CN109491097A - A method of axisymmetric vectoring light beam is generated based on crystal optical activity - Google Patents
A method of axisymmetric vectoring light beam is generated based on crystal optical activity Download PDFInfo
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- CN109491097A CN109491097A CN201910034350.2A CN201910034350A CN109491097A CN 109491097 A CN109491097 A CN 109491097A CN 201910034350 A CN201910034350 A CN 201910034350A CN 109491097 A CN109491097 A CN 109491097A
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- G—PHYSICS
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- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
- G02B27/0938—Using specific optical elements
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
- G02B27/286—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising for controlling or changing the state of polarisation, e.g. transforming one polarisation state into another
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Abstract
The invention discloses a kind of methods for generating axisymmetric vectoring light beam based on crystal optical activity, method includes the following steps: step 1, gyrotropi crystal is selected, according to the specific rotatory power α of environment temperature T, linearly polarized laser wavelength X to be converted and gyrotropi crystal, designs helical structure crystal element;Step 2, reverse acting spiral element identical with helical structure crystal element refractive index is manufactured;Step 3, helical structure crystal element upper surface and the lower surface of reverse acting spiral element are carried out glued;Step 4, linearly polarized laser is incident along the z-axis direction of polarization rotation element, and keep the central point of polarization laser hot spot and polarization rotation element bottom center coaxial, by adjusting the polarization direction of polarization laser and the angle in the direction polarization rotation element x, obtain required axisymmetric vectoring light beam.Element of the present invention is few, realizes radial, angular and any axisymmetric vectoring light beam using discrete component, adjusts simple.
Description
Technical field
The invention belongs to optical fields, and in particular to a kind of side that axisymmetric vectoring light beam is generated based on crystal optical activity
Method.
Background technique
It polarizes the vector beam being axisymmetricly distributed to be widely noticed because its special spatial polarization is distributed, the axis pair of tightly focused
Claim vector beam have surmount diffraction limit focused radius and adjustable focused spot, laser processing, information storage,
The fields such as micro-imaging, surface phasmon regulation, optical acquisition and manipulation, particle acceleration have important application.
The method for generating axisymmetric vectoring light beam is broadly divided into active technique and passive method: active technique is passed through in laser cavity
The method for the vector beam that addition polarization selection element generates, has preferable beam quality and higher efficiency, but laser
Intracavitary element regulation is difficult, and flexibility is lower;Passive method is that polarization conversion is realized outside laser chamber, passes through beam interference, sky
Between the methods of segmented phase delayer, spatially-variable sub-wave length grating, liquid crystal device, spatial light modulator generate axisymmetric vectoring
Light beam.These methods usually require multiple conversion elements, and transfer efficiency is lower, and the damage threshold of element is lower, can not apply
In high power laser system, high-intensitive axisymmetric vectoring light beam is generated.
Summary of the invention
Aiming at the problems existing in the prior art, the present invention provides a kind of based on crystal optical activity generation axisymmetric vectoring light
The method of beam, the present invention utilize screw type gyrotropi crystal element, by the linearly polarized photon of laser output in space different angle
It is rotated, so that generating has high conversion efficiency, high-power axisymmetric vectoring light beam.
