A phonon band edge polarized laser

Abstract

The application discloses a phonon band edge line polarized laser, and belongs to the technical field of lasers. Compared with a traditional band edge laser obtained by stimulated Raman scattering effect, the electronic-phonon coupling process only involves laser effect, the device is simple in design, and is good in performance stability. The laser comprises an excitation source, a focusing system, a laser medium crystal and a laser resonant cavity. The excitation source emits laser with a wavelength of 780nm-880nm. The laser medium crystal is a neodymium ion doped yttrium aluminum garnet crystal, the crystal is a gain medium in the laser, belongs to a cubic crystal structure, and is optical isotropic. The laser resonant cavity is composed of an input mirror and an output mirror, and is coated with a suitable film system to obtain effective output of 1100nm-1200nm band electronic-phonon coupling laser, and the polarization of the laser depends on the lattice vibration mode involved in the coupling. The laser has the advantages of simple and compact structure, low cost and high working stability.

Description

Technical Field

[0001] This invention relates to the field of laser technology, and in particular to a phonon bandside polarized laser based on neodymium-doped yttrium aluminum garnet crystal. Background Technology

[0002] Lasers in the 1130nm-1300nm band can be converted to output lasers in the 550nm-650nm band using nonlinear frequency conversion technology. This band falls within the visible light region, which is sensitive to human vision, and has important applications and demands in military, industrial, commercial, medical, and astronomical research fields. Currently, the main method for achieving 1130nm-1300nm lasers is through Raman frequency shifting technology. The most common Raman laser crystal is a neodymium-doped vanadate system crystal (Nd:RVO4, R=Y,Gd,Lu), which produces 1176nm Raman laser light due to its high Raman gain activity. This 1176nm light can then be converted to 588nm yellow light through nonlinear frequency conversion. However, stimulated Raman scattering is a third-order nonlinear optical effect with a high laser threshold and complex device design. Therefore, seeking compact and efficient coherent radiation in the 1130-1300nm band is of great significance.

[0003] Considering that during the luminescence process of crystalline materials, electronic transitions are inevitably affected by the vibrations of the surrounding lattice, thus altering energy transfer and leading to the generation of new "virtual" energy levels, as well as transitions from higher energy levels to new "virtual" energy levels, thereby broadening the emission spectrum, researchers first discovered in Ni3+:MgF2 crystals that the electron-phonon coupling effect could be used to extend the laser wavelength, obtaining phonon sideband lasers [Phys. Rev. Lett. 11, 318-320 (1963)]. This process only involves laser radiation transition effects, does not require very high light intensity, does not involve nonlinear frequency conversion effects, and has a simple and compact structure.

[0004] Rare-earth ion-doped laser crystals are commonly used laser gain media and are the core materials of all-solid-state lasers. For rare-earth ions, the electrons involved in energy level transitions are generally electrons in the 4f shell. However, due to the shielding effect of the 5s and 5p shell electrons, they are not easily coupled with the lattice after being incorporated into the matrix crystal, resulting in a narrow emission spectrum and high gain. It is generally believed that the electron-phonon coupling effect in rare-earth-doped crystals is weak. However, P. Loiko et al., through their study of Tm:KLu(WO4)2 crystals, found that during the formation of a 1948 nm laser oscillation, phonons are involved in the 4f shell electron transition of Tm3+ ions, causing changes in the electronic energy levels and thus extending the laser wavelength, obtaining a vibrational laser with an emission wavelength of 2109-2133 nm [Journal of the Optical Society of America B,33,11,(2016)]. This shows that even if the coupling between electrons and the lattice is weak, as long as the phonon energy can reach the energy difference between the two electronic energy states, it will have a significant impact on the spectrum. In 1982, scientists reported the influence of electron-phonon coupling on the absorption and emission spectra of Nd:YAG crystals, indicating that this vibrational interaction broke the "reciprocity" between the absorption and emission cross-sections [IEEE Journal of Quantum Electronics, QE-18, 925, (1982)]. This research provided support for the generation of phonon band-edge lasers. However, there are currently no reports of Nd:YAG crystals successfully emitting lasers in the 1130nm-1300nm band. Furthermore, Nd:YAG crystals belong to the cubic crystal system and are optically isotropic. Purely electron-transition Nd:YAG crystal lasers (including 1064nm, 1319nm, etc.) are unpolarized lasers, which are unfavorable for subsequent nonlinear optical frequency conversion processes. Currently, there are also no studies on Nd:YAG crystals achieving linearly polarized lasers in the 1130-1300nm band. Summary of the Invention

