JP2017090585A - Broadband wave plate and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin broadband wave plate.SOLUTION: The broadband wave plate includes: a glass substrate; a first laminated body including a first liquid crystal alignment layer and a first polymerizable liquid crystal layer; a second laminated body which is formed over the first laminated body and includes from the first polymerizable liquid crystal layer in order, a second liquid crystal alignment layer and a second polymerizable liquid crystal layer. The first polymerizable liquid crystal layer and the second polymerizable liquid crystal layer are different in alignment direction. The birefringence of the polymerizable liquid crystals is 0.1 or more respectively.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a thin wave plate applicable to a waveguide in a wide band and a manufacturing method thereof.

  Conventionally, it is known that a thin wave plate is used to control the polarization of an optical waveguide (Non-Patent Document 1). FIG. 1 shows an optical device 100 in which such a wave plate is inserted into a waveguide. In the optical device 100, for example, a groove 102 having a width of 20 μm and a depth of 150 μm is formed at the center target position of the lattice element of the arrayed waveguide 101, and a λ having a thickness of 15 μm is formed in the groove 102. By inserting the polyimide wave plate 103 having / 2, polarization dependency is eliminated. In FIG. 1, reference numeral 104 denotes a substrate, and reference numeral 105 denotes a principal axis direction (an axis giving an inclination of 45 ° with respect to the thickness direction of the optical device 100). Reference numeral d1 indicates an optical input, and reference numeral d2 indicates an optical output.

  The wave plate 103 described above has wavelength dependence, and has a λ / 2 wavelength region (region where the phase difference of birefringent light is λ / 2 wavelength) and a λ / 4 wavelength region (phase difference of birefringent light is λ). / 4 wavelength region) is narrow. For this reason, the wave plate 103 functions as a desired wave plate only in the vicinity of 1550 nm.

  Here, a crossed Nicol (two wavelength plates arranged in a straight line so that their main cross sections are perpendicular to each other) for a general single-layer λ / 2 wavelength plate and λ / 4 wavelength plate, FIG. 2 shows the calculation result of wavelength dependence with parallel Nicols (two wave plates arranged in a straight line so that their main cross sections are parallel to each other).

  FIG. 2A shows the calculation result of such a single-layer quarter-wave plate. FIG. 2B shows the calculation result of such a single-layer half-wave plate.

  According to the calculation results of FIGS. 2 (a) and 2 (b), it can be understood that only the vicinity of 1.55 μm functions as the half-wave plate and the quarter-wave plate. A method for improving the characteristics of a wave plate operating only in such a narrow wavelength band has been proposed in the display field.

In order to widen the above-mentioned half-wave plate, the half-wave plate whose delay axis θ ₂ is 22.5 ° relative to the optical axis in the plane of the wave plate and the delay axis θ ₁ is 67.5 °. It is known that a direction half-wave plate may be laminated. On the other hand, in order to make the quarter-wave plate broadband, it is only necessary to stack a half-wave plate with a delay axis θ1 of 15 ° direction and a quarter-wave plate with a delay axis θ2 of 75 ° direction. Are known. The calculation results at this time are shown in FIG.

FIG. 3A shows the calculation result of such a laminated half-wave plate (θ ₁ = 67.5 °, θ ₂ = 22.5 °). FIG. 3B shows a calculation result of such a laminated quarter wave plate (θ ₁ = 15 °, θ ₂ = 75 °). According to the calculation results of FIGS. 3A and 3B, it can be seen that the wavelength band is 1.3 μm to 1.9 μm.

  In order to improve the viewing angle of the liquid crystal display and correct the color using such a laminated wave plate, a birefringent film is laminated and bonded to the panel. In general, a stretched film is often used as the retardation film. The retardation Δn of the retardation film at this time is about 0.01 to 0.05, and the thickness of the half-wave plate or quarter-wave plate is several tens of μm. If these wave plates are bonded together with an acrylic or epoxy adhesive, a wide band can be realized, but the thickness of the entire wave plate becomes close to 100 μm.

