An ultra- picosecond laser

Abstract

The application discloses an ultrashort pulse laser, comprising: a fundamental laser light source for providing fundamental laser light; a first laser resonant cavity connected with the fundamental laser light source, the first laser resonant cavity is used for oscillating the fundamental laser light from the fundamental laser light source and converting the fundamental laser light into frequency-doubled laser light; a second laser resonant cavity connected with the first laser resonant cavity, the second laser resonant cavity is used for oscillating the frequency-doubled laser light from the first laser resonant cavity and generating optical parametric laser light by taking the frequency-doubled laser light as pump light; a third laser resonant cavity connected with the second laser resonant cavity, the third laser resonant cavity is used for oscillating the optical parametric laser light from the second laser resonant cavity and outputting the optical parametric laser light after laser coupling.

Description

Technical Field

[0001] This application relates to the field of medical devices, specifically to an ultra-picosecond laser. Background Technology

[0002] Currently, lasers are widely used in the field of medical aesthetics for tattoo removal, freckle removal and skin rejuvenation, skin improvement and treatment of skin diseases. The lasers used are mainly divided into three categories according to their pulse width: microsecond lasers, nanosecond lasers and picosecond lasers. Specifically, microsecond-level lasers, with their relatively wide pulse widths on the order of microseconds, tend to have a longer interaction time with the human body, resulting in a significant photothermal effect. This leads to noticeable heat and pain in the treated area. Therefore, microsecond-level lasers are generally used for hair removal. Nanosecond-level lasers, with their relatively narrow pulse widths on the order of nanoseconds, have a reduced photothermal effect upon contact with the human body, but the effect still exists. Therefore, nanosecond-level lasers can be used for freckle removal, but the treatment effect is limited. However, picosecond-level lasers, especially those with pulse widths below 500 picoseconds (i.e., ultra-picosecond laser pulses), have very narrow pulse widths, resulting in a very short interaction time with human tissue. They do not exhibit a photothermal effect but instead primarily function through photoacoustic effects. The sound waves generated by this laser upon contact with the human body can shatter melanin or tattoo ink. Therefore, the aforementioned picosecond-level lasers can be used for freckle removal, tattoo removal, and other treatments. Compared to microsecond-level and nanosecond-level lasers, picosecond-level laser pulses cause almost no heat or pain upon contact with the human body, resulting in better treatment effects. Studies have shown that lasers with a wavelength of 785 nanometers (760nm–810nm) can be fully absorbed by green and blue tattoos, and also show good absorption by melanin. Furthermore, this wavelength is not affected by hemoglobin in the human body. Compared to lasers with a wavelength of 755 nanometers, green and blue tattoos have a better absorption rate to the 785 nanometer wavelength laser, meaning it is more effective at removing green and blue tattoos. Therefore, the 785 nanometer wavelength laser is more suitable for applications in medical fields such as tattoo removal, skin rejuvenation, and improvement of fine lines and acne scars. 1064 nanometer and 532 nanometer lasers are widely used in vascular diseases because the peak absorption values ​​of oxygenated hemoglobin in tissues for lasers are 418nm, 532nm, and 577nm, respectively. The 418nm laser is rarely used clinically due to its shallow penetration depth. 532nm and 577nm lasers are commonly used to treat vascular skin diseases. These wavelengths are the absorption peaks of oxyhemoglobin and melanin. Therefore, when treating vascular diseases, the melanin in the epidermis can also absorb the energy, causing epidermal damage and other adverse reactions. 1064nm lasers have another absorption peak for oxyhemoglobin, and due to their deep penetration depth, they are less easily absorbed by epidermal melanin, making them suitable for treating some deeper vascular skin diseases. Currently, only low-power continuous lasers with a wavelength of 785nm are available on the market; there are no 785nm picosecond pulsed laser products. Therefore, further development of related products is needed. Summary of the Invention

[0003] The purpose of this invention is to provide a picosecond laser capable of outputting picosecond pulsed laser light.

[0004] To solve the above problems, the present invention adopts the following technical solution:

[0005] A picosecond laser includes: a fundamental frequency laser source for providing fundamental frequency laser light; a first laser resonator connected to the fundamental frequency laser source for oscillating the fundamental frequency laser light incident from the fundamental frequency laser source and converting the fundamental frequency laser light into a frequency-doubled laser light; a second laser resonator connected to the first laser resonator for oscillating the frequency-doubled laser light incident from the first laser resonator and using the frequency-doubled laser light as pump light to generate optical parametric laser light; and a third laser resonator connected to the second laser resonator for oscillating the optical parametric laser light incident from the second laser resonator and outputting the optical parametric laser light after laser coupling.

[0006] Optionally, it also includes: a fundamental frequency high-reflectivity mirror, which is coated with a high-reflectivity film for fundamental frequency lasers and is used to output fundamental frequency lasers; the fundamental frequency high-reflectivity mirror is movably positioned at the optical axis of the fundamental frequency laser and is used to control the on or off of the output fundamental frequency laser; a frequency-doubled high-reflectivity mirror, which is coated with a high-reflectivity film for frequency-doubled lasers and is used to output frequency-doubled lasers; the frequency-doubled high-reflectivity mirror is movably positioned at the optical axis of the frequency-doubled laser and is used to control the on or off of the output frequency-doubled laser; and an optical parametric high-reflectivity mirror, which is coated with a high-reflectivity film for optical parametric lasers and is used to output optical parametric lasers; the optical parametric high-reflectivity mirror is positioned at the optical axis after the optical parametric laser has undergone laser coupling.