[0005] In view of this, the present invention provides a phonon bandside linearly polarized laser, which mainly broadens the emission spectrum of the gain medium through the electron-phonon coupling effect and realizes linearly polarized phonon bandside laser operation in a neodymium ion-doped yttrium aluminum garnet crystal. This type of laser has the advantages of simple and compact structure, low cost and high operating stability.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides a phonon bandside linearly polarized laser, comprising, arranged sequentially along the optical path: an excitation source, a focusing system, an input mirror, a laser medium crystal, and an output mirror; the laser medium crystal is a neodymium-doped yttrium aluminum garnet crystal; the input mirror and the output mirror constitute a laser resonant cavity; the pump light emitted from the excitation source is collimated by the focusing system, passes through the input mirror, and then enters the laser medium crystal, whereby the laser medium crystal absorbs the pump energy and undergoes energy level transitions to generate phonon bandside laser light, which oscillates between the input mirror and the output mirror, and is finally output at one end of the output mirror.

[0008] Preferably, the excitation source is a light source with an emission wavelength of 780nm-880nm, including: a Ti:sapphire laser and a laser diode laser.

[0009] Preferably, the focusing system includes one or more convex lenses to collimate and focus the pump light emitted from the excitation source into the laser dielectric crystal.

[0010] Preferably, the input mirror is coated with a dielectric film A, which is a dielectric film with high transmittance in the 780nm-880nm, 1000nm-1130nm, and 1320nm-1460nm wavelength bands and high reflectance in the 1150nm-1300nm wavelength band.

[0011] Preferably, the output mirror is coated with a dielectric film B, which is a dielectric film that has high reflectivity in the 780nm-880nm band, high transmittance in the 1000nm-1130nm and 1320nm-1460nm bands, and partial transmittance in the 1150nm-1300nm band.

[0012] Preferably, the neodymium ion-doped yttrium aluminum garnet crystal has a neodymium ion doping concentration of 0.1%-2%; the crystal tangential direction is the crystallographic axis a.

[0013] Preferably, the light-transmitting surface of the neodymium ion-doped yttrium aluminum garnet crystal is circular, square, or rectangular, and the length of the light-transmitting direction is 0.5 mm to 50 mm.

[0014] Secondly, the present invention also provides a phonon bandside linearly polarized laser with another structure, comprising, arranged sequentially along the optical path, an excitation source, a focusing system, and a laser medium crystal, constituting a microchip-type phonon bandside linearly polarized laser; wherein the laser medium crystal is a neodymium ion-doped yttrium aluminum garnet crystal.

[0015] Preferably, the incident end of the neodymium ion-doped yttrium aluminum garnet crystal is coated with a dielectric film A, and the exit end is coated with a dielectric film B. The dielectric film A and the dielectric film B constitute a laser resonant cavity. The dielectric film A is a dielectric film with high transmittance in the 780nm-880nm, 1000nm-1130nm, and 1320nm-1460nm wavelength bands and high reflectance in the 1150nm-1300nm wavelength band. The dielectric film B is a dielectric film with high reflectance in the 780nm-880nm wavelength band, high transmittance in the 1000nm-1130nm and 1320nm-1460nm wavelength bands, and partial transmittance in the 1150nm-1300nm wavelength band.

[0016] Compared with the prior art, the technical solution of the present invention has at least the following beneficial technical effects:

[0017] This invention provides a phonon band-edge linearly polarized laser based on neodymium-doped yttrium aluminum garnet crystal. By broadening the emission spectrum of the gain medium through electron-phonon coupling, linearly polarized phonon band-edge laser operation is achieved in the neodymium-doped yttrium aluminum garnet crystal. This phonon band-edge laser has a simple and compact structure and low cost. Compared with traditional stimulated Raman scattering (SRS) effects (involving both laser and nonlinear effects) for generating band-edge lasers, this invention offers advantages such as high operational stability and strong temperature adaptability.

