Pulse compression system and method based on hollow-core anti-resonance optical fiber

Abstract

The invention relates to the technical field of femtosecond laser, and discloses a pulse compression system and method based on a hollow-core anti-resonance optical fiber, and the system comprises a laser input device, the hollow-core anti-resonance optical fiber, and a collimating lens. The laser input device comprises a laser light source, a coupling device and a focusing lens; the laser light source, the coupling device, the focusing lens, the hollow-core anti-resonance optical fiber and the collimating lens are arranged in sequence; the axis of the focusing lens, the axis of the hollow-core anti-resonance optical fiber and the axis of the collimating lens coincide. According to the invention, the problems of complex compression process and low efficiency in the prior art are solved, and the pulse output quality can be improved.

Description

Technical Field

[0001] The present invention relates to the field of ultrafast laser technology, and more specifically, to a pulse compression system and method based on hollow-core anti-resonant optical fiber. Background Art

[0002] Ultrafast laser refers to the ultrashort pulses that output picoseconds or even femtoseconds. In real life, it is widely used in precision measurement, medical imaging, material processing and other fields. The peak power of ultrashort pulses directly generated by current mode-locked lasers is still insufficient to meet the needs of certain high-precision and high-intensity applications. Pulse compression technology is an effective means to solve this problem. Pulse compression technology can compress the output pulse width to a few hundred femtoseconds or even tens of femtoseconds, significantly improving the peak power of the pulse. Introducing an element with opposite dispersion to the mode-locked laser at the output end of the mode-locked laser can compress the pulse to a pulse width close to the limit of variation. Pulse compression technology occupies an important position in the generation of ultrashort pulses, greatly promoting research progress and technological applications in related fields. In previous studies, pulse compression technology mainly relied on a pair of simple grating pairs for compression, and dispersion compensation for the output pulses was performed to obtain ultrashort pulses. Hollow-core antiresonant fiber has been widely used in various industries recently due to its ultra-low nonlinearity and excellent transmission performance. In recent years, with the in-depth study of hollow-core antiresonant fiber, researchers have used the ultra-low nonlinearity of hollow-core antiresonant fiber to achieve various functions. At present, hollow-core optical fibers include hollow-core photonic bandgap fiber and hollow-core antiresonant fiber. Hollow-core antiresonant fiber has the advantages of low loss, wide working band window, single-mode transmission supporting large mode field, and low nonlinear coefficient. Its nonlinearity is one thousandth of that of solid-core quartz fiber. Pulse compression based on hollow-core antiresonant fiber can achieve efficient compression of pulses without changing the spectral characteristics of pulses. Using hollow-core antiresonant fiber to compress pulses has the potential to achieve high peak power femtosecond pulses, and there is a huge application demand for obtaining narrower pulse widths.

[0003] The prior art has a wavelength-stable semiconductor laser, which includes a semiconductor laser chip; a cylindrical lens is placed behind the semiconductor laser chip to perform fast-axis compression on the emitted light spot; a volume Bragg grating (VBG) and the rear cavity surface of the semiconductor laser chip together constitute an external cavity resonant cavity to achieve a narrow spectral width and stable wavelength laser output; a focusing lens focuses the output stable wavelength laser into an optical fiber pigtail to achieve the pigtail output of the laser.

[0004] However, the existing technology has problems such as complex compression process and low efficiency. Therefore, how to invent an efficient pulse compression system based on hollow-core antiresonant optical fiber is a technical problem that urgently needs to be solved in this technical field. Summary of the invention

[0005] In order to solve the problems of complex compression process and low efficiency in the prior art, the present invention provides a pulse compression system and method based on hollow-core antiresonant optical fiber, which has the characteristic of being able to improve the quality of pulse output.

[0006] In order to achieve the above-mentioned purpose of the present invention, the technical scheme adopted is as follows: A pulse compression system based on hollow-core anti-resonance fiber comprises a laser input device, a hollow-core anti-resonance fiber and a collimating lens; the laser input device comprises a laser light source, a coupling device and a focusing lens; the laser light source, the coupling device, the focusing lens, the hollow-core anti-resonance fiber and the collimating lens are arranged in sequence; the axes of the focusing lens, the hollow-core anti-resonance fiber and the collimating lens coincide.