[0007] Optionally, the wavelength of the fundamental frequency laser is 1064 nanometers, and the pulse width of the fundamental frequency laser is 100 picoseconds to 500 picoseconds; the wavelength of the frequency-doubled laser is 532 nanometers, and the pulse width of the frequency-doubled laser is 100 picoseconds to 500 picoseconds; the wavelength range of the optical parametric laser is 760 nanometers to 810 nanometers, and the pulse width of the optical parametric laser is 100 picoseconds to 500 picoseconds.

[0008] Optionally, the first laser resonator and the second laser resonator are coupled together, or the second laser resonator and the third laser resonator are coupled together.

[0009] Optionally, the first laser resonant cavity includes a first A high-reflectivity mirror, an M electro-optic crystal, an E polarizer, a first beam shaper, a first beam splitter, a frequency doubling crystal, and a first B high-reflectivity mirror. The fundamental frequency laser, after entering through the E polarizer, sequentially passes through the M electro-optic crystal, the first A high-reflectivity mirror, the M electro-optic crystal, the E polarizer, the first beam shaper, the first beam splitter, the frequency doubling crystal, and the first B high-reflectivity mirror before oscillating within the first laser resonant cavity. The first beam splitter is used to separate the frequency-doubled laser generated by the frequency doubling crystal, and the M electro-optic crystal is used to control the polarization direction of the fundamental frequency laser. The second laser resonant cavity includes a frequency doubling crystal, a first B high-reflectivity mirror, a first beam splitter, a second A high-reflectivity mirror, a second beam shaper, a second beam splitter, an optical parametric crystal, and a second B high-reflectivity mirror. The frequency-doubled laser, after being generated by the frequency doubling crystal, sequentially passes through the first B high-reflectivity mirror, the M electro-optic crystal, the E polarizer, the first beam shaper, the first beam splitter, the optical parametric crystal, and the second B high-reflectivity mirror. The optical parametric laser generated by the optical parametric crystal, the first beam splitter, the second A high-reflection mirror, the second beam shaper, the second beam splitter, the optical parametric crystal, and the second B high-reflection mirror oscillate within the second laser resonant cavity. The second beam splitter is used to separate the optical parametric laser generated by the optical parametric crystal. The third laser resonant cavity includes an optical parametric crystal, the second B high-reflection mirror, the second beam splitter, the third A high-reflection mirror, the third beam shaper, the F polarizer, the N electro-optic crystal, and the third B high-reflection mirror. After being generated by the optical parametric crystal, the optical parametric laser passes sequentially through the second B high-reflection mirror, the optical parametric crystal, the second beam splitter, the third A high-reflection mirror, the third beam shaper, the F polarizer, the N electro-optic crystal, and the third B high-reflection mirror before oscillating within the third laser resonant cavity. The N electro-optic crystal is used to control the polarization direction of the optical parametric laser, and the F polarizer is used to output the coupled optical parametric laser.

[0010] Optionally, the first beam splitter is coated with a high-transmittance film for the fundamental frequency laser and a high-reflectance film for the frequency-doubled laser, which provides reflection conditions for the frequency-doubled laser to oscillate in the second resonant cavity without affecting the oscillation of the fundamental frequency laser in the first resonant cavity; the second beam splitter is coated with a high-transmittance film for the frequency-doubled laser and a high-reflectance film for the optical parametric laser, which provides reflection conditions for the optical parametric laser to oscillate in the third resonant cavity without affecting the oscillation of the frequency-doubled laser in the second resonant cavity.

[0011] Optionally, the first A high-reflectivity mirror is coated with a high-reflectivity film for the fundamental frequency laser, used to provide reflection conditions for the fundamental frequency laser to oscillate within the first laser resonant cavity; the first B high-reflectivity mirror is coated with a high-reflectivity film for the fundamental frequency laser, used to provide reflection conditions for the fundamental frequency laser to oscillate within the first laser resonant cavity; the first B high-reflectivity mirror is coated with a high-reflectivity film for the frequency-doubled laser, used to provide reflection conditions for the frequency-doubled laser to oscillate within the second laser resonant cavity; the second A high-reflectivity mirror is coated with a high-reflectivity film for the frequency-doubled laser, used to provide reflection conditions for the frequency-doubled laser to oscillate within the second laser resonant cavity; the second B high-reflectivity mirror is coated with a high-reflectivity film for the frequency-doubled laser... The first mirror has a high-reflectivity coating to provide reflection conditions for the frequency-doubled laser to oscillate in the second laser resonant cavity; the second mirror B has a high-reflectivity coating specifically for optical parametric lasers to provide reflection conditions for the optical parametric laser to oscillate in the third laser resonant cavity; the third mirror A has a high-reflectivity coating specifically for optical parametric lasers to provide reflection conditions for the optical parametric laser to oscillate in the third laser resonant cavity; the third mirror B has a high-reflectivity coating specifically for optical parametric lasers to provide reflection conditions for the optical parametric laser to oscillate in the third laser resonant cavity, and together with the F polarizer and the N photoelectric crystal, they achieve coupling and output of optical parametric picosecond laser.

[0012] Optionally, the first A high-reflection mirror and the first B high-reflection mirror are arranged perpendicularly; the first A high-reflection mirror, the first B high-reflection mirror, the second B high-reflection mirror, and the third B high-reflection mirror are all arranged perpendicularly to their respective optical axes; the first B high-reflection mirror, the second B high-reflection mirror, and the third B high-reflection mirror are arranged parallel to each other; the second A high-reflection mirror, the third A high-reflection mirror, the frequency doubling high-reflection mirror, the E polarizer, and the optical parametric high-reflection mirror are arranged parallel to each other; and the first beam splitter, the second beam splitter, the F polarizer, and the fundamental frequency high-reflection mirror are arranged parallel to each other.

