Picosecond seed source and laser

Abstract

The utility model relates to a picosecond seed source and a laser. The picosecond seed source comprises a pumping source, a short optical fiber, a bonding crystal and a refrigerator. The pumping source is used for outputting pumping light; the short optical fiber is used for transmitting pump light; the bonding crystal is used for receiving the pump light transmitted through the short optical fiber and outputting picosecond laser pulses with the pulse width of 250-900 picoseconds; the refrigerator comprises a water-cooling bottom plate and two thermoelectric refrigeration sheets, the two thermoelectric refrigeration sheets are arranged below the pumping source and the bonding crystal respectively and used for controlling the temperature of the pumping source and the bonding crystal respectively, the water-cooling bottom plate is arranged at the bottoms of the two thermoelectric refrigeration sheets, and a water-cooling channel is formed in the water-cooling bottom plate and used for cooling the thermoelectric refrigeration sheets through circulating cooling water.

Description

Technical Field

[0001] The utility model relates to the technical field of picosecond lasers, in particular to a picosecond seed source and a laser. Background Art

[0002] Picosecond lasers, due to their ultrashort pulses and extremely high peak power, are widely used in the medical aesthetics industry, particularly in treating various skin types and tattoo removal. The core component of a picosecond laser is the picosecond seed source, which is amplified to produce high-energy, ultrashort picosecond laser pulses.

[0003] Traditional picosecond lasers utilize a seed-source amplification scheme, typically employing passive Q-switching, where the pump light is transmitted via optical fiber to the laser crystal. This approach is capable of generating the required ultrashort pulses and high-energy output needed to meet the demands of the medical aesthetics industry. However, the long optical fiber transmission used in conventional seed-source schemes presents a significant technical drawback: the long fiber can cause changes in the laser's polarization state, which can affect the laser's performance and stability, thereby compromising the therapeutic effect.

[0004] Furthermore, existing seed source solutions still face technical challenges in achieving ultra-narrow pulse widths (e.g., in the range of 250-900 picoseconds). Achieving narrower pulse widths while maintaining high energy output has become a pressing technical challenge. Utility Model Content

[0005] The utility model discloses a picosecond seed source and a laser, aiming to solve the technical problems existing in the prior art.

[0006] The utility model adopts the following technical solutions:

[0007] In one embodiment of the present invention, a picosecond seed source is provided, comprising a pump source, a short optical fiber, a bonded crystal, and a refrigerator;

[0008] The pump source is used to output pump light;

[0009] A short optical fiber is used to transmit the pump light;

[0010] The bonded crystal is used to receive pump light transmitted through a short optical fiber and output picosecond laser pulses with a pulse width of 250 to 900 picoseconds;

[0011] The cooler includes a water-cooled base plate and two thermoelectric cooling plates. The two thermoelectric cooling plates are respectively arranged below the pump source and the bonded crystal, and are used to control the temperature of the pump source and the bonded crystal respectively. The water-cooled base plate is arranged at the bottom of the two thermoelectric cooling plates, and a water cooling channel is provided inside for dissipating heat to the thermoelectric cooling plates through circulating cooling water.

[0012] As a preferred technical solution, the pump source is used to output pulsed pump light with a wavelength of 808 nm.

[0013] As a preferred technical solution, the pump source is configured as multiple single-tube semiconductor lasers or bar semiconductor lasers.

[0014] As a preferred technical solution, the length of the short optical fiber is configured to be 20-60 mm, the core diameter is no more than 400 μm, and the distance between the output end of the short optical fiber and the bonded crystal is less than 1 mm.

[0015] As a preferred technical solution, the short optical fiber is configured as a polygonal core structure.

[0016] As a preferred technical solution, the bonded crystals include Nd:YAG crystals and Cr:YAG crystals, which are used to output picosecond laser pulses with an energy of 0.3-1 mJ, a wavelength of 1064 nm, and a pulse width of 250-900 picoseconds.

[0017] As an optimal technical solution, it also includes a crystal fixture for fixing the bonded crystal, the crystal fixture includes an upper cover plate and a lower base, both the upper cover plate and the lower base are V-shaped structures, and the bonded crystal is placed obliquely in a V shape between the upper cover plate and the lower base.

[0018] As a preferred technical solution, the two lower side surfaces of the bonded crystal are bonded to the lower base by thermally conductive adhesive, and a gap is provided between the two upper side surfaces of the bonded crystal and the upper cover plate;

[0019] The length of the crystal holder is greater than the length of the bonded crystal, so that the bonded crystal is recessed in the crystal holder.

[0020] As a preferred technical solution, a copper base is provided between the crystal fixture and the thermoelectric cooling plate, and between the pump source and the thermoelectric cooling plate, and indium foil is provided on the top and bottom surfaces of the thermoelectric cooling plate.

