A pulse compressor and a pulse compression method

Abstract

The application discloses a pulse compressor and a pulse compression method. The pulse compressor comprises: a grating, which is used for diffracting a stretched pulse incident on a first side of the grating to obtain first diffracted light and compensating second-order dispersion of the stretched pulse; a prism assembly, which is located on a second side of the grating and is used for refracting the first diffracted light to obtain refracted light and eliminating third-order dispersion of the stretched pulse while again compensating the second-order dispersion of the stretched pulse; a reflection assembly, which is used for reflecting the refracted light to obtain reflected light, and is used for diffracting the reflected light in the grating again after the reflected light is refracted in the prism assembly, to obtain second diffracted light parallel to the first side of the grating; and a first mirror, which is used for reflecting the second diffracted light to return and be parallel to the first diffracted light, so that the stretched pulse generates a doubled dispersion amount and the spot of the stretched pulse is restored to an initial state. According to the pulse compressor, the occupied space of the pulse compressor can be reduced, and the pulse compressor is easy to integrate.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of laser pulse processing, in particular to a pulse compressor and a pulse compression method. BACKGROUND

[0002] Chirped-pulse amplification (CPA) technology is the main method to realize ultra-short pulse and high peak power. In the traditional CPA working mode, a certain dispersion is usually introduced to the oscillator output ultra-short femtosecond pulse or picosecond pulse by using a stretcher before the input amplifier, so as to expand the pulse width in the time domain. In this way, the peak power is reduced, the risk of damage to related elements is reduced, and many adverse nonlinear effects such as gain saturation are avoided, which is beneficial to the efficient absorption of gain medium energy storage.

[0003] Since different frequencies of light usually bring positive dispersion after passing through the optical elements in the stretcher structure, negative second-order dispersion needs to be introduced in the pulse compressor for dispersion compensation, so as to realize pulse compression.

[0004] The common dispersion compensation method at present is to use the wavelength-dependent optical phenomena such as refraction, diffraction and interference to separate the components of different frequencies in the pulse, so that they propagate different optical paths, and negative dispersion is introduced by geometric means, for example, the grating pair structure used in the pulse compressor of the prior art, which is to add two symmetrical prisms (prism pair) between two symmetrical gratings (grating pair). But this structure needs to arrange the grating pair and the prism pair in turn, so that the optical path of the incident light is lengthened to facilitate better dispersion compensation. This way causes the optical path to occupy a large space in the pulse compressor, which is not easy to integrate in the pulse compressor. SUMMARY

[0005] The present application provides a pulse compressor and a pulse compression method, which reduces the occupied space of the pulse compressor and is easy to integrate.

[0006] In a first aspect, embodiments of the present application provide a pulse compressor, comprising: a grating configured to diffract a stretched pulse incident on a first side of the grating to obtain a first diffracted light and to compensate for second-order dispersion of the stretched pulse; a prism assembly located on a second side of the grating and configured to refract the first diffracted light to obtain a refracted light and to eliminate third-order dispersion of the stretched pulse while re-compensating for the second-order dispersion of the stretched pulse; a reflection assembly configured to reflect the refracted light to obtain a reflected light and to be incident into the prism assembly to be refracted again into the grating to obtain a second diffracted light parallel to the first side of the grating; and a first mirror configured to reflect the second diffracted light to return and be parallel to the first diffracted light, so as to generate a doubled dispersion amount of the stretched pulse and to restore a spot of the stretched pulse to an initial state.

[0007] According to any one of the foregoing embodiments of the first aspect of the present application, the prism assembly comprises a first dispersion prism configured to refract the first diffracted light and to refract the reflected light again, wherein the grating is configured to diffract the light incident multiple times to re-compensate for the second-order dispersion of the stretched pulse, and the first dispersion prism is configured to refract the light incident multiple times to eliminate the third-order dispersion of the stretched pulse while re-compensating for the second-order dispersion of the stretched pulse.

[0008] According to any one of the foregoing embodiments of the first aspect of the present application, the reflection assembly comprises a hollow ridge prism configured to reflect the refracted light twice to obtain the reflected light and to be incident into the first dispersion prism.

[0009] According to any one of the foregoing embodiments of the first aspect of the present application, the prism assembly comprises a second dispersion prism and a third dispersion prism, the second dispersion prism is configured to refract the first diffracted light, and the third dispersion prism is configured to refract the reflected light again, wherein the grating is configured to diffract the light incident multiple times to re-compensate for the second-order dispersion of the stretched pulse, and the second dispersion prism and the third dispersion prism are configured to refract the light incident multiple times to finally eliminate the third-order dispersion of the stretched pulse while re-compensating for the second-order dispersion of the stretched pulse.