[0013] Optionally, a quarter-wave plate is disposed between the M photoelectric crystal and the E polarizer within the first resonant cavity.

[0014] Optionally, it also includes: a high-speed photodetector, which is located behind the third B high-reflectivity mirror and is used to detect the transmitted light of the third B high-reflectivity mirror in real time and convert the transmitted light into an electrical signal; an oscilloscope, which is connected to the high-speed photodetector and is used to receive and display the electrical signal converted by the high-speed photodetector; and a controller, which is connected to the oscilloscope and is used to control the N electro-optic crystal when the electrical signal displayed on the oscilloscope reaches a preset value.

[0015] Optionally, the frequency doubling crystal can be an LBO crystal or a KTP crystal; the optical parametric crystal can be an LBO crystal, a BBO crystal, a KTP crystal, or a KTA crystal.

[0016] Optionally, the optical cavity lengths of the first laser resonator, the second laser resonator, and the third laser resonator are equal.

[0017] A device comprising the aforementioned picosecond laser.

[0018] A medical device for skin treatment, including the aforementioned picosecond laser.

[0019] The above-mentioned technical solution of the present invention has the following beneficial technical effects: Through the design of the present invention, ultra-picosecond pulsed lasers in the 785 nm band can be obtained, and through oscillation in the resonant cavity, the obtained 785 nm ultra-picosecond laser has higher single-pulse energy. The present invention is particularly suitable for skin medical devices, and can achieve better therapeutic effects. Furthermore, ultra-picosecond lasers in the 1064, 532, or 785 nm bands can be selectively output in the same device or equipment, enriching the applications of lasers, saving operating costs and equipment costs, and improving work efficiency. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the output at the 785 nanometer wavelength.

[0021] Figure 2 This is a schematic diagram showing the selective output of 1064, 532, or 785 nanometer wavelengths.

[0022] Among them, 100-fundamental frequency laser source; 101-first A-high reflection mirror; 102-M-electro-optic crystal; 103-quarter-wave plate; 104-E-polarizer; 105-first beam shaper; 106-first beam splitter; 107-frequency doubling crystal; 108-first B-high reflection mirror; 109-second A-high reflection mirror; 110-second beam shaper; 111-second beam splitter; 112-optical parametric crystal; 113-second B-high reflection mirror; 114-third A-high reflection mirror; 115-third beam shaper; 116-F-polarizer; 117-N-electro-optic crystal; 118-third B-high reflection mirror; 119-fundamental frequency high reflection mirror; 120-frequency doubling high reflection mirror; 121-optical parametric high reflection mirror. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0024] A picosecond laser includes: a fundamental frequency laser source 100 for providing fundamental frequency laser light; a first laser resonant cavity connected to the fundamental frequency laser source 100 for oscillating the fundamental frequency laser light incident from the source 100 and converting it into a frequency-doubled laser; a second laser resonant cavity connected to the first laser resonant cavity for oscillating the frequency-doubled laser light incident from the first laser resonant cavity and using it as pump light to generate optical parametric laser light; and a third laser resonant cavity connected to the second laser resonant cavity for oscillating the optical parametric laser light incident from the second laser resonant cavity and outputting it after laser coupling. This design enables the generation of 785 nm ultra-picosecond pulsed laser light, and through oscillation within the resonant cavities, the obtained 785 nm ultra-picosecond laser light possesses higher single-pulse energy. It is particularly suitable for skin medical devices, achieving better therapeutic effects.

[0025] In an optional embodiment, the system further includes: a fundamental frequency high-reflectivity mirror 119, which is coated with a high-reflectivity film for fundamental frequency lasers and is used to output fundamental frequency lasers; the fundamental frequency high-reflectivity mirror 119 is movably disposed at the optical axis of the fundamental frequency laser and is used to control the on or off of the output of the fundamental frequency laser; a frequency-doubled high-reflectivity mirror 120, which is coated with a high-reflectivity film for frequency-doubled lasers and is used to output frequency-doubled lasers; the frequency-doubled high-reflectivity mirror 120 is movably disposed at the optical axis of the frequency-doubled laser and is used to control the on or off of the output of the frequency-doubled laser; and an optical parametric high-reflectivity mirror 121, which is coated with a high-reflectivity film for optical parametric lasers and is used to output optical parametric lasers; the optical parametric high-reflectivity mirror 121 is disposed at the optical axis after the optical parametric laser has undergone laser coupling. The fundamental frequency laser has a wavelength of 1064 nanometers and a pulse width of 100-500 picoseconds; the frequency-doubled laser has a wavelength of 532 nanometers and a pulse width of 100-500 picoseconds; the optical parametric laser has a wavelength range of 760-810 nanometers and a pulse width of 100-500 picoseconds. The same device or equipment can selectively output ultra-picosecond lasers in the 1064, 532, or 785 nanometer bands, enriching the applications of lasers, saving on operating and equipment costs, and improving work efficiency.