[0021] In another embodiment of the present invention, a laser is provided. The laser includes the picosecond seed source as described in any one of the above items.

[0022] One embodiment of the above utility model has the following advantages or beneficial effects:

[0023] The utility model mainly provides a picosecond seed source and a laser containing the seed source. The aforementioned picosecond seed light adopts a short optical fiber transmission design, which effectively solves the problem of laser polarization state change caused by long optical fiber transmission. By using a short optical fiber with a length of 20-60mm and a core diameter of no more than 400μm, it not only ensures that the polarization state of 808nm light will not change after passing through the optical fiber, but also ensures the divergence angle of the 808nm laser and homogenizes the beam quality. This design greatly improves the stability and consistency of the laser output, providing a more reliable light source for subsequent applications.

[0024] Secondly, the picosecond seed source achieves ultra-narrow pulse width output, capable of generating laser pulses in the range of 250-900 picoseconds, and can achieve any pulse width of 250-500 picoseconds by controlling the crystal length. This ultra-narrow pulse width characteristic gives the laser a wider application prospect in fields such as medical beauty, and can more effectively treat various skin types and tattoo colors, thereby improving treatment effects.

[0025] Furthermore, the picosecond seed source uses a cooling system that combines a water-cooled base plate and a thermoelectric refrigeration plate to control the temperature of the pump source and the bonded crystal respectively, ensuring the stable operation of the entire system. In particular, the V-shaped mounting structure of the bonded crystal and the fixture that matches it not only ensure that the polarization state of the output laser is linear polarization, but also avoid the influence of clamping stress on the crystal, while facilitating constant temperature heat conduction. This temperature control design greatly improves the reliability and service life of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments, which constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0027] Figure 1 This is a schematic structural diagram of a picosecond seed source in a preferred embodiment disclosed in the present utility model;

[0028] Figure 2 This is a front view of a picosecond seed source in a preferred embodiment disclosed in an embodiment of the present utility model;

[0029] Figure 3 A top view of a picosecond seed source in a preferred embodiment disclosed in an embodiment of the present utility model;

[0030] Figure 4 This is a right view of a picosecond seed source in a preferred embodiment disclosed in the embodiment of the present utility model;

[0031] Figure 5 This is a schematic structural diagram of a crystal holder in a preferred embodiment disclosed in the present utility model.

[0032] Description of reference numerals:

[0033] Pump source 10 , short optical fiber 20 , bonded crystal 30 , crystal holder 40 , upper cover 41 , lower base 42 , refrigerator 50 , water-cooled base plate 51 , copper base 52 , thermoelectric cooling sheet 53 . DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the present invention more clear, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. In the description of the present invention, it should be noted that the term "or" is generally used in the sense of including "and / or" unless the content clearly indicates otherwise.

[0035] Obviously, the embodiments described are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] refer to Figures 1 to 5 In order to solve the defects of the existing long optical fiber transmission scheme in the laser, the embodiment of the present invention provides a picosecond seed source, including a refrigerator 50 and a pump source 10, a short optical fiber 20 and a bonded crystal 30 arranged in sequence above the refrigerator 50, wherein the pump source 10 is used to output pump light, the short optical fiber 20 is used to transmit the pump light, and the bonded crystal 30 is used to receive the pump light transmitted through the short optical fiber 20 and output picosecond laser pulses with a pulse width of 250 to 900 ps. The refrigerator 50 is used to control the temperature of the pump source 10 and the bonded crystal 30 to ensure normal heat dissipation of the seed source.

[0037] In a preferred embodiment, the pump source 10 is configured as a multi-single-tube semiconductor laser or a bar semiconductor laser, capable of outputting pulsed pump light with a wavelength of 808 nm.

[0038] In a preferred embodiment, the short optical fiber 20 is configured as a short optical fiber with a polygonal core structure with a length of 20-60 mm, and its length is more preferably 40 mm, which can ensure sufficient light transmission and homogenization effect without introducing the polarization state change problem that may be caused by a long optical fiber; the step optical fiber is transmitted to the bonded crystal 30, and the distance between the output end of the short optical fiber 20 and the bonded crystal 30 is less than 1 mm, and the core diameter of the short optical fiber 20 is not greater than 400 μm, so as to ensure a smaller pump light spot incident on the bonded crystal 30, without the need for a coupling lens, simplifying the overall structure, and reducing cost and complexity.

[0039] The short optical fiber 20 ensures that the polarization state of the 808nm pump light does not change after passing through the optical fiber. It also ensures the divergence angle of the 808nm laser and homogenizes the beam quality, which helps to improve the pumping efficiency and the spatial uniformity of the laser output.