[0018] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings.

[0019] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0022] Figure 1 This is a schematic diagram of a phonon bandside linearly polarized laser provided by the present invention.

[0023] Figure 2 This is a schematic diagram of a microchip-type phonon bandside linearly polarized laser provided by the present invention.

[0024] Figure 3 A schematic diagram of the laser wavelength output spectrum of the neodymium ion-doped yttrium aluminum garnet crystal phonon band-edge laser provided by the present invention.

[0025] Figure 4 A schematic diagram of the 1151nm and 1166nm laser polarization intensity distribution of the neodymium ion-doped yttrium aluminum garnet crystal phonon band-edge laser provided by the present invention.

[0026] Wherein, 1-excitation source; 2-focusing system; 3-input mirror; 4-laser medium crystal; 5-output mirror; 6-phonon band edge laser; 7-crystal incident surface; 8-crystal exit surface. Detailed Implementation

[0027] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0028] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "top," and "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, various serial numbers are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0029] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0030] See Figure 1As shown, this invention provides a phonon band-edge linearly polarized laser (a band-edge laser based on electron-phonon coupling theory). When the inherent lattice vibrations (phonons) in the crystal interact with the electronic energy levels of rare-earth activated ions, "virtual" energy levels can be constructed in the crystal, thereby breaking the limitation of intrinsic electronic energy level transitions and realizing electron transitions between different "virtual" energy levels, thus broadening the emission spectrum to obtain phonon band-edge laser light. The laser mainly includes, arranged sequentially along the optical path: excitation source 1, focusing system 2, input mirror 3, laser medium crystal 4, and output mirror 5; wherein:

[0031] Excitation source 1 is a light source that emits wavelengths of 780nm-880nm, including Ti:sapphire lasers, laser diode lasers, etc. Laser diode lasers are preferred because they have stable output wavelengths and high output power.

[0032] The focusing system 2 consists of one or more convex lenses, which collimate and focus the pump light emitted from the excitation source 1 into the laser medium crystal 4. The focal length can be 1 to 10 cm depending on the specific application.

[0033] The laser dielectric crystal 4 is a neodymium-doped yttrium aluminum garnet crystal with a neodymium doping concentration of 0.1%-2%, preferably 0.3%-1%; the crystal tangent is along the crystallographic axis a; the light-transmitting surface is circular, square, or rectangular, and is polished and coated with a dielectric film under certain conditions or uncoated, with a light-transmitting length of 0.5mm-50mm, preferably 4mm-15mm.

[0034] Input mirror 3 and output mirror 5 constitute a laser resonant cavity. To reduce excitation light loss and suppress intrinsic electron transition emission, input mirror 3 needs to be coated with a dielectric film with high transmittance in the 780nm-880nm, 1000nm-1130nm, and 1320nm-1460nm wavelength bands, while output mirror 5 is coated with a dielectric film with high transmittance in the 1000nm-1130nm and 1320nm-1460nm wavelength bands. To selectively amplify phonon-assisted activated transitions and achieve effective output of phonon band-edge laser, input mirror 3 needs to be coated with a dielectric film with high reflectance in the 1150nm-1300nm wavelength band, while output mirror is coated with dielectric films with different transmittance in the 1150nm-1300nm wavelength band, selectively amplifying phonon-assisted activated transitions to obtain phonon band-edge laser output. In addition, to increase the effective absorption of excitation light by the crystal, output mirror 5 is coated with a dielectric film with high reflectance in the 780nm-880nm wavelength band.

[0035] The term "high reflectivity" refers to a reflectivity greater than 99% for a specific wavelength or band of light. The term "high transmittance" refers to a transmittance greater than 99% for a specific wavelength or band of light. The term "partial transmittance" refers to a transmittance between 0.1% and 60% for a specific wavelength or band of light.

[0036] In actual operation, the pump light emitted from the excitation source 1 is collimated by the focusing system 2, and after passing through the input mirror 3, it is incident on the laser medium crystal 4. The crystal absorbs the pump energy and undergoes energy level transition, generating phonon band-edge laser 6, which oscillates between the input mirror 3 and the output mirror 4, and is finally output at one end of the output mirror 5.