[0026] In an optional embodiment, the first laser resonator and the second laser resonator are coupled together, and the second laser resonator and the third laser resonator are coupled together. The optical cavity lengths of the first laser resonator, the second laser resonator, and the third laser resonator are equal. The first laser resonator includes a first A high-reflection mirror 101, an M electro-optic crystal 102, an E polarizer 104, a first beam shaper 105, a first beam splitter 106, a frequency doubling crystal 107, and a first B high-reflection mirror 108. After the fundamental frequency laser is incident through the E polarizer 104, it sequentially passes through the M electro-optic crystal 102, the first A high-reflection mirror 101, the M electro-optic crystal 102, the E polarizer 104, the first beam shaper 105, the first beam splitter 106, the frequency doubling crystal 107, and the first B high-reflection mirror 108 before entering the first laser resonator. The resonant cavity oscillates. The first beam splitter 106 is used to separate the frequency-doubled laser generated by the frequency-doubled crystal 107, and the M-electro-optic crystal 102 is used to control the polarization direction of the fundamental frequency laser. The second laser resonant cavity includes the frequency-doubled crystal 107, the first B-high reflection mirror 108, the first beam splitter 106, the second A-high reflection mirror 109, the second beam shaper 110, the second beam splitter 111, the optical parametric crystal 112, and the second B-high reflection mirror 113. After being generated by the frequency-doubled crystal 107, the frequency-doubled laser sequentially passes through the first B-high reflection mirror 108, the frequency-doubled crystal 109, the first B-high reflection mirror 109, the second A-high reflection mirror 109, the second A-high reflection mirror 100, the second A-high reflection mirror 101, the second A-high reflection mirror 102, the second A-high reflection mirror 103, the second A-high reflection mirror 104, the second A-high reflection mirror 105, the second A-high reflection mirror 106, the second A-high reflection mirror 106, the second A-high reflection mirror 107 ...7, the second A-high reflection mirror 108, the second A-high reflection mirror 109, the second A-high reflection mirror 100, the second A-high reflection mirror 100, the second A-high reflection mirror 100, and the second A-high reflection mirror 109. The second laser resonator comprises a crystal 107, a first beam splitter 106, a second A-type high-reflection mirror 109, a second beam shaper 110, a second beam splitter 111, an optical parametric crystal 112, and a second B-type high-reflection mirror 113, which oscillate within the second laser resonator. The second beam splitter 111 separates the optical parametric laser generated by the optical parametric crystal 112. The third laser resonator includes the optical parametric crystal 112, the second B-type high-reflection mirror 113, the second beam splitter 111, the third A-type high-reflection mirror 114, the third beam shaper 115, and an F-type polarizer 116. The N-electro-optic crystal 117 and the third B-high reflective mirror 118 are used to control the polarization direction of the optical parametric laser. After being generated by the optical parametric crystal 112, the optical parametric laser passes sequentially through the second B-high reflective mirror 113, the optical parametric crystal 112, the second beam splitter 111, the third A-high reflective mirror 114, the third beam shaper 115, the F-polarizer 116, the N-electro-optic crystal 117, and the third B-high reflective mirror 118 before oscillating in the third laser resonant cavity. The N-electro-optic crystal 117 is used to control the polarization direction of the optical parametric laser, and the F-polarizer 116 is used to output the coupled optical parametric laser. A quarter-wave plate 103 is placed between the M-electro-optic crystal and the E-polarizer 104 in the first resonant cavity.

[0027] The first laser resonator and the second laser resonator share a first beam splitter 106, a frequency doubling crystal 107, and a first B-high reflection mirror 108; the second laser resonator and the third laser resonator share a second beam splitter 111, an optical parametric crystal 112, and a second B-high reflection mirror 113. This achieves deep coupling between adjacent resonators of the first laser resonator, the second laser resonator, and the third laser resonator, thereby ensuring efficient resonance between the fundamental frequency laser and the optical parametric laser, and thus ensuring efficient coupling and output of the target picosecond laser. During operation, when the fundamental frequency laser and the frequency-doubled laser oscillate in the first laser resonant cavity and the second laser resonant cavity, respectively, the fundamental frequency laser and the frequency-doubled laser can be synchronously incident into the frequency-doubled crystal 107 to achieve phase matching, and after appropriate oscillation or delay, the energy of the frequency-doubled laser is enhanced. When the frequency-doubled laser and the optical parametric laser oscillate in the second laser resonant cavity and the third laser resonant cavity, respectively, the frequency-doubled laser and the optical parametric laser can be synchronously incident into the optical parametric crystal 112, and after appropriate oscillation or delay, the energy of the optical parametric laser reaches its maximum. At this time, the optical parametric laser with the maximum energy is coupled and output, that is, the output of the optical parametric picosecond laser with the maximum energy is obtained.

[0028] like Figure 1As shown, in the first laser resonant cavity, the fundamental frequency laser provided by the fundamental frequency laser source 100 is polarized by the E polarizer 104 to obtain polarized laser. The obtained polarized laser includes first polarized light and first polarized light, wherein the first P polarized light is the fundamental frequency laser polarized parallel to the incident plane, and the first S polarized light is the fundamental frequency laser polarized perpendicular to the incident plane. The E polarizer 104 has high transmittance for the first P polarized light and high reflectivity for the first S polarized light. The fundamental frequency laser transmitted through the E polarizer 104 is incident on the first A high reflectivity mirror 101 after its polarization direction is changed by the M electro-optic crystal 102. After being reflected by the first A high reflectivity mirror 101, it is incident on the E polarizer 104 again after its polarization direction is changed by the M electro-optic crystal 102. The fundamental frequency laser reflected by the E polarizer 104 passes sequentially through the first beam shaper 105. The first beam splitter 106 and the frequency doubling crystal 107 are incident on the first B high-reflection mirror 108. High voltage is input to both ends of the M electro-optic crystal 102 to change the polarization direction of the fundamental frequency laser passing through it. The fundamental frequency laser is highly reflected by the first A high-reflection mirror 101. The input fundamental frequency laser is shaped by the first beam shaper 105, and the shaped laser is injected into the frequency doubling crystal 107. The frequency doubling crystal 107 performs frequency doubling on the injected laser shaped by the first beam shaper 105 to generate a frequency-doubled laser. The first beam splitter 106 separates the fundamental frequency laser and the frequency-doubled laser, where the first beam splitter 106 provides high transmission to the fundamental frequency laser and high reflection to the frequency-doubled laser. The first B high-reflection mirror 108 provides high reflection to both the fundamental frequency laser and the frequency-doubled laser. Specifically, the fundamental frequency laser is preferably a picosecond laser with a wavelength of 1064 nanometers, and the pulse width of the fundamental frequency laser is preferably 100 picoseconds to 500 picoseconds. The frequency-doubled laser obtained by frequency doubling the fundamental frequency laser is a laser with a wavelength of 532 nanometers. Preferably, the fundamental frequency laser, after its polarization direction is changed by the M-electro-optic crystal 102, is incident on the E-polarizer 104 perpendicularly to the E-polarizer 104. More preferably, the high voltage input at both ends of the M-electro-optic crystal 102 is preferably a half-wave voltage. The specific value of the half-wave voltage is set according to the specific working conditions of the material of the M-electro-optic crystal 102, so as to ensure that the optical parametric laser coupling outputs maximum energy stably and efficiently.

