JPH1010306A - Artificial lattice and method of forming artificial lattice - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a micron-scale 3 formed perpendicularly or at an angle to a substrate by a relatively simple method.
It is an object of the present invention to provide a three-dimensional artificial lattice structure and a method for forming the same, and in particular to provide a method for forming a novel optical functional device by an optically assisted process. SOLUTION: A refractive index n1 region 1 in a region having a different refractive index.
And a refractive index n2 region 2 are alternately repeated to form a lattice structure by combining two-divided interference irradiation of energy rays having high coherence and irradiation of energy rays having different wavelengths.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional artificial lattice structure and a method for forming the same, and more particularly, to microstructure formation using a light assist process by a laser beam and formation of an artificial lattice and an artificial lattice using its function control technology. About the method.

[0002]

2. Description of the Related Art Various devices are increasingly miniaturized and combined with the advancement of material utilization technology, and creation of new functions is required. Even in a single material system, there are many cases where the physical properties and the way of use are different depending on whether it is a bulk mixture or a thin film. Further, a structure having a minute repetition period, for example, a semiconductor superlattice, plays a significant role in expressing unique physical properties and functions. There are various periodic structures such as multilayer stack structure, artificial lattice structure, and multiple quantum well, and the materials that make them up are composed of inorganic materials to organic materials, as well as combinations of different materials from the same type. There is a wide variety of things to do.

[0003] Examples of compound semiconductors include, for example, molecular beam epitaxy, which requires an ultra-high vacuum apparatus, and chemical vapor deposition, which requires various highly harmful source gases requiring high purity. It requires sophisticated technology and extensive facilities. These methods were suitable mainly for forming a lattice plane parallel to or close to the substrate plane.
Therefore, in order to form a substrate that is nearly perpendicular or completely perpendicular to the substrate, the laminated thin film is processed using, for example, a focused ion beam, or a pattern is formed using photolithography. Need a way.

[0004]

However, although it is expected that various functions can be created by artificial periodic structures and lattice structures, many possibilities remain without using many possibilities in the materials used and the forming method. ing.

An object of the present invention is to provide a micron-scale three-dimensional artificial lattice structure formed perpendicularly or at an angle to a substrate by a relatively simple method, and a method of forming the same. Also, the present invention provides a method for forming a novel optical functional element by an optical assist process.

[0006]

According to a first aspect of the present invention, there is provided a laminated structure in which a region A1 and a region A2 are alternately repeated, wherein the region A1 has a desired refractive index n1, and The region A2 has a refractive index n2 different from the refractive index n1, and the laminated structure is disposed on or between substrates having a normal direction not parallel to the normal direction of the laminated structure. It is an artificial lattice.

According to a second structure of the present invention, in a laminated structure in which the regions A1 and A2 are alternately repeated, at least one of the regions A1 and A2 is refracted by the action of energy from outside the laminated structure. A rate of change material, wherein the laminated structure is disposed on or between substrates having a normal direction that is not parallel to the normal direction of the laminated structure, and the region A1 and the region are disposed on the substrate. A2, a common energy applying mechanism is provided, and the refractive index n1 of the region A1 and the refractive index n2 of the region A2 are provided.
Is an artificial lattice that can be set to have different or mutually equal values.

In a first forming method of the present invention, a plurality of types of energy rays having different energies are used, and the other one of the plurality of types of energy rays is divided into two parts,
The two-divided energy beam is irradiated so as to cause interference at the artificial lattice forming position, and a material system containing a substance capable of absorbing the energy of the two-divided energy beam is used. A part of the material system is modified by irradiation with a ray to form a repeating structure in a different region, and then formed by irradiating the undivided energy ray.

In a second forming method according to the present invention, a plurality of types of energy rays having different energies are used, and one of the plurality of types of energy rays is divided into two except for one type.
The energy beam divided into two is irradiated so as to cause interference at the position where the artificial lattice is formed, and the energy beam divided into two by using a material system containing a substance capable of absorbing energy of a specific wavelength of the energy beam. In the method of forming an artificial lattice in which a repetitive structure of a different region is formed by modifying a part of the material system by irradiation, the object to be processed is processed by the undivided energy beam prior to the irradiation of the two-divided energy beam. Irradiation.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention has a wide range of applications and can be applied to materials from inorganic materials such as metals, semiconductors and ceramics to organic materials such as polymer compounds.
In addition, energy rays to be used are in a wide energy range such as infrared light, visible light, ultraviolet light, X-ray,
That is, the wavelength range is included. However, since formation of the grating structure requires good coherence, it is desirable to use various lasers as energy rays used for the two-way interference. Here, a material system is sandwiched between two substrates having a high transmittance to irradiation light, and details of a case where an artificial lattice is formed by light irradiation will be described in detail, but the material system is applied on one substrate, It is of course possible to form an artificial lattice by irradiating it with light.

In the embodiment, a case of using a visible light laser, a material system mainly composed of various organic polymer materials, and a case of using a glass substrate as a substrate will be described. It is easy to imagine that infrared light or ultraviolet light can be used if different sensitivity characteristics are used, and if the temperature conditions are within the appropriate range, a transparent synthetic resin should be used for the substrate. Further, it is needless to say that the material system is not limited to an organic substance, and there may be many combinations with inorganic materials such as metals, semiconductors, and ceramics from the correlation between the energy of laser light used and the chemical bond energy.

First, as a common feature of the details of the invention described below, a schematic cross section of an artificial grating to be formed, a schematic configuration of an optical system for two-division interference irradiation of laser light, and a method of cleaning a glass substrate will be described. To

FIG. 1 is a schematic sectional view showing an example of an artificial lattice to be formed. The object to be processed has a material system 3 on a base 4, and regions having different physical properties, for example, a refractive index n1 region 1 and a refractive index n2 region 2 (n1 ≠ n2) having different refractive indexes are formed by light irradiation described later. You.