To achieve the above object, the invention adopts the following technical scheme:
A method of axisymmetric vectoring light beam is generated based on crystal optical activity, method includes the following steps:
Step 1, gyrotropi crystal is selected, according to environment temperature T, linearly polarized laser wavelength X to be converted and gyrotropi crystal
Specific rotatory power α, design helical structure crystal element: cartesian coordinate system is established, using the optical axis of gyrotropi crystal as z-axis, vertical
In in z-axis plane, x-axis is mutually perpendicular to y-axis, on this basis, defines projection of the vector in x-y plane with x-axis forward direction along inverse
The angle of hour hands is θ1, processing gyrotropi crystal is helical structure crystal element, and the bottom surface of the helical structure crystal element is circle
Shape, radius r1, any point coordinate meets x on side1 2+y1 2=r1 2;Point grid azimuth on upper surface is θ1When, spiral knot
Structure crystal element with a thickness of d=k θ1+d0, wherein k=1/ α, d0For θ1The thickness of helical structure crystal element, meets d when=00
> 0, corresponding azimuth are θ1Incident light pass through the position rear polarizer rotate angle φ0=α z0;
Step 2, reverse acting spiral element identical with helical structure crystal element refractive index, the reverse acting spiral element are manufactured
Upper surface be circle, radius r2;Any point coordinate meets x on side2 2+y2 2=r2 2;Point grid azimuth on lower surface
For θ2When, reverse acting spiral element with a thickness of d'=-k θ2+d1, wherein k=1/ α, d1For θ2The height of reverse acting spiral element when=0
Degree, meets d1360/ α of >, the height of reverse acting spiral element when wherein d1 is theta_2=0,
Step 3, helical structure crystal element upper surface and the lower surface of reverse acting spiral element are carried out to glued, guarantee spiral
θ in structure crystal element1With θ in reverse acting spiral element2Polarization rotation element, the polarization rotation is made in identical aligned in position
Element is cylindrical structure, and bottom surface radius is r3, the r1=r2=r3, the height h=d of cylindrical body0+d1;
Step 4, linearly polarized laser is incident along the z-axis direction of polarization rotation element, and make the center of polarization laser hot spot
Point is coaxial with polarization rotation element bottom center, by the polarization direction and the direction polarization rotation element x that adjust polarization laser
Angle obtains required axisymmetric vectoring light beam.
The helical structure crystal element is hollow cylinder structure, i.e., by helical structure crystal element x2+y2< δ2Part
Remove, the hollow cylinder structure meets x2+y2< δ2, x, y are respectively the coordinate of any point in the hollow cylinder structure outer circle
Value, the δ are less than r1* 2%, δ are the value for not influencing axisymmetric vectoring beam arrangement, need to be according to axisymmetric vectoring beam intensity point
Cloth determines, should be less than the radius of axisymmetric vectoring light beam hollow space, generally less than spiral result crystal element bottom surface radius r1
2%.
Polarizing film, the polarizing film and polarization rotation element are set between the linearly polarized laser and polarization rotation element
Coaxial arrangement.
Gyrotropi crystal is quartz crystal in the step 1.
Reverse acting spiral element is quartz glass in the step 2.
Gyrotropi crystal is at room temperature along plug Mir's equation of gyrotropi crystal optical axis direction specific rotatory power in the step 1 are as follows:Wherein the unit of λ is μm, and the unit of α is °/mm.
Compared with prior art, the invention has the benefit that
1. power is high, select the gyrotropi crystal material with high damage threshold that high-power axisymmetric vectoring light may be implemented
The output of beam.Such as quartz crystal damage threshold is up to 10J/cm2(@1053nm)
2. it is higher to generate axisymmetric vectoring beam efficiency for high-efficient, this method salt free ligands and interventional procedures.
3. element is few, radial, angular and any axisymmetric vectoring light beam is realized using discrete component, is adjusted simple.
4. easy processing, gyrotropi crystal material processes helical structure, and crystal thickness is easy to process in millimeter magnitude, such as λ
Polarization rotation element is made using quartz crystal when=1053nm, crystal thickness is about 57~65mm.
Detailed description of the invention
In order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, to embodiment or will show below
There is attached drawing needed in technical description to be briefly described, it should be apparent that, the accompanying drawings in the following description is only this
Some embodiments of invention for those of ordinary skill in the art without creative efforts, can be with
It obtains other drawings based on these drawings.
Fig. 1 is the structural schematic diagram of helical structure crystal element in the present invention.
Fig. 2 is the structural schematic diagram of reverse acting spiral element in the present invention.
Fig. 3 is the structural schematic diagram of polarization rotation element in the present invention.