[0029] like Figure 2 As shown, its picosecond laser generation method is similar to... Figure 1The method for generating ultra-picosecond lasers shown is basically the same, except that in the first laser resonant cavity, a quarter-wave plate 103 is used to change the polarization direction of the fundamental frequency laser passing through it. Specifically, the fundamental frequency laser passing through the E polarizer 104 passes through the quarter-wave plate 103 and the M electro-optic crystal 102 in sequence to change its polarization direction before being incident on the first A high-reflection mirror 101. After being reflected by the first A high-reflection mirror 101, it passes through the M electro-optic crystal 102 and the quarter-wave plate 103 in sequence to change its polarization direction before being incident on the E polarizer 104 again. The fundamental frequency laser that is incident on the E polarizer 104 again after its polarization direction is changed by the M electro-optic crystal 102 and the quarter-wave plate 103 is perpendicular to the E polarizer 104. The high voltage input at both ends of the M-electro-optic crystal 102 is preferably a quarter-wave voltage to change the polarization direction of the fundamental frequency laser passing through the M-electro-optic crystal 102; wherein, the specific value of the quarter-wave voltage is set according to the specific working conditions of the material of the M-electro-optic crystal 102, so as to ensure that the optical parametric laser coupling is performed with maximum energy stable and efficient output as the standard.

[0030] like Figure 1 and 2As shown, in the second laser resonant cavity, the frequency-doubled laser reflected by the first beam splitter 106 is incident on the second A high-reflection mirror 109. After being reflected by the second A high-reflection mirror 109, it passes sequentially through the second beam shaper 110, the second beam splitter 111, and the optical parametric crystal 112 before being incident on the second B high-reflection mirror 113. The second beam shaper 110 shapes the input frequency-doubled laser beam, and the shaped frequency-doubled laser is injected into the optical parametric crystal 112. The optical parametric crystal 112 absorbs the injected frequency-doubled laser shaped by the second beam shaper 110, generating an optical parametric laser. The second beam splitter 111 separates the frequency-doubled laser and the optical parametric laser, wherein the second beam splitter 111 provides high transmission for the frequency-doubled laser and high reflection for the optical parametric laser. The second B high-reflection mirror 113 provides high reflection for both the frequency-doubled laser and the optical parametric laser. In the third laser resonant cavity, the optical parametric laser reflected by the second beam splitter 111 is incident on the third A high-reflection mirror 114. After being reflected by the third A high-reflection mirror 114, it passes sequentially through the third beam shaper 115, the F polarizer 116, and the N electro-optic crystal 117 before being incident on the third B high-reflection mirror 118. The third beam shaper 115 shapes the input optical parametric laser beam, and the shaped optical parametric laser beam is incident on the F polarizer 116. The F polarizer 116, the N electro-optic crystal 117, and the third B high-reflection mirror 118 work together to couple and output an optical parametric picosecond laser. The wavelength range of the resulting optical parametric picosecond laser is 760 nm to 810 nm, and the pulse width is 100 picoseconds to 500 picoseconds. After the optical parametric laser is incident on the F polarizer 116, it generates third P-polarized light and third S-polarized light through the F polarizer 116. The third S-polarized light is output after coupling. When no voltage is applied to the N electro-optic crystal 117, the third P-polarized light is confined to oscillate within the third laser resonant cavity. When a quarter-wave voltage is applied to the N electro-optic crystal 117, the third P-polarized light is changed to the same direction as the third S-polarized light, and after coupling together with the third S-polarized light, it is reflected by the F polarizer 116 and output. The specific value of the quarter-wave voltage is set according to the material and other specific operating conditions of the N electro-optic crystal 117 to ensure that the optical parametric laser outputs stable and efficient maximum energy after coupling.When the fundamental frequency laser and the frequency-doubled laser oscillate in the first and second laser resonant cavities, respectively, the first and second laser resonant cavities have equal optical cavity lengths, allowing the fundamental frequency laser and the frequency-doubled laser to be synchronously incident on the frequency-doubled crystal 107 to achieve phase matching. After an appropriate number of oscillations or delays, the energy of the frequency-doubled laser continuously increases. Correspondingly, when the frequency-doubled laser and the optical parametric laser oscillate in the second and third laser resonant cavities, respectively, the second and third laser resonant cavities have equal optical cavity lengths, allowing the fundamental frequency laser and the frequency-doubled laser to be synchronously incident on the frequency-doubled crystal 107 to achieve phase matching. The optical cavity lengths are equal, allowing the frequency-doubled laser and the optical parametric laser to be synchronously incident into the optical parametric crystal 112. After an appropriate number of oscillations or delays, the energy of the optical parametric laser reaches its maximum. At this point, the optical parametric laser is coupled and output, thereby ensuring the acquisition of a single pulse of high-energy target picosecond laser. The number of oscillations for the frequency-doubled laser and the optical parametric laser is preferably less than one hundred, and the delay for the frequency-doubled laser and the optical parametric laser is preferably less than one microsecond, thus ensuring both the high energy of the output target picosecond laser and the overall efficient operation of the picosecond laser.

