Two-dimensional beam deflection device and method based on lithium tantalate crystal

Abstract

The application provides a two-dimensional light beam deflection device and method based on a lithium tantalate crystal. The device comprises a lithium tantalate crystal, wherein the lithium tantalate crystal comprises a light input surface, a light output surface opposite to the light input surface, a first surface, a second surface opposite to the first surface, a third surface and a fourth surface opposite to the third surface; the first surface and the second surface are provided with a first-dimension light beam deflection area in correspondence; and the third surface and the fourth surface are provided with a second-dimension light beam deflection area in correspondence. The application has the advantages of easy integration, high speed, small volume and multi-dimension deflection.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electro-optical regulation, and in particular to a two-dimensional light beam deflection device and method based on lithium tantalate crystal. BACKGROUND

[0002] A light beam deflector (or scanner) is a device for changing the direction of light beam propagation in space, which has a wide range of applications in laser radar, laser processing, optical storage, optical display and optical communication. The main techniques of light beam deflection include mechanical light beam deflection, acousto-optic light beam deflection and electro-optic light beam deflection. Traditional mechanical deflection changes the incident angle of light beam by rotating or vibrating optical elements, thereby realizing the deflection scanning of reflected light or transmitted light, but has problems such as large weight and volume, slow response speed, poor stability, etc. Acousto-optic deflection changes the refractive index of medium by changing the frequency of sound wave, so as to deflect the light beam. However, this method is not suitable for high-speed scanning. Electro-optic deflection changes the propagation direction of light beam by using electro-optic effect, and the scanning speed is determined by the crystal itself, so high-speed scanning can be realized, but the light beam can only be deflected or scanned in one dimension, and two-dimensional light beam deflection cannot be realized. SUMMARY

[0003] Therefore, the present application aims to provide a two-dimensional light beam deflection device and method based on lithium tantalate crystal to solve the above problems.

[0004] The technical scheme adopted by the present application is as follows:

[0005] A two-dimensional light beam deflection device based on lithium tantalate crystal comprises:

[0006] A lithium tantalate crystal, which comprises a light input surface, a light output surface opposite to the light input surface, a first surface and a second surface opposite to the first surface, a third surface and a fourth surface opposite to the third surface; the first surface and the second surface form a first-dimensional light beam deflection area arranged correspondingly, and the third surface and the fourth surface form a second-dimensional light beam deflection area arranged correspondingly; wherein:

[0007] The first-dimensional light beam deflection area is configured to change the refractive index of the lithium tantalate crystal in the area based on electro-optic effect under the action of an applied electric field, so as to deflect the light beam;

[0008] The second-dimensional light beam deflection area is configured to rotate the principal axis of the lithium tantalate crystal in the area based on the quasi-phase matching condition under the action of an applied electric field, so as to deflect the output light.

[0009] Preferably, the first-dimensional light beam deflection area and the second-dimensional light beam deflection area do not overlap in the direction of light beam propagation.

[0010] Preferably, the first-dimension light beam deflection region comprises a first structure electrode arranged on the first surface for connecting the positive pole of the power supply, and a first substrate electrode arranged on the second surface for connecting the negative pole of the power supply.

[0011] Preferably, the first structure electrode is formed by a plurality of continuous isosceles triangle units arranged along the light transmission direction, and the adjacent isosceles triangle units are in contact.

[0012] Preferably, the second-dimension light beam deflection region comprises a second structure electrode arranged on the third surface for connecting the positive pole of the power supply, and a second substrate electrode arranged on the fourth surface for connecting the negative pole of the power supply.

[0013] Preferably, the second structure electrode is formed by a plurality of continuous wedge units arranged along the light transmission direction, and the adjacent wedge units are in contact.

[0014] Preferably, the period of the wedge unit is Λ = λ / |n o -n e | to meet the quasi-phase matching condition, λ is the wavelength of the incident light, n o is the ordinary light refractive index, and n e is the extraordinary light refractive index.

[0015] Preferably, the structure electrode and the substrate electrode are made of gold, and the thickness is 200 nm.

[0016] The embodiment of the present application also provides a two-dimensional light beam deflection method based on the two-dimensional light beam deflection device based on the lithium tantalate crystal as described above, which comprises the following steps:

[0017] The positive pole of the first voltage source is connected to the first structure electrode of the first-dimension light beam deflection region, and the negative pole is connected to the first substrate electrode.

[0018] The positive pole of the second voltage source is connected to the second structure electrode of the second-dimension light beam deflection region, and the negative pole is connected to the corresponding second substrate electrode.

[0019] The polarized input light is incident from the light input surface.