FIG. 2 is a configuration diagram of an optical system for irradiating light.
In order to utilize the interference of light, especially the phase, the optical path length and the uniformity of the luminous flux are important. The laser beam emitted from the laser 21 is converted into a uniform parallel light beam by the collimating lens system 22 and is split into two by the half mirror 23. Each of the two divided laser beams is processed by the mirror 24 into the workpiece 2
Irradiated so as to cause interference on 5.

After cleaning a glass substrate (eg, ordinary slide glass, Corning 7059, Asahi Glass AN635, etc.) with a surfactant and ultrasonic waves and with pure water and ultrasonic waves,
PA steam dry. After drying at 110 ° C. for 30 minutes in a drying bake oven, it is placed on a hot plate set to the temperature at the time of formation, and it is confirmed that the temperature is stabilized. This removes microscopic dust, deposits, and impurities, and eliminates residual moisture.

In addition, since all material systems use various light irradiation processes, after cleaning the glass, all operations are performed under a dark red light source. Do not expose. Hereinafter, specific examples will be described in detail.

(Embodiment 1) Various kinds of glass are used as a substrate, and a material composed mainly of an oligomer and a liquid crystal to which a sensitizer and a dye are added is used, and this material is sandwiched between glass substrates. An artificial lattice structure was formed by performing two-division interference irradiation of laser light without using techniques such as photolithography and electron beam drawing.
Laser light has high coherence, and the intensity distribution due to interference can be created by irradiating the split light on the same surface by precisely adjusting the optical path length. A photopolymerization reaction is used to create different regions corresponding to the intensity distribution.

This is not possible with all material systems and requires a certain combination of materials, but does not have a problem with the compatibility of the polymer and the liquid crystal formed and a highly efficient polymerization initiator system. The scope of application is wide.

Example 1 An ordinary slide glass was used as a glass substrate, the material system was about 0.5 g of nematic liquid crystal (Chisso), the oligomer was about 0.5 g of an urethane oligomer having an acrylic terminal, and the sensitizer was About 2 × 10 ⁻³ g of N-phenylglycine and about 1 × 1 of rhodamine B
0 ^-3 g, about 1 × 10 ^-4 g to 10 micron diameter glass beads as a spacer (the amount is not important to the value itself, it can be maintained uniform space when tucked into a glass substrate) using .

Approximately 75 washed slide glasses
Heat to ° C. and keep the material system at the same temperature. After confirming that the temperature has stabilized, a small amount of the material system (attached to the tip of a spatula or using a microdropper) is dropped on one glass substrate. Place the other glass substrate while taking care not to introduce air bubbles, etc., and apply an appropriate weight (about several tens to several hundreds g: to help the material spread quickly and evenly between the glass substrates. Weight) and leave for a few minutes. Quickly mount on the substrate holder and irradiate laser light.

Needless to say, the substrate holder needs to have a light passage window. At the same time, a device provided with a heating mechanism for temperature control is desirable. An Ar laser of 514.5 nm to form a grating with a period of about 1 micron
Is adjusted so that the optical paths of the two split light beams are exactly the same, and the incident angle on the substrate is set to 15 °. Irradiate at a laser power of 150 mW (meter value attached to the laser power supply) for about 15 seconds. Immediately thereafter, irradiation is performed at about 30 mW for 2 minutes using a high-pressure mercury lamp. This completes the formation of the artificial lattice, but since the change slightly progresses until the temperature returns to room temperature, it is left in a dark room.

When the formed artificial lattice is observed under a polarizing microscope, the overall brightness changes with the rotation of the stage.
This is because the liquid crystal contained in the material system is oriented with a certain direction. When observed at a high magnification of about 1000 times, fine lattice fringes are seen. Furthermore, when a monochromatic spot light, for example, a red light of a He-Ne laser is incident on the sample, a diffraction spot is observed in addition to the direct light, and it can be confirmed that a diffraction grating is formed.

(Embodiment 2) Various kinds of glass are used as a substrate, and a material mainly composed of an oligomer and liquid crystal to which a sensitizer and a dye are added is used, and this material is sandwiched between glass substrates. A transparent conductive film formed on glass as a substrate using a technique that enables the formation of an artificial lattice structure without using techniques such as photolithography and electron beam drawing by performing laser beam splitting interference irradiation. Thus, an optical functional device capable of electrically controlling the diffraction direction of light was formed.

The laser light has high coherence, and the intensity distribution due to interference can be created by irradiating the split light on the same surface by precisely adjusting the optical path length. The process using a photopolymerization reaction to create a region is common to the previous embodiment.

Example 2 A transparent conductive thin film (here, I
Although TO was used, a glass substrate (Corning 7059) provided with other usable metals and metal oxides, such as SnO ₂ , In ₂ O ₃ , and ZnO, was used. About 0.5 g of Chisso) and about 0.5 g of urethane oligomer having acrylic terminal
g, the sensitizer is about 2 × 10 ⁻³ g of N-phenylglycine,
About 1 × 10 ⁻³ g of rhodamine B as a dye and about 1 × 10 ⁻⁴ g of glass beads having a diameter of 10 μm as a spacer.
(This amount is not important for the value itself, as long as it can maintain a uniform space when sandwiched between glass substrates.)
use. 75 ° C two glass substrates with ITO
And the material system is kept at the same temperature. After confirming that the temperature has stabilized, a small amount of the material system (attached to the tip of a spatula or using a microdropper) is dropped onto one of the glass substrates with the ITO attached.

