Method and structure for suppressing energy loss

Abstract

The invention relates to a method and a structure for inhibiting energy loss, which solve the problems of low energy transmittance and the like of the existing liquid crystal wave plate. The structure comprises a liquid crystal layer; the first alignment film and the second alignment film are respectively contacted with two sides of the liquid crystal layer and are used for aligning the liquid crystal layer; a first substrate and a second substrate; the air-substrate interface refractive index matching films are respectively plated on the outer sides of the two substrates and are used for reducing Fresnel reflection energy loss between the air and the interface of the first substrate and between the air and the interface of the second substrate; the conductive films are respectively plated on the inner sides of the two substrates and are used for driving the liquid crystal layer; and the first conducting film-liquid crystal refractive index matching film and the second conducting film-liquid crystal refractive index matching film are respectively plated on the two conducting films and are respectively used for reducing energy loss caused by an interface between the conducting films and the liquid crystal layer. According to the structure, the energy utilization efficiency of the liquid crystal wave plate can be remarkably improved, and the requirements of efficient, large-angle and non-continuous light beam deflection based on the liquid crystal wave plate and the liquid crystal polarization grating are met.

Description

Technical Field

[0001] The invention belongs to the technical field of non-mechanical light beam deflection, and specifically refers to a method and structure for suppressing energy loss. Background Art

[0002] As a core component in optoelectronic information fields such as laser radar, laser communication, and laser active imaging, the performance of the beam deflection module directly determines the overall efficiency of the system. As an emerging geometric phase optical element, the liquid crystal polarization grating has brought a revolutionary breakthrough in beam deflection technology with its unique advantages such as large aperture, high efficiency, and wide angle. The new beam deflection technology based on liquid crystal polarization grating can not only meet the two key performance indicators of large aperture and large angle at the same time, but also significantly improve the overall performance of the system, making it have broad application prospects in defense and national security fields such as satellite laser communication, airborne laser radar, medium-wave infrared staring imaging, ToF camera, laser confrontation, and laser guidance.

[0003] At present, the beam deflection technology based on liquid crystal polarization grating mainly adopts a cascade structure, that is, a combination of multiple liquid crystal wave plates and liquid crystal polarization gratings is used to achieve large-angle, non-continuous beam deflection. Although this structure has the advantages of simple control strategy, high reliability, easy to achieve lightweight and miniaturization, flexible control and low power consumption, it also has obvious limitations. Since the energy utilization efficiency of each liquid crystal wave plate in the cascade structure will have a cumulative effect on the overall performance, the energy loss problem of a single liquid crystal wave plate has become a bottleneck restricting the engineering application of liquid crystal polarization grating technology.

[0004] The energy utilization efficiency of liquid crystal wave plates is mainly determined by two key factors: energy transmittance and light control efficiency. Among them, energy transmittance is significantly affected by the refractive index matching degree of the liquid crystal wave plate interface and the Fabry-Perot effect of the liquid crystal layer. Moreover, as the birefringence difference of the liquid crystal (Δn = n e -n o ) increases, the refractive index of the conductive film will be more difficult to match n e and n o , which will make the Fabry-Perot effect in the liquid crystal layer more significant, leading to more serious energy loss. Summary of the invention

[0005] In order to solve the problems of severe energy loss and low energy transmittance caused by the mismatch of refractive index of multiple interfaces in the current liquid crystal wave plate, the present invention provides a method and structure for suppressing energy loss, which can eliminate the interface energy loss to the maximum extent by optimizing the design of each film layer system of the liquid crystal wave plate, and effectively suppress the Fabry-Perot effect in the liquid crystal layer, thereby realizing a liquid crystal wave plate with high energy transmittance. The present invention can not only significantly improve the overall energy utilization efficiency of the cascade structure, but also lay a solid foundation for the engineering application of liquid crystal polarization grating technology.