[0010] According to any one of the foregoing embodiments of the first aspect of the present application, the reflection assembly comprises at least one second mirror, and the refracted light is reflected by the at least one second mirror to obtain the reflected light incident into the third dispersion prism.

[0011] According to any one of the foregoing embodiments of the first aspect of the present application, the pulse compressor further comprises at least one half-wave plate arranged on an optical path in the pulse compressor, and the half-wave plate is configured to change a polarization direction of the light passing through.

[0012] According to any one of the preceding embodiments of the first aspect of the present application, the at least one half-wave plate comprises a first half-wave plate located at the first side of the grating, the stretched pulse is incident on the grating after passing through the first half-wave plate, and the first half-wave plate is configured to adjust the stretched pulse into vertically polarized light.

[0013] According to any one of the preceding embodiments of the first aspect of the present application, the at least one half-wave plate comprises a second half-wave plate located between the grating and the prism assembly, the first diffracted light is incident on the prism assembly after passing through the second half-wave plate, and the second half-wave plate is configured to adjust the first diffracted light into horizontally polarized light.

[0014] According to any one of the preceding embodiments of the first aspect of the present application, the at least one half-wave plate comprises a third half-wave plate located between the prism assembly and the grating, the light ray refracted by the prism assembly again is incident on the grating after passing through the third half-wave plate, and the third half-wave plate is configured to adjust the light ray passing through into vertically polarized light.

[0015] According to any one of the preceding embodiments of the first aspect of the present application, the distance between the grating and the prism assembly is adjustable; and the prism assembly comprises at least one dispersion prism, and the dispersion prism is capable of rotational adjustment.

[0016] In a second aspect, embodiments of the present application provide a pulse compression method for compressing a stretched pulse by using the pulse compressor according to any one of the preceding embodiments of the first aspect of the present application, the pulse compression method comprising: controlling the stretched pulse to be incident on the grating from the first side at a first incident angle, and the first diffracted light obtained by diffraction of the stretched pulse by the grating, wherein the initial value of the first incident angle is the Littrow angle; and controlling the first diffracted light to be incident on the prism assembly at a second incident angle, wherein the initial value of the second incident angle is the Brewster angle.

[0017] According to any one of the preceding embodiments of the second aspect of the present application, the reflection assembly and the prism assembly have a first distance therebetween, the first distance is adjustable, and the pulse compression method further comprises: based on a preset distance adjustment model, obtaining a target value of the first distance matched with an actual pulse width of the stretched pulse, and adjusting the distance between the reflection assembly and the prism assembly to the target value of the first distance.

[0018] According to any one of the foregoing embodiments of the second aspect of the present application, the prism assembly comprises a first dispersion prism, the first dispersion prism is configured to refract the first diffracted light and to refract the reflected light again, and the pulse compression method further comprises: adjusting at least one of a plurality of parameters of the pulse compressor to adjust an actual compensation amount of the second-order dispersion and the third-order dispersion opposite to the stretched pulse symbol provided by the pulse compressor, wherein the plurality of parameters comprises a line density of the grating, the first incidence angle, the second incidence angle, an insertion amount, and a distance between the grating and the first dispersion prism, the insertion amount being a distance between an incidence point of the first diffracted light incident on the first dispersion prism and an apex of the first dispersion prism.

[0019] According to any one of the foregoing embodiments of the second aspect of the present application, the adjusting at least one of the plurality of parameters of the pulse compressor comprises: adjusting the second incidence angle by rotating the first dispersion prism.

[0020] According to the pulse compressor and the pulse compression method, the pulse compression is performed by using the pulse compressor, the pulse compressor comprises a grating, a prism assembly, a reflection assembly, and a first mirror, a stretched pulse is incident on the grating from a first side, first diffracted light obtained by diffraction of the grating is incident on the prism assembly, refracted light obtained by the prism assembly is reflected by the reflection assembly to obtain reflected light, the reflected light is incident on the prism assembly again to be refracted by the prism assembly to be diffracted by the grating to obtain second diffracted light located on the first side of the grating, and the second diffracted light is reflected by the first mirror and returned. The above pulse compressor adopts a folded optical path, occupies a small space, can reduce the cost compared with a grating pair structure (including two symmetrical gratings and two symmetrical dispersion prisms), and is easier to integrate. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor based on the drawings shown.

[0022] Figure 1 It is a structural schematic diagram of the first embodiment of the pulse compressor of the present application.

[0023] Figure 2 It is a three-dimensional schematic diagram of the first embodiment of the pulse compressor of the present application.

[0024] Figure 3 It is a structural schematic diagram of the second embodiment of the pulse compressor of the present application.

[0025] Figure 4 Fig. 3 is a structural schematic diagram of a third embodiment of the pulse compressor of the present application.

