhole aperture D1.

[0040] According to the above method: the plane mirror M1 and the plane mirror M2 transmit the pump light and the signal light, and reflect the idler light, and the plane mirror M1 and the plane mirror M2 are perpendicular to the transmission direction of the pulse laser; in the optical parametric oscillator, the pulse laser is used as the pump light to pump the BGSe crystal after passing through the plane mirror M1, and is decomposed into signal light and idler light, the signal light is transmitted by the plane mirror M2, and the idler light is reflected by the plane mirror M2; the near-infrared tunable laser output by the optical parametric oscillator is the signal light, the residual pump light and the idler light.

[0041] According to the above method: under type I phase matching conditions, when the cutting angle of the BGSe crystal varies between 50.5° and 56.9°, the near-infrared tunable laser with a wavelength range of 1.3-1.6 μm is output.

[0042] According to the above method: the plane mirror F1 and the plane mirror F2 transmit signal light and reflect pump light and idler light; the plane mirror F1, the plane mirror F2 and the plane mirror F3 have an angle with the transmission direction of the pulsed laser, and the angle ranges from 85° to 89°, so as to prevent the laser reflected by the plane mirror F1, the plane mirror F2 and the plane mirror F3 from damaging the various components configured on the optical transmission axis.

[0043] According to the above method: after the near-infrared tunable laser output by the optical parametric oscillator passes through the plane mirror F1 and the plane mirror F2, only the signal light reaches the KTP crystal, and under the type II phase matching condition, when the KTP crystal changes between 58.4° and 52.4°, the output frequency-doubled laser with a wavelength range of 670-760nm is output; the plane mirror F3 transmits the red-edge laser and reflects the signal light, and the frequency-doubled laser obtains the red-edge laser after passing through the plane mirror F3.

[0044] According to the above method: the cutting angle range of the BGSe crystal is (53.7°, 0°), it is tuned within the range of (50.5°, 56.9°), and an anti-reflection film is plated in the corresponding bands of the pump light with a wavelength of 1.06μm, the signal light with a wavelength of 1.3-1.6μm, and the idler light with a wavelength of 3.1-5.9μm.

[0045] According to the above method: the cutting angle range of the KTP crystal is (55.4°, 0°), it is tuned in the range of (52.4°, 58.4)°, and an anti-reflection film is plated in the corresponding bands of the signal light with a wavelength of 1.3-1.6 μm and the red edge laser with a wavelength of 670-760 nm.

[0046] The technical solution proposed by the present invention first uses a 1.06μm laser to pump a BaGa4Se7 (BGSe) crystal to generate a 1340-1520nm laser, and then multiplies the generated 1340-1520nm laser to 670-760nm through a KTiOPO4 (KTP) crystal. The laser generating device proposed by the present invention has a wide tunable range, high tuning accuracy, simple structure, and is fully solidified, and has broad application prospects in the fields of agriculture, remote sensing, and earth monitoring.

[0047] Example 1

[0048] Firstly, a new nonlinear crystal BGSe was pumped using a 1.06μm laser. Under type I phase matching conditions, when the cutting angle of the BGSe crystal varied between 50.5°-56.9°, a near-infrared tunable laser output of 1.3-1.6μm could be achieved.

[0049] The output 1.3-1.6μm laser is then used to pump the KTP crystal. Under type II phase matching conditions, when the KTP crystal changes between 58.4°-52.4°, a frequency-doubled laser output of 670-760nm can be achieved.

[0050] This method can be used to obtain a higher wavelength tuning resolution, with an average tuning resolution of (760-670nm) / (56.9°-50.5°)≈14nm / °. The angle tuning resolution of general commercial electric rotary platforms is better than 0.01°, so a red-edge band laser output of at least better than 0.14nm can be obtained.

[0051] Example 2

[0052] Nd:YAG outputs 1.06μm pulsed laser with a pulse width of several nanoseconds to tens of nanoseconds. D1 and D2 are small apertures, and T is a telescope system. M1 and M2 mirrors are highly transparent to pump light (1.06μm), highly transparent to signal light (1.3-1.6μm), and highly reflective to idler light (3.5-5.2μm). F1, F2, and F3 are placed at a small angle. F1 and F2 are highly reflective to pump light (1.06μm), highly transparent to signal light (1.3-1.6μm), and highly reflective to idler light (3.5-5.2μm), so that the laser between F2 and KTP is signal light (1.3-1.6μm). F3 is highly reflective to signal light (1.3-1.6μm) and highly transparent to red-edge laser (670-760nm), so that the lasers after F3 are all red-edge lasers.

[0053] The cutting angle of BGSe crystal is (53.7°, 0°), and it can be tuned between 50.5°-56.9°, and anti-reflection coating is applied in three bands: pump light (1.06μm), signal light (1.3-1.6μm), and idler light (3.1-5.9μm). Figure 2 As shown, when the angle of the BGSe crystal in the optical path is 50.5°, a 1340nm laser can be output; when the angle of the BGSe crystal in the optical path is 56.9°, a 1520nm laser can be output.