Place the other glass substrate with the ITO side facing the material side while taking care not to introduce air bubbles, etc., and apply an appropriate weight (about several tens to several hundreds g: the material is quickly and uniformly mixed with glass). (This is to help spread between the substrates, and may be of an appropriate weight.) And left for several minutes. Quickly mount on the substrate holder and irradiate laser light. Needless to say, the substrate holder needs to have a light passage window. At the same time, a device provided with a heating mechanism for temperature control is desirable. Using an Ar laser 514.5 nm oscillation line to form a grating with a period of about 1 micron,
Adjust the split light so that the optical path is exactly the same,
The angle of incidence on the substrate is set at 15 °. Laser output 1
Irradiate at 50 mW (meter value attached to laser power supply) for about 15 seconds. Immediately thereafter, irradiation is performed at about 30 mW for 2 minutes using a high-pressure mercury lamp. This completes the formation of the artificial lattice, but since the change slightly progresses until the temperature returns to room temperature, it is left in a dark room.

When the formed artificial lattice is observed under a polarizing microscope, the overall brightness changes with the rotation of the stage, because the liquid crystal contained in the material system is oriented with a certain direction. When observed at a high magnification of about 1000 times, fine lattice fringes are seen. Furthermore, when a monochromatic spot light, for example, red light of a He-Ne laser is incident on the sample, a diffraction spot is seen in addition to the direct light,
It can be confirmed that a diffraction grating is formed.

It is confirmed that the deflection can be controlled by applying a voltage. Since a liquid crystal material is contained, AC pulse driving (1 KHz, 50% duty cycle) is performed. The red light of the He-Ne laser is incident on the sample, and the applied voltage is gradually increased while continuously monitoring the intensity of the direct light and the intensity of the diffraction spot with a power meter. It is observed that the intensity of the diffraction spot becomes weaker as the voltage increases, and when it reaches a certain value, almost only direct light is observed.
This operation varies depending on the condition of each sample, but about 50% of the He-Ne laser beam is emitted.
From the state where% is diffracted, the diffracted light starts to become weak at around 40 to 50 V, and almost disappears at about 100 to 130 V.

This operation is explained as follows in relation to the formed three-dimensional lattice structure. The lattice structure is formed as a result of a polymerization reaction caused by irradiation of an interference laser beam having a three-dimensional intensity distribution in a material system mainly composed of an oligomer and a liquid crystal, but the liquid crystal is not uniformly distributed during the formation process and the light intensity is weak. Many are present in the area. This state is fixed by the subsequent ultraviolet irradiation, and a region where a large amount of liquid crystal exists and a region where the liquid crystal is not so are formed. On the other hand, only the liquid crystal part responds to the application of voltage from the outside, not the resin part. Therefore, the direction of liquid crystal molecules changes due to the application of voltage, and the refractive index of the area where there is a large amount of liquid crystal changes. Can be controlled by an external voltage.

(Embodiment 3) A substrate composed of various kinds of glass or a transparent conductive film formed thereon is used as a substrate, and a material composed mainly of an oligomer and a liquid crystal to which a sensitizer and a dye are added is used. We have developed a method for improving the diffraction efficiency and preventing various defects caused by segregation of liquid crystal in a method of forming a diffraction grating by interposing the material between glass substrates and irradiating the laser beam with two-division interference. Prior to the laser beam splitting interference irradiation, light irradiation is performed for a relatively short time using a high-pressure mercury lamp. Here, a high-pressure mercury lamp is used, but the light source is not limited to this, and any light source having a spectrum distribution in a similar wavelength region can be used. At present, no understanding of the mechanism at the atomic or molecular level has been obtained. A typical example is shown below.

Example 3 An ordinary slide glass was used as a glass substrate. The material system was about 0.6 g of nematic liquid crystal (Chisso), the oligomer was about 0.4 g of an acrylic-terminal urethane oligomer, and the sensitizer was About 2 × 10 ^-3 g of N-phenylglycine and about 1 fluorescein dye
× 10 ⁻³ g, glass beads with a diameter of 10 μm used as spacers, about 1 × 10 ⁻⁴ g (this amount is not important in terms of value itself, as long as a uniform space can be maintained when sandwiched between glass substrates) I do. The two washed slide glasses are heated to approximately 78 ° C. and the material system is kept at the same temperature.

After confirming that the temperature has stabilized, a small amount of the material system (attached to the tip of a spatula or using a microdropper) is dropped onto one of the glass substrates. Place the other glass substrate while taking care not to introduce air bubbles, etc., and apply an appropriate weight (about several tens to several hundreds g: to help the material spread quickly and evenly between the glass substrates. Weight) and leave for a few minutes. A comparison between the laser irradiation and the light irradiation prior to the laser irradiation shows that the latter is effective in shortening the laser irradiation time and improving the diffraction efficiency. Here, a high-pressure mercury lamp is used, but the light source is not limited to this, and any light source having a spectrum distribution in a similar wavelength region can be used.

One of the two specimens prepared in the same manner is sandwiched with a material between glass substrates, and then mounted on a substrate holder and irradiated with a laser beam. Needless to say, the substrate holder needs to have a light passage window. at the same time,
It is desirable to have a heating mechanism for temperature control. Using an Ar laser 514.5 nm oscillation line to form a grating with a period of about 1 micron, the split light is adjusted so that the optical path is exactly the same, and the incident angle to the substrate is set to 15 ° I do. At a laser power of 100 mW (meter value associated with the laser power supply), formation of the grating requires irradiation for approximately 30 seconds.

On the other hand, first, irradiation is performed at about 9 mW for 4 seconds using a high-pressure mercury lamp. Then, a laser beam is irradiated under the same conditions as above. However, the time required for grid formation is 5
About 6 seconds. In both cases, immediately after irradiation with the laser beam, irradiation is performed using a high-pressure mercury lamp at approximately 30 mW for 2 minutes. This completes the formation of the artificial lattice, but since the change slightly progresses until the temperature returns to room temperature, it is left in a dark room.

