JPH08301695A - Optical material and its production - Google Patents

Abstract

PURPOSE: To obtain an optical material in a valence state of an activator element modulated in terms of space by irradiating an optical material containing a rare earth element or a transition metal element as an activator with a specific light during its synthesis. CONSTITUTION: In at least one process for synthesizing an optical material containing at least one of a rare earth element and a transition element as an activator and a process for heat treatment after the synthesis, the following treatment is carried out. Namely, the optical material is irradiated with a light in a light absorption wavelength range of the activator ion or a light including a wavelength in a light absorption wavelength range of the activator ion and the irradiation dose is modulated in terms of space to give the objective optical material. The optical material can provide a filter of a narrow range capable of designing an oscillation wavelength, and form an arbitrary indication pattern by few production processes and supply an eliminable indication element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical material and a method for manufacturing the same, and in particular, a narrow band laser material and a narrow band filter material whose oscillation wavelength can be designed, and an arbitrary display pattern can be formed by a small number of manufacturing steps. In addition, the present invention relates to a display optical material in which a display pattern can be erased and rewritten, and a manufacturing method of these optical materials.

[0002]

2. Description of the Related Art Optical materials containing a rare earth element or a transition metal element as an activator have been widely used as fluorescent material, solid-state laser material, or optical filter material for wavelength calibration. The optical characteristics of these optical materials are such that the transition between the intrinsic electronic levels of the activator ion, that is, when a rare earth element is used as the activator, the 4f electronic level and the 5d electronic level of the rare earth ion are used. When a transition metal element is used as an activator using a transition between positions (hereinafter described as fd transition) or a transition between 4f electronic levels (hereinafter described as ff transition), A transition between 3d electronic levels of a transition metal element ion (hereinafter referred to as d-d transition) is used.

Of these transitions, fd transitions and dd transitions
The transition has a broad wavelength change depending on the base material and exhibits broad absorption and emission characteristics, whereas the ff transition has a small wavelength variation due to the base material and exhibits a plurality of linear absorption and emission characteristics. There is a feature called. Therefore, fd transitions and dd transitions are used as optical materials such as wavelength tunable lasers that require broadband emission characteristics, and fd for materials that require sharp absorption lines such as wavelength calibration filters.
You are using transitions.

As an optical material utilizing the d-d transition,
Titanium Titanium sapphire laser with Ti added, Cr
There is a wavelength tunable laser such as a Cr: YAG laser with addition of Al, in particular the latter is 1.3 μm, which is the optical communication wavelength band.
It is useful as a laser that oscillates in the wavelength range of up to 1.5 μm. Further, as an optical material utilizing the f-f transition, a holmium glass filter containing Ho is widely used as a wavelength calibration filter for a spectroscope or the like.

As described above, the light absorption characteristics and the light emission characteristics of the rare earth element and the transition metal element added as the activator change depending on the kind of the element, the valence of the ion and the kind of the base material. , Light absorption characteristics if these three are decided,
The light emission characteristic is uniquely determined. Therefore, when a phosphor such as a color CRT that emits different colors from blue, green, and red is required, three types of phosphors that emit blue, green, and red, respectively, are spatially separated and used. .

[0006]

When a conventional broadband laser is used to select a desired oscillation wavelength from the oscillation wavelength band to oscillate, a wavelength selection element must be incorporated in the resonator to oscillate. In addition to the drawback that the structure of the resonator becomes complicated, there is also the drawback that the position of the optical element used as the resonator changes due to changes in the ambient temperature and the oscillation wavelength easily changes.

Further, in the wavelength calibration filter,
Since the wavelength of the absorption line due to the characteristic transition of rare earth is discrete, there is a drawback that the wavelength of the absorption line cannot be arbitrarily selected.

In addition, in a display device such as a color cathode ray tube, different phosphors are spatially separated, so that the phosphor coating process and the etching process need to be repeatedly performed, resulting in a large number of processes. In addition to the above, since the spatial separation is performed by etching, there is a drawback that the spatial resolution of the phosphor arrangement, that is, the resolution is limited and only a resolution of several μm can be obtained at most. Furthermore, the array pattern of the phosphors formed in this manner is fixed, and there is a drawback that the array pattern cannot be changed after the display element is manufactured.