[0006] To solve the above problems, the present invention adopts the following technical solutions:

[0007] A method for suppressing energy loss comprises the following steps:

[0008] Step 1: a first air-substrate interface refractive index matching film and a second air-substrate interface refractive index matching film are respectively plated on the outer sides of a first substrate and a second substrate for supporting a liquid crystal layer, wherein the first air-substrate interface refractive index matching film is used to reduce the Fresnel reflection energy loss at the interface between air and the first substrate, and the second air-substrate interface refractive index matching film is used to reduce the Fresnel reflection energy loss at the interface between air and the second substrate;

[0009] Step 2: coating a first conductive film and a second conductive film on inner sides of the first substrate and the second substrate respectively, wherein the first conductive film and the second conductive film are used to drive the liquid crystal layer;

[0010] Step 3: Forming a first conductive film-liquid crystal refractive index matching film and a second conductive film-liquid crystal refractive index matching film on the first conductive film and the second conductive film, respectively. The first conductive film-liquid crystal refractive index matching film is used to reduce energy loss caused by the interface between the first conductive film and the liquid crystal layer, and the second conductive film-liquid crystal refractive index matching film is used to reduce energy loss caused by the interface between the second conductive film and the liquid crystal layer.

[0011] Step 4: Spin coating the first conductive film-liquid crystal refractive index matching film and the second conductive film-liquid crystal refractive index matching film to form a first alignment film and a second alignment film, respectively, the first alignment film and the second alignment film being used to align the liquid crystal layer;

[0012] Step 5: injecting liquid crystal material between the first alignment film and the second alignment film to form a liquid crystal layer.

[0013] At the same time, the present invention also proposes a structure for suppressing energy loss, including:

[0014] Liquid crystal layer;

[0015] A first alignment film and a second alignment film respectively contacting two sides of the liquid crystal layer, and used for aligning the liquid crystal layer;

[0016] The first substrate and the second substrate are used to support the first alignment film, the second alignment film and the liquid crystal layer;

[0017] A first air-substrate interface refractive index matching film plated on the outer side of the first substrate, used to reduce Fresnel reflection energy loss at the interface between air and the first substrate;

[0018] A second air-substrate interface refractive index matching film plated on the outer side of the second substrate is used to reduce Fresnel reflection energy loss at the interface between the air and the second substrate;

[0019] A first conductive film and a second conductive film respectively plated on the inner sides of the first substrate and the second substrate, for driving the liquid crystal layer;

[0020] A first conductive film-liquid crystal refractive index matching film plated on the first conductive film and in contact with the first orientation film, used to reduce energy loss caused by the interface between the first conductive film and the liquid crystal layer;

[0021] The second conductive film-liquid crystal refractive index matching film plated on the second conductive film and in contact with the second orientation film is used to reduce the energy loss caused by the interface between the second conductive film and the liquid crystal layer.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention provides a method and structure for suppressing energy loss, which is different from the traditional method and structure for suppressing energy loss of liquid crystal wave plates. Instead, a refractive index matching film is plated between the conductive film and the liquid crystal layer, and the refractive index matching film is plated at the air-substrate interface. This can fundamentally eliminate the Fresnel reflection loss introduced by the multi-interface refractive index mismatch, greatly suppress the Fabry-Perot effect in the liquid crystal layer, and achieve energy loss suppression of the liquid crystal wave plate. By implementing the present invention, the energy utilization efficiency of the liquid crystal wave plate can be significantly improved, meeting the needs of efficient, large-angle, and discontinuous beam deflection based on the liquid crystal wave plate and the liquid crystal polarization grating. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of a structure for suppressing energy loss according to one embodiment of the present invention;

[0025] Figure 2 A flow chart of a method for suppressing energy loss according to another embodiment of the present invention;

[0026] Explanation of the accompanying drawings: 1. first air-substrate interface refractive index matching film; 2. first substrate; 3. first conductive film; 4. first conductive film-liquid crystal refractive index matching film; 5. first orientation film; 6. liquid crystal layer; 7. second orientation film; 8. second conductive film-liquid crystal refractive index matching film; 9. second conductive film; 10. second substrate; 11. second air-substrate interface refractive index matching film. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0028] See also Figure 1 The present embodiment provides a structure for suppressing energy loss, which specifically includes a first air-substrate interface refractive index matching film 1, a first substrate 2, a first conductive film 3, a first conductive film-liquid crystal refractive index matching film 4, a first orientation film 5, a liquid crystal layer 6, a second orientation film 7, a second conductive film-liquid crystal refractive index matching film 8, a second conductive film 9, a second substrate 10 and a second air-substrate interface refractive index matching film 11.

