CN104184032B - Novel pulse amplification device and method - Google Patents

Abstract

A novel pulse amplification device and amplification method, comprising an oscillator and an amplifier sequentially arranged on an optical path, and also comprising a first phase plate and a second phase plate, wherein the first phase plate and the second phase plate are located on both sides of the amplifier, These two phase plates have exactly the same shape and size, and are made of exactly the same material. If the center of the phase plate is defined as the origin coordinates of the phase plate, if the coordinates of a point on the first phase plate are ( x, y), where the phase is Φ1xy for the beam passing through the phase plate, and for the same point (x, y) on the second phase plate, the phase is Φ2xy for the same beam, Then for all the position points of the whole phase plate, Φ1xy+Φ2xy=constant, and each phase plate is a non-uniform phase plate, the light beams pass through in the same position and range in the vertical way on the two phase plates passed.

Description

A Novel Pulse Amplifying Device and Amplifying Method

technical field

The invention relates to a novel chirped pulse amplifying device, mainly relates to particle strong field experimental research, and belongs to the field of high-energy physics.

Background technique

Light is composed of electric and magnetic fields that oscillate orthogonally to each other in a plane perpendicular to its propagation direction. The intensity of light is proportional to the sum of the square of the electric field and the square of the magnetic field that make up the light wave. Due to the excellent spatial and temporal coherence of lasers, the electric field in a laser beam is many orders of magnitude larger than that of a typical incoherent light source. At present, it is believed that the smallest unit of matter, an atom, is composed of an atomic nucleus and electrons orbiting the nucleus. The main content of traditional atomic physics research is the behavior and properties of electrons in matter under the action of the internal electric field of atoms. In recent years, due to a major breakthrough in ultrashort pulse chirped pulse amplification (chirped pulse amplification) technology, the current ultrashort pulse laser can generate an electric field much stronger than the electric field in atoms, so that human beings finally have the ability to completely change And the ability to control the movement of electrons in matter and thereby change the nature and state of matter. The electric field strength inside the atom is very large. Taking the hydrogen atom as an example, the electric field in the atom that binds the electrons to move in the hydrogen atom is as high as 5*10 ⁹ V/cm. How strong is this electric field? Make a simple comparison: the power of lightning in nature is huge, and it is as powerful as thunder It is to describe its power; however, the electric field generated by lightning is only equivalent to one millionth of the electric field inside the atom! If the strength of the electric field inside the atom is used to accelerate electrons, only an acceleration distance of 10cm is needed to accelerate electrons To the energy of 5*10 ¹⁰ eV, this is roughly equivalent to the energy obtained by accelerating many circles on the LEP accelerator with a circumference of 27km in Geneva. In order to make the electric field of the laser so large that it can be compared with the electric field inside the atom, the light field of the laser must reach at least 3*10 ¹⁶ W/cm ² . This is an unattainable goal for general long-pulse (pulse width>10 ^-9 s) lasers. It is for this reason that human beings have basically blanked out the research on the law of motion of matter in an electric field stronger than the internal electric field of atoms; and this situation has changed dramatically now. In recent years, a major breakthrough in ultrashort pulse chirp amplification technology has increased the laser intensity by 5 to 6 orders of magnitude. The focused light intensity of this new type of laser is as high as 10 ²⁰ W/cm ² , and the electric field intensity generated is much greater than the internal electric field of atoms. 10 ^-12 s) The oscillator sends out the ultrashort optical pulse stretching-amplification-compression in Figure 1 to obtain an ultrashort laser pulse, which first passes through a dispersion delay optical element (such as a grating) to expand the pulse width by 10 ³ to 10 ⁵ times , and then injected into the laser amplifier for amplification to obtain as much energy as possible. Since the laser pulse at this time is very wide, the intensity of the amplified laser pulse is still lower than the damage threshold of the laser medium. After the laser amplifier, a conjugate dispersion compensation optical element is used to compress the amplified laser pulse back to the original pulse width. The resulting laser light can be focused to produce a light intensity in excess of 10 ²⁰ W/cm ² . At present, the laser devices of the Rutherford Laboratory in the UK, the Rimel Laboratory in France and the Livermore National Laboratory in the United States all have such capabilities. Laser installations in my country and other countries are also undergoing transformation. It is worth mentioning that the transformation of the original laser device with chirp amplification technology is much more economical and cost-effective than relying on expanding the laser output aperture and increasing the number of laser output channels to increase the laser power. These are all well-known technologies in the prior art. For more specific details, please refer to the article "Strong Field Physics-A Brand New Subject" by Zhang Jie. It is precisely because of the importance of chirped pulse amplification technology that the research on chirped pulse amplification in various countries in the world is also extremely active. Various chirped pulse amplifiers have appeared, and the principles used are as pointed out above , the stretcher and compressor used are all gratings or grating pairs. The production of gratings or grating pairs is relatively complicated and the cost is high. In some occasions with low requirements, it may not be suitable for all researchers. Aiming at this, the invention proposes an amplifying device that can replace the above-mentioned stretcher and compressor.