[0009]

The present invention has been made in view of the above-mentioned drawbacks, and in at least one of the step of synthesizing an optical material and the heat treatment step after the synthesis,
Irradiate light with a wavelength within the light absorption wavelength band of the activator ion, or light including a wavelength within the light absorption wavelength band of the activator ion, and irradiate by modulating the intensity of the irradiation light or the irradiation time spatially. By doing so, the above problem can be solved by using an optical material in which the valence state of the activator element is spatially modulated.

[0010]

According to the present invention, in at least one of the step of synthesizing an optical material and the heat treatment step after synthesis, the light having a wavelength within the light absorption wavelength band of the activator ion or the light absorption wavelength band of the activator ion is It utilizes the effect of changing the valence state of the activator when irradiated with light containing a wavelength.

In order to explain the operation in an easy-to-understand manner, Cr
The description will proceed with the added YAG single crystal as an example. Usually, in Cr-added YAG single crystal, Cr is contained in the state of trivalent ions. However, when heat treatment is performed by irradiating with light corresponding to the light absorption wavelength of trivalent Cr, the valence state of Cr is Changes from trivalent to tetravalent. The tetravalent Cr concentration generated by changing the valence is proportional to the total amount of irradiation light energy which is the product of the irradiation light intensity and the irradiation time. Therefore, the concentration of tetravalent Cr changes in proportion to the light intensity if the irradiation time is constant and in proportion to the irradiation time if the light intensity is constant.

Therefore, when the intensity of the irradiation light is spatially modulated and the light irradiation is performed, the tetravalent Cr concentration is high in the portion irradiated with the high intensity light and the weak intensity light is emitted. Since the tetravalent Cr concentration becomes low in the part, the valence state of Cr was spatially modulated, that is, trivalent Cr and tetravalent C.
A YAG single crystal having a partially different abundance ratio of r is obtained. Similarly, when the irradiation time is modulated, the tetravalent Cr concentration is high in the portion where the irradiation time is long, and the tetravalent Cr concentration is low in the portion where the irradiation time is short. Y in which the valence state of Cr is spatially modulated
An AG single crystal is obtained.

[0013]

Example 1 Yttrium aluminum garnet (YAG) containing Cr as an activator (hereinafter Cr: YAG
The following describes an example of producing a YAG in which the valence state of Cr is spatially modulated by irradiating light within the light absorption wavelength band of trivalent Cr in the single crystal (described above) and performing heat treatment.

In this embodiment, Cr is 6 × 10 ¹⁷ pieces / cm 2.
Using YAG single crystal with ³ added, wavelength of 51
A 4 nm Ar ion laser was used. Wavelength 514nm
Is the wavelength within the light absorption band of trivalent Cr in YAG.

FIG. 1 is a view showing the arrangement of the apparatus used in this embodiment. The beam diameter of the light from the Ar ion laser 11 is expanded by the beam expander 12, the optical path is divided into two by the half mirror 13, and one of them travels straight. Cr: YAG (optical material sample) 15 installed on the heating mechanism 16
It is directly irradiated on. The other is reflected by the total reflection mirror 14 and then irradiated on the Cr: YAG 15. The interference of these two beams produces an interference fringe whose intensity is spatially and periodically modulated. Therefore, in the portion of Cr: YAG15, which is installed in the interference region of the light beam, the intensity is spatially and periodically. The modulated light is emitted. Cr: YAG
In irradiating the laser with the laser beam, the entire Cr: YAG was not irradiated with the laser beam but was partially irradiated with the laser beam so that it did not hit both end faces in the longitudinal direction of Cr: YAG.
This is to prevent light that has entered the interior of Cr: YAG from being reflected by the end faces and causing unnecessary interference.