[0040] In a preferred embodiment, both ends of the short optical fiber 20 are provided with SMA connectors. The SMA connectors have good mechanical stability and repeatability, are easy to install with the output port of the pump source 10 , and are beneficial to the maintenance and replacement of the short optical fiber 20 .

[0041] In a preferred embodiment, the bonded crystal 30 includes a Nd:YAG crystal and a Cr:YAG crystal, and is used to output picosecond laser pulses with an energy of 0.3-1 mJ, a wavelength of 1064 nm, and a pulse width of 250-900 ps.

[0042] Specifically, the Nd:YAG crystal serves as a gain medium, capable of providing 1064nm laser output; while the Cr:YAG crystal acts as a saturable absorber, enabling passive Q-switching without the need for additional Q-switching devices. Optionally, the total length of the bonded crystal 30 is configured to be (3.25±1)+(2.5±0.5)mm. The lengths of the Nd:YAG and Cr:YAG crystals can be fine-tuned based on specific needs. By controlling the crystal length, particularly the length of the Cr:YAG crystal, any pulse width output within the range of 250-900ps can be achieved, allowing the seed source to adapt to different application requirements.

[0043] In a preferred embodiment, the bonded crystal 30 is placed in a crystal holder 40, such as Figure 2 and Figure 5 The crystal fixture 40 includes an upper cover plate 41 and a lower base 42, both of which are made of copper. The upper cover plate 41 can be removed to facilitate inspection or replacement of the bonded crystal 30; the upper cover plate 41 and the lower base 42 are both V-shaped structures, and the angle of the V-shaped structure is preferably 45°. The V-shaped structure provides a larger contact area, which is conducive to heat conduction between the bonded crystal 30 and the crystal fixture 40, and the V-shaped structure allows the bonded crystal 30 to have a certain degree of freedom in the crystal fixture 40, which can reduce the stress caused by thermal expansion or mechanical pressure.

[0044] Preferably, the bonded crystal 30 is placed in a V-shape between the upper cover plate 41 and the lower base 42 so that the laser can maintain a stable polarization direction when propagating in the bonded crystal 30, ensuring that the polarization state of the output laser is linear polarization.

[0045] In a preferred embodiment, the two lower side surfaces of the bonded crystal 30 are bonded to the lower base 42 by thermal conductive adhesive to provide stable mechanical support and a good heat conduction path. The thermal conductive adhesive can not only fix the bonded crystal 30, but also fill the gap between the bonded crystal 30 and the lower base 42 to improve the heat conduction efficiency.

[0046] In a preferred embodiment, a gap is provided between the upper two side surfaces of the bonded crystal 30 and the upper cover plate 41, such as Figure 2, which prevents the upper cover plate 41 from directly contacting the bonded crystal 30, reduces stress that may be caused by thermal expansion or mechanical pressure, and provides a certain expansion space for the bonded crystal 30 to reduce the impact of thermal stress.

[0047] In a preferred embodiment, the length of the crystal holder 40 is greater than the length of the bonded crystal 30, so that the bonded crystal 30 is recessed in the crystal holder 40. The two have a larger contact area, creating a more uniform temperature environment, which helps to reduce the temperature gradient inside the bonded crystal 30 and improve the stability of the laser output. At the same time, it also provides a certain degree of heat shielding for the bonded crystal 30, reducing the impact of external temperature fluctuations on the crystal.

[0048] refer to Figure 2 — Figure 4 In a preferred embodiment, the refrigerator 50 includes a water-cooled base plate 51, two copper bases 52, and two thermoelectric cooling sheets 53 (i.e., TECs). The two copper bases 52 are respectively disposed between the crystal fixture 40 and the thermoelectric cooling sheets 53, and between the pump source 10 and the thermoelectric cooling sheets 53. The two thermoelectric cooling sheets 53 are respectively disposed below the two copper bases 52 to control the temperature of the pump source 10 and the bonded crystal 30, respectively, to ensure that both operate within the optimal operating range. Copper has excellent thermal conductivity, which can ensure that heat is quickly and evenly transferred from the bonding fixture and pump source 10 to the thermoelectric cooling sheets 53. The water-cooled base plate 51 is disposed at the bottom of the two thermoelectric cooling sheets 53 and is internally provided with a water cooling channel. The circulating cooling water can effectively remove the heat generated by the thermoelectric cooling sheets 53, ensuring the cooling efficiency of the thermoelectric cooling sheets 53.

[0049] Preferably, the top and bottom surfaces of the two thermoelectric cooling sheets 53 are both provided with indium foil. Indium foil has excellent thermal conductivity and good plasticity, and can fill the tiny gaps on the contact surface to increase the area and efficiency of heat conduction.