[0031] In an optional embodiment, the first beam splitter 106 is coated with a high-transmittance film for the fundamental frequency laser and a high-reflectance film for the frequency-doubled laser, which provides reflection conditions for the frequency-doubled laser to oscillate in the second resonant cavity without affecting the oscillation of the fundamental frequency laser in the first resonant cavity; the second beam splitter 111 is coated with a high-transmittance film for the frequency-doubled laser and a high-reflectance film for the optical parametric laser, which provides reflection conditions for the optical parametric laser to oscillate in the third resonant cavity without affecting the oscillation of the frequency-doubled laser in the second resonant cavity. The first A high-reflection mirror 101 is coated with a high-reflection film for the fundamental frequency laser, used to provide reflection conditions for the fundamental frequency laser to oscillate within the first laser resonant cavity; the first B high-reflection mirror 108 is coated with a high-reflection film for the fundamental frequency laser, used to provide reflection conditions for the fundamental frequency laser to oscillate within the first laser resonant cavity; the first B high-reflection mirror 108 is coated with a high-reflection film for the frequency-doubled laser, used to provide reflection conditions for the frequency-doubled laser to oscillate within the second laser resonant cavity; the second A high-reflection mirror 109 is coated with a high-reflection film for the frequency-doubled laser, used to provide reflection conditions for the frequency-doubled laser to oscillate within the second laser resonant cavity; the second B high-reflection mirror 113 is coated with a high-reflection film for the frequency-doubled laser. The first mirror has a reflective coating to provide reflection conditions for the frequency-doubled laser to oscillate in the second laser resonant cavity; the second B high-reflectivity mirror 113 is coated with a high-reflectivity coating for optical parametric lasers to provide reflection conditions for the optical parametric laser to oscillate in the third laser resonant cavity; the third A high-reflectivity mirror 114 is coated with a high-reflectivity coating for optical parametric lasers to provide reflection conditions for the optical parametric laser to oscillate in the third laser resonant cavity; the third B high-reflectivity mirror 118 is coated with a high-reflectivity coating for optical parametric lasers to provide reflection conditions for the optical parametric laser to oscillate in the third laser resonant cavity, and together with the F polarizer 116 and the N photoelectric crystal, it achieves coupled output of optical parametric picosecond laser. To ensure the high-power, efficient, and stable output of the target picosecond laser, preferably, the first A high-reflectivity mirror 101 and the first B high-reflectivity mirror 108 have a reflectivity of 99.5%–99.8% for the fundamental frequency laser; the first beam splitter 106 has a transmittance of 98.25%–99.6% for the fundamental frequency laser; the first beam splitter 106, the first B high-reflectivity mirror 108, the second A high-reflectivity mirror 109, and the second B high-reflectivity mirror 113 have a reflectivity of 99.5%–99.8% for the frequency-doubled laser; the second beam splitter 111 has a transmittance of 98.25%–99.6% for the frequency-doubled laser; and the second beam splitter 111, the second B high-reflectivity mirror 113, the third A high-reflectivity mirror 114, and the third B high-reflectivity mirror 118 are coated with a reflectivity of 99.5%–99.8% for the optical parametric laser. The fundamental frequency high-reflectivity mirror 119 is coated with a reflectivity of 99.5% to 99.8% for the fundamental frequency laser. The frequency-doubled high-reflectivity mirror 120 is coated with a reflectivity of 99.5% to 99.8% for the frequency-doubled laser. The optical parametric high-reflectivity mirror 121 is coated with a reflectivity of 99.5% to 99.8% for the optical parametric laser.

[0032] In an optional embodiment, the first A high-reflection mirror 101 and the first B high-reflection mirror 108 are arranged perpendicularly to each other; the first A high-reflection mirror 101, the first B high-reflection mirror 108, the second B high-reflection mirror 113, and the third B high-reflection mirror 118 are all arranged perpendicularly to their respective optical axes; the first B high-reflection mirror 108, the second B high-reflection mirror 113, and the third B high-reflection mirror 118 are arranged parallel to each other; the second A high-reflection mirror 109, the third A high-reflection mirror 114, the frequency doubling high-reflection mirror 120, the E polarizer 104, and the optical parametric high-reflection mirror 121 are arranged parallel to each other; the first beam splitter 106, the second beam splitter 111, the F polarizer 116, and the fundamental frequency high-reflection mirror 119 are arranged parallel to each other.

[0033] In an optional embodiment, the device further includes: a high-speed photodetector disposed behind the third B high-reflectivity mirror 118, used to detect the transmitted light of the third B high-reflectivity mirror 118 in real time and convert the transmitted light into an electrical signal; an oscilloscope connected to the high-speed photodetector, used to receive and display the electrical signal converted by the high-speed photodetector; and a controller connected to the oscilloscope, used to control the N electro-optic crystal 117 when the electrical signal displayed on the oscilloscope reaches a preset value. During operation, a high-speed photoelectric probe detects the parametric laser transmitted through the third laser resonant cavity in real time and converts it into an electrical signal, which is then transmitted to the oscilloscope for display. The controller receives the signal displayed on the oscilloscope and controls the electro-optic crystal in the third laser resonant cavity based on this signal. When the signal displayed on the oscilloscope reaches its maximum, a high voltage is applied to the electro-optic crystal in the third laser resonant cavity, ensuring that the polarized light generated by the polarizer in the third laser resonant cavity has the same direction. Then, the polarized light with the same direction is coupled together and reflected by the polarizer in the third laser resonant cavity before being output. This achieves the coupling and output of the parametric laser with maximum energy, obtaining the target picosecond laser with the highest energy. The high voltage applied to the electro-optic crystal in the third laser resonant cavity is a quarter-wave voltage. The specific value of the quarter-wave voltage is set according to the material and specific operating conditions of the electro-optic crystal in the third laser resonant cavity to ensure stable and efficient output of the parametric laser after coupling at maximum energy.