Contents of the invention

Aiming at the above problems, the present invention proposes a novel chirped pulse amplification device.

The invention provides a chirped pulse amplification device, which includes an oscillator and an amplifier sequentially arranged on the optical path, and is characterized in that it also includes a first phase plate and a second phase plate, and the first phase plate and the second phase plate are separated from the amplifier On both sides, these two phase plates have exactly the same shape and size, and are made of exactly the same material, if the center of the phase plate is defined as the origin coordinate of the phase plate, if a point on the first phase plate is The coordinates are (x, y), the phase at this place is Φ1xy for the beam passing through the phase plate, and the phase at the same point (x, y) for the same beam on the second phase plate is Φ2xy, then for all the position points of the whole phase plate, the phase sum at the same position of the two phase plates is constant, that is, Φ1xy+Φ2xy = constant, and each phase plate is a non-uniform phase plate, that is, the whole The phase values on the phase plates cannot be exactly the same, and the light beams pass through the two phase plates in the same position and range in a vertical manner. The first phase plate and the second phase plate are made of light-transmitting materials Manufactured, where each phase plate is a plate-like structure, including two sides, one of which is a plane, and the other side is a surface with a convex column structure of different heights, and two of the two phase plates at the same position The sum of the heights of the convex columns is constant, that is, if the surfaces with the convex columns of the two phase plates are placed facing each other and merged, a cuboid without any space inside will be formed, because the two phase plates at the same position The height of the bosses is the same on the whole phase plate, and they form a complementary structure.

According to an embodiment of the present invention, the first phase plate and the second phase plate are glass, quartz or resin plates made of the same material.

Description of drawings

Fig. 1 is the schematic diagram of chirped pulse amplification device in the prior art;

Fig. 2 is the schematic diagram of the chirped pulse amplification device of the present invention;

Fig. 3 shows a schematic diagram of phases used in the present invention.

detailed description

The content of the present invention will be described in more detail below in conjunction with the accompanying drawings.

Figure 2 shows a schematic diagram of the high power laser device of the present invention. Wherein 1 indicates an oscillator, and 3 indicates an amplifier, all of which belong to the prior art, and will not be described in detail here. Wherein 2 and 4 are two phase plates that adopt in the present invention, and these two phase plates are separated in the both sides of amplifier, carry out detailed description for these two phase plates below, these two phase plates have identical shape and size, and made of exactly the same material, if the center of the phase plate is defined as the origin coordinates of the phase plate, where the coordinates of a point on the phase plate 2 are (x, y), for a beam passing through this phase For example, the phase here is Φ1xy, the point (x, y) on the phase plate 4, for the same light beam, the phase here is Φ2xy, then for the entire phase plate, the phases at the same position of the two phase plates The sum is constant, that is, Φ1xy+Φ2xy = constant, that is, the phase sum of two points at the same coordinates on the two phase plates does not change, and each phase plate is a non-uniform phase plate, that is, the phase of the entire phase plate The phase values cannot be exactly the same, and the light beams pass through the two phase plates in the same vertical and identical position and range, that is, if the light beam is irradiated on the phase plate 2, the range is (x1, y1) to (x2, y2), then the range irradiated on the phase plate 4 should also be (x1, y1) to (x2, y2).