[0020] The voltage is applied between the corresponding two electrodes according to the required light beam deflection; wherein the voltage applied between the two electrodes of the first-dimension light beam deflection region realizes the light beam deflection in the first dimension, and the voltage applied between the two electrodes of the second-dimension light beam deflection region realizes the light beam deflection in the second dimension; the angles and directions of the light beam deflection in the two dimensions are controlled by adjusting the voltage of the respective voltage source.

[0021] In summary, the embodiment of the present application divides the lithium tantalate crystal into a first dimension beam deflection area and a second dimension beam deflection area, and can realize single first dimension beam deflection or second dimension beam deflection, or two-dimensional beam deflection. The embodiment can solve the problems of slow response speed, large volume and single dimension deflection of the current beam deflection device, and provides a new scheme for two-dimensional beam deflection technology, and has the technical effects of easy integration, high speed, small volume and multi-dimension deflection. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a structure schematic diagram of a two-dimensional beam deflection device based on a lithium tantalate crystal provided by the first embodiment of the present application.

[0023] Figure 2 is a working effect schematic diagram of a specific embodiment of the present application;

[0024] Figure 3 is another working effect schematic diagram of a specific embodiment of the present application;

[0025] Figure 4 is another working effect schematic diagram of a specific embodiment of the present application. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only 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 other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0027] Please refer to Figure 1 The first embodiment of the present application provides a two-dimensional beam deflection device based on a lithium tantalate crystal, which comprises:

[0028] The lithium tantalate crystal 10 comprises a light input face 11, a light output face 12 opposite to the light input face 11, a first surface 13 and a second surface 14 opposite to the first surface 13, a third surface 15 and a fourth surface 16 opposite to the third surface 15.

[0029] In the embodiment, the chemical formula of the lithium tantalate is LiTaO3, which is colorless or light yellow crystal. The ferroelectric phase lithium tantalate crystal is a “universal” material in the field of functional materials, which has good mechanical and physical properties and low cost, and is widely used in the IT industry centered on the optical technology industry as a nonlinear optical crystal, electro-optic crystal, piezoelectric crystal, acousto-optic crystal and birefringent crystal.

[0030] In the embodiment, the direction in which the light input face 11 points to the light output face 12 is the transmission direction of light, as shown in the y direction in FIG. Figure 1 .

[0031] In the embodiment, the first surface 13 and the second surface 14 are formed with a first dimension light beam deflection region 17 arranged correspondingly, and the third surface 15 and the fourth surface 16 are formed with a second dimension light beam deflection region 18 arranged correspondingly. As shown in FIG. Figure 1 , the direction in which the first surface 13 points to the second surface 14 is the z direction, and the direction in which the third surface 15 points to the fourth surface 16 is the x direction.

[0032] In the embodiment, the first dimension light beam deflection region 17 includes a first structure electrode 21 arranged on the first surface 13 for connecting the positive pole of a power supply and a first substrate electrode 22 arranged on the second surface 14 for connecting the negative pole of the power supply, which are configured to change the refractive index of the lithium tantalate crystal in the region based on the electro-optic effect under the action of an applied electric field, so as to deflect the light beam.

[0033] Specifically, the first structure electrode 21 is formed by arranging a plurality of continuous isosceles triangle units with equal height along the light transmission direction, and the adjacent isosceles triangle units are in contact at the base. In particular, the height of the isosceles triangle unit is the length of the lithium tantalate crystal 10 in the x direction, but is not limited thereto.

[0034] In the embodiment, the second dimension light beam deflection region 18 includes a second structure electrode 23 arranged on the third surface for connecting the positive pole of a power supply and a second substrate electrode 24 arranged on the fourth surface for connecting the negative pole of the power supply, which are configured to rotate the principal axis of the lithium tantalate crystal in the region based on the S-G effect under the action of an applied electric field, and to deflect the output light when the quasi-phase matching condition is met.

[0035] Specifically, the second structure electrode 23 is formed by arranging a plurality of continuous wedge units with fixed height along the light transmission direction, and the adjacent wedge units are in contact at the base. In particular, the height of the wedge unit is the length of the lithium tantalate crystal 10 in the z direction, but is not limited thereto.

[0036] In addition, it should be noted that the second dimension light beam deflection needs to meet the quasi-phase matching condition (structure electrode period Λ = λ / |n o -n e |) to realize the light beam deflection function. Since the period Λ of the second structure electrode 23 is fixed, it is necessary to control the wavelength λ of the input light or to perform quasi-phase matching by changing the refractive index difference |n o -n e | of the crystal, where no n0 is the ordinary light refractive index e n0 is the ordinary light refractive index

[0037] It should be noted that the above-mentioned various structural electrodes and substrate electrodes can be made of conductive materials, such as conductive metals such as gold, aluminum, silver, etc. In particular, in the present embodiment, each of the structural electrodes and the substrate electrodes is made of gold, and the thickness is 200 nm. The structural electrodes and the substrate electrodes can be implemented by plating, and the specific thickness can be set according to actual needs.

