CN104993363B - One kind is based on maglev turntable laser - Google Patents

Abstract

A spinning disk laser based on magnetic levitation, including a pump source, also includes a coupling collimator lens on the same optical axis, a 45-degree reflector, a coupling focusing lens, and a 45-degree two-color Mirrors, laser gain medium disks, diamagnetic material disks and magnetic material blocks. The invention effectively reduces the influence of thermal effects on the laser output characteristics, effectively improves the average power and beam quality of the output laser, utilizes the magnetic levitation characteristics of the diamagnetic material to realize the rotation of the circular laser gain medium disk, and has a simple and compact structure. Low cost and strong achievability.

Description

A spinning disk laser based on magnetic levitation

technical field

The invention relates to the technical field of lasers, in particular to the technical field of solid-state lasers, in particular to a magnetic levitation-based rotating disk laser.

Background technique

With the development of laser application technology, the demand for high average power and high beam quality lasers in many application fields is getting higher and higher. However, in the operation of solid-state lasers, the pumping source provides the working medium with the energy necessary to generate laser light, and at the same time, it will generate a large amount of useless heat. This unwanted heat can lead to undesirable effects such as thermal lensing, thermal stress, depolarization, and thermally induced birefringence. These effects will reduce the beam quality of the solid-state laser output laser, limit the output power, and even cause damage to the working medium, which seriously limits the maximum output average power and brightness of the solid-state laser. In order to make the solid-state laser operate continuously and stably, these useless heat must be taken away in time.

Relevant studies abroad have shown that by introducing rotation characteristics to the disk-type solid gain medium, the thermal effect in the gain medium can be effectively reduced ^[1] , and the power and brightness of the output laser can be increased ^[2] . Materials with diamagnetic properties can be suspended in a magnetic field, and their translation and rotation in the magnetic field can be manipulated by laser irradiation ^[3] .

Existing literature:

1. Alan H. Paxton et.al, "Rotating-Disk Solid-State Lasers, Thermal Properties" in Laser Resonators and Beam Control VII, A. Kudryashov, ed., Proc. SPIE 5333, P12-17, 2004.

2. Santanu Basu et.al, "Disk motion–a new control element in high-brightness solid state laser design" Optics Express, Vol 12, P3114-3124, 2004.

3. Masayuki Kobayashi et. Al, "Optical Motion Control of Maglev Graphite", Journal of the American Chemical, V134, P20593-20596, 2012.

Contents of the invention

The present invention aims to combine the good heat treatment capability of the rotating disk laser and the magnetic levitation characteristics of the diamagnetic material, and propose a magnetic levitation-based rotating disk laser and its realization method. The laser can effectively reduce the effect of useless heat in the laser gain medium on the laser output characteristics. It can effectively improve the average power and beam quality of the output laser.

The technical scheme adopted in the present invention is:

A rotating disk laser based on magnetic levitation, including a pumping source, is characterized in that it also includes a coupling collimating lens, a 45-degree reflector, and a coupling focusing lens arranged in sequence along the direction of the pumping light output by the pumping source. , 45-degree dichroic mirror, laser gain medium disk, diamagnetic material disk and magnetic material block;

The output end of the pump source is placed at the object focus of the coupling collimator lens, and the laser gain medium disk is located at the image focus of the coupling collimation lens;

The center of the diamagnetic material disk coincides with the center of the laser gain medium disk, and the coupling focusing lens vertically focuses the pump light to the edge of the laser gain medium disk;

The upper surface of the laser gain medium disc is coated with an anti-reflection film for the pump light band and a partial reflection film for the oscillation light band, as a laser output coupling mirror, and the lower surface of the laser gain medium disc is coated with The high-reflection film for oscillating light is used as a laser rear cavity mirror, so that the upper and lower surfaces of the circular laser gain medium disc form a laser resonator;

The magnetic material block is used to provide a confinement magnetic field to suspend the diamagnetic material disk and the laser gain medium disk.

The output end of the pumping source is placed at the focal point of the object side of the coupling collimator lens.

The 45-degree reflector has high reflection characteristics for the pump light, and is used to deflect the pump light transmitted along the horizontal direction to be transmitted vertically downward.

