阅读说明：本技术 高速光开关引擎 (High-speed optical switch engine ) 是由 上塚尚登 于 2018-06-27 设计创作，主要内容包括：当以叉指式电极驱动聚合物稳定的蓝相液晶时,在液晶中产生大的电场分布,并且在电极附近产生大的电场,因电伸缩效应引起的聚合物稳定的蓝相液晶的切换速度恶化。使用形成现有薄膜电极的平行平板,在其之间插入聚合物稳定的蓝相液晶,并在其之间插入聚合物稳定的蓝相液晶之后粘粘偏振光栅,由硅制成的横截面与成三角形的两片硅楔以彼此旋转对称的方式被设置或粘贴在其两侧。(When polymer-stabilized blue phase liquid crystal is driven with interdigital electrodes, a large electric field distribution is generated in the liquid crystal, and a large electric field is generated in the vicinity of the electrodes, and the switching speed of the polymer-stabilized blue phase liquid crystal is deteriorated due to the electrostrictive effect. Using parallel flat plates forming existing thin film electrodes, between which polymer-stabilized blue phase liquid crystal is inserted, and after inserting polymer-stabilized blue phase liquid crystal therebetween, a polarization grating is bonded, two silicon wedges made of silicon having a cross section and a triangular shape are disposed or bonded on both sides thereof in a rotationally symmetric manner to each other.)

1. An optical switch engine is characterized in that two substrates of transparent thin film electrodes formed in a desired optical wavelength region on at least one surface of a transparent substrate are used in an optical wavelength region from ultraviolet to a used wavelength band; wherein the thin film electrodes are made into parallel electrodes in a desired gap in an opposed manner, and a polymer-stabilized blue phase liquid crystal is inserted in the middle, and on a parallel flat liquid crystal panel stabilized by irradiation with light, the birefringent axes of a birefringent medium (called director) which becomes the thickness of a half-wavelength plate at the wavelength used are composed of a polarization grating plate periodically rotated in a plane attached to the emission surface of the parallel plate liquid crystal panel, or composed of a plurality of liquid crystal phase panels stacked in the same direction and a material having a higher refractive index than the base material, and the cross section is composed of two wedge-shaped substrates having a right triangle shape;

laminating and bonding the inclined surfaces of the two wedge-shaped substrates in an overlapping manner in a manner that the axis of the complex bending axis rotating in the plane is perpendicular to the bevel edge of the wedge-shaped substrate with the right-angled triangle cross section;

incident light entering from an end face of one wedge-shaped substrate (referred to as an incident face on the opposite side of the polarization grating plate of the switching liquid crystal phase panel) is emitted with a desired polarization from the end face (referred to as an emission face) of the other wedge-shaped substrate in a parallel cross section.

2. The optical switch engine of claim 1, wherein said polarization grating plate is a chiral structure having the birefringent axes of said directors also rotated in the thickness direction.

3. An optical switch engine as defined in claim 1, wherein when light is incident from the end face of said one side wedge-shaped substrate, said one side wedge-shaped substrate operates as a nearly isotropic medium when no voltage is applied to said opposing thin film electrodes, and operates as said half-wavelength plate at said operating wavelength when a voltage is applied.

4. An optical switch engine as in any of claims 1-2 wherein said substrate is formed of SiO₂Glass or a Si substrate as a main component.

5. An optical switch engine as in any of claims 1-4 wherein said wedge-shaped substrate is made of silicon.

6. An optical switch engine as in any of claims 1-5, wherein a non-reflective, non-reflective coating is formed for the refractive index of the material of the inclined surface of the wedge-shaped substrate adjacent to the entrance or exit surface.

7. An optical switch engine as claimed in any one of claims 1 to 6, wherein said optical switch engine is used in 2 stages, and the emitting surface of the front stage optical switch engine and the incident surface of the rear stage optical switch engine are respectively rotated and adhered at 90 °.

8. The optical switch engine as claimed in claim 7, wherein said parallel plate liquid crystal panel of said switch liquid crystal phase panel is segmented into two or more pieces of regions, and said switch liquid crystal phase panel is constituted by a polarization grating plate formed with said different period segments with respect to said segment, and the incident light incident on said segment can be independently deflected and emitted from the polarization grating plate.

9. An optical switch engine as claimed in any one of claims 7 or 8, characterized in that the surroundings thereof are controlled to a desired temperature by means of a Peltier element.

Technical Field

The invention relates to a high-speed optical switch engine.