[0007] Preferably, the coupling device comprises a first reflector, a second reflector, a first lens, and a second lens which are arranged in sequence.

[0008] Furthermore, the positions and angles of the first reflector and the second reflector are adjustable, and the second reflector is coaxial with the first reflector.

[0009] Furthermore, the first lens and the second lens are coaxial, and the positions and the distance between the first lens and the second lens are adjustable.

[0010] Furthermore, the light path output by the second lens is located at the center of the focusing lens, and the focus of the focusing lens is located at the incident end of the hollow-core anti-resonant optical fiber.

[0011] Furthermore, the focus of the collimating lens is located at the output end face of the hollow-core anti-resonant optical fiber.

[0012] A pulse compression method based on hollow core antiresonant optical fiber comprises the following specific steps: The hollow-core anti-resonant optical fiber-based pulse compression system is used to emit laser light through its laser light source; coupling the laser beam into a coupling device; The coupled laser beam is coupled into a hollow-core anti-resonant optical fiber through a focusing lens for transmission; The output light beam of the hollow core anti-resonance optical fiber is collimated by a focusing lens and then injected into the subsequent monitoring device.

[0013] Preferably, after the laser is input into the coupling device, it passes through the telescope system composed of the first lens and the second lens in sequence, and then passes through the focusing lens to couple the light into the hollow-core anti-resonant optical fiber.

[0014] Furthermore, the laser light source is an ultrashort pulse laser light source.

[0015] Furthermore, when the laser beam is coupled through the coupling device, the adjustment method includes coarse adjustment of the optical path and fine adjustment of the optical path.

[0016] The beneficial effects of the present invention are as follows: A pulse compression system based on hollow-core antiresonant fiber is proposed; the pulse compression system couples the laser into the hollow-core antiresonant fiber in the form of spatial light through a lens with extremely high coupling efficiency for transmission; since the nonlinear effect of the hollow-core antiresonant fiber has very little effect on the pulse and carries negative dispersion, during the transmission of the pulse in the hollow-core antiresonant fiber, the positive dispersion carried by the pulse will be compensated by the negative dispersion in the hollow-core antiresonant fiber, making the output pulse close to chirp-free, achieving the effect of compressed pulse. Therefore, the present invention provides a pulse evolution technology based on hollow-core fiber, which uses hollow-core fiber as a medium for pulse compression, and can obtain better results than using gratings for compressing pulse quality. The pulse compression technology relying on this hollow-core fiber as a pulse compression medium can solve the problems of complex compression process and low efficiency in the prior art, and achieve a high-quality pulse output with a pulse width of tens of femtoseconds. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of a pulse compression system based on hollow-core antiresonant optical fiber according to an embodiment of the present invention.

[0018] Figure 2 It is a schematic flow chart of a pulse compression method based on hollow-core antiresonant optical fiber according to an embodiment of the present invention.

[0019] Figure 3 1 is a diagram of laser pulses incident on a hollow-core antiresonant optical fiber according to an embodiment of the present invention.

[0020] Figure 4 1 is a diagram of laser pulses emitted from a hollow-core antiresonant optical fiber according to an embodiment of the present invention.

[0021] Among them, 1-laser light source, 2-first reflector, 3-second reflector, 4-first lens, 5- The second lens, 6-focusing lens, 7-hollow core antiresonant optical fiber, 8-collimating lens, 9-monitoring device. DETAILED DESCRIPTION

[0022] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0023] In the description of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0024] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] Furthermore, in the description of the present invention, unless otherwise specified, “plurality” means two or more.

[0026] Example 1 like Figure 1 As shown, a pulse compression system based on hollow-core anti-resonant fiber is characterized in that: it includes a laser input device, a hollow-core anti-resonant fiber 7, and a collimating lens 8; the laser input device includes a laser light source 1, a coupling device and a focusing lens 6; the laser light source 1, the coupling device, the focusing lens 6, the hollow-core anti-resonant fiber 7, and the collimating lens 8 are arranged in sequence; the axis of the focusing lens 6, the hollow-core anti-resonant fiber 7, and the collimating lens 8 coincide.