FIG. 2 is a diagram showing the appearance of interference fringes formed in the sample. The crystal longitudinal direction is the Y axis, and the vertical direction is the X axis.
The angle between the indirect incident light a reflected by the mirror 14 and indirectly incident on the axis and the X axis, the direct incident light b.
The crystals are set so that the angles formed by the X axis and the X axis are equal. When the crystal is placed in such an arrangement, interference fringes are formed in the direction perpendicular to the crystal longitudinal direction. When heat treatment is performed in this state, the trivalent Cr in the light-irradiated portion becomes tetravalent C.
The valence changes to r, and the amount of change increases with the light intensity.
4 depending on the cycle of the interference fringes, that is, the cycle of the intensity of light
A Cr: YAG crystal in which the valence Cr concentration is modulated is obtained.
In this way, the light having the wavelength λ that travels in the Y-axis direction in the crystal in which the tetravalent Cr concentration is periodically modulated at the period d is λ = nd
Light having a wavelength satisfying (where n is an integer) reinforces each other due to the interference effect.

The period d of the interference fringes is d = λ / 2s, where λ is the wavelength of the incident light and α is the cross angle between the incident light a and the incident light b.
It is given by in (α / 2). In the present embodiment, the wavelength λ of the incident light is 514 nm, and the crossing angle α of the incident lights a and b in the device configuration of FIG. 1 is in the range of 0 <α <180. Therefore, by continuously changing α, The interval d of the interference fringes can be continuously changed within the range of 0 <d <257 nm.

In manufacturing this sample, the heating mechanism 16
Was used to heat Cr: YAG15 and the temperature was raised to 1600 ° C., and then light irradiation was performed while the temperature was kept constant. The fluctuation of the sample temperature at this time was within 50 ° C.
The intensity of laser light was 10 mW. The temperature was kept for 2 hours, and after 2 hours, the temperature was lowered at a temperature lowering rate of 150 ° C./hour and the light irradiation was stopped when the sample temperature dropped to 300 ° C. or lower. This manufacturing process was performed 15 times by changing the crossing angle α to manufacture 15 types of crystals having different interference fringe intervals d. The crossing angle α was changed by changing the arrangement of the total reflection mirror 14 and the sample 15 and the angle of the total reflection mirror 14. The crossing angle α at the time of manufacturing each crystal is 1.37 μ when 6 times the interference fringe spacing d is
It was determined so as to have discrete values that differ by 0.01 μm in the range from m to 1.51 μm. This is because the light traveling in the crystal in the Y-axis direction has a lasing wavelength of λ when the tetravalent Cr concentration is periodically modulated and the period is d.
This is because light having a wavelength that satisfies λ = nd (where n is an integer) reinforces each other due to the interference effect.

15 kinds of Cr produced in this way:
After cutting both end faces of the YAG crystal, it was mirror-polished to obtain a laser crystal. When laser oscillation was carried out using these laser crystals, they each oscillated at a single wavelength, and the respective oscillation wavelengths were discretely different from 1.37 μm to 1.51 μm at 0.01 μm intervals. This is because the valence state of Cr is periodically modulated and the tetravalent Cr concentration is periodically increased or decreased, so that an interference effect occurs and oscillation of a single wavelength occurs.

When a YAG laser containing tetravalent Cr produced by the conventional method is oscillated at a single wavelength,
It was necessary to incorporate a wavelength selection element into the laser resonator to perform wavelength selection, but by using the Cr: YAG crystal of the present invention, it is possible to provide a laser element that oscillates at a single wavelength without using a wavelength selection element. It was Also, conventional C
In the laser element using the r: YAG crystal, the oscillation wavelength fluctuates due to the variation of the cavity length due to the temperature change during operation. However, the Cr: YAG crystal of the present invention has a wavelength selecting function, and therefore the oscillation wavelength Has not fluctuated. Further, the Cr: YAG crystal of the present invention has an advantage that it can provide a narrow band laser having a desired oscillation wavelength within the oscillating wavelength range of tetravalent Cr-doped YAG by controlling the interval of the interference fringes of the irradiation light. are doing.

[0021]

Example 2 Cr as an activator and Ca as a charge compensator
In the single crystal of Cr, Ca: YAG added with
The valence state of Cr is spatially modulated by irradiating light within the light absorption wavelength band of valence Cr and performing heat treatment.
An example of manufacturing AG will be described.