Background

Fig. 1 shows an example of a conventional liquid crystal phase panel (non-patent document 1) in which a nematic liquid crystal 24 is inserted between two parallel plate electrode panels 23.

In the case of Zero-twisted ECB (electrically controlled birefringence), when no voltage is applied to two parallel plate electrodes, a director (n) of liquid crystal is arranged parallel to the plate electrodes, and incident light experiences an elliptical XZ cross section (refractive index of the elliptical shape) of the refractive index of the director (n) and receives retardation. In this case, by setting a desired liquid crystal thickness, for example, the liquid crystal display device can be operated as a half-wavelength plate.

On the other hand, when a voltage is applied to the two pieces of parallel flat electrode panels 23, the electric field becomes perpendicular to the flat electrodes, and the director of the liquid crystal also becomes perpendicular following the electric field. The incident light receives an XZ cross section (circular refractive index) with an elliptical refractive index, does not receive a retardation, and operates as an isotropic medium.

Conventional nematic liquid crystals are widely used in displays, but they cannot be used in applications requiring high switching speeds because their switching speed is as slow as milliseconds. Therefore, a polymer-stabilized blue phase liquid crystal which can be switched at high speed has been studied.

The liquid crystal utilizes the Kerr effect (Kerr effect), and although it can be switched quickly, it must generate an electric field parallel to the plate electrodes. In the parallel plate electrode panel 23, since a general electric field is perpendicular to the plate electrodes, and the blue phase liquid crystal stabilized by a polymer cannot be directly applied in this state, an interdigital electrode called ips (in plane switching) as shown in fig. 2 is studied.

The electrode is a voltage which applies positive or negative or positive or zero to the adjacent interdigital electrode 21 and generates an electric field in the transverse direction (X direction).

However, in the polymer-stabilized blue phase liquid crystal 22, the electric field distribution is not uniform and a large electric field distribution is generated, and particularly, a large electric field is generated in the vicinity of the interdigital electrode 21, and the switching speed of the polymer-stabilized blue phase liquid crystal 22 is deteriorated due to the electrostrictive effect.

Also, at long wavelengths, the required liquid crystal thickness increases and a larger electric field distribution is required in the liquid crystal to obtain the required performance. Therefore, the electric field distribution in the vicinity of the interdigital electrode 21 is further increased, leading to a phase distribution in the outgoing beam, and various performance degradations such as loss and crosstalk occur.

The parallel plate electrode panel 23 can obtain a uniform electric field distribution compared to the interdigital electrode 21. In order to utilize this state, the light beam may be obliquely incident. To realize this, an example has been reported in which parallel plate electrodes are attached to a polymer-stabilized blue phase liquid crystal and driven in a conventional vertical electric field to obtain a gradation characteristic of eliminating hysteresis (hystersis) (patent document 1, fig. 3). However, this structure is effective in the case of vertical incidence, but if the incidence is inclined at a large angle, a large phase is generated in the outgoing beam due to non-uniformity in the light refraction efficiency of the prism sheet in the beam.

On the other hand, an optical switching engine using a liquid crystal and a polarization grating has been reported (patent document 2, fig. 4). This presupposes that a phase plate (LC Half-wave plate) and a polarization grating (Passive PG) are stuck together and light is made to enter almost perpendicularly.

The reason why light is incident almost perpendicularly is that, as shown in fig. 8 (by simulation), when the incident surface is (a), the ± 1 st order diffraction efficiency is drastically deteriorated.

Therefore, this conventional structure is effective in the case of using a phase plate (LC Half-Waveplate) of a general nematic liquid crystal, but in the case of using a blue phase liquid crystal stabilized by a polymer, it is necessary to adopt a structure of an ips (in plane switching) type phase plate or a prism sheet, which, as described above, in any case causes great deterioration in switching speed, beam phase distribution, and the like.

Disclosure of Invention

[ problems to be solved by the invention ]

The above problems are summarized as follows.

(1) In the ips (in Plane switching) interdigital electrode, a large electric field distribution is generated in the liquid crystal, a large electric field is generated in the vicinity of the electrode, and the switching speed of the polymer-stabilized blue phase liquid crystal is deteriorated due to the electrostrictive effect.

(2) Particularly at long wavelengths, the required liquid crystal thickness increases and a large electric field distribution is generated within the liquid crystal.

(3) The in-plane electric field distribution is large, resulting in phase distribution in the outgoing beam and various performance degradations such as loss and crosstalk are generated.