The 45-degree dichroic mirror is highly transparent to the pumping light and highly reflective to the oscillating light.

The laser circular laser gain medium disk is located at the focal point of the image side of the coupling focusing lens.

The coupling focusing lens vertically focuses the pumping light near the edge of the circular laser gain medium disk.

The upper surface of the laser gain medium disc is coated with an anti-reflection film for the pump light band and a partial reflection film for the oscillation light band as a laser output coupling mirror, and the lower surface of the laser gain medium disc is coated with an anti-oscillation film. The high-reflection film of light acts as a laser rear cavity mirror, and the upper and lower surfaces of the laser gain medium disc form a laser resonant cavity.

The diamagnetic material disc can be superconducting material, pyrolytic graphite, bismuth, magnet, etc.

The center of the diamagnetic material disc coincides with the circular laser gain medium disc and is fixed under the circular laser gain medium with ultraviolet curing glue.

The magnetic material block provides a confinement magnetic field, which can levitate the circular diamagnetic material disk and the circular laser gain medium disk, which can be magnets, electromagnets, and energized solenoids Wait.

The pumping source is used to pump the circular laser gain medium disk to achieve population inversion, and it may be a fiber-coupled semiconductor laser, a solid-state laser, or a fiber laser.

The laser gain medium disk has an energy level structure matched with the emission spectrum of the pump light source, and can be crystal, ceramic or laser glass doped with rare earth ions, such as Nd:YAG crystal, Yb:YAG crystal, Yb: YAG laser ceramics, Nd:YAG laser ceramics, Nd:YAG glass, Nd:YVO ₄ crystal, etc.

The circular laser gain medium disc can also be Nd:YAG/Cr ⁴⁺ :YAG bonded crystal structure to realize passive Q-switched pulsed laser output.

Compared with existing solid-state lasers, the present invention has the following advantages:

1. The laser adopts a turntable structure, which can effectively reduce the influence of thermal effects on the laser output characteristics, and can effectively improve the average power and beam quality of the output laser.

2. In this laser, the magnetic levitation characteristic of the diamagnetic material is used to realize the rotation of the circular laser gain medium disc, which has a simple and compact structure, low cost and strong realizability.

3. Using Nd:YAG/Cr4+:YAG bonded crystal flakes as the gain medium can realize sub-nanosecond passive Q-switched pulsed laser output with high repetition rate.

Description of drawings

FIG. 1 is a structural diagram of the optical path of the first embodiment of the magnetic levitation-based spinning disk laser of the present invention.

Fig. 2 is an optical path structure diagram of the second embodiment of the magnetic levitation-based spinning disk laser of the present invention.

Detailed ways

Below in conjunction with accompanying drawing and embodiment the present invention will be further described, but should not limit protection scope of the present invention with this

As can be seen from Fig. 1, a magnetically levitated turntable laser of the present invention includes a pumping source 1, and is characterized in that: it also includes a coaxial coupling collimating lens 2 arranged in sequence along the direction of the pumping light output by the pumping source , 45-degree reflector 3, coupling focusing lens 4, 45-degree dichroic mirror 5, laser gain medium disk 6, diamagnetic material disk 7 and magnetic material block 8; the output end of the pump source is placed in the At the object focal point of the coupled collimating lens, the laser gain medium disk is located at the image focal point of the coupling collimating lens; the center of the diamagnetic material disk coincides with the center of the laser gain medium disk , the coupling focusing lens 4 focuses the pump light vertically to the edge of the laser gain medium disk 6; the upper surface of the laser gain medium disk is coated with an anti-reflection coating and The partial reflection film for the oscillating light band is used as a laser output coupling mirror, and the lower surface of the laser gain medium disc is coated with a high reflection film for oscillating light, which serves as a laser rear cavity mirror, so that the circular laser gain medium disc The upper and lower surfaces of the upper and lower surfaces constitute the laser cavity; the magnetic material block 8 is used to provide a confinement magnetic field to suspend the diamagnetic material disk and the laser gain medium disk.