[0037] Alternatively, the input mirror 3 and output mirror 4 can be omitted, and the dielectric film can be directly deposited on the crystal incident surface 7 and crystal exit surface 8 of the laser dielectric crystal 4, respectively, to form a micro-chip phonon bandside polarized laser, the structure of which is as follows: Figure 2 As shown.

[0038] The specific embodiments of the present invention will be described in detail below:

[0039] Example 1:

[0040] In this embodiment, the excitation source 1 is a laser diode laser with an emission wavelength of 808nm; the focusing system 2 is a focusing lens with a focal length of 5cm; the input mirror 3 is a flat mirror coated with a highly reflective dielectric film; and the laser dielectric crystal 4 is a neodymium-doped yttrium aluminum garnet crystal with a neodymium doping concentration of 0.3%, a light transmission direction along the crystallographic axis a, a crystal length of 4mm, and a light transmission surface of 3*3mm. 2 The first mirror is double-sided polished and coated with a dielectric film that provides high transmittance for 780nm-880nm and 1000nm-1460nm; the second mirror is a flat mirror coated with a dielectric film that provides high reflectance for 780nm-880nm, high transmittance for 1000nm-1130nm and 1320nm-1460nm, and partial transmittance for 1150nm-1300nm (transmittance T). oc =0.1%) dielectric film. Increasing the excitation source power can achieve phonon band-edge laser output at 1151nm and 1166nm, with wavelengths such as Figure 3 As shown, Figure 3 Part (a) shows the 1151nm phonon band-edge laser output. Figure 3 Part (b) shows the phonon band-edge laser output at 1166 nm. The horizontal axis represents wavelength (nm), and the vertical axis represents intensity. Figure 4 Parts (a) and (b) show the polarization intensity distribution of the phonon band-edge laser at 1151 nm and 1166 nm, respectively, of the neodymium-doped yttrium aluminum garnet crystal. The horizontal axis represents the polarizer rotation angle (°), and the vertical axis represents the laser power (mW).

[0041] Example 2:

[0042] This embodiment is similar to Embodiment 1, except that the excitation source 1 is a laser diode laser with an emission wavelength of 880nm. Other conditions are the same as described in Embodiment 1. Pumping with an 880nm laser diode can reduce quantum defect and heat generation in the laser, which is beneficial for improving conversion efficiency.

[0043] Example 3:

[0044] Similar to Example 1, except that the focusing system 2 consists of a combination of convex lenses with focal lengths of 10cm and 5cm, or 5cm and 2.5cm, while other conditions are consistent with those described in Example 1. This focusing system design helps to reduce the pump spot size and improve pumping efficiency.

[0045] Example 4:

[0046] Similar to Example 1, except that the length of the laser medium crystal 4 (neodymium-doped yttrium aluminum garnet crystal) is any one of 6 mm, 8 mm, or 10 mm, while other conditions are consistent with those described in Example 1. Increasing the crystal length can enhance the absorption of pump light by the crystal and improve the light-to-light conversion efficiency.

[0047] Example 5:

[0048] Similar to Example 1, except that the neodymium ion doping concentration in the laser medium crystal 4 (neodymium-doped yttrium aluminum garnet crystal) is any one of 0.5%, 0.8%, or 1%, while other conditions are the same as described in Example 1. Increasing the neodymium ion doping concentration can enhance the coupling strength of the Nd:YAG crystal, which is beneficial for achieving 1151nm and 1166nm laser output.

[0049] Example 6:

[0050] Similar to Example 1, except that the curvature of the output mirror 5 is any one of 50mm, 100mm, 150mm, or 200mm, while other conditions are the same as described in Example 1. Changing the curvature of the output mirror can adjust the laser output power.

[0051] Example 7:

[0052] Similar to Example 1, except that the transmittance of the output mirror 5 is any one of Toc = 0.5%, 1%, or 2%, while other conditions are the same as described in Example 1. Increasing the transmittance of the output mirror can increase the output power of the 1166nm laser.