[0034] In an optional embodiment, the frequency doubling crystal 107 is an LBO crystal or a KTP crystal; the optical parametric crystal 112 is an LBO crystal, a BBO crystal, a KTP crystal, or a KTA crystal.

[0035] A device comprising the aforementioned picosecond laser.

[0036] A medical device for skin treatment, including the aforementioned picosecond laser.

[0037] Compared with existing traditional single-pass frequency conversion technologies, the picosecond laser provided by the above embodiments of the present invention breaks through traditional concepts. For the first time, it employs solid-state laser frequency conversion technology and, for the first time, couples the laser resonators involving the fundamental frequency laser, frequency-doubled laser, and optical parametric laser together. This coupling structure is used to couple the optical parametric laser output, achieving higher efficiency and higher frequency conversion, thereby obtaining a picosecond laser with higher single-pulse energy. Furthermore, based on this technology, multi-wavelength range output of the picosecond laser can be achieved by controlling the working module. The resulting fundamental frequency laser has a pulse width of 100 picoseconds to 500 picoseconds and a wavelength of 1064 nanometers; the resulting frequency-doubled laser has a pulse width of 100 picoseconds to 500 picoseconds and a wavelength of 532 nanometers; and the resulting 785-nanometer band optical parametric laser has a wavelength range of 760 nanometers to 810 nanometers and a pulse width of 100 picoseconds to 500 picoseconds. Based on the picosecond laser provided by this invention, it can be used to manufacture equipment that requires 1064, 532, and 785 nanometer picosecond laser sources, especially to manufacture medical instruments for skin treatment. In the field of skin treatment, the provided picosecond laser can be well absorbed by melanin and can be widely used for tattoo removal, freckle and mole removal, skin rejuvenation, and improvement of fine lines and acne scars. In particular, in the removal of tattoos, it can achieve better treatment results with almost no heat or pain to the human body.

[0038] The above embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Although the invention has been described in detail with reference to the embodiments, those skilled in the art should understand that various combinations, modifications, or equivalent substitutions or improvements to the technical solutions of the invention do not depart from the scope of the invention and should be covered within the protection scope of the invention.

Claims

1. A picosecond laser, characterized in that, include: A fundamental frequency laser source, wherein the fundamental frequency laser source is used to provide fundamental frequency laser; A first laser resonant cavity is connected to the fundamental frequency laser source. The first laser resonant cavity is used to oscillate the fundamental frequency laser emitted from the fundamental frequency laser source and convert the fundamental frequency laser into a frequency-doubled laser. A second laser resonant cavity is connected to the first laser resonant cavity. The second laser resonant cavity is used to oscillate the frequency-doubled laser emitted from the first laser resonant cavity and use the frequency-doubled laser as pump light to generate optical parametric laser. A third laser resonant cavity is connected to the second laser resonant cavity. The third laser resonant cavity is used to oscillate the optical parametric laser emitted from the second laser resonant cavity and output the optical parametric laser after laser coupling. A fundamental frequency high-reflectivity mirror is coated with a high-reflectivity film for the fundamental frequency laser and is used to output the fundamental frequency laser. The fundamental frequency high-reflectivity mirror is movably disposed at the optical axis of the fundamental frequency laser and is used to control the on or off output of the fundamental frequency laser. A frequency-doubled high-reflectivity mirror, wherein the frequency-doubled high-reflectivity mirror is coated with a high-reflectivity film for the frequency-doubled laser, and is used to output the frequency-doubled laser; the frequency-doubled high-reflectivity mirror is movably disposed at the optical axis of the frequency-doubled laser, and is used to control the on or off output of the frequency-doubled laser; An optical parametric high-reflectivity mirror is coated with a high-reflectivity film for the optical parametric laser and is used to output the optical parametric laser; the optical parametric high-reflectivity mirror is positioned at the optical axis after the optical parametric laser undergoes laser coupling. The first laser resonant cavity and the second laser resonant cavity are coupled together, and the second laser resonant cavity and the third laser resonant cavity are coupled together. The first laser resonant cavity includes a first A high-reflectivity mirror, an M electro-optic crystal, an E polarizer, a first beam shaper, a first beam splitter, a frequency doubling crystal, and a first B high-reflectivity mirror. The fundamental frequency laser enters through the E polarizer and then passes sequentially through the M electro-optic crystal, the first A high-reflectivity mirror, the M electro-optic crystal, the E polarizer, the first beam shaper, the first beam splitter, the frequency doubling crystal, and the first B high-reflectivity mirror before oscillating within the first laser resonant cavity. The first beam splitter is used to separate the frequency-doubled laser generated by the frequency doubling crystal, and the M electro-optic crystal is used to control the polarization direction of the fundamental frequency laser. The second laser resonant cavity includes the frequency doubling crystal, the first B high-reflection mirror, the first beam splitter, the second A high-reflection mirror, the second beam shaper, the second beam splitter, the optical parametric crystal, and the second B high-reflection mirror. After being generated by the frequency doubling crystal, the frequency-doubled laser sequentially passes through the first B high-reflection mirror, the frequency doubling crystal, the first beam splitter, the second A high-reflection mirror, the second beam shaper, the second beam splitter, the optical parametric crystal, and the second B high-reflection mirror before oscillating within the second laser resonant cavity. The second beam splitter is used to separate the optical parametric laser generated by the optical parametric crystal. The third laser resonant cavity includes the optical parametric crystal, the second B high-reflection mirror, the second beam splitter, the third A high-reflection mirror, the third beam shaper, the F polarizer, the N electro-optic crystal, and the third B high-reflection mirror. After being generated by the optical parametric crystal, the optical parametric laser sequentially passes through the second B high-reflection mirror, the optical parametric crystal, the second beam splitter, the third A high-reflection mirror, the third beam shaper, the F polarizer, the N electro-optic crystal, and the third B high-reflection mirror before oscillating within the third laser resonant cavity. The N electro-optic crystal is used to control the polarization direction of the optical parametric laser, and the F polarizer is used to output the coupled optical parametric laser.