The output end of the pumping source 1 is placed at the object focal point of the coupling collimating lens 2, and the 45-degree mirror 3 deflects the pumping light to be transmitted vertically downward. The focusing coupling lens 4 focuses the pumping light onto the surface near the edge of the circular laser gain medium disk 5, and the 45-degree dichroic mirror 5 can transmit the pumping light transmitted vertically downwards and transmit it vertically. The laser light transmitted straight upward is reflected and transmitted in the horizontal direction, and the upper surface of the circular laser gain medium disc 6 is coated with an anti-reflection film for the pump light band and a partially reflective film for the oscillation light band as a laser output coupling mirror, The lower surface of the circular laser gain medium disc 6 is coated with a high reflection film for oscillating light as a laser rear cavity mirror. The upper and lower surfaces of the circular laser gain medium disk 6 constitute a laser resonator, and when the incident pump light is greater than the threshold of the laser, the upper surface of the circular laser gain medium disk 6 starts to output laser beams upward. The center of the circular inverse magnetic material disk 7 is overlapped with the circular laser gain medium disk 6 and fixed under the circular laser gain medium disk with ultraviolet curing glue. When the incident pump light reaches a certain intensity, the circular inverse The magnetic material disc 7 starts to rotate together with the circular laser gain medium disc 6 .

The magnetic material block 8 described in this embodiment includes a solid cylindrical rod magnet 81 and a hollow cylindrical magnet 82 . The outer diameter of the solid cylindrical rod magnet 81 is the same as the inner diameter of the hollow cylindrical magnet 82, and the solid cylindrical rod magnet 81 is inserted into the hollow cylindrical magnet 82 in the form of N and S polar opposites. In; the outer diameter of the hollow cylindrical magnet 82 will be greater than the diameter of the graphite sheet disc, and the outer diameter of the cylindrical bar magnet 81 will be slightly smaller than the diameter of the circular diamagnetic material disc 7 so that The circular diamagnetic material disc 7 is suspended and stably constrained at the center of the entire magnet.

Below are the concrete parameters of the embodiment of the present invention:

1. The pumping source 1 is a continuously operating fiber-coupled semiconductor laser with a pigtail core diameter of 400 μm, a numerical aperture of 0.22, and an emission wavelength of 808 nm.

2. The coupling collimating lens 2 and the coupling focusing lens 4 are K9 glass plano-convex lenses with focal lengths of 25.4mm and 35mm respectively.

3. The 45-degree reflector 3 is coated with a high-reflection film to 808nm; the 45-degree dichroic mirror 5 is coated with a high-transparency film to 808nm and a high-reflection film to 1064nm.

4. The circular laser gain medium disk 6 is Nd:YAG crystal, the doping concentration of Nd3+ ions is 1.0at.%, the specific size is 16mm in diameter, 0.5mm in thickness, and the upper surface is coated with an anti-reflection film of 808nm and a reflectivity of 1064nm It is a 98% partial reflection film (as an output coupling mirror), and the lower surface is coated with a 1064nm high reflection film (as a rear cavity mirror). Crystals work at room temperature.

5. The circular diamagnetic material disk 7 is a circular pyrolytic graphite sheet with a diameter of 15 mm and a thickness of 0.9 mm.

6. The size of the solid cylindrical bar magnet 8 is 12 mm in outer diameter and 40 mm in height; the size of the hollow cylindrical magnet 9 is 12 mm in inner diameter, 25 mm in outer diameter and 40 mm in height.

7. The pump light is focused on the upper surface of the circular gain medium disk 6 after passing through the focusing coupling lens 4, and the distance between the focal point and the center of the circular gain medium disk 6 is 7 mm.

8. In this embodiment, on both sides of the circular diamagnetic material disk 7, there are two relatively blown compressed nitrogen nozzles to assist in controlling the circular diamagnetic material disk 7 and the circular laser gain medium disk 6 speed. However, it should be noted that this is not a necessary condition for rotating the rotating circular diamagnetic material disk 7. When the overall weight of the circular diamagnetic material disk 7 and the circular laser gain medium disk 6 is relatively light, by Irradiation of pumping light can also make them rotate rapidly together; when the overall weight of the circular diamagnetic material disk 7 and the circular laser gain medium disk 6 is relatively heavy, the rapid rotation can be realized by introducing auxiliary airflow.