In this embodiment, 6 × 10 ¹⁷ tetravalent Cr /
cm ³ added YAG single crystal was used, and Nd: YAG laser having a wavelength of 1.064 μm was used as irradiation light. The wavelength 1.064 μm is a wavelength within the light absorption band of tetravalent Cr in YAG. The device configuration is the same as that of FIG.
An Nd: YAG laser was used instead of the r-ion laser. When heat treatment is performed with this apparatus configuration, the valence of the tetravalent Cr in the light-irradiated portion changes to trivalent Cr, and the amount of change increases with the light intensity. Therefore, the period of the interference fringes, that is, the period of light intensity Cr: Y whose tetravalent Cr concentration is modulated according to
AG crystals are obtained. In this way, it is 4 at the cycle d.
Light having a wavelength λ that propagates in the Y-axis direction in the crystal in which the valence Cr concentration is modulated, is strengthened by light having a wavelength satisfying λ = nd (where n is an integer) due to the interference effect.

The period d of the interference fringes is d = λ / 2s, where λ is the wavelength of the incident light and α is the cross angle between the incident light a and the incident light b.
It is given by in (α / 2). In this embodiment, the wavelength λ of the incident light is 1.064 μm, and the crossing angle α of the incident lights a and b is in the range of 0 <α <180 in the device configuration of FIG. 1, so α should be continuously changed. Therefore, the spacing d of the interference fringes
Can be continuously changed in the range of 0 <d <532 nm.

In producing this sample, the heating mechanism 16
Was used to heat Cr: YAG15 and the temperature was raised to 1600 ° C., and then light irradiation was performed while the temperature was kept constant. The fluctuation of the sample temperature at this time was within 50 ° C.
The intensity of laser light was 50 mW. The temperature was kept for 2 hours, and after 2 hours, the temperature was lowered at a temperature lowering rate of 150 ° C./hour and the light irradiation was stopped when the sample temperature dropped to 300 ° C. or lower. This manufacturing process was performed 15 times by changing the crossing angle α to manufacture 15 types of crystals having different interference fringe intervals d. The crossing angle α was changed by changing the arrangement of the total reflection mirror 14 and the sample 15 and the angle of the total reflection mirror 14. The crossing angle α at the time of manufacturing each crystal is 1.37 μm when three times the interference fringe spacing d is obtained.
It was determined so as to have discrete values that differ by 0.01 μm in the range from m to 1.51 μm. This is because the light traveling in the crystal in the Y-axis direction has a lasing wavelength of λ when the tetravalent Cr concentration is periodically modulated and the period is d.
This is because light having a wavelength that satisfies λ = nd (where n is an integer) reinforces each other due to the interference effect.

15 kinds of Cr produced in this way:
After cutting both end faces of the YAG crystal, it was mirror-polished to obtain a laser crystal. When laser oscillation was carried out using these laser crystals, they each oscillated at a single wavelength, and the respective oscillation wavelengths were discretely different from 1.37 μm to 1.51 μm at 0.01 μm intervals. This is because the valence state of Cr is periodically modulated and the tetravalent Cr concentration is periodically increased or decreased, so that an interference effect occurs and oscillation of a single wavelength occurs.

When a YAG laser containing tetravalent Cr produced by the conventional method is oscillated at a single wavelength,
It was necessary to incorporate a wavelength selection element into the laser resonator to perform wavelength selection, but by using the Cr: YAG crystal of the present invention, it is possible to provide a laser element that oscillates at a single wavelength without using a wavelength selection element. It was Also, conventional C
In the laser element using the r: YAG crystal, the oscillation wavelength fluctuates due to the variation of the cavity length due to the temperature change during operation. However, the Cr: YAG crystal of the present invention has a wavelength selecting function, and therefore the oscillation wavelength Has not fluctuated. Further, the Cr: YAG crystal of the present invention has an advantage that it can provide a narrow band laser having a desired oscillation wavelength within the oscillating wavelength range of tetravalent Cr-doped YAG by controlling the interval of the interference fringes of the irradiation light. are doing.