[0026] Reference signs:

[0027] 100 - pulse compressor;

[0028] 110 - grating;

[0029] 120 - prism assembly; 121 - first dispersion prism; 122 - second dispersion prism; 123 - third dispersion prism;

[0030] 130 - reflection assembly; 131 - hollow ridge prism; 131a - first reflection part; 131b - second reflection part; 132 - second mirror;

[0031] 140 - first mirror;

[0032] 151 - first half-wave plate; 152 - second half-wave plate; 153 - third half-wave plate;

[0033] X1 - stretched pulse.

[0034] The purposes, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work under the premise that the present application falls within the scope of protection.

[0036] It should be noted that all the directionality indications such as up, down, left, right, front, back, and the like in the embodiments of the present application are only used to explain the relative position relationship, movement condition and the like between the components in a certain specific posture such as shown in the accompanying drawings, and if the specific posture changes, the directionality indications will also change accordingly.

[0037] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0038] This invention provides a pulse compressor. Figure 1 , Figure 2 This is a schematic diagram and a perspective view of the first embodiment of the pulse compressor of the present invention. The pulse compressor 100 includes a grating 110, a prism assembly 120, a reflection assembly 130, and a first reflecting mirror 140. The grating 110 has a first side and a second side opposite to each other. The grating 110 is used to diffract the broadened pulse incident on the first side of the grating 110 to obtain first diffracted light, and to compensate for the second-order dispersion of the broadened pulse. The prism assembly 120 is located on the second side of the grating 110. The prism assembly 120 is used to refract the first diffracted light to obtain refracted light, and to compensate for the second-order dispersion of the broadened pulse again while eliminating the third-order dispersion of the broadened pulse. The reflection assembly 130 is located on the second side of the grating 110. The reflection assembly 130 is used to reflect the refracted light to obtain reflected light, which is then incident on the prism assembly 120 and refracted again to the grating 110 to obtain second diffracted light parallel to the first side of the grating 110. The first reflecting mirror 140 is located on the first side of the grating 110. The first reflecting mirror 140 is used to make the second diffracted light reflect back and parallel to the first diffracted light, so that the broadened pulse generates double the amount of dispersion and restores the light spot (i.e. the spatial distribution of the light field) of the broadened pulse to the initial state.

[0039] According to an embodiment of the present invention, a pulse compressor 100 includes a grating 110, a prism assembly 120, a reflector assembly 130, and a first reflector 140. First diffracted light, obtained by diffraction through the grating 110, is incident on the prism assembly 120, refracted by the prism assembly 120, and reflected by the reflector assembly 130. The reflected light is then incident on the prism assembly 120 and refracted again by the grating 110, resulting in second diffracted light located on the first side of the grating. This second diffracted light illuminates the first reflector 140 and is reflected back by the first reflector 140. The pulse compressor 100 employs a folded optical path, occupies less space, and compared to a prism-grating structure (including two symmetrical gratings and two symmetrical dispersive prisms), it can reduce costs and is easier to integrate.

[0040] likeFigure 1 In this embodiment, the prism assembly 120 includes a first dispersive prism 121, which is used to refract the first diffracted light and to refract the reflected light again. The grating 110 refracts the light multiple times (to... Figure 1 (Looking at it, it's 4 times) After the light is diffracted, the second-order dispersion of the pulse is compensated and broadened, and the first dispersive prism 121 achieves this by diffracting multiple (in order of magnitude) incident light. Figure 1 It can be seen that after the light is refracted (4 times), the second-order dispersion of the broadened pulse is compensated again, while the third-order dispersion of the broadened pulse is eliminated.

[0041] like Figure 1 In this embodiment, the reflective component 130 includes a hollow roof prism 131, which is used to cause the refracted light to undergo two reflections to obtain reflected light and then incident on the first dispersive prism 121.

[0042] In this embodiment, the hollow roof prism 131 includes a first reflective part 131a and a second reflective part 131b connected in an angled structure.

[0043] In this embodiment, the broadened pulse X1 is incident on the grating 110 from the first side. The first diffracted light obtained by the grating 110 is incident on the first dispersive prism 121. After being refracted by the first dispersive prism 121, refracted light is obtained. The hollow roof prism 131 causes the refracted light to undergo two reflections to obtain reflected light, which is then incident on the first dispersive prism 121 and refracted again to the grating 110 to undergo diffraction, resulting in a second diffracted light located on the first side of the grating 110. The second diffracted light shines on the first reflecting mirror 140 and is reflected back by the first reflecting mirror 140, resulting in... Figure 2 (in, Figure 1 for Figure 2 The top view, and Figure 3 and Figure 4 The required pulse X2 is shown in the top view of each of their respective three-dimensional structures.