[0029] The first alignment film 5 and the second alignment film 7 are respectively in contact with two sides of the liquid crystal layer 6 to align the liquid crystal layer 6 .

[0030] The first substrate 2 and the second substrate 10 are used to support the liquid crystal layer 6 and the first alignment film 5 and the second alignment film 7 .

[0031] The first air-substrate interface refractive index matching film 1 and the second air-substrate interface refractive index matching film 11 are respectively plated on the outer sides of the first substrate 2 and the second substrate 10. It can be seen from the Fresnel formula that the first air-substrate interface refractive index matching film 1 can significantly reduce the Fresnel reflection energy loss at the interface between air and the first substrate 2, and the second air-substrate interface refractive index matching film 11 can significantly reduce the Fresnel reflection energy loss at the interface between air and the second substrate 10.

[0032] The first conductive film 3 and the second conductive film 9 are respectively plated on the inner sides of the first substrate 2 and the second substrate 10, that is, the back sides opposite to the first air-substrate interface refractive index matching film 1 and the second air-substrate interface refractive index matching film 11. The first conductive film 3 and the second conductive film 9 are used to drive the liquid crystal layer 6 under the action of applied voltage V.

[0033] The first conductive film-liquid crystal refractive index matching film 4 and the second conductive film-liquid crystal refractive index matching film 8 are respectively plated on the first conductive film 3 and the second conductive film 9, and the first conductive film 3 is in contact with the first orientation film 5, and the second conductive film 9 is in contact with the second orientation film 7. It can be seen from the Fresnel formula that the first conductive film-liquid crystal refractive index matching film 4 can significantly reduce the energy loss caused by the interface between the first conductive film 3 and the liquid crystal layer 6, and the second conductive film-liquid crystal refractive index matching film 8 can significantly reduce the energy loss caused by the interface between the second conductive film 9 and the liquid crystal layer 6. In this embodiment, by plating the refractive index matching film between the conductive film and the liquid crystal layer, the Fresnel reflection energy loss caused by the interface refractive index mismatch can be significantly reduced, and the Fabry-Perot effect in the liquid crystal layer can also be reduced, thereby ultimately reducing the energy loss at the conductive film-liquid crystal interface.

[0034] Furthermore, the liquid crystal layer 6 in this embodiment is regularly oriented under the action of the first alignment film 5 and the second alignment film 7, forming a mode including but not limited to an antiparallel alignment mode, a parallel alignment mode, and a vertical alignment mode, and the effective refractive index of the liquid crystal layer 6 changes under the control of the voltage, and the effective refractive index of the liquid crystal layer 6 is:

[0035]

[0036] Among them, n eff is the effective refractive index of the liquid crystal layer 6 at a certain voltage V, n e and n o are the extraordinary refractive index and ordinary refractive index of the liquid crystal molecules, respectively, and θ is the tilt angle of the liquid crystal molecules in the direction perpendicular to the substrate.

[0037] Furthermore, the film structure of the first conductive film-liquid crystal refractive index matching film 4 and the second conductive film-liquid crystal refractive index matching film 8 in this embodiment is first designed according to the refractive index of the conductive film and the average refractive index of the liquid crystal layer 6, and a conventional film design method is used. Then, the designed film structure and the liquid crystal layer are combined to construct a light diffraction model, and the quality of the above film structure is evaluated based on the energy transmittance as a criterion. The design of the above film structure is achieved by repeated iterations, wherein the average refractive index of the liquid crystal layer 6 is:

[0038]

[0039] in, is the average refractive index of the liquid crystal layer 6, n e and n o They are the extraordinary refractive index and ordinary refractive index of the liquid crystal molecules respectively.