When the formed artificial lattice is observed under a polarizing microscope, the overall brightness changes with the rotation of the stage, because the liquid crystal contained in the material system is oriented with a certain direction. When observed at a high magnification of about 1000 times, fine lattice fringes are seen. Furthermore, when a monochromatic spot light, for example, red light of a He-Ne laser is incident on the sample, a diffraction spot is seen in addition to the direct light,
It can be confirmed that a diffraction grating is formed. Comparing the intensities of the diffracted lights, those irradiated with laser light without UV irradiation are less than 40% diffracted light, but those irradiated with UV light before laser light are nearly 90%,
Obviously, the ultraviolet irradiation at the first stage has resulted in the improvement of the characteristics.

(Example 4) As a substrate, a normal slide glass and a transparent conductive thin film (here, ITO was used,
Other usable metals and metal oxides such as SnO
₂ , In ₂ O ₃ , ZnO, etc.), a glass substrate (Corning 7059) is used, the material is about 0.6 g of nematic liquid crystal (Chisso), and the oligomer is about 0 g of urethane oligomer having acrylic terminal. 0.4 g, sensitizer about 2 × 10 ⁻³ g of N-phenylglycine, dye about 1 × 10 ⁻³ g of fluorescein, and about 1 × 10 ⁻⁴ g of glass beads having a diameter of 10 μm as a spacer. (This amount has no significance in the value itself, as long as a uniform space can be maintained when sandwiched between glass substrates). Washed slide glass and glass substrate with ITO 2 each
The sheet is heated to 78 ° C., and the material system is kept at the same temperature.

After confirming that the temperature was stabilized, a small amount of the material system (attached to the tip of a spatula or using a microdropper) was used for one of the slide glass and the ITO of the glass substrate.
Drop on the surface marked with. Be careful not to let any air bubbles, etc.
Place the surface with TO facing the material side, and apply an appropriate weight (several tens to several hundreds g: to help the material spread quickly and uniformly between the glass substrates, and may have an appropriate weight) ) And leave for a few minutes. Next, irradiation is performed at approximately 9 mW for 4 seconds using a high-pressure mercury lamp. Here, a high-pressure mercury lamp is used, but the light source is not limited to this, and any light source having a spectrum distribution in a similar wavelength region can be used.

Then, it is quickly mounted on the substrate holder and irradiated with a laser beam. Needless to say, the substrate holder needs to have a light passage window. At the same time, a device provided with a heating mechanism for temperature control is desirable. In order to form a grating having a period of about one micron, 51 of an Ar laser is used.
Using a 4.5 nm oscillation line, the light split into two is adjusted so that the optical path is exactly the same, and the angle of incidence on the substrate is set to 15 °. Irradiate for 5 to 20 seconds at a laser power of 100 mW (meter value attached to the laser power supply). Immediately thereafter, irradiation is performed at about 30 mW for 2 minutes using a high-pressure mercury lamp. This completes the formation of the artificial lattice, but since the change slightly progresses until the temperature returns to room temperature, it is left in a dark room.

When the formed artificial lattice is observed under a polarizing microscope, the overall brightness changes with the rotation of the stage, because the liquid crystal contained in the material system is oriented with a certain direction. When observed at a high magnification of about 1000 times, fine lattice fringes are seen. Furthermore, when a monochromatic spot light, for example, red light of a He-Ne laser is incident on the sample, a diffraction spot is seen in addition to the direct light,
It can be confirmed that a diffraction grating is formed.

It is confirmed that a sample formed using a glass substrate with ITO can control deflection by applying a voltage. AC pulse drive (1K
Hz, 50% duty cycle). He mentioned above
The applied voltage is gradually increased while the red light of the -Ne laser is incident on the sample and the intensity of each of the direct light and the diffraction spot is continuously monitored with a power meter. It is observed that the intensity of the diffraction spot becomes weaker as the voltage increases, and when it reaches a certain value, almost only direct light is observed. This operation varies depending on the condition of each sample, but the diffracted light starts to become weak at around 40 to 50 V from a state where about 90% of the He-Ne laser light is diffracted, and becomes 100 to 130 V. Almost no diffracted light is present. Compared with the case where no light is irradiated prior to the laser beam splitting interference irradiation, the latter clearly has a higher diffraction efficiency, that is, the on-state when operated by applying a voltage.
It shows excellent characteristics that a large -off ratio can be obtained.

Example 5 An ordinary slide glass was used as a glass substrate. The material system was about 0.6 g of nematic liquid crystal (Chisso), the oligomer was about 0.4 g of an acrylic-terminal urethane oligomer, and the sensitizer was About 2 × 10 ^-3 g of N-phenylglycine and about 1 fluorescein dye
× 10 ⁻³ g, glass beads with a diameter of 10 μm used as spacers, about 1 × 10 ⁻⁴ g (this amount is not important in terms of value itself, as long as a uniform space can be maintained when sandwiched between glass substrates) I do. The two washed slide glasses are heated to approximately 78 ° C. and the material system is kept at the same temperature. After confirming that the temperature has stabilized, a small amount of the material system (attached to the tip of a spatula or using a microdropper) is dropped on one glass substrate.

The other glass substrate is placed on the glass substrate while paying attention so that air bubbles and the like do not enter, and an appropriate weight is applied (about several tens to several hundreds g: to help the material spread quickly and uniformly between the glass substrates). , An appropriate weight) for several minutes. After that, a laser irradiation and a laser irradiation with a high-pressure mercury lamp prior to laser irradiation are compared. It is effective for reducing, preventing deterioration of diffraction characteristics such as segregation of liquid crystal material, and improving transparency. Here, a high-pressure mercury lamp is used, but the light source is not limited to this, and any light source having a spectrum distribution in a similar wavelength region can be used.

On the other hand, after inserting a material between glass substrates, it is mounted on a substrate holder and irradiated with a two-divided interference laser beam. Needless to say, the substrate holder needs to have a light passage window. At the same time, a device provided with a heating mechanism for temperature control is desirable. Using an Ar laser 514.5 nm oscillation line to form a grating with a period of about 1 micron, the split light is adjusted so that the optical path is exactly the same, and the incident angle to the substrate is set to 15 ° I do. Laser output 100mW (meter value attached to laser power supply)
Irradiate for about 30 seconds to form a grid.