(4) In the structure of patent document 1, when the light is incident on the blue phase liquid crystal at a large angle, the light refraction effect of the prism sheet is not uniform in the light flux, and the phase distribution is large in the emitted light flux.

(5) The structure of patent document 2 is based on the premise that a phase plate (LC Half-wave plate) and a polarization grating (passive PG) are joined together, and light is made to enter nearly perpendicularly. This is because, when PG is simulated, as shown in fig. 8, when the incident surface is (a), the ± 1 st order diffraction efficiency is rapidly deteriorated.

Therefore, in order to implement the existing structure, it is necessary to inject nearly perpendicularly into the phase plate affixed to the PG, and the phase plate of the ordinary nematic liquid crystal (LC hall-wave plate) is assumed by default.

In addition, when polymer-stabilized blue phase liquid crystals are used, it is necessary to apply the above-described IPS (in-plane switching) type phase plate or polymer-stabilized blue phase liquid crystal phase plate using a prism sheet, and in any case, as described above, characteristics (e.g., switching speed, loss, crosstalk, etc.) as an optical switching engine are greatly deteriorated.

Accordingly, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an optical switching engine having a feature of generating a uniform electric field distribution in a polymer-stabilized blue phase liquid crystal without deterioration of switching speed or phase distribution of an emitted light beam.

[ means for solving problems ]

In order to solve the above problems, the present invention is configured as follows with respect to an optical switch engine using a blue phase liquid crystal stabilized by a polymer.

(1) Using parallel flat plates (fig. 7) forming existing thin film electrodes, polymer-stabilized blue phase liquid crystal is inserted therebetween, and a set of Polarization Grating (PG) layers as shown in fig. 6 are pasted together, and a plurality of sets of polarization gratings are laminated, and a cross section made of silicon and two silicon wedges in a triangular shape are disposed or pasted on both sides thereof in a rotationally symmetrical manner to each other.

(2) Further, the Polarization Grating (PG) is the above-described Polarization Grating (PG) having a chiral structure in which the director rotates in the thickness direction as shown in fig. 6(C) as well, and the rotation axis a in the rotation direction of the director and the oblique side B of the silicon wedge at the surface (XY plane) of the Polarization Grating (PG) are disposed or attached in a perpendicular manner to each other (fig. 7).

(3) Two sets of the above-described structures are used and the structures are arranged or attached by being rotated 90 ° to each other (fig. 10).

However, the wedge angle θ a of the silicon wedge should satisfy the following condition.

[ equation 1]

θa＜sin^-1(N2/N1)-θb (1)

Here, θ b is sin^-1(No × sin θ o/N1), No is the refractive index of the surroundings (e.g., air), N1 is the refractive index of silicon, and θ o is the angle of incidence.

Specifically, the present invention may provide the following means:

(1) an optical switch engine, wherein, use in the wavelength region of light from ultraviolet to wavelength band used, and use the two pieces of base plate of the transparent thin-film electrode formed in the desired wavelength region on at least one surface of the transparent base plate; wherein the thin film electrodes are made into parallel electrodes in a desired gap in an opposed manner, and a polymer-stabilized blue phase liquid crystal is inserted in the middle, and on a parallel flat liquid crystal panel stabilized by irradiation with light, the birefringent axes of a birefringent medium (called director) which becomes the thickness of a half-wavelength plate at the wavelength used are composed of a polarization grating plate periodically rotated in a plane attached to the emission surface of the parallel plate liquid crystal panel, or composed of a plurality of liquid crystal phase panels stacked in the same direction and a material having a higher refractive index than the base material, and the cross section is composed of two wedge-shaped substrates having a right triangle shape; laminating and bonding the inclined surfaces of the two wedge-shaped substrates in an overlapping manner in a manner that the axis of the complex bending axis rotating in the plane is perpendicular to the bevel edge of the wedge-shaped substrate with the right-angled triangle cross section; incident light entering from an end face of one wedge-shaped substrate (referred to as an incident face on the opposite side of the polarization grating plate of the switching liquid crystal phase panel) is emitted with a desired polarization from the end face (referred to as an emission face) of the other wedge-shaped substrate in a parallel cross section.

This is the basic configuration of the present invention, and is in the form of the optical switch engine described in the following embodiment 1.

(2) The optical switch engine according to (1), wherein the polarization grating plate is a chiral structure having a birefringent axis of the director also rotated in a thickness direction.

(3) The optical switch engine according to (1), wherein when light is incident from an end face of the one-side wedge-shaped substrate, when no voltage is applied to the opposing film electrodes, the optical switch engine operates as a nearly isotropic medium, and when a voltage is applied, the optical switch engine operates as the half-wavelength plate at the use wavelength.