[0040] In this embodiment, the first air-substrate interface refractive index matching film 1, the second air-substrate interface refractive index matching film 11, the first conductive film-liquid crystal refractive index matching film 4 and the second conductive film-liquid crystal refractive index matching film 8 all depend on the wavelength and angle of the incident light, that is, the wavelength or angle of the incident light is different, and the first air-substrate interface refractive index matching film 1, the second air-substrate interface refractive index matching film 11, the first conductive film-liquid crystal refractive index matching film 4 and the second conductive film-liquid crystal refractive index matching film 8 have different parameters such as the number of layers, refractive index distribution, and thickness, and the corresponding plating processes are different. The specific corresponding relationship requires precise film layer structure design.

[0041] This embodiment also provides a specific example of a structure for suppressing the energy loss of a liquid crystal wave plate, and conducts an energy efficiency comparison experiment.

[0042] In this example, the first substrate 2 and the second substrate 10 are coated with the first air-substrate interface refractive index matching film 1 and the second air-substrate interface refractive index matching film 11. When the first conductive film-liquid crystal refractive index matching film 4 and the second conductive film-liquid crystal refractive index matching film 8 are not coated, the operating wavelength of the liquid crystal wave plate is 1550nm. e =1.86, n o =1.52, Δn=n e -n o =0.34, the thickness of the liquid crystal layer 6 is 5.0 μm, the liquid crystal layer 6 is in an anti-parallel orientation mode, and the linearly polarized light is vertically incident and emitted.

[0043] When the incident polarized light direction is aligned with the long axis direction of the liquid crystal molecules (n e ) is 0°, the energy transmittance of the liquid crystal wave plate is measured by a power meter to be 91.7%;

[0044] When the incident polarized light direction is aligned with the long axis direction of the liquid crystal molecules (n e ) is 45°, the energy transmittance of the liquid crystal wave plate is measured by a power meter to be 94.7%;

[0045] When the incident polarized light direction is aligned with the long axis direction of the liquid crystal molecules (n e ) is 90° (n o ), the energy transmittance of the liquid crystal wave plate was measured by a power meter and was found to be 97.1%.

[0046] After designing and coating the first conductive film-liquid crystal refractive index matching film 4 and the second conductive film-liquid crystal refractive index matching film 8 according to the above-mentioned conductive film, liquid crystal refractive index and liquid crystal thickness parameters, the energy transmittance of the liquid crystal wave plate is retested. e) are 0°, 45°, and 90°, respectively, the energy transmittance of the liquid crystal wave plate is 95.5%, 96.8%, and 97.2%, respectively. Compared with before the first conductive film-liquid crystal refractive index matching film 4 and the second conductive film-liquid crystal refractive index matching film 8 are plated, the energy transmittance is increased by 3.8%, 2.1%, and 0.1%, respectively.

[0047] It can be seen from the above examples that the structure for suppressing energy loss proposed by the present invention significantly improves the energy transmittance of the liquid crystal wave plate, and will play an important role especially when used in a cascade structure.

[0048] See also Figure 2 In another embodiment, a method for suppressing energy loss is provided, the method mainly comprising the following steps:

[0049] Step 1: A first air-substrate interface refractive index matching film 1 and a second air-substrate interface refractive index matching film 11 are respectively plated on the outer sides of the first substrate 2 and the second substrate 10 for supporting the liquid crystal layer 6, wherein the first air-substrate interface refractive index matching film 1 is used to reduce the Fresnel reflection energy loss at the interface between the air and the first substrate 2, and the second air-substrate interface refractive index matching film 11 is used to reduce the Fresnel reflection energy loss at the interface between the air and the second substrate 10.

[0050] Step 2: The first conductive film 3 and the second conductive film 9 are respectively plated on the outer sides of the first substrate 2 and the second substrate 10. The first conductive film 3 and the second conductive film 9 are used to drive the liquid crystal layer 6 under the action of the applied voltage V.