On the other hand, first, a 10 mm thick glass (BSL-7, OHARA Inc.,
Through the light transmission characteristic shown in FIG.
UV irradiation is performed for a second. Then, irradiation is performed for about 20 seconds at a laser output of 25 mW using the above optical system. In both cases, immediately after irradiation with the laser beam, irradiation is performed using a high-pressure mercury lamp at approximately 30 mW for 2 minutes. This completes the formation of the artificial lattice, but since the change slightly progresses until the temperature returns to room temperature, it is left in a dark room.

When the formed artificial lattice is observed under a polarizing microscope, the overall brightness changes with the rotation of the stage, because the liquid crystal contained in the material system is oriented with a certain direction. When observed at a high magnification of about 1000 times, fine lattice fringes are seen.

When red light of a He—Ne laser is incident on the sample as monochromatic spot light, diffraction spots are observed in addition to the direct light, and it can be confirmed that a diffraction grating is formed. In the sample which was not irradiated with the ultraviolet light prior to the irradiation with the laser light at the time of formation, the spread of the light scattered dimly with the diffraction spot light, or a bright line shining so as to penetrate the spot is observed. This tendency cannot be solved, even if the aforementioned forming conditions, for example, the light irradiation time, irradiation light power, etc., are changed, although the degree of difference is observed. On the other hand, in the sample subjected to ultraviolet light irradiation prior to laser irradiation, only a bright spot is observed in diffraction light evaluation using a He-Ne laser.

Observation with a microscope of a sample in which scattered light and bright lines are observed shows that the liquid crystal is not uniformly present between the lattices and segregates, and that the polymerized resin has an uneven pattern. It was found that some micro defects occurred. That is, these defects are avoided by the irradiation of ultraviolet light in the first stage. Also, comparing the intensity of the diffracted light, it is clear that the diffraction efficiency is higher when ultraviolet light is irradiated before laser light irradiation than when laser light is irradiated without ultraviolet light irradiation, and the ultraviolet light irradiation in the first stage improves the characteristics. ing.

(Embodiment 4) Various kinds of glass are used as a substrate, and a material composed mainly of an oligomer and a liquid crystal to which a sensitizer and a dye are added is used, and this material is sandwiched between glass substrates. In a method of forming a diffraction grating by irradiating a laser beam with two-division interference, a method was developed that enables control of polarization. This is not possible with all material systems, but only with the interaction of certain materials with special light irradiation methods. The polarization characteristics of the diffraction grating are controlled by optimizing the liquid crystal material, adding one or more types of monomers to the material system, and irradiating mainly with ultraviolet light performed prior to laser light irradiation. Since there are an extremely large number of types of liquid crystal materials and monomers, and new ones are being developed one after another, it is impossible to verify them all. However, certain trends were obtained from the results of the studies conducted by the inventors.

First, a liquid crystal material considered to be desirable is M
The TL series among those sold by erck Japan. Although the substance name, molecular structure, and the like are not clear, they are a series of liquid crystal material groups each having some remarkable characteristics such as high birefringence and easy operation at low voltage.

The monomer to be added does not differ depending on whether it is monofunctional or polyfunctional, and has a benzene ring, for example, phenoxyethyl acrylate, phenoxypolyethylene glycol acrylate, nonylphenol EO adduct acrylate, hydroxyphenoxy. Propyl acrylate, EO adduct diacrylate of bisphenol A, neopentyl glycol acrylate benzoate, phenoxyethyl methacrylate,
Benzyl methacrylate, bisphenol A EO adduct dimethacrylate and the like are effective.

Further, it goes without saying that the combination with the oligomer and the polymerization initiator system has an influence, and it is needless to say that various materials can be used for these, but the green oscillation line (514. 5nm)
When using amines, for example, N-phenylglycine, rhodamine B, fluorescein, rose bengal, eosin Y, erythrosine, etc. are sensitive and provide a good combination.

Prior to the laser beam splitting interference irradiation, light irradiation is performed for a relatively short time using a high-pressure mercury lamp, and it is important to control the irradiation time and spectral distribution at that time.
Although a high-pressure mercury lamp is used as the light source, the light source is not limited to this, and any light source having a spectrum distribution in a similar wavelength region can be used. Instead of directly irradiating the object with the light of the lamp, one or more types of filters are used depending on the material.

Although specific examples will be described later, these absorb or transmit light in a specific wavelength region, and by combination, create an energy distribution different from the wavelength of the lamp itself, that is, an energy distribution, and form a three-dimensional lattice structure. It controls the formation process and the preferred orientation direction of the liquid crystal molecules. At present, no understanding of the mechanism at the atomic or molecular level has been obtained. A typical example is shown below.

(Example 6) As a substrate, a normal slide glass and a transparent conductive thin film (ITO was used here, but other usable metals and metal oxides such as SnO ₂ , In ₂ O ₃ , ZnO Using a glass substrate (Corning 7059 and Asahi Glass AN635), the material system is about 0.3 g of nematic liquid crystal (TL-216 from Merck), and the oligomer is phenyl glycidyl ether acrylate hexamethylene diisocyanate urethane oligomer. 0.7 g, monomer: 0.1 g of diacrylate of EO adduct of bisphenol A
(This is not essential, but has the effect of lowering the viscosity of the oligomer and accelerating the polymerization, and also partially contributing to the control of the polarization characteristics.) The sensitizer is N-phenylglycine of about 2 ×
10 ^-3 g, the dye is about 1 × 10 ^-3 g of fluorescein,
Approximately 3 × 10 ^-4 g of glass beads having a diameter of 10 μm as a spacer (this amount is not important,
It is sufficient that a uniform space can be maintained when sandwiched between glass substrates).