[0027]

Example 3 An example of manufacturing Cr: YAG in which the valence state of light is modulated in the film thickness direction by modulating the light intensity in the thin film synthesizing process using the thin film synthesizing method by electron beam evaporation in the synthesizing process. I will describe.

A single crystal YAG substrate is used as the substrate, and Y ₂
The salamics obtained by mixing and sintering O ₃ , Al ₂ O ₃ and Cr ₂ O ₃ was used as an evaporation source, and this ceramics was heated and evaporated by an electron beam to form a thin film on the substrate.

During the thin film formation, light from a halogen lamp installed in the chamber was irradiated onto the substrate from the thin film growth surface. A bandpass filter that transmits light with a wavelength of 500 to 700 nm is installed on the front surface of the halogen lamp, and 500 to 700 nm of the light from the halogen lamp is installed on the thin film growth surface.
The light of the wavelength is radiated. Light of this wavelength is 3
It contains a light absorption band due to the d-d transition of valent Cr ions. Thus, the use of the wavelength cut filter has an advantage that the light source can be configured more easily than the case of using the laser. The thin film growth rate is 10 nm / min, and 10
The halogen lamp was turned on and off repeatedly in a minute cycle.

While the halogen lamp is lit, trivalent Cr is excited by light absorption to cause a valence change and is likely to change to tetravalent Cr. Therefore, the layer formed during lighting of the halogen lamp has a high tetravalent Cr concentration. On the other hand, since the trivalent state of Cr is originally stable in YAG, it becomes a layer containing only trivalent Cr during extinguishment. Therefore, by repeatedly turning on and off the halogen lamp in the above-described cycle, a region having a high tetravalent Cr concentration and a region having a low tetravalent Cr concentration are alternately repeated every 100 nm in the film thickness direction, and the repeating period is 20.
An optical material is formed in which the valence state of Cr is modulated to 0 nm. Since tetravalent Cr absorbs light in a wide wavelength range from 0.8 μm to 1.1 μm, when light in this wavelength range is incident from the direction perpendicular to the film surface of this element, the incident light has an absorption region with a cycle of 200 nm. And the transparent area are alternately passed. Due to this periodic light absorption, of the incident light, light having an integral multiple of the absorption period, that is, a wavelength having an integral multiple of 200 nm is particularly strongly absorbed.

As a result of inspecting the wavelength dispersion of the light transmission characteristics of the sample manufactured by the above-mentioned method, the wavelength 1.00 in the region of 0.8 μm to 1.1 μm which is the absorption wavelength band of tetravalent Cr.
Sharp absorption was confirmed at μm. This means that tetravalent Cr is modulated in 200 nm intervals in Cr: YAG to form a periodic structure. As described above, a narrow band filter could be provided by using the element having the structure of the present invention in which the valence state of the activator changes periodically. Further, in this embodiment, the halogen lamp is turned on,
Since the wavelength can be arbitrarily designed by manufacturing by changing the turn-off period, it is possible to provide a narrow band filter having a desired wavelength.

[0032]

Example 4 An example of producing a display element using calcium fluoride (CaF ₂ ) (hereinafter referred to as CaF ₂ : Eu) to which europium (Eu) is added will be described.

In calcium fluoride, europium is 2
Since the state of valent ions is the most thermodynamically stable, CaF ₂ : Eu produced by the conventional production method contains Eu as divalent ions. When CaF ₂ : Eu is excited by ultraviolet rays to emit light, a broad emission spectrum having a peak in the vicinity of 420 nm is exhibited, and deep blue emission is obtained. In this example, plate-like Ca containing 0.3 mol% of Eu added
A display element was manufactured using F ₂ : Eu.

FIG. 3 is a diagram showing the structure of the apparatus used in this embodiment. The plate-like CaF ₂ : Eu31 (optical material sample) is
It is installed on the sample heating mechanism 32, and He- serves as the light source 33.
He-Cd laser (light source) 33 using Cd laser
The beam diameter of the light from the laser beam is expanded by the beam expander 34 and reflected by the mirror 35.
The plate-like CaF ₂ : Eu31 is irradiated through 6. The mask pattern 36 is patterned in advance so that the transmitted light intensity is modulated according to a desired display pattern.