[0051] Step 3: A first conductive film-liquid crystal refractive index matching film 4 and a second conductive film-liquid crystal refractive index matching film 8 are respectively deposited on the first conductive film 3 and the second conductive film 9, wherein the first conductive film-liquid crystal refractive index matching film 4 is used to reduce the energy loss caused by the interface between the first conductive film 3 and the liquid crystal layer 6, and the second conductive film-liquid crystal refractive index matching film 8 is used to reduce the energy loss caused by the interface between the second conductive film 9 and the liquid crystal layer 6.

[0052] Step 4: Spin-coat the first alignment film 5 and the second alignment film 7 on the first conductive film-liquid crystal refractive index matching film 4 and the second conductive film-liquid crystal refractive index matching film 8 respectively, wherein the first alignment film 5 and the second alignment film 7 are used to align the liquid crystal layer 6 .

[0053] Step 5: After orientation, the film is pressed into a box, and then a liquid crystal material is poured between the first orientation film 5 and the second orientation film 7 to form a liquid crystal layer (6), and finally a liquid crystal wave plate capable of suppressing energy loss is obtained.

[0054] Furthermore, the liquid crystal layer 6 in this embodiment is regularly oriented under the action of the first orientation film 5 and the second orientation film 7, forming an antiparallel orientation mode, a parallel orientation mode, and a vertical orientation mode, and the effective refractive index of the liquid crystal layer 6 changes under the control of the voltage, and the effective refractive index of the liquid crystal layer 6 is:

[0055]

[0056] Among them, n eff is the effective refractive index of the liquid crystal layer 6 at a certain voltage V, n e and n o are the extraordinary refractive index and ordinary refractive index of the liquid crystal molecules, respectively, and θ is the tilt angle of the liquid crystal molecules in the direction perpendicular to the substrate.

[0057] Furthermore, the film structure of the first conductive film-liquid crystal refractive index matching film 4 and the second conductive film-liquid crystal refractive index matching film 8 in this embodiment is first designed according to the refractive index of the conductive film and the average refractive index of the liquid crystal layer 6, and a conventional film design method is used. Then, the designed film structure and the liquid crystal layer are combined to construct a light diffraction model, and the quality of the above film structure is evaluated based on the energy transmittance as a criterion. The design of the above film structure is achieved by repeated iterations, wherein the average refractive index of the liquid crystal layer 6 is:

[0058]

[0059] in, is the average refractive index of the liquid crystal layer 6, n e and n o They are the extraordinary refractive index and ordinary refractive index of the liquid crystal molecules respectively.

[0060] The method and structure for suppressing the energy loss of liquid crystal wave plates proposed in the present invention are different from the traditional methods and structures for suppressing the energy loss of liquid crystal wave plates. Instead, a refractive index matching film is plated between the conductive film and the liquid crystal layer, and the refractive index matching film is plated at the air-substrate interface. This can fundamentally eliminate the Fresnel reflection loss introduced by the multi-interface refractive index mismatch, greatly suppress the Fabry-Perot effect in the liquid crystal layer, and achieve the suppression of the energy loss of the liquid crystal wave plates. By implementing the present invention, the energy utilization efficiency of the liquid crystal wave plates can be significantly improved, meeting the needs of efficient, large-angle, and discontinuous beam deflection based on liquid crystal wave plates and liquid crystal polarization gratings.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for suppressing energy loss, characterized in that: The following steps are involved: Step 1: A first air-substrate interface refractive index matching film (1) and a second air-substrate interface refractive index matching film (11) are respectively plated on the outer sides of a first substrate (2) and a second substrate (10) for supporting a liquid crystal layer (6), wherein the first air-substrate interface refractive index matching film (1) is used to reduce the Fresnel reflection energy loss at the interface between air and the first substrate (2), and the second air-substrate interface refractive index matching film (11) is used to reduce the Fresnel reflection energy loss at the interface between air and the second substrate (10); Step 2: coating the first conductive film (3) and the second conductive film (9) on the inner sides of the first substrate (2) and the second substrate (10), respectively, wherein the first conductive film (3) and the second conductive film (9) are used to drive the liquid crystal layer (6); Step 3: a first conductive film-liquid crystal refractive index matching film (4) and a second conductive film-liquid crystal refractive index matching film (8) are respectively plated on the first conductive film (3) and the second conductive film (9), wherein the first conductive film-liquid crystal refractive index matching film (4) is used to reduce energy loss caused by the interface between the first conductive film (3) and the liquid crystal layer (6), and the second conductive film-liquid crystal refractive index matching film (8) is used to reduce energy loss caused by the interface between the second conductive film (9) and the liquid crystal layer (6); Step 4: Spin coating the first conductive film-liquid crystal refractive index matching film (4) and the second conductive film-liquid crystal refractive index matching film (8) to form a first orientation film (5) and a second orientation film (7), respectively, wherein the first orientation film (5) and the second orientation film (7) are used to orient the liquid crystal layer (6); Step 5: injecting liquid crystal material between the first orientation film (5) and the second orientation film (7) to form a liquid crystal layer (6).