[0027] In this embodiment, the laser is coupled into the hollow core anti-resonance fiber 7 for transmission, and the coupling efficiency can be greater than 90%. In addition, since the nonlinear coefficient of the hollow core anti-resonance fiber 7 is extremely low, the influence of the nonlinear effect on the pulse during the transmission process can be ignored.

[0028] In a specific embodiment, the coupling device includes a first reflector 2, a second reflector 3, a first lens 4, and a second lens 5 which are arranged in sequence.

[0029] In a specific embodiment, the positions and angles of the first reflector 2 and the second reflector 3 are adjustable, and the second reflector 3 is coaxial with the first reflector 2 .

[0030] In a specific embodiment, the first lens 3 is coaxial with the second lens 4, and the position and spacing of the first lens 3 and the second lens 4 are adjustable. By adjusting the distance, the spot diameter can be effectively controlled to better achieve mode field matching with the hollow-core antiresonant optical fiber, thereby reducing the loss, and the coupling can reach more than 90%.

[0031] In a specific embodiment, the optical path output by the second lens 5 is located at the center of the focusing lens 6 , and the focus of the focusing lens 6 is located at the incident end of the hollow-core anti-resonant optical fiber 7 .

[0032] In a specific embodiment, the focus of the collimating lens 6 is located at the output end face of the hollow-core anti-resonant fiber 7, so that the laser beam can accurately pass through the center of the first lens 4 and be coaxial with the second lens 5, the focusing lens 6, the hollow-core anti-resonant fiber 7, and the collimating lens 8 to achieve higher coupling efficiency.

[0033] The present invention provides a pulse compression system based on hollow-core anti-resonant fiber, which solves the problems of low pulse compression efficiency and inability to achieve flexible transmission of existing femtosecond lasers. The system includes a laser input device, a hollow-core anti-resonant fiber 7, and a collimating lens 9, which are arranged from left to right in sequence; the laser input device includes a laser light source 1, a coupling device, and a focusing lens 6, and the laser beam passes through the focusing lens 6 after passing through the coupling device; the axis of the focusing lens 6 coincides with the axis of the hollow-core anti-resonant fiber 7. By coupling the pulse light into the hollow-core anti-resonant fiber 7 for transmission, the negative dispersion of the hollow-core fiber is used to compensate for the positive chirp of the input pulse light, thereby achieving pulse width narrowing. When the negative dispersion provided by the hollow-core fiber of a specific length can just compensate for the positive chirp of the input pulse, the pulse width is minimized, thereby achieving pulse compression.

[0034] Example 2 like Figure 2 As shown, a pulse compression method based on hollow core antiresonant fiber includes the following specific steps: The hollow-core anti-resonant optical fiber-based pulse compression system is used to emit laser light through its laser light source 1; coupling the laser beam into a coupling device; The coupled laser beam is coupled to the hollow core anti-resonant optical fiber 7 through the focusing lens 6 for transmission; The output light beam of the hollow core anti-resonance optical fiber 7 is collimated by the focusing lens 6 and then injected into the subsequent monitoring device 9 .

[0035] In a specific embodiment, after the laser is input into the coupling device, it passes through the telescope system composed of the first lens 4 and the second lens 5 in sequence, and then passes through the focusing lens 6 to couple the light into the hollow core anti-resonant optical fiber 7.

[0036] In a specific embodiment, the laser light source 1 is an ultrashort pulse laser light source.

[0037] In a specific embodiment, when the laser beam is coupled through a coupling device, the adjustment method includes coarse adjustment of the optical path and fine adjustment of the optical path.

[0038] In this embodiment, the light path emitted from the laser incident end 1 is first aligned with the center of the first lens 4 through the first reflector 2 and the second reflector 3, and the light path is magnified or reduced through the telescope system composed of the first lens 4 and the second lens 5, so as to achieve mode field matching with the hollow-core anti-resonant optical fiber 7 and reduce loss. The output light is incident on the center of the focusing lens 6, and the laser is coupled into the hollow-core anti-resonant optical fiber 7, with high coupling efficiency and no influence of nonlinear effects.

[0039] Example 3 In this embodiment, a laser emission experiment was carried out using the pulse compression system based on hollow-core anti-resonant optical fiber of the present invention.