In producing this element, first, a plate-like Ca
F ₂ : Eu 31 was heated to 1000 ° C. by the sample heating mechanism 32, and when the temperature reached 1000 ° C., irradiation with He—Cd laser was started. Since the light with a wavelength of 325 nm from the He-Cd laser is in the light absorption wavelength band of divalent Eu, the energy of the portion irradiated with this light is increased due to the excitation of the divalent Eu by the light absorption, and the energy of the trivalent Eu is increased. Two-value E
It will be thermodynamically more stable than u. When heat treatment is carried out while holding this state for 1 hour, atomic vacancy and atoms in CaF ₂ are rearranged so that trivalent Eu can be contained more stably by thermal energy, so that trivalent Eu is stably contained. It will be in a state of being. The heat treatment was performed for 1 hour while keeping the temperature constant at 1000 ° C. After completion of the heat treatment, the temperature was gradually lowered and cooled, and the temperature was lowered to room temperature, and then the light irradiation was stopped.

The CaF ₂ : Eu thus obtained was inspected by the PL method. As a result, the light-irradiated portion contained trivalent at a high concentration of one digit or more relative to the divalent Eu, while the light-irradiated portion contained ₂ %. It was confirmed that only the valence Eu was contained. By this method,
It was confirmed that a display element in which the valence state was spatially modulated was realized. When this element was irradiated with ultraviolet light to emit light, the light-irradiated portion emitted light of orange, which is the emission color of trivalent Eu, and the non-irradiated portion emitted light of deep blue, which was the emission color of divalent Eu, and thus emitted two-color light. A light emitting device was realized.

Furthermore, when the display element thus manufactured is heated again to 1000 ° C. and heat-treated for 1 hour without light irradiation, divalent Eu is thermodynamically more thermodynamic than trivalent Eu. Since it is a stable material, the valence of trivalent Eu changes to divalent Eu due to the rearrangement of atomic vacancies and atoms due to the heat treatment, and the entire element is in a state containing only divalent Eu. After heat treatment,
When inspected by irradiation with ultraviolet rays, it was confirmed that the entire device emitted dark blue light and the previously written pattern was erased. After that, light was irradiated again using a mask pattern that was patterned differently from the previous time to fabricate a display element in which the valence state of Eu was spatially modulated. It was confirmed that a spatially modulated display element could be manufactured, and that repeated patterning could be performed by this method.

In the conventional method, it was necessary to use two or more kinds of light emitting materials in order to realize a multicolor light emitting device, but in the method of the present invention, only one kind of light emitting material is irradiated with light. A two-color light-emitting device can be realized, a two-color light-emitting display device can be realized with a small number of manufacturing steps, and a light-emitting device capable of erasing a display pattern and writing a different display pattern can be provided.

[0039]

Fifth Embodiment: Cerium (Ce) or Terbium (T)
b) added yttrium aluminum garnet (YAG) (hereinafter Ce: YAG, Tb: YA, respectively)
An example in which an optical element is manufactured using (G) is described.

In YAG, both cerium and terbium are thermodynamically most stable in the state of trivalent ions.
Ce: YAG and Tb: YAG manufactured by the conventional manufacturing method are
It contains Ce or Tb as trivalent ions. This C
When e: YAG and Tb: YAG are excited by ultraviolet rays to emit light, both emit green light. On the other hand, trivalent Ce, Tb
When the valence is changed to tetravalent Ce or Tb, the electron level structure changes and both do not have a luminescence transition in the visible region, and therefore, no light emission in the visible region occurs even if ultraviolet rays are applied.

