CN111384655B

CN111384655B - Self-feedback high-stability laser pulse compressor

Info

Publication number: CN111384655B
Application number: CN202010217983.XA
Authority: CN
Inventors: 龙天洋
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-03-25
Filing date: 2020-03-25
Publication date: 2023-03-14
Anticipated expiration: 2040-03-25
Also published as: CN111384655A

Abstract

The invention discloses a self-feedback high-stability laser pulse compressor, which belongs to the technical field of ultrashort ultrastrong laser and consists of two parallel grating pairs, a main datum, secondary datums arranged at the tops of the gratings, a feedback prism and a control system, wherein the two parallel grating pairs are provided with driving devices; the number of the main references is one, the number of the secondary references is three, and the main references and the secondary references are both composed of light sources and detectors; the primary datum is positioned outside the gratings, and the secondary datum is respectively fixed at the tops of three of the gratings; the number of the feedback prisms is four, and the four feedback prisms are respectively fixed at the tops of the four gratings; the control system is electrically connected with the driving devices of the four gratings; the self-feedback high-stability laser pulse compressor has better stability, can improve the time-space characteristic of output laser pulse, and shortens the operation debugging time of a system.

Description

Self-feedback high-stability laser pulse compressor

Technical Field

The invention relates to the technical field of ultrashort and ultrastrong laser, in particular to a self-feedback high-stability laser pulse compressor.

Background

Ultrashort ultrastrong laser generally refers to laser with peak power greater than 1 terawatt (1 terawatt =1 terawatt) and pulse width less than 100 femtoseconds (1 femtosecond equals to 1 femtosecond in parts per billion).

At present, in a large ultrashort ultrastrong laser system, laser pulses are generally stretched and compressed by using a dispersion effect of a reflective grating, and the state of the compressor grating generally directly influences the time-space characteristics of the output laser pulses. Ideally, each pair of parallel gratings should have plane and line parallelism simultaneously, and should be stable in posture. When the three-dimensional attitude of the grating changes, the spatial-temporal characteristics of the output laser (such as pulse width widening and focal spot shape deterioration) are often affected, so that the quality of the output light beam is deteriorated. In fact, since the compressed grating usually carries a relatively high light intensity, the compressed grating is usually placed in a vacuum environment, and the posture of the grating is often changed during the vacuum pumping process.

At present, the commonly used laser system does not monitor the grating postures in the compressor one by one, and generally the spatial-temporal distortion of the laser pulse output by the system as a whole needs to be detected and compensated, for example, a deformable mirror is used for compensating spatial distortion, and AOPDF (programmable acousto-optic spectral dispersion filter) or other dispersion elements (such as a grating prism and the like) are used for compensating time-domain distortion.

Disclosure of Invention

The present invention is directed to a self-feedback high-stability laser pulse compressor to solve the above-mentioned problems.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows: a self-feedback high-stability laser pulse compressor comprises a parallel grating pair, a main reference, a secondary reference arranged on the top of each grating, a feedback prism and a control system,

the parallel grating pairs are two pairs, each grating is provided with a driving device, and the two pairs of gratings are reflective gratings with the same linear density;

the driving means may be a stepper motor or a piezoelectric actuator or the like.

The number of the main references is one, the number of the secondary references is three, and the main references and the secondary references are both composed of light sources and detectors;

the primary datum is positioned outside the gratings, and the secondary datum is respectively fixed at the tops of three of the gratings;

the number of the feedback prisms is four, and the four feedback prisms are respectively fixed at the tops of the four gratings;

the control system is electrically connected with the four gratings.

As a preferred technical scheme: the detectors in the main reference and the three secondary references each have two sub-regions, an XY sub-region and a Z sub-region.

The self-feedback high-stability laser pulse compressor provided by the invention has better stability, can improve the time-space characteristic of output laser pulse, and shortens the operation debugging time of a system. Specifically, if the grating posture of the conventional compressor is changed by external influence, the debugging is usually carried out for several hours or more, but the self-feedback high-stability laser pulse compressor provided by the invention can automatically correct the grating posture according to the reference parameters, and the required time is not more than 3 minutes.

The working principle of the compressor is as follows: the light emitted by the light source in the main reference B0 hits different surfaces of the feedback prism P1 and returns, and is received by the detector D in the main reference B0, and the position of the light spot received by the detector changes when the posture of the grating G1 changes.

Similarly, the light beams of the secondary references B1, B2, B3 are respectively reflected on the feedback prisms P2, P3, P4 and received by their respective detectors, and the change in the position of the light spot reflects the change in the posture of the grating G2 with respect to the grating G1, the grating G3 with respect to the grating G2, and the grating G4 with respect to the grating G3.

Therefore, the change of the grating posture can be monitored one by one, each detector feeds back the received light spot position change information to the control system, and the control system controls the three-dimensional rotation of the grating to correct the posture in time.

As known to those skilled in the art, controlling the rotation of the grating is a very common and general technique, and the present invention also uses a known technique to control the rotation of the grating, for example, a driving device such as a stepping motor or a piezoelectric driver is provided on the grating support adjusting frame, and the control system controls the three-dimensional rotation of the grating through the stepping motor or the piezoelectric driver.

The reflection of light on different surfaces of the prism and the detection of the detector in different areas can be carried out in various ways, and three ways are shown in the three embodiments of the invention and can be selected according to actual conditions.

Compared with the prior art, the invention has the advantages that: the invention decomposes the three-dimensional attitude change of the grating by utilizing the reflected light of different surfaces of the prism, monitors all the gratings one by one, has higher stability compared with a universal compressor, can ensure that the output laser performance is better, and is beneficial to improving the operation efficiency of a system.