[0038] In the actual working process, the voltage can be applied between the corresponding two electrodes according to the required beam deflection; wherein the voltage applied between the two electrodes in the first dimension beam deflection area realizes the light beam deflection in the first dimension, and the voltage applied between the two electrodes in the second dimension beam deflection area realizes the light beam deflection in the second dimension; the angle and direction of the light beam deflection in two dimensions are controlled by adjusting the voltage of the respective voltage source. The application of the present application will be described below with some practical examples.

[0039] (1), the voltage applied between the first structural electrode 21 and the first substrate electrode 22 in the first dimension beam deflection area 17 realizes the light beam deflection in the first dimension

[0040] First, the polarized light is incident into the lithium tantalate crystal 10 through the light input surface 11, and the light beam propagates along the central axis direction of the first structural electrode 21 and the second structural electrode 23;

[0041] Then, the first structural electrode 21 in the first dimension beam deflection area is connected to the positive electrode of the first voltage source, and the corresponding first substrate electrode 22 is connected to the negative electrode of the first voltage source, that is, the voltage is applied between the two electrodes in the first dimension beam deflection area 17 of the lithium tantalate crystal 10. Due to the electro-optic effect of the lithium tantalate crystal 10, the refractive index of the lithium tantalate crystal under the first structural electrode 21 area will change, so the propagation direction of the light will deflect left and right along the x axis.

[0042] Wherein, the direction of the light beam deflection is controlled by the direction of the applied electric field, which is specifically manifested as, if the voltage source applies a positive voltage, the refractive index of the lithium tantalate crystal under the first structural electrode 21 area will increase, according to the refraction law, the light beam will deflect to the place with high refractive index, thereby realizing the light beam deflection effect, and if the first voltage source applies a negative voltage, the direction of the light beam deflection is opposite, as shown in Figure 2

[0043] (2), the voltage applied between the second structural electrode 23 and the second substrate electrode 24 in the second dimension beam deflection area 18 realizes the light beam deflection in the second dimension

[0044] ​Firstly, polarized light is incident into the lithium tantalate crystal 10 through the light input face 11, and the light beam propagates along the central axis direction of the first structure electrode 21 and the second structure electrode 23;

[0045] Then, the second structure electrode 23 of the second dimension light beam deflection region 18 is connected to the positive pole of the second voltage source, and the second substrate electrode 24 is connected to the negative pole of the second voltage source, that is, the voltage is applied to the two electrodes in the second dimension light beam deflection region 18 of the lithium tantalate crystal 10. Under the action of the applied electric field, the principal axis of the lithium tantalate crystal under the second structure electrode 23 rotates, and the principal axes of other regions remain unchanged. When the quasi-phase matching condition (the period of the second structure electrode 23 Λ = λ / |n o –n e |) is met, the propagation direction of the output light will deflect up and down along the z axis.

[0046] Wherein, the direction of the light beam deflection is controlled by the direction of the applied electric field, and specifically, if the second voltage source applies a positive voltage, the light beam deflects to the -z axis direction, and if the second voltage source applies a negative voltage, the light beam deflects to the +z axis direction, as shown in Figure 3 .

[0047] (3), the voltage is applied between the electrodes of the first dimension light beam deflection region 17 and the second dimension light beam deflection region 18

[0048] Firstly, polarized light is incident into the lithium tantalate crystal 10 through the light input face 11, and the light beam propagates along the central axis direction of the first structure electrode 21 and the second structure electrode 23;

[0049] Then, the first structure electrode 21 of the first dimension light beam deflection region 17 is connected to the positive pole of the first voltage source, and the first substrate electrode 22 is connected to the negative pole of the first voltage source, and at the same time, the second structure electrode 23 of the second dimension light beam deflection region 18 is connected to the positive pole of the second voltage source, and the second substrate electrode 24 is connected to the negative pole of the second voltage source, that is, the voltage is applied to the first dimension light beam deflection region 17 and the second dimension light beam deflection region 18 of the lithium tantalate crystal 10. When the light beam passes through the first dimension light beam deflection region 17 of the lithium tantalate crystal, it will deflect along the x axis direction, and when it passes through the second dimension light beam deflection region 18, it will deflect along the z axis direction, finally realizing two-dimensional light beam deflection, as shown in Figure 4 .