T. Niwa, H. Hasegawa, K. Sato, “A 270 × 270 optical cross-connect switch utilizing wavelength routing with cascaded AWGs,” Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference (OFC / NFOEC) 2013, OTh1A.3 (2013).

  The laminated wave plate is laminated with a birefringent film. However, when the birefringent film is bonded, the thickness of the wave plate itself becomes too thick, so that it cannot be applied as a broadband wave plate for optical fibers or waveguides.

  For example, a film having a thickness of 30 μm causes a loss of 0.12 dB when inserted into a waveguide, whereas a film having a thickness of 100 μm causes a loss of 2.2 dB. A wave plate that causes such a large loss is not practical.

  In order to reduce the thickness of the wave plate, it is preferable that the birefringence Δn is large, but the Δn of the stretched film is only about 0.01 to 0.05 at the maximum. On the other hand, Δn of ordinary commercially available polymerizable liquid crystals has a birefringence of 0.15 to 0.2, which is several times that of a stretched film. Therefore, it is suitable for thinning. The following table shows Δn of polymerizable liquid crystals commercially available from typical liquid crystal manufacturers.

  However, since the polymerizable liquid crystal is a coating-type material, a substrate is required. However, if this substrate is thick, the total film thickness is increased.

  The present invention has been made under such circumstances, and an object thereof is to provide a thin and broadband wave plate.

  The invention for solving the above-described problems includes a transparent material layer, a first laminate formed on the transparent material layer and including a first liquid crystal alignment film layer and a first polymerizable liquid crystal layer, A second laminate including a second liquid crystal alignment film layer and a second polymerizable liquid crystal layer formed in order from the first polymerizable liquid crystal layer side, and formed on the first laminate. The first polymerizable liquid crystal layer and the second polymerizable liquid crystal layer have different orientation directions, and the birefringence of the first polymerizable liquid crystal layer and the second polymerizable liquid crystal layer is 0. .1 or more.

  Here, the retardation of birefringent light in the first polymerizable liquid crystal layer and the second polymerizable liquid crystal layer is λ / 2, and the first polymerizable liquid crystal layer and the second polymerizable liquid crystal layer are The angle formed by the optical axis with the liquid crystal layer may be not less than 35 ° and not more than 55 °.

  The phase difference of birefringent light in the first polymerizable liquid crystal layer is λ / 2, the phase difference of birefringent light in the second polymerizable liquid crystal layer is λ / 4, and the first The angle formed by the optical axis of the polymerizable liquid crystal layer and the second polymerizable liquid crystal layer may be 50 ° or more and 70 ° or less.

  The transparent material layer may be made of glass or polyimide.

  The overall thickness of the wave plate may be 30 μm or less.

  The invention for solving the above-mentioned problems is a method for producing a wave plate, wherein a first liquid crystal alignment film layer is applied on a transparent material layer and subjected to a rubbing treatment, and then the first liquid crystal alignment is performed. A step of applying and curing a first polymerizable liquid crystal layer on the film layer; and a second liquid crystal alignment film on the first polymerizable liquid crystal layer in this order from the first polymerizable liquid crystal layer side. And applying a rubbing treatment to the layer, and then applying and curing a second polymerizable liquid crystal layer on the second liquid crystal alignment film layer, and polishing the transparent material layer to obtain the wave plate. And making the total thickness of the substrate 30 μm or less.

  The invention for solving the above-mentioned problem is a method for producing a wave plate, which comprises applying a fluorinated polyimide to a Si substrate, applying a first liquid crystal alignment film layer, performing a rubbing treatment, Applying and curing a first polymerizable liquid crystal layer on one liquid crystal alignment film layer; and, on the first polymerizable liquid crystal layer, in order from the first polymerizable liquid crystal layer side, a second Applying a rubbing treatment after applying the liquid crystal alignment film layer, and applying and curing a second polymerizable liquid crystal layer on the second liquid crystal alignment film layer; and the fluorinated polyimide from the Si substrate. And the step of reducing the total thickness of the wave plate to 30 μm or less.

