CN202749676U - End-pumped dual-wavelength coaxial switching output laser device - Google Patents

Abstract

The utility model discloses an end-pumped dual-wavelength coaxial switching output laser, which comprises a laser source, a steering mirror, a focusing lens, a frequency doubling crystal, a collimating mirror, a harmonic separation mirror and a polarization rotator. Generate linearly polarized, high-peak-power quasi-continuous fundamental-frequency laser output through Q-switching, and then the output fundamental-frequency laser is focused on the frequency-doubling crystal through a lens to produce a small spot and high optical power density, and frequency doubling is obtained after the frequency-doubling crystal Laser output. When the polarization rotator is inserted in the optical path and the harmonic separation mirror is removed, the polarization direction of the fundamental frequency laser is rotated by 90 degrees, the laser switches to the fundamental frequency laser output, and has relatively consistent focusing parameters after passing through the same focusing system. The utility model can ensure that the system efficiency is maximized when the two wavelengths are switched for output, and can be widely used in fields such as industrial processing, scientific research, medical treatment, and military affairs.

Description

An end-pumped dual-wavelength coaxial switching output laser

technical field

The utility model relates to the field of laser technology, in particular to an end-pumped dual-wavelength coaxial switching output laser. the

Background technique

Most end-pumped lasers currently on the market are single-wavelength output. This method has a compact structure, better beam quality, and higher efficiency; most frequency-doubling lasers based on end-pump technology use intracavity frequency doubling, which can use the high power density in the cavity to obtain a larger frequency-doubling laser output, but this This method is prone to poor stability caused by longitudinal mode competition. In order to meet the selective processing of different materials, lasers with different wavelengths are usually required. Especially when the fundamental frequency laser and frequency doubled laser are required to be alternately processed, two lasers have to be used alternately. The complexity of the system is high, which not only increases the cost, but also increases the process. The dual-wavelength laser made by using the spectral characteristics of the laser crystal itself can obtain two fundamental-frequency laser wavelength outputs, but cannot obtain frequency-doubled laser output, and cannot output two wavelength lasers in an alternate switching manner. A small number of high-energy dual-wavelength or multi-wavelength lasers use extra-cavity frequency doubling and sum-frequency methods to generate laser outputs of two or more wavelengths, but generally the output paths of different wavelengths are different, and various wavelengths are generated simultaneously. The rate is lower. the

Utility model content

The purpose of this utility model is to provide an end-pumped dual-wavelength coaxial switching output laser in order to solve the problems in the above-mentioned prior art such as poor stability, insufficient efficiency and misalignment of beams. The structure of the laser is flexible and simple, and it is not constrained by the design structure of the laser resonator. The focus frequency doubling method is used to make up for the shortcomings of the external frequency doubling power density lower than the intracavity frequency doubling method, and the fundamental frequency laser can be freely selected on the frequency doubling crystal. The waist size of the focusing beam to obtain the best frequency doubling conversion efficiency. Whether the frequency doubling process occurs is controlled by the polarization direction of the fundamental frequency laser, without changing the beam propagation path, different wavelengths propagate in a coaxial manner, and the beam parameters are consistent. the

The purpose of the utility model is achieved by the following scheme: after the fundamental frequency laser with pulse output linear polarization Q-switching is focused by the focusing lens, a smaller laser beam waist size can be obtained, thereby greatly increasing the laser power density. The waist position of the fundamental frequency laser beam after the light-passing lens is focused coincides with the incident end face of the nonlinear frequency doubling crystal, so as to obtain the best frequency doubling conversion efficiency. Use a polarization rotator to change the polarization direction of the fundamental frequency laser to control whether the frequency doubling process occurs, and cooperate with the harmonic separator to switch the alternate output of the fundamental frequency laser and the frequency doubling laser. the

An end-pumped dual-wavelength coaxial switching output laser, which includes a laser source, a polarization rotator, a focusing lens, a frequency doubling crystal, a collimating lens, a small aperture diaphragm, a harmonic separation mirror, a first steering mirror, a second The steering mirror, the third steering mirror, and the fourth steering mirror are characterized in that the fundamental frequency laser output by the laser source pulse is a linearly polarized Q-switched pulse laser, and the first steering mirror, the second steering mirror, the third steering mirror, and the fourth steering mirror Steering mirrors, polarization rotators, focusing lenses, frequency doubling crystals, collimating lenses, pinhole diaphragms, and harmonic separation mirrors are placed outside the resonator; the fundamental frequency laser pulsed by the laser source passes through the first steering mirror and the second The steering mirror adjusts the incident direction, and focuses on the incident end face of the frequency doubling crystal through the focusing lens arranged outside the resonator to generate the frequency doubling laser and the remaining fundamental frequency laser, which are then collimated by the collimating lens, and then pass through the third steering mirror and the first The four steering mirrors adjust the output direction; the harmonic separation mirror reflects the remaining fundamental frequency laser and transmits the frequency doubled laser; the pinhole diaphragm absorbs the reflected remaining fundamental frequency laser to prevent the reflected light from damaging other components; the polarization rotator controls the fundamental frequency The polarization direction of the laser, after inserting the polarization rotator, the polarization direction of the fundamental frequency laser rotates 45 degrees or 90 degrees around the beam propagation direction. the