Fig. 4 is the structural schematic diagram that linearly polarized light is converted to axisymmetric vectoring light beam in the present invention.
Fig. 5 is the axisymmetric vectoring light beam polarization distribution schematic diagram obtained in the present invention.
Fig. 6 is the structural schematic diagram of embodiment 2 in the present invention.
Specific embodiment
Following will be combined with the drawings in the embodiments of the present invention, and technical solution in the embodiment of the present invention carries out clear, complete
Site preparation description, it is clear that described embodiments are only a part of the embodiments of the present invention, instead of all the embodiments.It is based on
Embodiment in the present invention, those of ordinary skill in the art are obtained every other under that premise of not paying creative labor
Embodiment shall fall within the protection scope of the present invention.
In the description of the present invention, it is to be understood that, term " longitudinal direction ", " transverse direction ", "upper", "lower", "front", "rear",
The orientation or positional relationship of the instructions such as "left", "right", "vertical", "horizontal", "top", "bottom" "inner", "outside" is based on attached drawing institute
The orientation or positional relationship shown, is merely for convenience of description of the present invention and simplification of the description, rather than the dress of indication or suggestion meaning
It sets or element must have a particular orientation, be constructed and operated in a specific orientation, therefore should not be understood as to limit of the invention
System.
Embodiment 1
As Figure 1-Figure 5, the method that the present embodiment generates axisymmetric vectoring light beam based on crystal optical activity, this method packet
Include following steps:
Step 1, gyrotropi crystal is selected, according to environment temperature T, linearly polarized laser wavelength X to be converted and gyrotropi crystal
Specific rotatory power α, design helical structure crystal element 1: cartesian coordinate system is established, using the optical axis of gyrotropi crystal as z-axis, vertical
In in z-axis plane, x-axis is mutually perpendicular to y-axis, on this basis, defines projection of the vector in x-y plane with x-axis forward direction along inverse
The angle of hour hands is θ1, processing gyrotropi crystal is helical structure crystal element 1, and the bottom surface of the helical structure crystal element 1 is
Circle, radius r1, any point coordinate meets x on side1 2+y1 2=r1 2;Point grid azimuth on upper surface is θ1When, spiral
Structure crystal element 1 with a thickness of d=k θ1+d0, wherein k=1/ α, d0For θ1The thickness of helical structure crystal element 1 when=0,
Meet d0> 0, corresponding azimuth are θ1Incident light pass through the position rear polarizer rotate angle φ0=α z0;
Step 2, reverse acting spiral element 2 identical with 1 refractive index of helical structure crystal element, the reverse acting spiral member are manufactured
The upper surface of part 2 is circle, radius r2;Any point coordinate meets x on side2 2+y2 2=r2 2;Point coordinate side on lower surface
Parallactic angle is θ2When, reverse acting spiral element 2 with a thickness of d'=-k θ2+d1, wherein k=1/ α, d1For θ2Reverse acting spiral element 2 when=0
Height, meet d1360/ α of >;
Step 3,1 upper surface of helical structure crystal element and the lower surface of reverse acting spiral element 2 are carried out to glued, guarantee spiral shell
Revolve θ in structure crystal element 11With θ in reverse acting spiral element 22Polarization rotation element 3 is made in identical aligned in position, described inclined
Vibration rotating element 3 is cylindrical structure, and bottom surface radius is r3, the r1=r2=r3, the height h=d of cylindrical body0+d1;
Step 4, linearly polarized laser 4 is incident along the z-axis direction of polarization rotation element 3, and make in 4 hot spot of polarization laser
Heart point and 3 bottom center of polarization rotation element are coaxial, by the polarization direction and the polarization rotation element side 3x that adjust polarization laser 4
To angle, obtain required axisymmetric vectoring light beam 5.
Preferably, helical structure crystal element 1 described in the present embodiment is hollow cylinder structure, the hollow cylinder structure
Meet x2+y2< δ2, x, y are respectively the coordinate value of any point in the hollow cylinder structure outer circle, and the δ is less than r1* 2%.