[0044] The total phase introduced by the pulse compressor after the light travels back and forth once is as follows. It can be represented by the following formula (1):

[0045]

[0046] In equation (1), n ​​is the refractive index of the first dispersive prism 121, R is the phase difference caused by the different diffraction positions of light components of different frequencies on the grating 110, and L1 to L7 are the lengths of the light path from the grating 110 through the first dispersive prism 121, after two reflections at the hollow roof prism 131, and after passing through the first dispersive prism 121 again to reach the grating 110 again. Figure 1L1 is the optical path length of the first diffracted light to the incident point of the first dispersion prism 121, L2 is the optical path length of the first diffracted light in the first dispersion prism 121 when the first diffracted light enters the first dispersion prism 121 and is refracted, L3 is the optical path length of the light ray refracted by the first dispersion prism 121 to the hollow ridge prism 131, L4 is the optical path length between the two reflections in the hollow ridge prism 131, L5 is the optical path length of the light ray after the two reflections in the hollow ridge prism 131 to the incident point of the first dispersion prism 121, L6 is the optical path length in the first dispersion prism 121 when the light ray is refracted again in the first dispersion prism 121, and L7 is the optical path length of the light ray after the light ray is refracted again in the first dispersion prism 121 to the grating 110 again.

[0047] The derivative of formula (1) is The derivative of formula (1) is

[0048] According to the pulse compressor of the above embodiment, the prism assembly 120 includes a single first dispersion prism 121, and the reflection assembly 130 includes a hollow ridge prism 131. In one aspect, the above pulse compressor adopts a folded optical path, occupies a small space, and compared with a grating pair structure, the embodiment includes a single grating and a single dispersion prism, so that the cost can be further reduced, and the integration is easier. In a second aspect, the pulse compressor of the embodiment of the present application adopts a combination scheme of a dispersion prism and a grating, solves the problem that the third-order dispersion introduced by the grating pair in the traditional structure does not match the expanded pulse X1, eliminates the adverse effects of the mismatch of the third-order dispersion on the pulse, and more easily obtains a transform-limited pulse.

[0049] According to the pulse compressor of the above embodiment, not only the amount of dispersion provided can be doubled, but also the spot can be compressed to the initial size. By adjusting the pulse compressor, the pulse compressor can simultaneously provide the second-order dispersion and the third-order dispersion opposite in sign to the expanded pulse X1, that is, the dispersion of the expanded pulse X1 can be offset, so that a clean pedestal-free pulse can be obtained.

[0050] In some embodiments, the pulse compressor further includes at least one half-wave plate arranged on an optical path in the pulse compressor, and the half-wave plate is used to change the polarization direction of the light ray passing through.

[0051] In the embodiment, the at least one half-wave plate includes a first half-wave plate 151 located on a first side of the grating 110, and the expanded pulse X1 enters the grating 110 after passing through the first half-wave plate 151. The first half-wave plate 151 is configured to adjust the expanded pulse X1 to be vertically polarized light. The grating 110 has the highest diffraction efficiency when the light is vertically polarized, and the first half-wave plate 151 adjusts the expanded pulse X1 to be vertically polarized light. Therefore, the expanded pulse X1 can pass through the grating 110 at the best efficiency.

[0052] In some embodiments, the at least one half-wave plate includes a second half-wave plate 152 located between the grating 110 and the prism assembly 120, the first diffracted light passes through the second half-wave plate 152 before being incident on the prism assembly 120, and the second half-wave plate 152 is configured to adjust the first diffracted light to be horizontally polarized light. In this embodiment, the second half-wave plate 152 is located between the grating 110 and the first dispersion prism 121, and the first diffracted light passes through the second half-wave plate 152 before being incident on the first dispersion prism 121. The dispersion prisms included in the prism assembly have the highest efficiency, i.e. the highest transmittance, when horizontally polarized. Since the second half-wave plate 152 adjusts the first diffracted light to be horizontally polarized light, according to the Fresnel equation, the first diffracted light passes through the dispersion prisms of the prism assembly almost without loss.

[0053] In some embodiments, the at least one half-wave plate includes a third half-wave plate 153 located between the prism assembly 120 and the grating 110, the light rays refracted again by the prism assembly 120 pass through the third half-wave plate 153 before being incident on the grating 110, and the third half-wave plate 153 is configured to adjust the first diffracted light to be vertically polarized light. In this embodiment, the third half-wave plate 153 is located between the first dispersion prism 121 and the grating 110, and the light rays refracted again by the first dispersion prism 121 pass through the third half-wave plate 153 before being incident on the grating 110.

[0054] The distance between the reflection assembly 130 and the prism assembly 120 can be adjusted according to the amount of dispersion to be compensated. The wider the pulse width, the greater the distance required. The distance between the first mirror 140 and the grating 110 is not limited.