Drawings

FIG. 1 is a schematic diagram of a self-feedback high-stability laser pulse compressor according to an embodiment of the present invention;

in the figure, G1, G2, G3 and G4 are reflection gratings with the same linear density, P1, P2, P3 and P4 are feedback prisms, B0 is a main reference, and B1, B2 and B3 are secondary references;

FIG. 2 is a schematic diagram of the coordinate axes of the grating of FIG. 1;

FIG. 3 is a schematic view of prism reflection and detector partition detection in embodiment 1 of the present invention;

in the figure, L is a light source, D is a detector,

FIG. 4 is a schematic view of prism reflection and detector partition detection in embodiment 2 of the present invention;

fig. 5 is a schematic diagram of prism reflection and detector partition detection in embodiment 3 of the present invention.

Detailed Description

The invention will be further explained with reference to the drawings.

Example 1:

a self-feedback high-stability laser pulse compressor is composed of parallel grating pair, primary and secondary reference, feedback prism and control system, referring to FIGS. 1 and 2,

the parallel grating pairs are two pairs, namely G1, G2, G3 and G4, the G1 is parallel to the G2, the G3 is parallel to the G4, and the four gratings are reflective gratings with the same linear density;

the main datum B0 is one and is placed on a stable support outside the grating, and the main datum B0 is placed on a wall in the embodiment; the three secondary references are B1, B2 and B3 respectively, and B1, B2 and B3 are fixed on the tops of the gratings G1, G2 and G3 respectively;

the main datum B0 and the secondary datums B1, B2, B3 are both composed of a light source L and a detector D (see FIG. 3);

four feedback prisms are provided, which are respectively P1, P2, P3 and P4, and P1, P2, P3 and P4 are respectively fixed on the tops of the gratings G1, G2, G3 and G4;

as shown in fig. 3, the light spot directly reflected and returned by the surface of the prism a enters the XY sub-area of the detector D, which can reflect the rotation of the grating around the X axis and the Y axis; the light spot transmitted by the surface a, the surface b and the surface c is transmitted through the surface a, reflected by the surface b and transmitted by the surface a enters a Z sub-area of the detector D, and can reflect the rotation of the grating around a Z axis;

the light emitted by the light source in the main reference B0 is reflected on the feedback prism P1 and received by the detector D in the main reference B0, and when the posture of the grating G1 changes, the position of a light spot received by the detector D changes; similarly, the light beams of the secondary references B1, B2, B3 are respectively reflected on the feedback prisms P2, P3, P4 and received by their respective detectors D, and the change in the position of the light spot reflects the change in the posture of the grating G2 with respect to the grating G1, the grating G3 with respect to the grating G2, and the grating G4 with respect to the grating G3.

The detector in each standard has 8 sub-areas which are respectively marked as XY1, Z1, XY2, Z2, XY3, Z3, XY4 and Z4, the light returned by the feedback prism is respectively received by the 8 sub-areas, the detector feeds back the position change information of the received light spot to the control system, and the control system controls the three-dimensional rotation of the grating to correct the posture of the grating in time. The control objects corresponding to the information of each subarea are shown in table 1.

TABLE 1. Feedback detection subarea and corresponding control correspondence table

The sequence from top to bottom in the table 1 represents the sequence of monitoring and control, and the change of the light spot position of the XY sub-area can reflect the rotation of the grating surface around the X axis and the Y axis; the change in the position of the Z-spot reflects the rotation of the grating about the Z-axis.

The rotation of the grating around the X axis and the Y axis is controlled according to the change of the coordinates of the light spots in the XY subarea to return the feedback light spot to the reference position, and the rotation of the grating around the Z axis is controlled according to the change of the coordinates of the light spots in the Z subarea to return the feedback light spot to the reference position. The compressor has better stability because the postures of all the gratings are monitored one by one.

Example 2

The feedback mode and the partition detection method of the present embodiment are shown in fig. 4, and the rest is the same as embodiment 1; the light spot reflected by the surface a of the prism enters an XY subarea of the detector and can reflect the rotation of the grating around an X axis and a Y axis; transmission through the a-surface- > b-surface reflection- > c-surface reflection- > transmission of the return spot by the a-surface into the Z sub-region of the detector may reflect the rotation of the grating about the Z axis.

Example 3

The feedback mode and the partition detection method of this embodiment are shown in fig. 5, where the feedback prism is composed of two prisms, and the light spot reflected by the surface a of the prism 1 enters the XY sub-area of the detector, which can reflect the rotation of the grating around the X-axis and the Y-axis; the light spot reflected back by the a surface of the prism 1- > b surface reflection- > c surface transmission- > d surface of the prism 2 enters the Z sub-area of the detector, which can reflect the rotation of the grating around the Z axis.

Compared with the

embodiments

1 and 2, the embodiment can increase the offset of the light spot reaching the Z sub-area when the grating rotates around the Z axis, and improve the sensitivity of the monitoring system to the error of the grating rotating around the Z axis.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims

1. A self-feedback high-stability laser pulse compressor is characterized in that: consists of a parallel grating pair, a main reference, a secondary reference arranged on the top of each grating, a feedback prism and a control system,

the parallel grating pairs are two pairs, and each grating is provided with a driving device;

the control system is electrically connected with the driving devices of the four gratings.

2. The self-feedback high-stability laser pulse compressor according to claim 1, wherein: the detectors in the primary reference and the three secondary references each have two sub-regions.