As further preferred, polarizing film is arranged between the linearly polarized laser 4 and polarization rotation element 3 in the present embodiment
6, the polarizing film 6 is coaxially disposed with polarization rotation element 3.
As further preferred, gyrotropi crystal is quartz crystal in step 1 described in the present embodiment.
As further preferred, reverse acting spiral element is quartz glass in step 2 described in the present embodiment.
As still more preferably, gyrotropi crystal is at room temperature along gyrotropi crystal optical axis direction in step 1 described in the present embodiment
Plug Mir's equation of specific rotatory power are as follows:Wherein the unit of λ be μm,
The unit of α be °/mm.
As shown in figure 5, required axisymmetric vectoring light beam any point polarization direction and angle of radial direction on section areAdjust the angle of linear polarization and the direction xUnder this Parameter Conditions, linearly polarized light is by polarization rotation
After turning element, beam cross section azimuth is that the optical electric field polarization rotation at θ isThe axisymmetric vectoring light beam of generation is being cut
Any point polarization direction is with radial angle on faceSuch asWhen, polarization rotating element turns linearly polarized light
It is changed to radial polarisation lightγ=90 °-φ0When, linearly polarized light is converted to angularly polarized light by polarization rotating element
θ, θ in the present embodiment1、θ2, all it is to define vector in the projection of x-y plane and x-axis forward direction along angle counterclockwise
Embodiment 2
The present embodiment is arranged polarizing film 6 between the linearly polarized laser 4 and polarization rotation element 3, the polarizing film 6 with
Polarization rotation element 3 is coaxially disposed.Remaining technical solution is the same as embodiment 1.
Although above-described embodiment makes specific descriptions to the present invention, come for those of ordinary skill in the art
It says, it is understood that can be modified within spirit and scope of the invention based on present disclosure not departing from
Or improve, these modification and improvement are all within spirit and scope of the invention.
Claims (6)
1. a kind of method for generating axisymmetric vectoring light beam based on crystal optical activity, which is characterized in that this method includes following step
It is rapid:
Step 1, gyrotropi crystal is selected, according to the rotation of environment temperature T, linearly polarized laser wavelength X to be converted and gyrotropi crystal
Light rate α, design helical structure crystal element (1): establish cartesian coordinate system, using the optical axis of gyrotropi crystal as z-axis, perpendicular to
In z-axis plane, x-axis is mutually perpendicular to y-axis, on this basis, defines vector in the projection of x-y plane and x-axis forward direction along the inverse time
The angle of needle is θ1, processing gyrotropi crystal is helical structure crystal element (1), the bottom surface of the helical structure crystal element (1)
For circle, radius r1, any point coordinate meets x on side1 2+y1 2=r1 2;Point grid azimuth on upper surface is θ1When, spiral shell
Revolve structure crystal element (1) with a thickness of d=k θ1+d0, wherein k=1/ α, d0For θ1Helical structure crystal element (1) when=0
Thickness meets d0> 0, corresponding azimuth are θ1Incident light pass through the position rear polarizer rotate angle φ0=α z0;
Step 2, reverse acting spiral element (2) identical with helical structure crystal element (1) refractive index, the reverse acting spiral member are manufactured
The upper surface of part (2) is circle, radius r2;Any point coordinate meets x on side2 2+y2 2=r2 2;Point coordinate on lower surface
Azimuth is θ2When, reverse acting spiral element (2) with a thickness of d'=-k θ2+d1, wherein k=1/ α, d1For θ2Reverse acting spiral when=0
The height of element (2), meets d1360/ α of >;
Step 3, the lower surface of helical structure crystal element (1) upper surface and reverse acting spiral element (2) is carried out to glued, guarantee spiral shell
Revolve θ in structure crystal element (1)1With θ in reverse acting spiral element (2)2Identical aligned in position is made polarization rotation element (3),
The polarization rotation element (3) is cylindrical structure, and bottom surface radius is r3, the r1=r2=r3, the height h=d of cylindrical body0+
d1;
Step 4, linearly polarized laser (4) is incident along the z-axis direction of polarization rotation element (3), and make polarization laser (4) hot spot
Central point and polarization rotation element (3) bottom center are coaxial, by the polarization direction and the polarization rotation member that adjust polarization laser (4)
The angle in part (3) direction x obtains required axisymmetric vectoring light beam (5).