For the two phase plates, the higher the non-uniformity, the stronger the ability to increase the upper limit of the amplification energy of the entire amplifier. For two phase plates, a simple example can be two glass plates, the two glass plates are made of exactly the same material, in order to make the two glass plates meet the above phase conditions, the thickness of the glass plates can be simply adjusted Modulation, for the same optical medium, the phase is the thickness, so as long as the sum of the thicknesses at the same position of the two glass plates remains constant, for example, the thickness at the point (x1, y1) of the first glass plate is 1, and the thickness of the second glass plate is The thickness at the two glass plate points (x1, y1) can be set to 2, the thickness at the first glass plate point (x2, y2) is 1.5, and the thickness at the second glass plate point (x2, y2) is 1.5, then the requirement of 1+2=1.5+1.5=3 is satisfied, and at the same time, the phase sum of all other points can be kept as 3, and each phase can be made as a non-uniform phase plate, that is, The thickness of the entire phase plate cannot be the same. At the same time, for the convenience of production, it is not required to change the phase at each point during production, and the entire phase can be divided into a grid-like structure, where each grid is a unit, and the unit network The phase in the grid is constant, in this case, it is only necessary to ensure that the phase sum of the two grids at the same position on the two phase plates remains constant.

Fig. 3 shows a pair of phase plates used in the present invention, wherein 2 and 4 each represent a phase plate, and these two phase plates can be made of any light-transmitting material, such as quartz, glass, or materials such as resin, wherein Each phase plate is a plate-like structure, including two sides, one of which is a plane, and the other side is a surface with different heights of convex pillars, and the heights of the two convex pillars at the same position of the two phase plates and is constant, that is, if the faces with convex columns of the two phase plates are placed opposite and combined, then exactly a cuboid structure is formed, that is, phase plate 2 and phase plate 4 as shown in Figure 3, if according to Combine the two phase plates in the way shown in the figure, then a cuboid without any space inside will be formed, because the heights of the two convex posts at the same position of the two phase plates are the same on the entire phase plate, and they form a a complementary structure.

Using the phase plate of the present invention, firstly, after the laser beam passes through the first phase plate, the phase of the laser beam is spatially modulated, since the phase plate is a non-uniform phase plate, thereby reducing the spatial coherence of the laser beam (It is precisely because of this that the stronger the aperiodicity of the phase plate, the greater the reduction in spatial coherence it brings), so that the energy density per unit area of the laser beam is reduced, and when the beam passes through the second phase plate Later, since the phase sum at the phase points of the two phase plates is constant, the second phase plate will re-modulate the modulation phase caused by the first phase plate, so that the spatial phase distribution of the laser beam returns to the original The coherent case, in this way, can somewhat replace the original stretcher and compressor.