[0050] In a preferred embodiment, the pump source 10 and bonded crystal 30 are also equipped with a temperature sensor, such as a thermistor, for real-time monitoring of the operating temperature of the pump source 10 and bonded crystal 30. The temperature sensor can be mounted on the copper base 52 and connected to the temperature control circuit board of the refrigerator 50, forming a closed-loop control system to ensure that the pump source 10 and bonded crystal 30 operate within the optimal operating temperature range, thereby ensuring the stable operation of the entire picosecond seed source.

[0051] In another embodiment of the present invention, a picosecond laser is provided. The picosecond laser is provided with the picosecond seed source described in the above embodiment.

[0052] Although example embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above example embodiments are merely illustrative and are not intended to limit the scope of the present application. Various changes and modifications may be made therein by those skilled in the art without departing from the scope and spirit of the present application. All such changes and modifications are intended to be included within the scope of the present application as required by the appended claims.

[0053] In the description provided herein, a large number of specific details are described. However, it is understood that the embodiments of the present application can be practiced without these specific details. In some instances, well-known methods, structures, and techniques are not shown in detail so as not to obscure the understanding of this description.

[0054] Similarly, it should be understood that in order to streamline the present application and aid in understanding one or more of the various utility model aspects, in the description of the exemplary embodiments of the present application, the various features of the present application are sometimes grouped together into a single embodiment, figure, or description thereof. However, this method of the present application should not be interpreted as reflecting the following intention: that the application claimed for protection requires more features than the features explicitly recited in each claim. More precisely, as reflected in the corresponding claims, its utility model point is that the corresponding technical problem can be solved with features that are less than all the features of a single disclosed embodiment. Therefore, the claims following the specific embodiment are hereby expressly incorporated into the specific embodiment, with each claim itself serving as a separate embodiment of the present application.

[0055] Those skilled in the art will understand that, except where mutually exclusive, all features disclosed in this specification (including the accompanying claims, abstract, and drawings) and all processes or units of any method or apparatus disclosed herein may be combined in any combination. Unless expressly stated otherwise, each feature disclosed in this specification (including the accompanying claims, abstract, and drawings) may be replaced by an alternative feature that provides the same, equivalent, or similar purpose.

Claims

1. A picosecond seed source, characterized in that: Including pump source, short optical fiber, bonded crystal and cooler; The pump source is used to output pump light; The short optical fiber is used to transmit pump light; The bonded crystal is used to receive the pump light transmitted through the short optical fiber and output picosecond laser pulses with a pulse width of 250 to 900 picoseconds; The refrigerator includes a water-cooled base plate and two thermoelectric cooling plates. The two thermoelectric cooling plates are respectively arranged below the pump source and the bonded crystal, and are used to control the temperature of the pump source and the bonded crystal respectively. The water-cooled base plate is arranged at the bottom of the two thermoelectric cooling plates, and is provided with a water cooling channel inside for dissipating heat to the thermoelectric cooling plates through circulating cooling water.

2. The picosecond seed source according to claim 1, characterized in that: The pump source is used to output pulsed pump light with a wavelength of 808 nm.

3. The picosecond seed source according to claim 2, characterized in that: The pump source is configured as multiple single-tube semiconductor lasers or bar semiconductor lasers.

4. The picosecond seed source according to claim 1, characterized in that: The length of the short optical fiber is configured to be 20-60 mm, the core diameter is no more than 400 μm, and the distance between the output end of the short optical fiber and the bonded crystal is less than 1 mm.

5. The picosecond seed source according to claim 4, characterized in that: The optical fiber stub is configured as a polygonal core structure.

6. The picosecond seed source according to claim 1, characterized in that: The bonded crystals include Nd:YAG crystals and Cr:YAG crystals, and are used to output picosecond laser pulses with an energy of 0.3-1 mJ, a wavelength of 1064 nm, and a pulse width of 250-900 picoseconds.

7. The picosecond seed source according to claim 6, characterized in that: It also includes a crystal fixture for fixing the bonded crystal, the crystal fixture includes an upper cover plate and a lower base, the upper cover plate and the lower base are both V-shaped structures, and the bonded crystal is placed obliquely in a V shape between the upper cover plate and the lower base.

8. The picosecond seed source according to claim 7, characterized in that: The two lower side surfaces of the bonded crystal are bonded to the lower base by heat-conducting adhesive, and a gap is provided between the two upper side surfaces of the bonded crystal and the upper cover plate; The length of the crystal holder is greater than the length of the bonded crystal, so that the bonded crystal is recessed in the crystal holder.

9. The picosecond seed source according to claim 7, characterized in that: A copper base is provided between the crystal fixture and the thermoelectric cooling plate, and between the pump source and the thermoelectric cooling plate. Indium foil is provided on the top and bottom surfaces of the thermoelectric cooling plate.

10. A laser, characterized in that: Comprising the picosecond seed source according to any one of claims 1 to 9.

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