[0055] In some embodiments, the distance between the grating 110 and the prism assembly 120 is adjustable, for example, the distance between the grating 110 and the first dispersion prism 121 is adjustable. In some embodiments, the prism assembly 120 includes at least one dispersion prism that can be adjusted by rotation. For example, in this embodiment, the prism assembly 120 includes the first dispersion prism 121, which can be adjusted by rotation.

[0056] Figure 3FIG. 2 is a schematic diagram of a second embodiment of the pulse compressor of the present application. The pulse compressor 100 includes a grating 110, a prism assembly 120, a reflection assembly 130, and a first mirror 140. The grating 110 has opposite first and second sides. The grating 110 is configured to diffract a stretched pulse incident on the first side of the grating 110 to produce first diffracted light and to compensate for second order dispersion of the stretched pulse. The prism assembly 120 is positioned on the second side of the grating 110. The prism assembly 120 is configured to refract the first diffracted light to produce refracted light and to compensate for second order dispersion of the stretched pulse while eliminating third order dispersion of the stretched pulse. The reflection assembly 130 is positioned on the second side of the grating 110. The reflection assembly 130 is configured to reflect the refracted light to produce reflected light and to direct the reflected light into the prism assembly 120 to be refracted by the prism assembly 120 and diffracted by the grating 110 to produce second diffracted light that is parallel to the first diffracted light. The first mirror 140 is positioned on the first side of the grating 110. The first mirror 140 is configured to reflect the second diffracted light to return the second diffracted light parallel to the first diffracted light to double the amount of dispersion of the stretched pulse and to restore the spot of the stretched pulse to an initial state.

[0057] In this embodiment, the prism assembly 120 includes a second dispersion prism 122 and a third dispersion prism 123. The second dispersion prism 122 is configured to refract the first diffracted light. The third dispersion prism 123 is configured to refract the reflected light. The grating 110 is configured to diffract the light multiple times (e.g., twice) to compensate for second order dispersion of the stretched pulse. The second dispersion prism 122 is configured to refract the light multiple times (e.g., twice) to compensate for second order dispersion of the stretched pulse. The third dispersion prism 123 is configured to refract the light multiple times (e.g., twice) to compensate for second order dispersion of the stretched pulse while eliminating third order dispersion of the stretched pulse. Figure 3 Figure 3 Figure 3

[0058] In some embodiments, the reflection assembly 130 includes at least one second mirror 132. The refracted light is reflected by the at least one second mirror 132 to produce the reflected light that is directed into the third dispersion prism 123. As shown in FIG. 2, the reflection assembly 130 includes two second mirrors 132. Figure 3 In this embodiment, the reflection assembly 130 includes two second mirrors 132.

[0059] ​​​According to the pulse compressor 100 of the above embodiment, the prism assembly 120 comprises a second dispersion prism 122 and a third dispersion prism 123, and the reflection assembly 130 comprises two second mirrors 132. The first diffraction light obtained by diffraction of the grating 110 is incident to the second dispersion prism 122, the refracted light is obtained by the second dispersion prism 122, the refracted light is reflected twice by the two second mirrors 132 to obtain reflected light, and the reflected light is incident to the third dispersion prism 123 to be refracted to the grating 110 again to obtain the second diffraction light located at the first side of the grating 110, the second diffraction light is reflected by the first mirror 140 and returned. In one aspect, the above pulse compressor adopts a folded optical path, occupies a small space, and compared with the grating pair structure, the embodiment is a single grating structure, so that the cost can be reduced, and the integration is easier. In a second aspect, the pulse compressor of the above embodiment adopts a combination scheme of dispersion prisms and gratings, solves the problem of mismatching between the third-order dispersion introduced by the grating pair in the traditional structure and the expanded pulse X1, eliminates the adverse effects of the mismatching of the third-order dispersion on the pulse, and more easily obtains the transform-limited pulse.

[0060] Figure 4 A structure diagram of a third embodiment of the pulse compressor of the present application is shown. The pulse compressor 100 comprises a grating 110, a prism assembly 120, a reflection assembly 130, and a first mirror 140. The grating 110 has opposite first and second sides. The grating 110 is used to diffract the expanded pulse incident to the first side of the grating 110 to obtain first diffraction light, and to compensate the second-order dispersion of the expanded pulse. The prism assembly 120 is located at the second side of the grating 110, and the prism assembly 120 is used to refract the first diffraction light to obtain refracted light, and to compensate the second-order dispersion of the expanded pulse again while eliminating the third-order dispersion of the expanded pulse. The reflection assembly 130 is located at the second side of the grating 110, and the reflection assembly 130 is used to reflect the refracted light to obtain reflected light, and to refract the reflected light to the prism assembly 120 again to diffract the light to the grating 110 to obtain the second diffraction light parallel to the first side of the grating 110. The first mirror 140 is located at the first side of the grating 110, and the first mirror 140 is used to reflect the second diffraction light parallel to the first diffraction light to return, so as to double the dispersion amount of the expanded pulse and restore the spot of the expanded pulse to the initial state.