In this embodiment, Ce or Tb is 0.3 mo.
A display element was manufactured using plate-like Ce: YAG and plate-like Tb: YAG added with 1%. The apparatus configuration used in this example is shown in FIG. A plate-shaped optical element (optical material sample) 41 made of a plate-shaped Ce: YAG or a plate-shaped Tb: YAG is installed on a sample heating mechanism 42, and light from a He-Cd laser 43 is directed by a laser beam scanner in a beam traveling direction. Is controlled to irradiate the plate-shaped optical element 41. In manufacturing this element, first, the plate-shaped optical element 41 was heated to 1500 ° C. by the sample heating mechanism 42, and when the temperature reached 1500 ° C., irradiation with He—Cd laser was started.

Wavelength 325 nm from He-Cd laser
Since the light is within the light absorption wavelength band of both trivalent Ce and Tb shown in FIG. 5, the valence of trivalent Ce or Tb is changed to become tetravalent Ce or Tb in the portion irradiated with this light. With the temperature kept constant at 1500 ° C., the beam traveling direction is controlled in the XY axis direction by the laser beam scanner 44, and each time the X coordinate is changed, the beam scanning in the Y axis direction is increased once, and the plate-like optics is obtained. The surface of the element 41 was repeatedly scanned with a laser beam so that the light irradiation time increased as the X coordinate increased. In this state, the sample temperature was held for 1 hour to perform heat treatment, and after the heat treatment was finished, the temperature was gradually lowered and cooled, and the temperature was lowered to room temperature, and then the light irradiation was stopped.

The obtained Ce: YAG and Tb: YAG were added to P
As a result of inspection using L method, trivalent C depending on the light irradiation time
It was confirmed that e or Tb was decreased. By this method, it was confirmed that a display element in which the valence state was spatially modulated was realized. When this device was irradiated with ultraviolet rays to emit light, it was possible to realize a light-emitting device in which the green light emission intensity decreased as the X coordinate increased.

Further, as a result of inspecting the light transmittances of Ce: YAG and Tb: YAG, a bandpass filter in which the light transmittance of the wavelength region shown in FIG. 5 increases with the increase of the X coordinate can be realized.

In the conventional method, there is no example in which an optical element in which the emission intensity or the light transmittance continuously changes in the uniaxial direction within the same optical element has been realized, and the optical element according to the present method has a function not existed in the related art. It has been shown to provide an optical element.

[0046]

As described above, an optical material containing at least one element selected from rare earth elements or transition metal elements as an activator is prepared by the production method of the present invention, that is, an active material. A narrow band laser and a narrow band filter capable of designing an oscillation wavelength can be provided by using an optical material characterized in that the valence state of at least one of the agent elements is spatially modulated. At the same time, it was possible to provide an erasable display element in which an arbitrary display pattern can be formed by a small number of manufacturing steps.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an apparatus used in Examples 1 and 2.

FIG. 2 is a diagram showing a state of interference fringes formed in a sample in the device configuration used in Examples 1 and 2.

FIG. 3 is a diagram showing a device configuration used in Example 4;

FIG. 4 is a diagram showing a device configuration used in Example 5;

FIG. 5 is a diagram showing absorption bands resulting from fd transitions of Ce ³⁺ and Tb ^{3+ in} YAG.

[Explanation of symbols]

 11 Ar Ion Laser 12 Beam Expander 13 Half Mirror 14 Total Reflection Mirror 15 Optical Material Sample 16 Heating Mechanism 31 Optical Material Sample 32 Heating Mechanism 33 He-Cd Laser 34 Beam Expander 35 Mirror 36 Mack Pattern 41 Plate-shaped Optical Element (Optical Material) Sample) 42 Heating mechanism 43 He-Cd laser 44 Beam scanner

Claims (2)

[Claims] 1. An optical material containing, as an activator, at least one element selected from rare earth elements and transition metal elements, and the valence state of at least one of the activator elements is spatially modulated. An optical material characterized by being formed. 2. A method for producing an optical material containing, as an activator, at least one element selected from rare earth elements and transition metal elements, and at least one of a step of synthesizing the optical material and a heat treatment step after the synthesis. In one step, light within the light absorption wavelength band of the activator ion or light including a wavelength within the light absorption wavelength band of the activator ion is irradiated,
Moreover, a method for manufacturing an optical material, characterized in that the irradiation light amount is spatially modulated.