  According to the present invention, it is possible to realize a wave plate that is thinner and wider than the conventional one.

It is a figure which shows the structure of the optical device which inserted the conventional wavelength plate in the waveguide. It is a figure for demonstrating the calculation result of the wavelength dependence of a crossed Nicol and a parallel Nicol in a normal single layer 1/2 wavelength plate and a 1/4 wavelength plate. It is a figure for demonstrating the calculation result of the wavelength dependence of the crossed Nicol and parallel Nicol of the laminated | stacked broadband 1/2 wavelength plate and the laminated broadband 1/4 wavelength plate. FIG. 5 is a diagram for explaining a method for producing a broadband quarter-wave plate of Example 1. It is a figure for demonstrating the relationship between the wavelength of the broadband 1/2 wavelength plate in Example 1, and the transmittance | permeability. It is a figure for demonstrating the relationship between the wavelength and transmittance | permeability of a broadband quarter wavelength plate in Example 1. FIG. It is a figure for demonstrating the relationship between the wavelength of a normal half-wave plate, and the transmittance | permeability. It is a figure for demonstrating the relationship between the wavelength of a normal quarter wavelength plate, and the transmittance | permeability. FIG. 6 is a diagram for explaining a wave plate manufacturing process in Example 2. In the waveplate of Example 3, it is a figure for demonstrating the transmission spectrum in a visible region. It is a figure for demonstrating the transmission spectrum of a normal 1/2 wavelength plate and a 1/4 wavelength plate.

<Example 1>
FIGS. 4A and 4B are diagrams for explaining an example of the broadband quarter-wave plate of the first embodiment. FIGS. 4A to 4E are steps for producing a broadband quarter-wave plate, and FIG. Sectional drawing of / 4 wavelength plate is shown.

  First, a polyimide alignment film (liquid crystal alignment film layer) 12 is applied to a glass substrate (transparent material layer) 11 (FIG. 4A). For the polyimide alignment film 12, for example, a product (product name SE150) manufactured by Nissan Chemical Industries, Ltd. is used. In the example of FIG. 4A, the polyimide alignment film 12 is rubbed in the right direction by 15 ° with respect to the short direction of the polyimide alignment film 12.

  A polymerizable liquid crystal 13 is applied on the polyimide alignment film 12, and the polymerizable liquid crystal 13 is cured by irradiating the polymerizable liquid crystal 13 with UV (ultraviolet rays) (FIG. 4B). As the polymerizable liquid crystal 13, for example, a product (product name UCL017A, birefringence = 0.16) of DIC Corporation is used. The birefringence of the polymerizable liquid crystal 13 is preferably 0.1 or more.

  In this example, the process shown in FIG. 4B (polymerizable liquid crystal application + UV irradiation curing) was repeated 5 times, and the film thickness of the entire wave plate was about 5 μm to produce a half-wave plate.

  In the description of this embodiment, the half-wave plate described above is a laminate 40 including the polyimide alignment film 12 and the polymerizable liquid crystal 13.

  Next, a polyimide alignment film 14 is applied on the polymerizable liquid crystal 13 shown in FIG. 4B (FIG. 4C). For the polyimide alignment film 14, for example, a product similar to the polyimide alignment film 12 described above is used. Further, a polymerizable liquid crystal 15 is formed on the polyimide alignment film 14, and the polymerizable liquid crystal 15 is cured by irradiating the polymerizable liquid crystal 15 with UV (ultraviolet rays) (FIG. 4C). For the polymerizable liquid crystal 15, for example, a product similar to the above-described polymerizable liquid crystal 13 is used. The birefringence of the polymerizable liquid crystal 15 is also preferably 0.1 or more.

  In the example of FIG. 4C, the polyimide alignment film 14 is rubbed in the right direction by 75 ° with respect to the short direction of the polymerizable liquid crystal 13.