[0061] In the embodiment, the prism assembly 120 comprises a second dispersion prism 122 and a third dispersion prism 123, the second dispersion prism 122 is used to refract the first diffraction light, and the third dispersion prism 123 is used to refract the reflected light again, wherein the grating 110 diffracts the light incident multiple times (for example, twice) to compensate the second-order dispersion of the expanded pulse, and the second dispersion prism 122 refracts the light multiple times (for example, twice) to compensate the second-order dispersion of the expanded pulse again while eliminating the third-order dispersion of the expanded pulse. Figure 3 In the embodiment, the prism assembly 120 comprises a second dispersion prism 122 and a third dispersion prism 123, the second dispersion prism 122 is used to refract the first diffraction light, and the third dispersion prism 123 is used to refract the reflected light again, wherein the grating 110 diffracts the light incident multiple times (for example, twice) to compensate the second-order dispersion of the expanded pulse, and the second dispersion prism 122 refracts the light multiple times (for example, twice) to compensate the second-order dispersion of the expanded pulse again while eliminating the third-order dispersion of the expanded pulse. Figure 3Looking at it, after the light is refracted twice (in two stages), and after the third dispersive prism 123 refracts the light after multiple (in two stages), the light is refracted twice (in two stages). Figure 3 It can be seen that after the light is refracted twice, the second-order dispersion of the broadened pulse is compensated again, while the third-order dispersion of the broadened pulse is eliminated.

[0062] In some embodiments, the reflective assembly 130 includes at least one second reflector 132, and the refracted light, after being reflected by the at least one second reflector 132, becomes reflected light that is incident on the third dispersive prism 123. For example... Figure 4 In this embodiment, the reflective component 130 includes a single second reflector 132.

[0063] According to the pulse compressor 100 of the above embodiment, the prism assembly 120 includes a second dispersive prism 122 and a third dispersive prism 123, and the reflection assembly 130 includes a single second reflector 132. The first diffracted light, obtained by diffraction through the grating 110, is incident on the second dispersive prism 122, refracted by the second dispersive prism 122, and reflected by the second reflector 132. The reflected light is then incident on the third dispersive prism 123 and refracted again by the grating 110, resulting in a second diffracted light located on the first side of the grating. The second diffracted light illuminates the first reflector 140 and is reflected back by the first reflector 140, returning parallel to the first diffracted light. On the one hand, the pulse compressor uses a folded optical path, occupying less space. Compared to a prism-grating pair structure, this embodiment uses a single grating structure, thereby reducing costs and making it easier to integrate. Secondly, the pulse compressor in the above embodiment adopts a combination of a dispersive prism and a grating, which solves the problem of mismatch between the third-order dispersion introduced by the grating and the broadened pulse X1 in the traditional structure, eliminates the adverse effects of the third-order dispersion mismatch on the pulse, and makes it easier to obtain the transform-limited pulse.

[0064] This invention also provides a pulse compression method, which compresses the broadened pulse X1 using a pulse compressor according to any of the foregoing embodiments.

[0065] The pulse compression method will be described below, taking the compression of the broadened pulse X1 by the pulse compressor 100 of the first embodiment as an example.

[0066] The pulse compression method can include the following steps: controlling the broadened pulse X1 to be incident on the grating 110 from the first side at a first incident angle a1, and the first diffraction light obtained by diffraction of the broadened pulse X1 by the grating 110, wherein the initial value of the first incident angle a1 is the Littrow angle; and controlling the first diffraction light to be incident on the prism assembly 120 at a second incident angle a2, wherein the initial value of the second incident angle a2 is the Brewster's angle. In the embodiment, controlling the first diffraction light to be incident on the prism assembly 120 at the second incident angle a2 means controlling the first diffraction light to be incident on the first dispersion prism 121 at the second incident angle a2.

[0067] According to the pulse compression method of the embodiment of the present application, the pulse compression is performed by using a pulse compressor, the pulse compressor includes a grating 110, a prism assembly 120, a reflection assembly 130, and a first mirror 140, the broadened pulse X1 is incident on the grating 110 from the first side, the first diffraction light obtained by diffraction of the broadened pulse X1 by the grating 110 is incident on the prism assembly 120, the light rays refracted by the prism assembly 120 are reflected at the reflection assembly 130 and then pass through the prism assembly 120 again to be refracted again, the light rays refracted again by the prism assembly 120 are diffracted again by the grating 110 to obtain second diffraction light, and the second diffraction light is reflected by the first mirror 140 and returns. The above-mentioned pulse compressor adopts a folded optical path, occupies a small space, can reduce the cost compared with the grating pair structure, and is easier to integrate. In addition, the prism assembly 120 includes at least one dispersion prism, for example, the prism assembly 120 includes a first dispersion prism 121, the pulse compressor adopts the combination scheme of the prism assembly 120 and the grating 110, solves the problem of mismatch between the third-order dispersion introduced by the grating pair in the traditional structure and the broadened pulse X1, eliminates the adverse effects of the mismatch of the third-order dispersion on the pulse, and is easier to obtain the transform-limited pulse.