At the same time, a method according to the above-mentioned device is also disclosed, comprising, the pulsed laser output by the oscillator passes through the first phase plate, the amplifier, and the second phase plate in sequence, the two phase plates have exactly the same shape and size, and are formed by Made of exactly the same material, if the center of the phase plate is defined as the origin coordinates of the phase plate, if the coordinates of a point on the first phase plate are (x, y), for the beam passing through the phase plate The phase here is Φ1xy, for the same point (x, y) on the second phase plate, the phase here is Φ2xy for the same light beam, then for all the positions of the entire phase plate, the two phases The phase sum at the same position of the plates is constant, that is, Φ1xy+Φ2xy = constant, and each phase plate is a non-uniform phase plate, that is, the phase values of the entire phase plate cannot be completely the same, and the beam on the two phase plates is The first phase plate and the second phase plate are made of light-transmitting materials, and each phase plate is a plate-like structure, including two There are two sides, one of which is a plane, and the other side is a surface with a structure of convex columns with different heights, and the sum of the heights of the two convex columns at the same position of the two phase plates is constant, that is, if the two phase plates are Faces with convex pillars are placed opposite and merged, then exactly a cuboid without any space inside is formed, because the height of the two convex pillars at the same position of the two phase plates is the same on the entire phase plate, they form a complementary structure.

Claims (4)

1. a kind of chirped pulse amplification device, including the oscillator setting gradually in light path and amplifier it is characterised in that：Also wrap Include the both sides that first phase plate and second phase plate, wherein first phase plate and second phase plate are located at amplifier, and first Phase-plate is located between amplifier and oscillator, and this two phase-plates have same shape and size, and by complete Identical material manufacture forms, if being defined as the origin of phase-plate with the center of phase-plate, if on first phase plate The coordinate of certain point is (x, y), and the phase place for the light beam through this first phase plate it is assumed that at this is Φ 1xy, for Identical point (x, y) on second phase plate, it is assumed that phase place at this for the second phase plate is Φ 2xy for identical light beam, Then for all of location point for whole phase-plate, phase place at two phase-plate same positions and be constant, namely Φ 1xy + Φ 2xy=constant, and each phase-plate is all non-even phase plate, namely the phase number on whole phase-plate can not be complete Exactly the same, light beam passes through on two phase-plates in vertical manner in identical position and scope, therein First phase plate and second phase plate are fabricated by by translucent material, and wherein each phase-plate is all a platy structure, bag Include two sides, one of side is plane, and another one side is the face with differing heights convex cylinder, two of which The height of two projections of phase-plate same position and be constant, namely if the face phase with projection by two phase-plates To placing and merge, then just can form an inside does not have the cuboid in any space, because two phase-plate identical bits The height of two projections at the place of putting be consistent on whole phase-plate, they constitute a complementary structure.

2. chirped pulse amplification device according to claim 1 it is characterised in that：Described first phase plate and the second phase Position plate is that one or more of materials described below is fabricated by：Glass, quartz, resin.

3. a kind of chirped pulse amplification method it is characterised in that：First phase is sequentially passed through by the pulse laser that oscillator exports Plate, amplifier, and second phase plate, this two phase-plates have same shape and size, and by identical Material manufacture forms, if being defined as the origin of phase-plate with the center of phase-plate, if certain point on first phase plate Coordinate be (x, y), the phase place for the light beam through this first phase plate it is assumed that at this be Φ 1xy, for the second phase Identical point (x, y) on the plate of position, it is assumed that phase place at this for the second phase plate is Φ 2xy for identical light beam, then for For the whole all of location point of phase-plate, phase place at two phase-plate same positions and be constant, namely Φ 1xy+ Φ 2xy =constant, and each phase-plate is all non-even phase plate, namely the phase number on whole phase-plate can not be identical, Light beam passes through on two phase-plates in vertical manner in identical position and scope, first phase therein Plate and second phase plate are fabricated by by translucent material, and wherein each phase-plate is all a platy structure, including two sides Face, one of side is plane, and another one side is the face with differing heights convex cylinder, two of which phase-plate phase With position two projections height and be constant, namely if by two phase-plates have projection face staggered relatively simultaneously Merge, then just can form an inside does not have the cuboid in any space, because two at two phase-plate same positions The height of individual projection be consistent on whole phase-plate, they constitute a complementary structure.

4. chirped pulse amplification method according to claim 3 it is characterised in that：Described first phase plate and the second phase Position plate is that one or more of materials described below is fabricated by：Glass, quartz, resin.