[0050] Wherein, the direction of the light beam deflection in each dimension is controlled by the direction of the electric field applied between the electrodes of the light beam deflection region, and the deflection angle is controlled by the strength of the electric field, but the maximum deflection angle is limited by the design of the crystal itself and the structure electrode.

[0051] In summary, the embodiment of the present application divides the lithium tantalate crystal into a first dimension light beam deflection area and a second dimension light beam deflection area, and can realize single first dimension light beam deflection or second dimension light beam deflection, or two-dimensional light beam deflection. The embodiment can solve the problems of slow response speed, large volume and single dimension deflection of current light beam deflection devices, and provides a new scheme for two-dimensional light beam deflection technology, and has technical effects of easy integration, high speed, small volume, multi-dimension deflection and the like.

[0052] The above merely describes the preferred embodiments of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement and the like within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A two-dimensional beam deflection device based on lithium tantalate crystals, characterized in that The application relates to a lithium tantalate crystal-based two-dimensional light beam deflection device. The lithium tantalate crystal comprises a light input surface, a light output surface opposite to the light input surface, a first surface and a second surface opposite to the first surface, a third surface and a fourth surface opposite to the third surface; the first surface and the second surface are provided with a first-dimensional light beam deflection area arranged correspondingly, and the third surface and the fourth surface are provided with a second-dimensional light beam deflection area arranged correspondingly; wherein: the first-dimensional light beam deflection area is configured to change the refractive index of the lithium tantalate crystal in the area based on the electro-optic effect under the action of an applied electric field, so as to deflect the light beam; the second-dimensional light beam deflection area is configured to rotate the principal axis of the lithium tantalate crystal in the area based on the quasi-Stern-Gerlach effect under the action of an applied electric field, and deflect the output light when the quasi-phase matching condition is met.

2. The lithium tantalate crystal-based two-dimensional light beam deflection device according to claim 1, wherein the first-dimensional light beam deflection area and the second-dimensional light beam deflection area do not overlap in the light beam propagation direction. The first-dimensional light beam deflection area comprises a first structure electrode arranged on the first surface for connecting the positive pole of a power supply and a first substrate electrode arranged on the second surface for connecting the negative pole of the power supply. The first structure electrode is formed by arranging a plurality of continuous isosceles triangle units in the light transmission direction, and the bottom edges of adjacent isosceles triangle units are in contact.

3. The two-dimensional beam deflector based on lithium tantalate crystals according to claim 1, characterized in that The second-dimensional light beam deflection area comprises a second structure electrode arranged on the third surface for connecting the positive pole of a power supply and a second substrate electrode arranged on the fourth surface for connecting the negative pole of the power supply.

4. The two-dimensional beam deflector based on lithium tantalate crystal according to claim 3, characterized in that The second structure electrode is formed by arranging a plurality of continuous wedge units in the light transmission direction, and the bottom edges of adjacent wedge units are in contact.

5. The two-dimensional beam deflector based on lithium tantalate crystals according to claim 3, characterized in that The structure electrode and the substrate electrode are made of gold and have a thickness of 200 nm.

6. The two-dimensional beam deflector based on lithium tantalate crystal according to claim 5, characterized in that The application further relates to a method for deflecting a light beam by using the lithium tantalate crystal-based two-dimensional light beam deflection device.

7. The two-dimensional beam deflector based on lithium tantalate crystals according to claim 6, characterized in that Λ = λ / |n o –n e | to satisfy the quasi-phase matching condition, λ is the wavelength of the incident light, n o is the ordinary light refractive index, n e is the extraordinary light refractive index.

8. The two-dimensional beam deflector based on lithium tantalate crystal according to claim 5, characterized in that The positive pole of a first voltage source is connected to the first structure electrode of the first-dimensional light beam deflection area, and the negative pole is connected to the first substrate electrode.

9. A two-dimensional light beam deflection method based on a two-dimensional light beam deflection device based on lithium tantalate crystals according to any one of claims 1 to 8, characterized in that The positive pole of a second voltage source is connected to the second structure electrode of the second-dimensional light beam deflection area, and the negative pole is connected to the corresponding second substrate electrode. Polarized input light is incident from the light input surface. The voltage between the corresponding two electrodes is applied according to the required light beam deflection; wherein the voltage between the two electrodes in the first-dimensional light beam deflection area realizes the light beam deflection in the first dimension, and the voltage between the two electrodes in the second-dimensional light beam deflection area realizes the light beam deflection in the second dimension; the angles and directions of the light beam deflection in the two dimensions are controlled by adjusting the voltage of the respective voltage source. ​ ​

Images