An end-pumped dual-wavelength coaxial switching output laser described in the utility model, its polarization rotator is a 1/4 wave plate, or a 1/2 wave plate, or a 45-degree quartz optical crystal, or a 90-degree quartz optical crystal . the

The laser light of the end-pumped dual-wavelength coaxial switching output laser described in the utility model is a linearly polarized Q-switched pulse laser. the

In the end-pumped dual-wavelength coaxial switching output laser described in the utility model, its polarization rotator is inserted into the optical path before the nonlinear frequency-doubling crystal, and the polarization direction of the linearly polarized fundamental-frequency laser is rotated by 45 degrees or 90 degrees. The frequency process does not occur; or the polarization rotator is not inserted in the optical path before the frequency doubling crystal, the frequency doubling process does not occur:

According to the principle of nonlinear optics, lasers with different wavelengths, different polarization directions, and different incident directions have different refractive indices when propagating inside a nonlinear crystal. For the frequency doubling process, the frequency doubling process can only occur when the refractive index of the fundamental frequency laser and the frequency doubling laser are equal when propagating inside the nonlinear crystal, that is, when the phase matching condition is satisfied. the

For the frequency multiplication process that meets the phase matching conditions, it is divided into type I phase matching and type II phase matching. When type I phase matching is used, the polarization direction of the fundamental frequency laser with linear polarization Q-switching is rotated by 90 degrees, and the frequency doubling process occurs or not; when type II phase matching is used, the polarization direction of the fundamental frequency laser with linear polarization Q-switching Rotated by 45 degrees, the frequency doubling process occurs or does not occur. the

The frequency doubling crystal described in the utility model is potassium dihydrogen phosphate (KDP), or lithium triborate (LBO), or potassium titanyl phosphate (KTP) or barium metaborate (BBO) nonlinear optical crystal. the

In the end-pumped dual-wavelength coaxial switching output laser described in the utility model, the first steering mirror, the second steering mirror, the third steering mirror and the fourth steering mirror may not be used or only some of them may be used. The placement and steering angle can vary. the

An end-pumped dual-wavelength coaxial switching output laser described in the utility model has a coaxial output characteristic of the fundamental frequency laser and the frequency doubled laser switching output. the

The utility model is suitable for applications in the fields of laser marking, laser marking, laser scribing, other laser pumping sources, laser medical treatment and scientific research. the

Description of drawings

Fig. 1 is a schematic diagram of laser structure;

Figure 2 is a schematic diagram of the principle of nonlinear crystal frequency doubling;

Fig. 3 is a schematic diagram of the working principle of the polarization rotator;

Detailed ways

An end-pumped dual-wavelength coaxial switching output laser related to the utility model, its technical scheme is described in detail in conjunction with accompanying drawings 1, 2 and 3 as follows:

The laser source 1 of the utility model pulses the fundamental frequency laser 2 of linear polarization Q-switching; the fundamental frequency laser 2 of the pulse output changes the propagation direction through the turning mirrors 4 and 5 (both coated with the fundamental frequency light high reflection film); the fundamental frequency laser 2 of the pulse output The frequency laser 2 is focused by the focusing lens 6 (coated with anti-reflection coating for fundamental frequency light) placed outside the resonator to the incident end surface of frequency doubling crystal 7 (LBO, both sides are coated with antireflection coating for fundamental frequency light and frequency doubling light) , and form a nonlinear frequency conversion process inside the frequency doubling crystal 7; the frequency doubling laser 13 produced by the frequency doubling crystal 7 and the remaining fundamental frequency laser 2 pass through the lens 8 (both sides are coated with the fundamental frequency light and the frequency doubling light antireflection film) after collimation, the direction of propagation is changed by turning mirrors 9 and 10 (both coated with fundamental frequency light and frequency doubled light high-reflection film), and pass through the aperture diaphragm 11; harmonic separation mirror 12 (coated with 0 degree frequency doubled Optical anti-reflection coating and base frequency optical high-reflection coating) output frequency-doubled laser and reflect base frequency laser; Rotate 45 degrees or 90 degrees, the frequency doubling process may not occur, and the harmonic separator 12 is removed on the optical path, only the fundamental frequency laser output. the