[0053] Example 8:

[0054] In this embodiment, the input mirror 3 and output mirror 4 are not provided, forming a micro-chip phonon band-edge polarized laser. The dielectric film is directly deposited on the crystal incident surface 7 and crystal exit surface 8 of the laser dielectric crystal 4, respectively. Its structure is as follows: Figure 2 As shown, the laser consists of an excitation source 1, a focusing system 2, and a laser dielectric crystal 4 arranged sequentially along the optical path. The excitation source 1 is a laser diode with an emission wavelength of 808 nm, the focusing system 2 is a focusing lens with a focal length of 5 cm, and the laser dielectric crystal 4 is a neodymium ion-doped yttrium aluminum garnet crystal with the light transmission direction along the crystallographic axis a, a crystal length of 4 mm, and a polished light transmission surface. The incident end (crystal incident surface 7) of the laser dielectric crystal is coated with a dielectric film A, which has high transmittance for 780nm-880nm, 1000nm-1130nm, and 1320nm-1460nm and high reflectance for 1000nm-1130nm. The exit end (crystal exit surface 8) is coated with a dielectric film B, which has high reflectance for 780nm-880nm, high transmittance for 1000nm-1130nm and 1320nm-1460nm and partial transmittance for 1150nm-1300nm (transmittance Toc = 0.1%). The dielectric film A and the dielectric film B constitute the laser resonator of the microchip phonon bandside polarized laser.

[0055] Example 9:

[0056] Similar to Example 8, except that the excitation source 1 is a laser diode laser emitting a wavelength of 880 nm, while other conditions are the same as described in Example 8. Pumping with an 880 nm laser diode can reduce quantum defect and heat generation in the laser, thus improving conversion efficiency.

[0057] Example 10:

[0058] Similar to Example 8, except that the focusing system 2 consists of a combination of convex lenses with focal lengths of 10cm and 5cm, or 5cm and 2.5cm, while other conditions remain the same as described in Example 8. This focusing system design helps to reduce the pump spot size and improve pumping efficiency.

[0059] Example 11:

[0060] Similar to Example 8, except that the length of the laser medium crystal 4 (neodymium-doped yttrium aluminum garnet crystal) is any one of 6 mm, 8 mm, or 10 mm, while other conditions are the same as described in Example 8. Increasing the crystal length can enhance the absorption of pump light by the crystal and improve the light-to-light conversion efficiency.

[0061] Example 12:

[0062] Similar to Example 8, except that the neodymium ion doping concentration in the laser medium crystal 4 (neodymium-doped yttrium aluminum garnet crystal) is any one of 0.5%, 0.8%, or 1%, while other conditions are the same as described in Example 8. Increasing the neodymium ion doping concentration can enhance the coupling strength of the Nd:YAG crystal, which is beneficial for achieving 1151nm and 1166nm laser output.

[0063] Example 13:

[0064] Similar to Example 8, the difference is that the transmittance of the laser medium crystal 4 at the exit end (crystal exit surface 8) is T. oc =0.5%, 1%, 2%, with other conditions consistent with those described in Example 8. Increasing the transmittance of the output mirror can improve the output power of the 1166nm laser.

[0065] As described in the above embodiments, this invention provides a phonon band-edge polarized laser. Compared with traditional stimulated Raman scattering (SRS) effects (involving both laser and nonlinear effects) for obtaining band-edge lasers, this invention only involves laser effects in the electron-phonon coupling process, resulting in a simpler device design and better performance stability. The laser includes an excitation source, a focusing system, a laser medium crystal, and a laser resonator. The laser medium crystal is a neodymium-doped yttrium aluminum garnet crystal, which serves as the gain medium in solid-state lasers. It has a cubic crystal structure and is optically isotropic. The laser resonator consists of an input mirror and an output mirror, coated with a suitable film system (or directly coated on the laser medium crystal) to obtain an effective output of electron-phonon coupled laser light in the 1100nm-1200nm band. The polarization of the laser depends on the lattice vibration modes involved in the coupling. This type of laser has advantages such as simple and compact structure, low cost, and high operational stability.

[0066] The phonon bandside linearly polarized laser provided by the present invention has been described in detail above. Specific examples have been used in this embodiment to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. The content of this specification should not be construed as a limitation of the present invention.