(4) The optical switch engine according to any one of (1) to (2), wherein the substrate is formed of SiO₂Glass or a Si substrate as a main component.

(5) The optical switch engine according to any one of (1) to (4), wherein the wedge-shaped substrate is made of silicon.

(6) The optical switch engine according to any one of (1) to (5), wherein a non-reflective coating layer is formed for a refractive index of a material of the inclined surface of the wedge-shaped substrate adjacent to the incident surface or the exit surface.

The above is a basic configuration of the present invention, and is another embodiment described in embodiment 1 described later.

(7) The optical switch engine according to any one of (1) to (6), wherein the exit surface of the front stage optical switch engine and the entrance surface of the rear stage optical switch engine are respectively rotated by 90 ° and bonded to each other, and the optical switch engine is used in 2 stages.

The above is an extended configuration of the present invention, and is a form of the optical switch engine described in embodiment 2 described later.

(8) The optical switch engine according to (7), wherein the parallel plate liquid crystal panel of the switched liquid crystal phase panel is segmented into two or more pieces of regions, and the switched liquid crystal phase panel is constituted by a polarization grating plate formed with the different period segments with respect to the segment, and the incident light incident on the segment can be independently deflected and emitted from the polarization grating plate.

The above is an extended configuration of the present invention, and is a form of the optical switch engine described in embodiment 3 to be described later.

(9) The optical switch engine according to any one of (7) or (8), wherein the surroundings thereof are controlled at a desired temperature by means of a peltier module.

This is an extension of the present invention, and is in the form of an optical switch engine described in embodiment 4 to be described later.

[ efficacy of the invention ]

The invention has the following effects:

(1) a high-speed 1 xn optical switching engine having the characteristics of generating a uniform electric field distribution in polymer-stabilized blue phase liquid crystal and deflecting a light beam in a plane without deteriorating a switching speed or a phase distribution of an emitted light beam, which is difficult in the prior art, can be realized.

(2) A high speed 1 xn steering device can be realized which is difficult to realize in the prior art.

Drawings

Fig. 1 is a schematic diagram of an example of a conventional nematic liquid crystal phase panel.

FIG. 2 is an illustration of an interdigitated electrode known as IPS (in Panel switching) as a prior art polymer-stabilized blue phase liquid crystal.

Fig. 3 is a schematic diagram of the structure of patent document 1, in which light is incident on a blue phase liquid crystal at a large angle tilt and input is performed using a prism sheet.

Fig. 4 is a schematic diagram of the structure of patent document 2, an example of which is a beam steering in which a phase plate (LC Half-Waveplate) and a polarization grating (pasivepg) are pasted together.

FIG. 5 is an illustration of parallel electrodes of a polymer stabilized blue phase liquid crystal of the prior art. (A) A refractive index ellipse showing isotropic characteristics of the polymer-stabilized blue phase liquid crystal section when no voltage is applied, and (B) a schematic diagram showing a refractive index ellipse of the polymer-stabilized blue phase liquid crystal section when a voltage is applied.

Fig. 6 is an explanatory diagram of a Polarization Grating (PG) used in the present invention. (A) When left-handed circularly polarized light enters the center perpendicularly, right-handed circularly polarized light exits from the opposite side with the angle θ changed in the X-axis direction. (B) When right-handed circularly polarized light enters the center perpendicularly, left-handed circularly polarized light is emitted from the opposite side while changing the angle θ in the direction opposite to the X-axis direction. In addition, (C) shows a schematic view in which the Z-axis direction is a chiral structure.

Fig. 7 is a schematic diagram of an embodiment of a1 × 2 optical switching engine, which refers to an optical switching engine in which two pieces of silicon wedges are bonded to each other in a point-symmetric manner using a polymer-stabilized blue phase liquid crystal panel and a polarization grating as basic structures of the present invention.

Fig. 8 is a calculation chart showing the efficiency of ± first-order diffracted light with respect to the incident surface of the Polarization Grating (PG).

Fig. 9 is a schematic diagram of another embodiment of the present invention.

Fig. 10 is a schematic diagram of another embodiment of the invention.

Fig. 11 is a schematic view of another embodiment of the present invention.

Figure 12 is a schematic diagram of one embodiment of a module for a temperature controlled high speed optical switch engine of the present invention.

Detailed Description

In the following, several embodiments of the present invention are shown.