[0068] In some embodiments, the first distance between the reflecting component 130 and the prism component 120 is adjustable. In some embodiments, the pulse compression method further comprises: based on a preset distance adjustment model, obtaining a target value of the first distance according to the actual pulse width of the stretched pulse X1, and adjusting the distance between the reflecting component 130 and the prism component 120 to the target value of the first distance. Specifically, the distance adjustment model includes a functional relationship between the target value of the first distance and the actual pulse width of the stretched pulse X1. In this embodiment, the prism component 120 includes the first dispersion prism 121, and the reflecting component 130 includes the hollow ridge prism 131. The first distance between the reflecting component 130 and the prism component 120 is the distance between the first dispersion prism 121 and the hollow ridge prism 131. According to the obtained target value of the first distance, at least one of the reflecting component 130 and the prism component 120 is adjusted, so that the first distance between the reflecting component 130 and the prism component 120 is adjusted to adapt to the actual pulse width of the stretched pulse X1.

[0069] In this embodiment, the prism component 120 includes the first dispersion prism 121, which is used to refract the first diffracted light and is used to refract the reflected light again.

[0070] In some embodiments, the pulse compression method further comprises: adjusting at least one of a plurality of parameters of the pulse compressor to adjust the actual compensation amount of the second-order dispersion and the third-order dispersion opposite to the stretched pulse symbol provided by the pulse compressor, wherein the plurality of parameters include the line density of the grating 110, the first incidence angle a1, the second incidence angle a2, the insertion amount, and the distance between the grating 110 and the first dispersion prism 121. The insertion amount is the distance between the incidence point of the first diffracted light incident on the first dispersion prism 121 and the vertex of the first dispersion prism 121.

[0071] In some embodiments, adjusting at least one of the plurality of parameters of the pulse compressor includes: adjusting the second incidence angle a2 by rotating the first dispersion prism 121. As Figure 1 , rotating the first dispersion prism 121, for example, is to rotate the first dispersion prism 121 clockwise or counterclockwise with reference to Figure 1 The initial value of the second incidence angle a2 is the Brewster angle, so when the first dispersion prism 121 is rotated, the first dispersion prism 121 is rotated within a small range near the Brewster angle.

[0072] According to the pulse compression method of the embodiments of the present application, at least one of the plurality of parameters is adjusted, so that the pulse compressor can simultaneously provide the second-order dispersion and the third-order dispersion opposite to the stretched pulse X1 symbol, that is, the dispersion of the stretched pulse X1 can be offset, so that a clean pedestal-free pulse is obtained.

[0073] The above merely describes the preferred embodiments of the present application, and is not intended to limit the patent scope of the present application. Any equivalent structural changes made under the concept of the present application, or direct / indirect application in other related technical fields, using the content of the present application specification and drawings, are included in the patent protection scope of the present application.

Claims

1. A pulse compressor characterized by, The pulse compressor comprises: a grating for diffracting a stretched pulse incident on a first side of the grating and compensating second-order dispersion of the stretched pulse; a prism assembly located on a second side of the grating for refracting the first diffracted light to obtain refracted light and eliminating third-order dispersion of the stretched pulse while again compensating the second-order dispersion of the stretched pulse; a reflection assembly for reflecting the refracted light to obtain reflected light and making the reflected light incident on the prism assembly to be refracted again in the grating to obtain second diffracted light parallel to the first side of the grating; a first mirror for reflecting the second diffracted light to return and be parallel to the first diffracted light, so as to double the dispersion amount of the stretched pulse and restore the spot of the stretched pulse to the initial state.

2. The pulse compressor of claim 1, wherein, The prism assembly comprises a first dispersion prism for refracting the first diffracted light and refracting the reflected light again, wherein the grating compensates the second-order dispersion of the stretched pulse after diffracting the light incident multiple times, and the first dispersion prism eliminates the third-order dispersion of the stretched pulse while again compensating the second-order dispersion of the stretched pulse after refracting the light incident multiple times.

3. The pulse compressor of claim 2, wherein, The reflection assembly comprises a hollow ridge prism for reflecting the refracted light twice to obtain reflected light and making the reflected light incident on the first dispersion prism.

4. The pulse compressor of claim 1, wherein, The prism assembly comprises a second dispersion prism for refracting the first diffracted light and a third dispersion prism for refracting the reflected light again, wherein the grating compensates the second-order dispersion of the stretched pulse after diffracting the light incident multiple times, and the second dispersion prism and the third dispersion prism finally eliminate the third-order dispersion of the stretched pulse while again compensating the second-order dispersion of the stretched pulse after refracting the light incident multiple times.