  In Example 1, the step shown in FIG. 4C (polymerization liquid crystal coating + UV irradiation curing) was repeated three times to make a quarter-wave plate with a total thickness of about 3 μm. .

  In the description of this embodiment, the above-described quarter wavelength plate is a laminate 41 including the polyimide alignment film 14 and the polymerizable liquid crystal 15.

  Further, the glass substrate 11 is turned over, the back surface of the polymerizable liquid crystal 15 is fixed with wax, and the glass surface of the glass substrate 11 is polished (FIG. 4D). In this embodiment, polishing is performed until the thickness of the entire manufactured wave plate is 30 μm or less. As a result, the film as the broadband quarter-wave plate 1 was completed without curling even when polished (FIGS. 4E and 4F).

  In the example of FIG. 4F, the polymerizable liquid crystal 15 is a quarter wavelength plate 1 whose delay axis direction is 75 °, and the thickness thereof is 3 μm. The thickness of the polyimide alignment film 14 is 0.04 μm. The polymerizable liquid crystal 13 is a half-wave plate whose delay axis direction is 15 °, and its thickness is 5 μm. The thickness of the polyimide alignment film 12 is 0.04 μm. The thickness of the glass substrate 11 is 8 μm.

  Thereafter, the wave plate 1 shown in FIG. 4F was cut by dicing. Then, for example, the groove 102 of the waveguide 101 as shown in FIG. 1 (in this embodiment, for example, width 30 μm × depth 150 μm) is inserted with vacuum tweezers. And in the state which inserted the wave plate 1 in the waveguide 101, specification of cross Nicole and parallel Nicol was measured, and the spectrum substantially the same as FIG. 5 and FIG. 6 mentioned later was acquired.

  The phase difference of the birefringent light in the polymerizable liquid crystal 13 is λ / 2, the phase difference of the birefringent light in the polymerizable liquid crystal 15 is λ / 4, and the polymerizable liquid crystal 13 and the polymerizable liquid crystal 15 are The angle formed by the optical axis is preferably 60 ° or 45 °, but may be, for example, 50 ° or more and 70 ° or less, or 35 ° or less and 55 ° or more. Even in this way, broadband characteristics can be realized (the same applies to a half-wave plate described later).

  Although the ¼ wavelength plate 1 applicable to a wide band has been described above with reference to FIG. 4, a ½ wavelength plate applicable to a wide band can be similarly manufactured. At this time, each layer of the half-wave plate is the same as that of the half-wave plate shown in FIG. 4, but the delay axis direction and the like are different as described later.

  That is, in the one shown in FIG. 4 (f), in the half-wave plate, the polymerizable liquid crystal 15 is a half-wave plate whose delay axis direction is 67.5 °, and its thickness is 5 μm. It is. The thickness of the polyimide alignment film 14 is 0.04 μm. The polymerizable liquid crystal 13 is a half-wave plate with a delay axis direction of 22.5 °, and its thickness is 5 μm. The thickness of the polyimide alignment film 12 is 0.04 μm. The thickness of the glass substrate 11 is 8 μm.

  About the half-wave plate and the quarter-wave plate produced as mentioned above, the spectrum in each crossed Nicol and parallel Nicol was measured. The results are shown in FIGS.

  FIG. 5 shows the relationship between the wavelength and transmittance of such a broadband half-wave plate. FIG. 6 shows the relationship between the wavelength and transmittance of such a broadband quarter-wave plate.

  From an example of FIG. 5, it can be seen that the crossed Nicols and parallel Nicols of the half-wave plate have a flat transmittance at wavelengths of 1300 nm to 1800 nm.

  From an example of FIG. 6, it can be seen that the crossed Nicols and parallel Nicols of the quarter-wave plate have a substantially flat transmittance at a wavelength of 1400 nm to 1700 nm.

  For comparison with FIGS. 5 to 6 described above, the spectra of a normal single-layer half-wave plate and a normal single-layer quarter-wave plate are shown in FIGS.