2. the method according to claim 1 for generating axisymmetric vectoring light beam based on crystal optical activity, which is characterized in that institute
Stating helical structure crystal element (1) is hollow cylinder structure, and the hollow cylinder structure meets x2+y2< δ2, x, y are respectively should
The coordinate value of any point in hollow cylinder structure outer circle, the δ are less than r1* 2%.
3. the method according to claim 1 for generating axisymmetric vectoring light beam based on crystal optical activity, which is characterized in that
Polarizing film (6) are set between the linearly polarized laser (4) and polarization rotation element (3), the polarizing film (6) and polarization rotation member
Part (3) coaxial arrangement.
4. the method according to claim 1 for generating axisymmetric vectoring light beam based on crystal optical activity, which is characterized in that institute
Stating gyrotropi crystal in step 1 is quartz crystal.
5. the method according to claim 1 for generating axisymmetric vectoring light beam based on crystal optical activity, which is characterized in that institute
Stating reverse acting spiral element in step 2 is quartz glass.
6. the method according to claim 1 for generating axisymmetric vectoring light beam based on crystal optical activity, which is characterized in that institute
Gyrotropi crystal is stated in step 1 at room temperature along plug Mir's equation of gyrotropi crystal optical axis direction specific rotatory power are as follows:Wherein the unit of λ is μm, and the unit of α is °/mm.
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Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
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CN109870823A (en) * | 2019-04-03 | 2019-06-11 | 中国科学院理化技术研究所 | A polarized light intensity shaping device |
CN115014532A (en) * | 2022-08-01 | 2022-09-06 | 中国工程物理研究院应用电子学研究所 | Three-dimensional polarization measurement system based on sub-wavelength unit structure |
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CN1910522A (en) * | 2004-01-16 | 2007-02-07 | 卡尔蔡司Smt股份公司 | Polarization-modulating optical element |
JP2011060870A (en) * | 2009-09-08 | 2011-03-24 | Nikon Corp | Polarization conversion unit, illumination optical system, aligner, and method of manufacturing device |
CN102830499A (en) * | 2012-09-05 | 2012-12-19 | 山东大学 | Vector light field converter and polarized light converting method |
CN107976821A (en) * | 2018-01-04 | 2018-05-01 | 中国人民解放军国防科技大学 | An optical converter from linearly polarized light to radially polarized light |
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US20050195480A1 (en) * | 2004-01-12 | 2005-09-08 | Brown Thomas G. | System and method converting the polarization state of an optical beam into an inhomogeneously polarized state |
CN1910522A (en) * | 2004-01-16 | 2007-02-07 | 卡尔蔡司Smt股份公司 | Polarization-modulating optical element |
JP2011060870A (en) * | 2009-09-08 | 2011-03-24 | Nikon Corp | Polarization conversion unit, illumination optical system, aligner, and method of manufacturing device |
CN102830499A (en) * | 2012-09-05 | 2012-12-19 | 山东大学 | Vector light field converter and polarized light converting method |
CN107976821A (en) * | 2018-01-04 | 2018-05-01 | 中国人民解放军国防科技大学 | An optical converter from linearly polarized light to radially polarized light |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
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CN109870823A (en) * | 2019-04-03 | 2019-06-11 | 中国科学院理化技术研究所 | A polarized light intensity shaping device |
CN115014532A (en) * | 2022-08-01 | 2022-09-06 | 中国工程物理研究院应用电子学研究所 | Three-dimensional polarization measurement system based on sub-wavelength unit structure |
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