The washed slide glass and two glass substrates with ITO are heated to about 55 ° C., and the material system is kept at the same temperature. Make sure the temperature is stable,
A small amount of the material system (attached to the tip of a spatula or using a microdropper) is dropped onto one of the glass slides and the ITO-coated side of the glass substrate. Place the other slide glass and the glass substrate with the ITO side facing the material side while taking care not to introduce air bubbles, etc., and apply an appropriate load (about several tens to several hundreds g: the material is quickly and uniformly glassy). (This is to help spread between the substrates, and may be of an appropriate weight.) And left for several minutes. After that, laser irradiation and light irradiation using a high-pressure mercury lamp prior to laser irradiation are compared, and a method for controlling polarization characteristics will be described.

The light has polarization properties, and the P wave and the S wave
There are waves. In order to control the polarization of the light diffracted by the diffraction grating, the material system including the liquid crystal of this example is used, and either the P wave or the S wave is prioritized by the process of forming the diffraction grating by irradiating the laser beam with two-part interference. A grating that is diffracted is formed as follows.

Formation of diffraction grating giving priority to P wave: In light irradiation using a high-pressure mercury lamp, in addition to the condition of about 9 mw for direct irradiation, BSM18 (OHARA) is used as a filter.
Inc. 4) and U330 showing light transmission characteristics.
(Made of Hoya glass, FIG. 5 showing light transmission characteristics)
Irradiate for approximately 12 seconds.

Formation of diffraction grating giving priority to S-wave: In light irradiation using a high-pressure mercury lamp, in addition to the condition of about 9 mw for direct irradiation, BSM18 (OHARA) is used as a filter.
Inc. ) And U330 (made of Hoya glass) for about 0 to 6 seconds.

Thereafter, it is quickly mounted on the substrate holder and irradiated with laser light. Needless to say, the substrate holder needs to have a light passage window. At the same time, a device provided with a heating mechanism for temperature control is desirable. In order to form a grating having a period of about one micron, 51 of an Ar laser is used.
Using a 4.5 nm oscillation line, the light split into two is adjusted so that the optical path is exactly the same, and the angle of incidence on the substrate is set to 15 °. Irradiate at a laser power of 50 mW (meter value attached to laser power supply) for 5 to 15 seconds. Immediately thereafter, irradiation is performed at about 19 mW for 2 minutes using a high-pressure mercury lamp.
This completes the formation of the artificial lattice, but since the change slightly progresses until the temperature returns to room temperature, it is left in a dark room.

When the formed artificial lattice is observed under a polarizing microscope, the overall brightness changes with the rotation of the stage, because the liquid crystal contained in the material system is oriented with a certain direction. When observed at a high magnification of about 1000 times, fine lattice fringes are seen. Furthermore, when a monochromatic spot light, for example, red light of a He-Ne laser is incident on the sample, a diffraction spot is seen in addition to the direct light,
It can be confirmed that a diffraction grating is formed.

It is confirmed that a sample formed using a glass substrate with ITO can control deflection by applying a voltage. AC pulse drive (1K
Hz, 50% duty cycle). He mentioned above
The applied voltage is gradually increased while the intensity of each of the direct light and the diffraction spot is continuously monitored by a power meter while the red light of the -Ne laser is incident on the sample. It is observed that the intensity of the diffraction spot becomes weaker as the voltage increases, and when it reaches a certain value, almost only direct light is observed. Here, the ratio of the direct light to the diffracted light is used as a measure of the diffraction efficiency, and the state of the change due to the application of the voltage is plotted in FIG. 6 for the S-polarized light preferentially, and in FIG. 7 for the P-polarized light preferential diffraction grating.

This operation varies depending on the condition of each sample, but the intensity of the diffraction spot of the He-Ne laser beam starts to weaken with the application of the voltage, and the diffracted light substantially disappears at about 20 V.

This operation is explained as follows in relation to the formed three-dimensional lattice structure. The lattice structure is formed as a result of a polymerization reaction caused by irradiation of an interference laser beam having a three-dimensional intensity distribution in a material system mainly composed of an oligomer and a liquid crystal, but the liquid crystal is not uniformly distributed during the formation process and the light intensity is weak. Many are present in the area. This state is fixed by the subsequent ultraviolet irradiation, and a region where a large amount of liquid crystal exists and a region where the liquid crystal is not so are formed. On the other hand, only the liquid crystal part responds to the application of voltage from the outside, not the resin part. Therefore, the direction of liquid crystal molecules changes due to the application of voltage, and the refractive index of the area where there is a large amount of liquid crystal changes. Can be controlled by an external voltage.

(Embodiment 7) A normal slide as a substrate
Glass and transparent conductive thin film (here, ITO
But other usable metals and metal oxides, such as
SnO_Two, In_TwoO_Three, ZnO, etc.)
Using a substrate (Asahi Glass AN635), the material system is nematic.
About 0.3 g of liquid crystal (Merck TL-203)
The ligomer is phenylglycidyl ether acrylate
About xamethylene diisocyanate urethane oligomer
0.8 g, monomer is phenoxy polyethylene glycol
About 0.09 g of acrylate (this is not required
Has the effect of lowering the viscosity of the oligomer and accelerating the polymerization.
And contributes in part to the control of polarization characteristics), sensitization
The agent is N-phenylglycine in about 2 × 10^-3g, pigment is
About 1 × 10 ^-3g, as a spacer
About 4 × 10 glass beads with a diameter of 10 microns^-Fourg (this
The quantity is not important for the value itself, it is sandwiched between glass substrates.
As long as it can maintain a uniform space when inserted)
You.

The washed slide glass and two glass substrates with ITO are heated to about 50 ° C., and the material system is kept at the same temperature. Make sure the temperature is stable,
A small amount of the material system (attached to the tip of a spatula or using a microdropper) is dropped onto one of the glass slides and the ITO-coated side of the glass substrate. Place the other slide glass and the glass substrate with the ITO side facing the material side while taking care not to introduce air bubbles, etc., and apply an appropriate load (about several tens to several hundreds g: the material is quickly and uniformly glassy). (This is to help spread between the substrates, and may be of an appropriate weight.) And left for several minutes. After that, laser irradiation and light irradiation using a high-pressure mercury lamp prior to laser irradiation are compared, and a method for controlling polarization characteristics will be described.