[0040] In the experiment, a pulse compression system based on hollow-core antiresonant fiber proposed by the present invention is used. By coupling the laser into the antiresonant hollow-core fiber 7, the ultra-low nonlinear coefficient of the hollow-core antiresonant fiber 7 is utilized. The nonlinear effect of the pulse transmission in the hollow-core antiresonant fiber 7 is extremely weak, and the hollow-core antiresonant fiber 7 carries negative dispersion, which effectively compresses the pulse. Compared with the traditional method of using a grating pair, using the hollow-core fiber 7 to compress the output pulse of the mode-locked laser can achieve higher compression efficiency and simplify the compression device, such as Figure 3 and Figure 4 As shown, Figure 3 is the original input autocorrelation curve, the pulse width is 1.74ps, Figure 4 This is the autocorrelation curve of the hollow-core antiresonant fiber, and the pulse width is 65.7fs. The pulse compression system based on the hollow-core antiresonant fiber is conducive to the realization of an all-fiber integrated pulse compression device, and has very good application prospects in industrial, medical, commercial, optical communications and military applications.

[0041] Obviously, the above embodiments of the present invention are only examples for clearly explaining the present invention, and are not intended to limit the implementation methods of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A pulse compression system based on hollow core antiresonant fiber, characterized in that: The invention comprises a laser input device, a hollow core anti-resonance optical fiber (7), and a collimating lens (8); the laser input device comprises a laser light source (1), a coupling device, and a focusing lens (6); the laser light source (1), the coupling device, the focusing lens (6), the hollow core anti-resonance optical fiber (7), and the collimating lens (8) are arranged in sequence; and the axes of the focusing lens (6), the hollow core anti-resonance optical fiber (7), and the collimating lens (8) coincide with each other.

2. The pulse compression system based on hollow core antiresonant fiber according to claim 1, characterized in that: The coupling device comprises a first reflector (2), a second reflector (3), a first lens (4), and a second lens (5) which are arranged in sequence.

3. The pulse compression system based on hollow core antiresonant fiber according to claim 2, characterized in that: The positions and angles of the first reflector (2) and the second reflector (3) are adjustable, and the second reflector (3) is coaxial with the first reflector (2).

4. The pulse compression system based on hollow core antiresonant fiber according to claim 2, characterized in that: The first lens (3) and the second lens (4) are coaxial, and the positions and spacings between the first lens (3) and the second lens (4) are adjustable.

5. The pulse compression system based on hollow core antiresonant fiber according to claim 2, characterized in that: The light path output by the second lens (5) is located at the center of the focusing lens (6), and the focus of the focusing lens (6) is located at the incident end of the hollow-core anti-resonance optical fiber (7).

6. The pulse compression system based on hollow core antiresonant fiber according to claim 1, characterized in that: The focal point of the collimating lens (6) is located at the output end face of the hollow-core anti-resonance optical fiber (7).

7. A pulse compression method based on hollow core antiresonant fiber, characterized in that: The specific steps include: A pulse compression system based on hollow-core antiresonant optical fiber as claimed in any one of claims 1 to 6 is used, wherein a laser light source (1) thereof emits laser light; coupling the laser beam into a coupling device; The coupled laser beam is coupled to a hollow core anti-resonance optical fiber (7) through a focusing lens (6) for transmission; The output light beam of the hollow core anti-resonance optical fiber (7) is collimated by a focusing lens (6) and then injected into a subsequent monitoring device (9).

8. The pulse compression method based on hollow core antiresonant fiber according to claim 7, characterized in that: After the laser is input into the coupling device, it passes through the telescope system composed of the first lens (4) and the second lens (5) in sequence, and then passes through the focusing lens (6) to couple the light into the hollow core anti-resonance optical fiber (7).

9. The pulse compression method based on hollow core antiresonant fiber according to claim 7, characterized in that: The laser light source (1) is an ultrashort pulse laser light source.

10. The pulse compression method based on hollow core antiresonant fiber according to claim 7, characterized in that: When the laser beam is coupled through a coupling device, the adjustment method includes coarse adjustment of the optical path and fine adjustment of the optical path.

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