[0067] This specification uses a progressive approach in its description; similar or identical parts between different embodiments can be referred to interchangeably. Parts of the embodiments of this invention not described herein can be obtained from the corresponding product manuals or existing technologies in the field, and will not be elaborated upon further.

[0068] It should be noted that the word "comprising" does not exclude the presence of components or steps not listed in the claims. The word "a" or "an" preceding a component does not exclude the presence of a plurality of such components.

[0069] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined in these embodiments may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A phonon bandside linearly polarized laser, comprising, arranged sequentially along the optical path: an excitation source, a focusing system, an input mirror, a laser dielectric crystal, and an output mirror; characterized in that, The laser medium crystal is a neodymium-doped yttrium aluminum garnet crystal; the input mirror and the output mirror constitute a laser resonant cavity; the pump light emitted from the excitation source is collimated by the focusing system, and after passing through the input mirror, it is incident on the laser medium crystal. The laser medium crystal absorbs the pump energy and undergoes energy level transitions to generate phonon band-edge laser, which oscillates between the input mirror and the output mirror, and is finally output at one end of the output mirror. When the lattice vibration phonons inherent in a crystal interact with the electronic energy levels of rare-earth activated ions, virtual energy levels can be constructed in the crystal, thereby breaking through the limitations of intrinsic electronic energy level transitions, realizing the transition of electrons between different virtual energy levels, broadening the emission spectrum, and obtaining phonon band-edge lasers. The input mirror is coated with a dielectric film A, which is a dielectric film with high transmittance in the 780nm-880nm, 1000nm-1130nm, and 1320nm-1460nm wavelength bands and high reflectance in the 1150nm-1300nm wavelength band. The output mirror is coated with a dielectric film B, which is a dielectric film that has high reflectivity in the 780nm-880nm band, high transmittance in the 1000nm-1130nm and 1320nm-1460nm bands, and partial transmittance in the 1150nm-1300nm band.

2. A phonon bandside linearly polarized laser according to claim 1, characterized in that, The excitation source is a light source emitting wavelengths of 780nm-880nm, including: Ti:sapphire lasers and laser diode lasers.

3. A phonon bandside linearly polarized laser according to claim 1, characterized in that, The focusing system includes one or more convex lenses that collimate and focus the pump light emitted from the excitation source into the laser dielectric crystal.

4. A phonon bandside linearly polarized laser according to claim 1, characterized in that, The neodymium ion-doped yttrium aluminum garnet crystal has a neodymium ion doping concentration of 0.1%-2%. The crystal tangential direction is the crystallographic axis a-direction.

5. A phonon bandside linearly polarized laser according to claim 4, characterized in that, The light-transmitting surface of the neodymium-doped yttrium aluminum garnet crystal is circular, square, or rectangular, and the length of the light-transmitting direction is 0.5 mm to 50 mm.

6. A phonon bandside linearly polarized laser, comprising, arranged sequentially along the optical path: an excitation source, a focusing system, and a laser dielectric crystal, constituting a microchip-type phonon bandside linearly polarized laser; characterized in that, The laser medium crystal is a neodymium ion-doped yttrium aluminum garnet crystal; The neodymium-doped yttrium aluminum garnet crystal has a dielectric film A deposited at its incident end and a dielectric film B deposited at its exit end. The dielectric film A and the dielectric film B constitute a laser resonant cavity. The dielectric film A is a dielectric film with high transmittance in the 780nm-880nm, 1000nm-1130nm, and 1320nm-1460nm wavelength bands and high reflectance in the 1150nm-1300nm wavelength band. The dielectric film B is a dielectric film with high reflectance in the 780nm-880nm wavelength band, high transmittance in the 1000nm-1130nm and 1320nm-1460nm wavelength bands, and partial transmittance in the 1150nm-1300nm wavelength band. When the lattice vibration phonons inherent in a crystal interact with the electronic energy levels of rare-earth activated ions, virtual energy levels can be constructed in the crystal, thereby breaking through the limitations of intrinsic electronic energy level transitions, realizing the transition of electrons between different virtual energy levels, broadening the emission spectrum, and obtaining phonon band-edge lasers.

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