The specific design example is as follows: according to Fig. 1, place various components of the laser on the optical path, including laser source 1, polarization rotator 3, focusing lens 6, frequency doubling crystal 7, collimating lens 8, pinhole diaphragm 11, harmonic separation Mirror 12 and turning mirrors 4, 5, 9, 10. The quasi-continuous pulse fundamental frequency laser 2 with stable output power passes through the steering mirrors 4 and 5 to change the transmission path and increase the optical path. A laser with a focal length of 50 mm is placed at a distance of about 300 mm from the output end of the laser source 1. The focusing lens 6 is used to focus and transform the fundamental frequency laser 2 into a focused beam with a beam waist diameter of about 0.1 mm, and the beam waist position is at the incident end face of the frequency doubling crystal 7 with a length of 10 mm. The polarization directions of the generated frequency-doubled laser and the fundamental-frequency laser are perpendicular to each other—as shown in Figure 2; when a polarization rotator 3 is inserted into the optical path, the polarization direction of the fundamental-frequency laser rotates 90 degrees around the propagation direction—as shown in Figure 3 As shown, the multiplication process occurs or does not occur. When the harmonic separation mirror 12 is placed in the optical path, only frequency-doubled laser light is output, and the remaining fundamental frequency laser light is reflected and absorbed by the pinhole diaphragm 11; when the harmonic separation mirror 12 is removed from the optical path, only the fundamental frequency laser light is output , no multiplication process takes place. the

In FIG. 2 , 7 is a frequency doubling crystal, 2 is a linearly polarized Q-switched fundamental frequency laser, and 13 is a linearly polarized frequency doubling laser. The nonlinear frequency doubling process can only occur when the linearly polarized Q-switched fundamental frequency laser 2 and the frequency doubled laser 13 meet the nonlinear optical phase matching conditions. According to the principle of nonlinear optics, lasers with different wavelengths, different polarization directions, and different incident directions have different refractive indices when propagating inside a nonlinear crystal. For the frequency doubling process, the frequency doubling process can only occur when the refractive indices of the fundamental frequency laser 2 and the frequency doubling laser 13 are equal when propagating inside the frequency doubling crystal 7 . the

In Figure 3, 3 is a polarization rotator, which can be a wave plate or a quartz optical crystal. After the linearly polarized Q-switched fundamental frequency laser 2 passes through the polarization rotator, the polarization direction changes and rotates around the propagation direction by a certain angle—45 degrees or 90 degrees. After the polarization direction of the fundamental frequency laser 2 is changed, the nonlinear phase matching condition is no longer satisfied (or just satisfied), and the frequency doubling process does not occur (or occurs). the

Obviously, those skilled in the art can make various changes and modifications to the utility model without departing from the spirit and scope of the utility model. In this way, if these modifications and variations of the utility model fall within the scope of the claims of the utility model and their equivalent technologies, the utility model also intends to include these modifications and variations. the

The content not described in detail in this specification belongs to the prior art known to those skilled in the art. the

Claims (2)

1. an end-pumped dual-wavelength coaxial switches output laser, comprise lasing light emitter (1), polarization rotator (3), condenser lens (6), frequency-doubling crystal (7), collimating lens (8), aperture (11), harmonic separation mirror (12), the first deviation mirror (4), the second deviation mirror (5), the 3rd deviation mirror (9), the 4th deviation mirror (10), it is characterized in that: the basic frequency laser (2) of lasing light emitter (1) pulse output is the linear polarization adjusting Q pulse laser, the first deviation mirror (4), the second deviation mirror (5), the 3rd deviation mirror (9), the 4th deviation mirror (10), polarization rotator (3), condenser lens (6), frequency-doubling crystal (7), collimating lens (8), aperture (11), harmonic separation mirror (12) is placed on outside the resonant cavity; Basic frequency laser (2) by lasing light emitter (1) pulse output is adjusted incident direction through the first deviation mirror (4) and the second deviation mirror (5), focus on the incident end face of frequency-doubling crystal (7) and produce double-frequency laser (13) and remaining basic frequency laser (2) passes through collimating lens (8) collimation again by being arranged on the outer condenser lens (6) of resonant cavity, then through the 3rd deviation mirror (9) and the 4th deviation mirror (10) adjustment exit direction; Harmonic separation mirror (12) reflects remaining basic frequency laser (2) and sees through double-frequency laser (13); Aperture (11) absorbs the residue basic frequency laser that is reflected; After inserting polarization rotator (3), the polarization direction of basic frequency laser (2) rotates 45 degree or 90 degree around direction of beam propagation.

2. a kind of end-pumped dual-wavelength coaxial according to claim 1 switches output laser, it is characterized in that: described polarization rotator (3) is quarter wave plate or 1/2 wave plate or the 45 quartzy gyrotropi crystals of degree or the quartzy gyrotropi crystal of 90 degree.

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