  FIG. 7 shows the relationship between the wavelength and transmittance of a normal single-layer half-wave plate. FIG. 8 shows the relationship between the wavelength and transmittance of a normal single-layer quarter-wave plate.

  7 is substantially the same as the calculation result of the half-wave plate shown in FIG. 2B, and the one shown in FIG. 8 is the quarter-wave plate shown in FIG. It almost agrees with the calculation result. 7-8, it turns out that it functions as a half-wave plate and a quarter-wave plate only around 1560 nm. That is, unlike the ones shown in FIGS.

  As described above, the wave plate of this embodiment includes the laminate 40 including the polyimide alignment film 12 and the polymerizable liquid crystal 13, and the laminate 41 including the polyimide alignment film 14 and the polymerizable liquid crystal 15. Here, the polymerizable liquid crystal 13 and the polymerizable liquid crystal 15 have different orientation directions, and the birefringence of the polymerizable liquid crystal 13 and the polymerizable liquid crystal 15 is 0.1 or more. For this reason, a thin and broadband wave plate can be realized.

<Example 2>
In Example 1, with reference to FIG. 4, the process of producing a wave plate using a glass substrate has been described. Apart from this, a glass substrate may be used instead of a polyimide film / Si substrate.

  FIGS. 9A and 9B are diagrams for explaining an example of the wave plate according to the second embodiment, where FIGS. 9A to 9F show a manufacturing process of the broadband wave plate, and FIG. 9G shows a cross-sectional view of the broadband wave plate. .

  First, a fluorinated polyimide (Luxvia) 22 is applied on the Si substrate 21 and annealed at 340 ° C. (FIG. 9A). As the fluorinated polyimide 22, for example, Luxvia PF series manufactured by JGC Catalysts & Chemicals Co., Ltd. is used. The fluorinated polyimide 22 does not have birefringence and is a transparent and strong film having a thickness of about 5 to 10 μm.

  Next, a polyimide alignment film (liquid crystal alignment film layer) 23 is applied on the fluorinated polyimide 22. Also in Example 2, the polyimide alignment film 23 uses, for example, a product (product name SE150) manufactured by Nissan Chemical Industries, Ltd. Then, the polyimide alignment film 23 is rubbed in the right direction by 15 ° with respect to the short direction of the polyimide alignment film 23 (FIG. 9B).

  Next, the polymerizable liquid crystal 24 is applied on the polyimide alignment film 23, and the polymerizable liquid crystal 24 is cured by irradiating the polymerizable liquid crystal 24 with UV (FIG. 9C). For the polymerizable liquid crystal 24, for example, a product of DIC Corporation (for example, product name UCL017A, birefringence = 0.16) is used. The birefringence of the polymerizable liquid crystal 24 is preferably 0.1 or more.

  In this example, in order to obtain a half-wave plate, the process shown in FIG. 9C (polymerization liquid crystal application + UV irradiation curing) was repeated 5 times to adjust the film thickness of the entire wave plate. The half-wave plate of this example includes the laminate 50 including the polyimide alignment film 23 and the polymerizable liquid crystal 24.

  A polyimide alignment film 25 is applied on the polymerizable liquid crystal 24 shown in FIG. 9C (FIG. 9D). As the polyimide alignment film 25, for example, the above-mentioned product (Nissan Chemical Industries SE150) is used. In the example of FIG. 9D, the polyimide alignment film 25 is rubbed in the right direction by 75 ° with respect to the diameter direction of the polymerizable liquid crystal 24.

  Further, a polymerizable liquid crystal 26 (for example, the above-mentioned UCL017A product) is applied on the polyimide alignment film 25, and the polymerizable liquid crystal 26 is cured by UV irradiation (FIG. 9E). The birefringence of the polymerizable liquid crystal 26 is preferably 0.1 or more.