2. The picosecond laser as described in claim 1, characterized in that, The wavelength of the fundamental frequency laser is 1064 nanometers, and the pulse width of the fundamental frequency laser is 100 picoseconds to 500 picoseconds. The wavelength of the frequency-doubled laser is 532 nanometers, and the pulse width of the frequency-doubled laser is 100 picoseconds to 500 picoseconds. The wavelength range of the optical parametric laser is 760 nm to 810 nm, and the pulse width of the optical parametric laser is 100 picoseconds to 500 picoseconds.

3. The picosecond laser as described in claim 1, characterized in that, The first beam splitter is coated with a high-transmittance film for the fundamental frequency laser and a high-reflectance film for the frequency-doubled laser, which is used to provide reflection conditions for the oscillation of the frequency-doubled laser in the second laser resonant cavity without affecting the oscillation of the fundamental frequency laser in the first laser resonant cavity; The second beam splitter is coated with a high-transmittance film for the frequency-doubled laser and a high-reflectance film for the optical parametric laser, which provides reflection conditions for the optical parametric laser to oscillate in the third laser resonant cavity without affecting the oscillation of the frequency-doubled laser in the second laser resonant cavity.

4. The picosecond laser as described in claim 1, characterized in that, The first A high-reflectivity mirror is coated with a high-reflectivity film for the fundamental frequency laser, which is used to provide reflection conditions for the fundamental frequency laser to oscillate in the first laser resonant cavity; The first B high-reflectivity mirror is coated with a high-reflectivity film for the fundamental frequency laser, which is used to provide reflection conditions for the fundamental frequency laser to oscillate in the first laser resonant cavity; the first B high-reflectivity mirror is coated with a high-reflectivity film for the frequency-doubled laser, which is used to provide reflection conditions for the frequency-doubled laser to oscillate in the second laser resonant cavity; The second A high-reflectivity mirror is coated with a high-reflectivity film for the frequency-doubled laser, which is used to provide reflection conditions for the frequency-doubled laser to oscillate in the second laser resonant cavity; The second B high-reflectivity mirror is coated with a high-reflectivity film for the frequency-doubled laser, which is used to provide reflection conditions for the frequency-doubled laser to oscillate in the second laser resonant cavity; the second B high-reflectivity mirror is coated with a high-reflectivity film for the optical parametric laser, which is used to provide reflection conditions for the optical parametric laser to oscillate in the third laser resonant cavity. The third A high-reflectivity mirror is coated with a high-reflectivity film for the optical parametric laser, which is used to provide reflection conditions for the optical parametric laser to oscillate in the third laser resonant cavity; The third B high-reflectivity mirror is coated with a high-reflectivity film for the optical parametric laser, which provides reflection conditions for the optical parametric laser to oscillate in the third laser resonant cavity, and together with the F polarizer and N photoelectric crystal, achieves coupled output of optical parametric picosecond laser.

5. The picosecond laser as described in claim 1, characterized in that, The first high-reflection mirror A and the first high-reflection mirror B are arranged perpendicularly to each other; The first A high-reflection mirror, the first B high-reflection mirror, the second B high-reflection mirror, and the third B high-reflection mirror are all set perpendicular to their respective optical axes; The first B high-reflection mirror, the second B high-reflection mirror, and the third B high-reflection mirror are arranged in parallel. The second A-high reflective mirror, the third A-high reflective mirror, the frequency doubling high reflective mirror, the E-polarizer, and the optical parametric high reflective mirror are arranged in parallel. The first beam splitter, the second beam splitter, the F polarizer, and the fundamental frequency high-reflection mirror are arranged in parallel.

6. The picosecond laser as described in claim 1, characterized in that, Also includes: A quarter-wave plate is disposed between the M electro-optic crystal and the E polarizer within the first laser resonant cavity.

7. The picosecond laser as described in claim 1, characterized in that, Also includes: A high-speed photoelectric probe is disposed behind the third B high-reflection mirror and is used to detect the transmitted light of the third B high-reflection mirror in real time and convert the transmitted light into an electrical signal. An oscilloscope, connected to the high-speed photoelectric probe, is used to receive and display the electrical signals converted by the high-speed photoelectric probe; A controller, connected to the oscilloscope, is used to control the N-electro-optic crystal when the electrical signal displayed on the oscilloscope reaches a preset value.

8. The picosecond laser as described in claim 1, characterized in that, The frequency doubling crystal is an LBO crystal or a KTP crystal; The optical parametric crystal is an LBO crystal, BBO crystal, KTP crystal, or KTA crystal.

9. The picosecond laser as described in claim 1, characterized in that, The optical cavity lengths of the first laser resonant cavity, the second laser resonant cavity, and the third laser resonant cavity are equal.

10. A medical device for skin treatment, characterized in that, Includes the picosecond laser according to any one of claims 1 to 9.

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