[0054] The cutting angle of KTP crystal is (55.4°, 0°), and it can be tuned between 52.4°-58.4°, and anti-reflection coating is applied in two bands: signal light (1.3-1.6μm) and red edge band (670-760nm). Figure 3 As shown, when the angle of the KTP crystal in the optical path is 52.4°, the 1520nm laser output by the BGSe OPO can be converted into a 760nm laser; when the angle of the KTP crystal in the optical path is 58.4°, the 1340nm laser output by the BGSe OPO can be converted into a 670nm laser.

[0055] Example 3

[0056] Nd:YAG outputs 1.06μm pulsed laser with a pulse width of several nanoseconds to tens of nanoseconds. D1 and D2 are small apertures, and T is a telescope system. M1 and M2 mirrors are highly transparent to pump light (1.06μm), highly transparent to signal light (1.3-1.6μm), and highly reflective to idler light (3.5-5.2μm). F1, F2, and F3 are placed at a small angle. F1 and F2 are highly reflective to pump light (1.06μm), highly transparent to signal light (1.3-1.6μm), and highly reflective to idler light (3.5-5.2μm). The laser between F2 and KTP is signal light (1.3-1.6μm), F3 is highly reflective to signal light (1.3-1.6μm), and highly transparent to red-edge laser (670-760nm), so that the lasers after F3 are all red-edge lasers.

[0057] The cutting angle of BGSe crystal is (52.3°, 0°), and it can be tuned between 50.5°-54.1°, and anti-reflection coating is applied in three bands: pump light (1.06μm), signal light (1.3-1.6μm), and idler light (3.1-5.9μm). Figure 2 As shown, when the angle of the BGSe crystal in the optical path is 50.5°, a 1340nm laser can be output; when the angle of the BGSe crystal in the optical path is 54.1°, a 1430nm laser can be output.

[0058] The cutting angle of KTP crystal is (56.7°, 0°), and it can be tuned between 55.1°-58.4°, and anti-reflection coating is applied in two bands: signal light (1.3-1.6μm) and red edge band (670-760nm). Figure 3As shown, when the angle of the KTP crystal in the optical path is 55.1°, the 1430nm laser output by the BGSe OPO can be converted into a 715nm laser; when the angle of the KTP crystal in the optical path is 58.4°, the 1340nm laser output by the BGSe OPO can be converted into a 670nm laser.

[0059] Example 4

[0060] Nd:YAG outputs 1.06μm pulsed laser with a pulse width of several nanoseconds to tens of nanoseconds. D1 and D2 are small apertures, and T is a telescope system. M1 and M2 mirrors are highly transparent to pump light (1.06μm), highly transparent to signal light (1.3-1.6μm), and highly reflective to idler light (3.5-5.2μm). F1, F2, and F3 are placed at a small angle. F1 and F2 are highly reflective to pump light (1.06μm), highly transparent to signal light (1.3-1.6μm), and highly reflective to idler light (3.5-5.2μm). The laser between F2 and KTP is signal light (1.3-1.6μm), F3 is highly reflective to signal light (1.3-1.6μm), and highly transparent to red-edge laser (670-760nm), so that the lasers after F3 are all red-edge lasers.

[0061] The cutting angle of BGSe crystal is (55.5°, 0°), and it can be tuned between 54.1°-56.9°, and anti-reflection coating is applied in three bands: pump light (1.06μm), signal light (1.3-1.6μm), and idler light (3.1-5.9μm). Figure 2 As shown, when the angle of the BGSe crystal in the optical path is 54.1°, a 1430nm laser can be output; when the angle of the BGSe crystal in the optical path is 56.9°, a 1520nm laser can be output.

[0062] The cutting angle of KTP crystal is (53.7°, 0°), and it can be tuned between 52.4°-55.1°, and anti-reflection coating is applied in two bands: signal light (1.3-1.6μm) and red edge band (670-760nm). Figure 3 As shown, when the angle of the KTP crystal in the optical path is 52.4°, the 1520nm laser output by the BGSe OPO can be converted into a 760nm laser; when the angle of the KTP crystal in the optical path is 55.1°, the 1430nm laser output by the BGSe OPO can be converted into a 715nm laser.

[0063] The red edge band laser generation method based on barium gallium selenide and potassium titanyl phosphate crystal provided by the present invention realizes a wide tuning range and high tuning accuracy in the red edge band, and its tuning range covers the entire red edge band of 670-760nm, and its wavelength tuning resolution is better than 0.14nm, and a higher output laser energy can be obtained, and the tuning range of its output wavelength has a large room for expansion. Therefore, it has a wide application prospect in the field of red edge detection.

[0064] In this technical solution, other mid-infrared crystals (such as AgGaSe2) can be used instead of BGSe crystal to output 1340-1520nm near-infrared laser, and other frequency-doubling crystals (such as LiB3O5) can be used instead of KTP to output 670-760nm red-edge laser.

[0065] Please note that the technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification. The above-mentioned embodiments only express several implementation methods of the present application, and their descriptions are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several variations and improvements can be made, which all belong to the scope of protection of the present application. Therefore, the scope of protection of the patent in this application shall be based on the attached claims.