  In this example, in order to obtain a quarter-wave plate, the steps shown in FIGS. 9 (d) and 9 (e) (application of polymerizable liquid crystal, UV curing) are repeated three times to form a film on the entire wave plate. The thickness was adjusted.

  In the description of this embodiment, the above-described quarter wavelength plate is a laminate 51 including the polyimide alignment film 25 and the polymerizable liquid crystal 26.

  Then, when the laminated body including the Si substrate 21 shown in FIG. 9E is immersed in water and scratched on the side surface with a cutter, the Si substrate 21 is laminated (in this embodiment, films 22 to 26). (FIG. 9 (f): a step of making the entire thickness of the wave plate 30 μm or less). At this time, the thickness of the entire laminate (that is, the films 22 to 26) is 15 μm. This laminate is cut out in a desired direction and inserted into the waveguide groove in the same manner as in the first embodiment. Even in this case, similarly to the first embodiment, the ½ wavelength plate and the ¼ wavelength plate can be widened.

  In the example of the wave plate 1A shown in FIG. 4G, the polymerizable liquid crystal 26 is a λ / 4 wave plate whose delay axis direction is 75 °, and its thickness is 3 μm. The thickness of the polyimide alignment film 25 is 0.04 μm. The polymerizable liquid crystal 24 is a λ / 2 wavelength plate with a delay axis direction of 15 °, and its thickness is 5 μm. The thickness of the polyimide alignment film 23 is 0.04 μm. The thickness of the fluorinated polyimide 22 is 5-10 μm.

  The phase difference of the birefringent light in the polymerizable liquid crystal 24 is λ / 2, and the phase difference of the birefringent light in the polymerizable liquid crystal 26 is λ / 4, and the polymerizable liquid crystal 24 and the polymerizable liquid crystal 26 are The angle formed by the optical axis is preferably 60 ° or 45 °, but may be, for example, 50 ° or more and 70 ° or less, or 35 ° or less and 55 ° or more. Even in this way, wideband characteristics can be realized.

  As described above, the wave plate of this embodiment includes the laminate 50 including the polyimide alignment film 23 and the polymerizable liquid crystal 24, and the laminate 51 including the polyimide alignment film 25 and the polymerizable liquid crystal 26. Here, the polymerizable liquid crystal 24 and the polymerizable liquid crystal 26 have different orientation directions, and the birefringence of the polymerizable liquid crystal 24 and the polymerizable liquid crystal 26 is 0.1 or more. Moreover, the fluorinated polyimide used as a board | substrate is 5-10 micrometers in thickness. For this reason, a thin and broadband wave plate can be realized.

<Example 3>
In the above, the optical fiber for the visible region and the broadening of the optical waveguide, that is, the blue to red wavelength region (450 nm to 650 nm) have not been mentioned. it can.

  For example, when using the above-mentioned product of DIC Corporation (for example, product name UCL017A, birefringence = 0.16) as a half-wave plate and a quarter-wave plate for 550 nm, the thickness of the half-wave plate Is about 4 μm, and the thickness of the quarter-wave plate is about 1 μm. In this case, even if the glass substrate shown in Example 1 is used and the thickness of the glass substrate is 8 μm, the thickness of the entire half-wave plate is 12 μm and the thickness of the entire quarter-wave plate. Is 11 μm.

  FIG. 10A illustrates the transmission spectrum in the visible range in such a half-wave plate. FIG.10 (b) has illustrated the transmission spectrum in the visible region in such a quarter wavelength plate.

  10A and 10B, the half-wave plate and the quarter-wave plate can function as a wave plate over a wavelength range of 450 nm (blue) to 650 nm (red). Recognize.

  For comparison with FIG. 10 described above, FIG. 11 shows transmission spectra of a normal single-layer half-wave plate and a normal single-layer quarter-wave plate that do not have a laminated film.

  FIG. 11A shows the transmission spectrum of a normal single-layer half-wave plate. FIG. 11B shows the transmission spectrum of a normal single-layer quarter-wave plate.