The light has a polarization property, and the P wave and the S wave
There are waves. In order to control the polarization of the light diffracted by the diffraction grating, the material system including the liquid crystal of this example is used, and either the P wave or the S wave is prioritized by the process of forming the diffraction grating by irradiating the laser beam with two-part interference. A grating that is diffracted is formed as follows.

Formation of diffraction grating giving priority to P wave: In light irradiation using a high-pressure mercury lamp, in addition to the condition of about 9 mw for direct irradiation, BSM18 (OHARA) is used as a filter.
Inc. 4) and U330 showing light transmission characteristics.
(Made of Hoya glass, FIG. 5 showing light transmission characteristics)
Irradiate for 8-12 seconds.

Formation of diffraction grating giving priority to S-wave: In light irradiation using a high-pressure mercury lamp, in addition to the condition of approximately 9 mw for direct irradiation, BSM18 (OHARA) is used as a filter.
Inc. ) And U330 (made of Hoya glass) for about 0 to 4 seconds.

Thereafter, it is quickly mounted on the substrate holder and irradiated with laser light. Needless to say, the substrate holder needs to have a light passage window. At the same time, a device provided with a heating mechanism for temperature control is desirable. In order to form a grating having a period of about one micron, 51 of an Ar laser is used.
Using a 4.5 nm oscillation line, the light split into two is adjusted so that the optical path is exactly the same, and the angle of incidence on the substrate is set to 15 °. Irradiate at a laser power of 50 mW (meter value attached to laser power supply) for 5 to 20 seconds. Immediately thereafter, irradiation is performed at about 19 mW for 2 minutes using a high-pressure mercury lamp.
This completes the formation of the artificial lattice, but since the change slightly progresses until the temperature returns to room temperature, it is left in a dark room.

When the formed artificial lattice is observed under a polarizing microscope, the overall brightness changes with the rotation of the stage, because the liquid crystal contained in the material system is oriented with a certain direction. When observed at a high magnification of about 1000 times, fine lattice fringes are seen. Furthermore, when a monochromatic spot light, for example, red light of a He-Ne laser is incident on the sample, a diffraction spot is seen in addition to the direct light,
It can be confirmed that a diffraction grating is formed.

It is confirmed that the deflection of the sample formed using the glass substrate with ITO can be controlled by applying a voltage. AC pulse drive (1K
Hz, 50% duty cycle). He mentioned above
The applied voltage is gradually increased while the red light of the -Ne laser is incident on the sample and the intensity of each of the direct light and the diffraction spot is continuously monitored with a power meter. It is observed that the intensity of the diffraction spot becomes weaker as the voltage increases, and when it reaches a certain value, almost only direct light is observed. Here, the ratio of the direct light to the diffracted light is used as a measure of the diffraction efficiency, and the state of the change due to the application of the voltage is plotted in FIG. 8 and FIG.

This operation varies depending on the condition of each sample, but the intensity of the diffraction spot of the He-Ne laser beam starts to weaken with the application of the voltage, and the intensity of the diffracted light is approximately 15 to 20 V. Disappears.

(Embodiment 8) A normal slide glass and a transparent conductive thin film (ITO was used here) were used as substrates, but other usable metals and metal oxides such as SnO ₂ , In ₂ O ₃ , ZnO The material system is about 0.3 g of nematic liquid crystal (TL-216 from Merck), and the oligomer is about 0.8 g of phenylglycidyl ether acrylate hexamethylene diisocyanate urethane oligomer. The monomers are about 0.05 g of phenoxy polyethylene glycol acrylate and about 0.4 g of diacrylate of EO adduct of bisphenol A (this is not essential, but has the effect of lowering the viscosity of the oligomer and accelerating the polymerization. Partially contribute to the control of characteristics),
The sensitizer was about 2 × 10 ⁻³ g of N-phenylglycine, the dye was about 1 × 10 ⁻³ g of fluorescein, and about 4 × 10 ⁻⁴ g of glass beads having a diameter of 10 μm as a spacer.
(This amount is not important for the value itself, as long as it can maintain a uniform space when sandwiched between glass substrates.)
use.

The washed slide glass and two glass substrates with ITO were heated to about 55 ° C., and the material system was kept at the same temperature. Make sure the temperature is stable,
A small amount of the material system (attached to the tip of a spatula or using a microdropper) is dropped onto one of the glass slides and the ITO-coated side of the glass substrate. Place the other slide glass and the glass substrate with the ITO side facing the material side while taking care not to introduce air bubbles, etc., and apply an appropriate load (about several tens to several hundreds g: the material is quickly and uniformly glassy). (This is to help spread between the substrates, and may be of an appropriate weight.) And left for several minutes. After that, laser irradiation and light irradiation using a high-pressure mercury lamp prior to laser irradiation are compared, and a method for controlling polarization characteristics will be described.

The light has a polarization property, and the P wave and the S wave
There are waves. In order to control the polarization of the light diffracted by the diffraction grating, the material system including the liquid crystal of this example is used, and either the P wave or the S wave is prioritized by the process of forming the diffraction grating by irradiating the laser beam with two-part interference. A grating that is diffracted is formed as follows.

Formation of diffraction grating giving priority to P-wave: In light irradiation using a high-pressure mercury lamp, in addition to the condition of about 9 mw for direct irradiation, BSM18 (OHARA) is used as a filter.
Inc. 4) and U330 showing light transmission characteristics.
(Made of Hoya glass, FIG. 5 showing light transmission characteristics)
Irradiate for 4-12 seconds.