Claims

1. A method for generating red-edge band laser based on barium gallium selenide and potassium titanyl phosphate crystal, characterized in that: The method uses a laser generating device to generate red edge band laser; wherein: The laser generating device comprises the following components: a laser, a pinhole aperture D1, a telescope system, a pinhole aperture D2, an optical parametric oscillator, a plane mirror F1, a plane mirror F2, a KTP crystal, a plane mirror F3, and a spectrometer, which are sequentially arranged along the optical transmission axis; The optical parametric oscillator comprises the following components: a plane mirror M1, a BGSe crystal located on a rotatable platform, and a plane mirror M2 arranged in sequence along the optical transmission axis; The optical transmission axis is located at the center of each of the above components; The pulse laser output by the laser pump reaches the optical parametric oscillator after passing through the pinhole aperture D1, the telescope system, and the pinhole aperture D2; In the optical parametric oscillator, the pulsed laser pumps the BGSe crystal after passing through the plane mirror M1, outputs near-infrared tunable laser under a type I phase matching condition, and the near-infrared tunable laser is output by the optical parametric oscillator after passing through the plane mirror M2; The near-infrared tunable laser reaches the KTP crystal after passing through the plane mirror F1 and the plane mirror F2. The near-infrared tunable laser pumps the KTP crystal to output a frequency-doubled laser under a type II phase matching condition, and obtains a red-edge laser after passing through the plane mirror F3. The red edge laser light is captured by a spectrometer to determine the wavelength of the red edge laser light.

2. A method for generating a red-edge band laser based on barium gallium selenide and potassium titanyl phosphate crystal according to claim 1, characterized in that: The laser is a Nd:YAG laser, and the wavelength of the output pulse laser is 1.06 μm; The pinhole aperture D1 and the pinhole aperture D2 are used to adjust the transmission direction of the pulse laser so that the transmission direction of the pulse laser is perpendicular to the vertical direction of the optical parametric oscillator; The telescope system is used to adjust the spot radius of the pulsed laser passing through the pinhole diaphragm D1.

3. The method for generating a red-edge band laser based on barium gallium selenide and potassium titanyl phosphate crystal according to claim 2, characterized in that: The plane mirror M1 and the plane mirror M2 transmit the pump light and the signal light, and reflect the idler light, and the plane mirror M1 and the plane mirror M2 are perpendicular to the transmission direction of the pulse laser; In the optical parametric oscillator, the pulse laser is used as pump light to pump the BGSe crystal after passing through the plane mirror M1, and is decomposed into signal light and idler light, the signal light is transmitted by the plane mirror M2, and the idler light is reflected by the plane mirror M2; The near-infrared tunable laser output by the optical parametric oscillator is signal light, residual pump light and idler light.

4. The method for generating a red-edge band laser based on barium gallium selenide and potassium titanyl phosphate crystal according to claim 3, characterized in that: Under type I phase matching conditions, when the cutting angle of the BGSe crystal varies between 50.5° and 56.9°, the near-infrared tunable laser with a wavelength range of 1.3-1.6 μm is output.

5. The method for generating red-edge laser based on barium gallium selenide and potassium titanyl phosphate crystal according to claim 4, characterized in that: The plane mirror F1 and the plane mirror F2 transmit the signal light and reflect the pump light and the idler light; The plane mirrors F1, F2 and F3 have an angle with the transmission direction of the pulsed laser, and the angle ranges from 85° to 89°, so as to prevent the laser reflected by the plane mirrors F1, F2 and F3 from damaging the various components configured on the optical transmission axis.

6. The method for generating red-edge laser based on barium gallium selenide and potassium titanyl phosphate crystal according to claim 5, characterized in that: After the near-infrared tunable laser output by the optical parametric oscillator passes through the plane mirrors F1 and F2, only the signal light reaches the KTP crystal, and under the type II phase matching condition, when the KTP crystal changes between 58.4° and 52.4°, the output frequency-doubled laser with a wavelength range of 670-760nm is output; The plane mirror F3 transmits the red-edge laser and reflects the signal light, and the frequency-doubled laser passes through the plane mirror F3 to obtain the red-edge laser.

7. The method for generating red-edge band laser based on barium gallium selenide and potassium titanyl phosphate crystal according to claim 6, characterized in that: The cutting angle range of the BGSe crystal is (53.7°, 0°), which is tuned within the range of (50.5°, 56.9°), and an anti-reflection film is plated in the corresponding bands of pump light with a wavelength of 1.06 μm, signal light with a wavelength of 1.3-1.6 μm, and idler light with a wavelength of 3.1-5.9 μm.

8. The method for generating red-edge laser based on barium gallium selenide and potassium titanyl phosphate crystal according to claim 7, characterized in that: The cutting angle range of the KTP crystal is (55.4°, 0°), which is tuned within the range of (52.4°, 58.4)°, and an anti-reflection film is plated in the corresponding bands of the signal light with a wavelength of 1.3-1.6 μm and the red edge laser with a wavelength of 670-760 nm.

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