  In FIGS. 11 (a) and 11 (b), it can be seen that the functioning as a wave plate is limited to only about 10 μm at 550 nm, unlike those in FIGS. 10 (a) and 10 (b).

  Although each example has been described in detail, the material of the specific layer is not limited to each example, and includes design changes and the like within a scope not departing from the gist of the present invention.

  For example, in the case shown in FIG. 4, the phase difference of birefringent light in the polymerizable liquid crystal 13 and the polymerizable liquid crystal 15 is λ / 2, and the angle between the optical axes of the polymerizable liquid crystal 13 and the polymerizable liquid crystal 15 is 35. You may make it be more than 55 degrees and below. Alternatively, in the structure shown in FIG. 9, the phase difference of the birefringent light in the polymerizable liquid crystal 24 and the polymerizable liquid crystal 26 is λ / 2, and the angle between the optical axes of the polymerizable liquid crystal 24 and the polymerizable liquid crystal 26 is 35. You may make it be more than 55 degrees and below.

1,1A wavelength plate 11 glass substrate 12, 14, 23, 25 polyimide alignment film 13, 15, 24, 26 polymerizable liquid crystal 21 Si substrate 22 fluorinated polyimide

Claims (7)

A transparent material layer;
A first laminate formed on the transparent material layer and including a first liquid crystal alignment film layer and a first polymerizable liquid crystal layer;
A second laminated body formed on the first laminated body and including, in order from the first polymerizable liquid crystal layer side, a second liquid crystal alignment film layer and a second polymerizable liquid crystal layer. ,
The first polymerizable liquid crystal layer and the second polymerizable liquid crystal layer have different orientation directions,
The wavelength plate, wherein the birefringence of the first polymerizable liquid crystal layer and the second polymerizable liquid crystal layer is 0.1 or more.   The phase difference of birefringent light in the first polymerizable liquid crystal layer and the second polymerizable liquid crystal layer is λ / 2, and the first polymerizable liquid crystal layer, the second polymerizable liquid crystal layer, The wave plate according to claim 1, wherein an angle formed by the optical axis is 35 ° or more and 55 ° or less.   The phase difference of birefringent light in the first polymerizable liquid crystal layer is λ / 2, the phase difference of birefringent light in the second polymerizable liquid crystal layer is λ / 4, and the first The wave plate according to claim 1, wherein an angle formed by an optical axis of the polymerizable liquid crystal layer and the second polymerizable liquid crystal layer is 50 ° or more and 70 ° or less.   The wavelength plate according to claim 1, wherein the transparent material layer is made of glass or polyimide.   5. The wave plate according to claim 1, wherein the entire thickness of the wave plate is 30 μm or less. 6. A method for producing a wave plate,
Applying a first liquid crystal alignment film layer on the transparent material layer and performing a rubbing treatment, then applying and curing the first polymerizable liquid crystal layer on the first liquid crystal alignment film layer;
On the first polymerizable liquid crystal layer, a second liquid crystal alignment film layer is applied in order from the first polymerizable liquid crystal layer side and subjected to a rubbing treatment, and then the second liquid crystal alignment film layer is applied. Applying and curing a second polymerizable liquid crystal layer thereon;
Polishing the transparent material layer to reduce the total thickness of the wave plate to 30 μm or less. A method for producing a wave plate,
A fluorinated polyimide is applied to a Si substrate, a first liquid crystal alignment film layer is applied and a rubbing treatment is performed, and then a first polymerizable liquid crystal layer is applied and cured on the first liquid crystal alignment film layer. Step to
On the first polymerizable liquid crystal layer, a second liquid crystal alignment film layer is applied in order from the first polymerizable liquid crystal layer side and subjected to a rubbing treatment, and then the second liquid crystal alignment film layer is applied. Applying and curing a second polymerizable liquid crystal layer thereon;
Peeling the fluorinated polyimide from the Si substrate to reduce the total thickness of the wave plate to 30 μm or less.