The following is the output of the example;

When the rotational speed of the circular diamagnetic material disk 7 and the circular laser gain medium disk 6 is 4Hz, the threshold pumping power of the laser is 870mW; when the incident pumping power is 2.1W, a fundamental of 20mW mode laser output.

Fig. 2 is a diagram of the optical path structure of the second embodiment of the maglev-based turntable laser of the present invention. When the magnetic material block 8 described in this embodiment is an electrified solenoid, it includes a solenoid and a driving power supply. The inner diameter of the energized solenoid 8 is larger than the diameters of the circular diamagnetic material disk 7 and the circular laser gain medium disk 6 .

Claims (8)

1. one kind is based on maglev turntable laser, including pumping source (1), it is characterised in that：Further include defeated along the pumping source The coupling collimation lens (2) for the same optical axis that the pump direction gone out is set gradually, 45 degree of speculums (3), coupling focusing lens (4), 45 degree of dichroic mirrors (5), laser gain medium disc (6), diamagnetism material disc (7) and piece of magnetic material (8)；

The output terminal of the pumping source is placed at the object focus of the coupling collimation lens；

The center of the diamagnetism material disc is overlapped with the center of laser gain medium disc, the coupling focusing lens (4) by pump light vertical focusing to the edge of the laser gain medium disc (6)；

The upper surface of the laser gain medium disc is coated with to the anti-reflection film of pumping optical band and the portion to vibrating optical band Divide reflectance coating, as laser output coupling mirror, the lower surface of the laser gain medium disc is coated with the high-reflecting film to oscillation light, makees For laser Effect of Back-Cavity Mirror, the upper and lower surface of the laser gain medium disc is set to constitute laserresonator；

The piece of magnetic material (8) makes the diamagnetism material disc and laser gain to provide a confining magnetic field Media discs suspend.

2. according to claim 1 be based on maglev turntable laser, it is characterised in that is situated between in the laser gain The both sides of matter disc (6) and diamagnetism material disc (7) are respectively equipped with the compressed nitrogen nozzle of opposite air blowing, to aid in controlling The diamagnetism material disc and the rotating speed of laser gain medium disc.

3. according to claim 1 be based on maglev turntable laser, it is characterised in that 45 degree of speculums tool Have anti-characteristic high to pump light, for by the pumping transmitted in the horizontal direction light deflection to transmitting straight down.

4. according to claim 1 be based on maglev turntable laser, it is characterised in that the laser gain medium Disc (6) and diamagnetism material disc (7) are circle, and the laser gain medium disc is rare earth ion doped crystalline substance Body, ceramics or laser glass, the diamagnetism material disc is superconductor, pyrolytic graphite, bismuth or magnet.

5. according to claim 1 be based on maglev turntable laser, it is characterised in that the pumping source is optical fiber Semiconductor laser, solid state laser or the optical fiber laser of output are coupled, for the laser gain medium disc described in pumping To realize population inversion.

6. according to claim 1 be based on maglev turntable laser, it is characterised in that the piece of magnetic material (8) it is magnet, electromagnet or energization solenoid.

7. according to claim 6 be based on maglev turntable laser, it is characterised in that when the piece of magnetic material (8) when being magnet, including the bar-shaped magnet of solid cylinder (81) and hollow cylindrical magnet (82), the bar-shaped magnet of the solid cylinder Outer diameter is identical with the internal diameter size of hollow cylindrical magnet, and the bar-shaped magnet of the solid cylinder is with N, S extremely opposite shape Formula is inserted in the hollow cylinder shape magnet；The outer diameter of the hollow cylinder shape magnet is more than circular diamagnetism material The diameter of charging tray piece, the outer diameter of the cylindrical bar shape magnet are less than the diameter of circular diamagnetism material disc, to incite somebody to action Circular diamagnetism material disc, the center for constraining in whole magnet for suspending and stablizing.

8. according to claim 6 be based on maglev turntable laser, it is characterised in that when the piece of magnetic material (8) when being switched on solenoid, including a solenoid and driving power, the internal diameter of the energization solenoid (8) are respectively greater than Circular diamagnetism material disc (7) and the diameter of circular laser gain medium disc (6).