2. A method for suppressing energy loss according to claim 1, characterized in that: The liquid crystal layer (6) is regularly oriented under the action of the first orientation film (5) and the second orientation film (7) to form any one of an antiparallel orientation mode, a parallel orientation mode, and a vertical orientation mode, and the effective refractive index of the liquid crystal layer (6) is: Among them, n eff is the effective refractive index of the liquid crystal layer (6) at voltage V, n e and n o are the extraordinary refractive index and ordinary refractive index of the liquid crystal molecules, respectively, and θ is the tilt angle of the liquid crystal molecules in the direction perpendicular to the substrate.

3. A method for suppressing energy loss according to claim 1 or 2, characterized in that: The average refractive index of the liquid crystal layer (6) is: n=(n e +n o ) / 2 Wherein, n is the average refractive index of the liquid crystal layer (6), n e and n o They are the extraordinary refractive index and ordinary refractive index of the liquid crystal molecules respectively.

4. A structure for suppressing energy loss, characterized in that: include: Liquid crystal layer (6); A first orientation film (5) and a second orientation film (7) respectively contacting two sides of the liquid crystal layer (6) and used for orienting the liquid crystal layer (6); A first substrate (2) and a second substrate (10), used for supporting a first alignment film (5), a second alignment film (7) and a liquid crystal layer (6); A first air-substrate interface refractive index matching film (1) plated on the outside of the first substrate (2) is used to reduce Fresnel reflection energy loss at the interface between air and the first substrate (2); A second air-substrate interface refractive index matching film (11) plated on the outside of the second substrate (10) is used to reduce Fresnel reflection energy loss at the interface between air and the second substrate (10); A first conductive film (3) and a second conductive film (9) respectively plated on the inner sides of the first substrate (2) and the second substrate (10), and used for driving the liquid crystal layer (6); A first conductive film-liquid crystal refractive index matching film (4) plated on the first conductive film (3) and in contact with the first orientation film (5), used to reduce energy loss caused by the interface between the first conductive film (3) and the liquid crystal layer (6); A second conductive film-liquid crystal refractive index matching film (8) plated on the second conductive film (9) and in contact with the second orientation film (7) is used to reduce energy loss caused by the interface between the second conductive film (9) and the liquid crystal layer (6).

5. The structure for suppressing energy loss according to claim 4, characterized in that: The liquid crystal layer (6) is regularly oriented under the action of the first orientation film (5) and the second orientation film (7) to form any one of an antiparallel orientation mode, a parallel orientation mode, and a vertical orientation mode, and the effective refractive index of the liquid crystal layer (6) is: Among them, n eff is the effective refractive index of the liquid crystal layer (6) at voltage V, n e and n o are the extraordinary refractive index and ordinary refractive index of the liquid crystal molecules, respectively, and θ is the tilt angle of the liquid crystal molecules in the direction perpendicular to the substrate.

6. A structure for suppressing energy loss according to claim 4 or 5, characterized in that: The average refractive index of the liquid crystal layer (6) is: in, is the average refractive index of the liquid crystal layer (6), n e and n o They are the extraordinary refractive index and ordinary refractive index of the liquid crystal molecules respectively.

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