5. The pulse compressor of claim 4, wherein, The reflection assembly comprises at least one second mirror, and the refracted light is reflected by the at least one second mirror to obtain reflected light incident on the third dispersion prism.

6. The pulse compressor of claim 1, wherein, Further comprising: at least one half-wave plate arranged on an optical path in the pulse compressor, the half-wave plate being configured to change a polarization direction of the light passing through.

7. The pulse compressor of claim 6, wherein, The at least one half-wave plate comprises a first half-wave plate located on the first side of the grating, the stretched pulse being incident on the grating after passing through the first half-wave plate, and the first half-wave plate being configured to adjust the stretched pulse to be vertically polarized light.

8. The pulse compressor of claim 6, wherein, The at least one half-wave plate comprises a second half-wave plate located between the grating and the prism assembly, the first diffracted light being incident on the prism assembly after passing through the second half-wave plate, and the second half-wave plate being configured to adjust the first diffracted light to be horizontally polarized light.

9. The pulse compressor of claim 6, wherein, The at least one half-wave plate comprises a third half-wave plate located between the prism assembly and the grating, the light refracted again in the prism assembly being incident on the grating after passing through the third half-wave plate, and the third half-wave plate being configured to adjust the light passing through to be vertically polarized light.

10. The pulse compressor of claim 1, wherein, The distance between the grating and the prism assembly is adjustable; the prism assembly comprises at least one dispersive prism, which can be adjusted by rotation.

11. A method of pulse compression, characterized by, The method for compressing a stretched pulse by the pulse compressor as claimed in any one of claims 1 to 10, the pulse compression method comprising: controlling the stretched pulse to be incident on the grating from the first side at a first incident angle, wherein the initial value of the first incident angle is Littrow angle; controlling the first diffracted light to be incident on the prism assembly at a second incident angle, wherein the initial value of the second incident angle is Brewster angle.

12. The pulse compression method of claim 11, wherein, The reflection assembly and the prism assembly have a first distance therebetween, the first distance being adjustable, and the pulse compression method further comprises: adjusting the distance between the reflection assembly and the prism assembly to a target value of the first distance based on a preset distance adjustment model according to the actual pulse width of the stretched pulse.

13. The method of pulse compression of claim 11, wherein, The prism assembly comprises a first dispersive prism for refracting the first diffracted light and for refracting the reflected light again, and the pulse compression method further comprises: adjusting at least one of a plurality of parameters of the pulse compressor to adjust the actual compensation amount of the second-order dispersion and the third-order dispersion opposite to the sign of the stretched pulse provided by the pulse compressor, wherein the plurality of parameters comprises the line density of the grating, the first incident angle, the second incident angle, an insertion amount, and the distance between the grating and the first dispersive prism, the insertion amount being the distance between the incident point of the first diffracted light incident on the first dispersive prism and the vertex of the first dispersive prism.

14. The pulse compression method of claim 13, wherein, The adjusting at least one of the plurality of parameters of the pulse compressor comprises: adjusting the second incident angle by rotating the first dispersive prism. The distance between the grating and the prism assembly is adjustable; the prism assembly comprises at least one dispersive prism, which can be adjusted by rotation. The method for compressing a stretched pulse by the pulse compressor as claimed in any one of claims 1 to 10, the pulse compression method comprising: controlling the stretched pulse to be incident on the grating from the first side at a first incident angle, wherein the initial value of the first incident angle is Littrow angle; controlling the first diffracted light to be incident on the prism assembly at a second incident angle, wherein the initial value of the second incident angle is Brewster angle. The reflection assembly and the prism assembly have a first distance therebetween, the first distance being adjustable, and the pulse compression method further comprises: adjusting the distance between the reflection assembly and the prism assembly to a target value of the first distance based on a preset distance adjustment model according to the actual pulse width of the stretched pulse. The prism assembly comprises a first dispersive prism for refracting the first diffracted light and for refracting the reflected light again, and the pulse compression method further comprises: adjusting at least one of a plurality of parameters of the pulse compressor to adjust the actual compensation amount of the second-order dispersion and the third-order dispersion opposite to the sign of the stretched pulse provided by the pulse compressor, wherein the plurality of parameters comprises the line density of the grating, the first incident angle, the second incident angle, an insertion amount, and the distance between the grating and the first dispersive prism, the insertion amount being the distance between the incident point of the first diffracted light incident on the first dispersive prism and the vertex of the first dispersive prism. The adjusting at least one of the plurality of parameters of the pulse compressor comprises: adjusting the second incident angle by rotating the first dispersive prism.

Images