Formation of diffraction grating giving priority to S-wave: In the case of direct irradiation in light irradiation using a high-pressure mercury lamp, in addition to the condition of approximately 9 mw, BSM18 (OHARA) is used as a filter.
Inc. ) And U330 (made of Hoya glass) for about 0 to 2 seconds.

Thereafter, it is quickly mounted on the substrate holder and irradiated with laser light. Needless to say, the substrate holder needs to have a light passage window. At the same time, a device provided with a heating mechanism for temperature control is desirable. In order to form a grating having a period of about one micron, 51 of an Ar laser is used.
Using a 4.5 nm oscillation line, the light split into two is adjusted so that the optical path is exactly the same, and the angle of incidence on the substrate is set to 15 °. Irradiate for 3 to 20 seconds with a laser power of 50 mW (meter value attached to the laser power supply). Immediately thereafter, irradiation is performed at about 19 mW for 2 minutes using a high-pressure mercury lamp.
This completes the formation of the artificial lattice, but since the change slightly progresses until the temperature returns to room temperature, it is left in a dark room.

When the formed artificial lattice is observed under a polarizing microscope, the overall brightness changes with the rotation of the stage, because the liquid crystal contained in the material system is oriented with a certain direction. When observed at a high magnification of about 1000 times, fine lattice fringes are seen. Furthermore, when a monochromatic spot light, for example, red light of a He-Ne laser is incident on the sample, a diffraction spot is seen in addition to the direct light,
It can be confirmed that a diffraction grating is formed.

It is confirmed that the deflection of the sample formed using the glass substrate with ITO can be controlled by applying a voltage. AC pulse drive (1K
Hz, 50% duty cycle). He mentioned above
The applied voltage is gradually increased while the intensity of each of the direct light and the diffraction spot is continuously monitored by the power meter while the red light of the -Ne laser is incident on the sample. It is observed that the intensity of the diffraction spot becomes weaker as the voltage increases, and when it reaches a certain value, almost only direct light is observed. Here, the ratio of the direct light to the diffracted light is used as a measure of the diffraction efficiency, and the state of the change with the applied voltage is plotted in FIG.
FIG. 11 shows a diffraction grating that gives priority to S-polarization, and FIG. 11 shows a diffraction grating that gives priority to P-polarization.

Although this operation varies depending on the condition of each sample, the intensity of the diffraction spot of the He-Ne laser beam begins to weaken with the application of voltage, and the intensity of the diffracted light is approximately 15 to 20 V. Disappears.

[0082]

As described above, the present invention makes it possible to form an artificial lattice structure by the action of energy rays on a certain material system, not by repeatedly laminating different thin films. Furthermore, by applying irradiation of another energy beam prior to irradiation of the energy beam divided into two for forming the lattice structure, shortening of the operation time, deterioration of the material whose refractive index can be changed,
It can prevent segregation and deterioration, improve diffraction efficiency when a diffraction grating is formed, and control polarization.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a cross section of an artificial lattice formed according to the present invention.

FIG. 2 is a configuration diagram of an optical system used for light irradiation.

FIG. 3 is a transmission characteristic diagram of glass (BSL7).

FIG. 4 is a transmission characteristic diagram of glass (BSM18).

FIG. 5 is a transmission characteristic diagram of glass (U330).

FIG. 6 is an electrical operating characteristic diagram of a diffraction grating giving priority to S-polarization.

FIG. 7 is an electrical operating characteristic diagram of a diffraction grating giving priority to P polarization.

FIG. 8 is an electrical operating characteristic diagram of a diffraction grating giving priority to S-polarization.

FIG. 9 is an electrical operation characteristic diagram of a diffraction grating giving priority to P-polarization.

FIG. 10 is an electrical operation characteristic diagram of a diffraction grating giving priority to S-polarization.

FIG. 11 is an electrical operation characteristic diagram of a diffraction grating giving priority to P-polarization.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Refractive index n1 area 2 Refractive index n2 area 3 Material system 4 Base 21 Laser 22 Collimating lens system 23 Half mirror 24 Mirror 25 Workpiece

Claims (4)

[Claims] 1. In a laminated structure in which a region A1 and a region A2 are alternately repeated, the region A1 has a desired refractive index n1, and the region A2 has a refractive index n2 different from the refractive index n1. An artificial lattice disposed on or between the substrates, wherein the laminated structure has a normal direction that is not parallel to the normal direction of the laminated structure. 2. In a laminated structure in which a region A1 and a region A2 are alternately repeated, at least one of the region A1 and the region A2 contains a material whose refractive index can be changed by the action of energy from the outside of the laminated structure. The laminated structure is disposed on or between substrates having a normal direction that is not parallel to the normal direction of the laminated structure, the substrate is provided with an energy applying mechanism, and the refractive index n1 of the region A1 is An artificial lattice that can be set to have a value different from or equal to the refractive index n2 of the region A2. 3. A method according to claim 1, wherein a plurality of types of energy rays having different energies are used, and one of the plurality of types of energy rays is divided into two except for one type. Irradiation is performed so as to cause interference at the artificial lattice formation position according to the above, using a material system containing a substance capable of absorbing the energy of the energy beam divided into two, the irradiation by the energy beam divided into two A method for forming an artificial lattice by irradiating the undivided energy beam after forming a repeating structure in a different region by modifying a part of a material system. 4. A method according to claim 1, wherein a plurality of types of energy rays having different energies are used, and one of the plurality of types of energy rays is divided into two except for one type. Irradiation is performed so as to cause interference at the artificial lattice forming position according to the above, using a material system containing a substance capable of absorbing energy of a specific wavelength of the energy beam, the material is irradiated by the energy beam divided into two, the material In a method of forming an artificial lattice by irradiating the undivided energy beam after forming a repeating structure of a different region by modifying a part of the system, the undivided energy beam is irradiated prior to the irradiation of the two-divided energy beam. A method for forming an artificial lattice, comprising irradiating an object to be processed with an energy ray.