JP5458471B2 - Two-photon absorbing material, optical function imparting method, optical function detecting method, optical recording / reproducing method, optical recording material, and three-dimensional optical recording medium - Google Patents

Description

  The present invention relates to a two-photon absorbing material, and an optical function imparting method, an optical function detecting method, an optical recording / reproducing method, an optical recording material, and a three-dimensional optical recording medium using the two-photon absorbing material.

Conventionally, many inorganic materials have been found as two-photon absorption materials. Such an inorganic material has been very difficult to put into practical use because it is difficult to design a molecule for optimizing the desired two-photon absorption characteristics and various physical properties necessary for manufacturing the device. In contrast, organic compounds can be optimized not only for the desired two-photon absorption by molecular design, but also for other physical properties, which is highly practical and promising two-photon absorption. Has attracted attention as a material.
As such organic two-photon absorption materials, for example, pigment compounds such as rhodamine and coumarin; compounds such as dithienothiophene derivatives and oligophenylenevinylene derivatives are known. However, these organic compounds have a small two-photon absorption cross section showing a two-photon absorption capacity per molecule, and in particular, a two-photon absorption cross-section when using a femtosecond pulse laser is 200 GM (× 10 ⁻⁵⁰ cm ^4. Most of them are less than s · molecule ⁻¹ · photon ⁻¹ ), and have not yet been put into practical use.

In addition, the two-photon absorption phenomenon enables various applications characterized by extremely high spatial resolution. At present, however, the laser wavelength that induces the optical function differs from the wavelength at which it is detected. There is a problem that it can be put into practical use only by the system.
Therefore, in order to realize a practical application using two-photon absorption with a small and inexpensive system, optical functions (absorption spectrum, refractive index, change in polarization state, fluorescence characteristics) are efficiently induced by two-photon absorption. Therefore, it is desired to provide a two-photon absorption material that can be detected with detection light having the same wavelength, a method for imparting the optical function thereof, and a detection method.

In addition, many proposals have been made as prior art relating to a two-photon absorption material, a material for a three-dimensional memory medium, and a light limiting material.
For example, Patent Document 1 proposes a method for recording and reproducing diallyl ethene by photoisomerization by two-photon absorption. In this proposal, recording has a new absorption band in a wavelength region longer than the maximum absorption wavelength of two-photon absorption. In the reproduction, an increase in extinction coefficient or an increase in refractive index due to recording is detected. Normally, recording / reproduction cannot be performed at the same wavelength, but it is possible by controlling the two-photon absorption characteristics of the ring-opened body and the linear absorption characteristics of the ring-closed body.
However, with this proposed method, the two-photon absorption characteristics (absorption cross section, absorption wavelength) of the ring-opened body that enable high-sensitivity recording and reproduction at the same wavelength and the control of the absorption wavelength of the ring-closed body are extremely important in terms of material design. It is difficult. In addition, since the photochromic compound is a reversible material, there is a problem in that the photochromic compound is photo-decolored by ambient light or detection light, resulting in poor storage stability and repeated durability.

Patent Document 2 proposes a method of recording a two-photon absorption photoisomerization of a diallylethene two-photon absorption ring-opened product into a closed ring. In this proposal, recording has a new absorption band in a wavelength region longer than the maximum absorption wavelength of two-photon absorption. Reproduction is performed by detecting an increase in extinction coefficient or refractive index due to recording. Normally, recording / reproduction cannot be performed at the same wavelength, but it is possible by controlling the two-photon absorption characteristics of the ring-opened body and the linear absorption characteristics of the ring-closed body.
However, with this proposed method, the two-photon absorption characteristics (absorption cross section, absorption wavelength) of the ring-opened body that enable high-sensitivity recording and reproduction at the same wavelength and the control of the absorption wavelength of the ring-closed body are extremely important in terms of material design. It is difficult. In addition, since the photochromic compound is a reversible material, there is a problem in that the photochromic compound is photo-decolored by ambient light or detection light, resulting in poor storage stability and repeated durability.

Patent Document 3 proposes a write-once (WORM) media that can be recorded by two-photon absorption with a small quantum yield of the ring-opening reaction and can be reproduced at the same wavelength. In this proposal, the two-photon absorption ring-opened ring of diallylethene is recorded as a closed ring by two-photon absorption photoisomerization. Reproduction is performed by detecting an increase in extinction coefficient or refractive index due to recording. Recording and reproduction can be performed at the same wavelength.
However, in this proposal, it is difficult to control the two-photon absorption characteristics (absorption cross section, absorption wavelength) of the ring-opened body and the absorption wavelength of the ring-closed body, which enables high-sensitivity recording and reproduction at the same wavelength. It is very difficult to control the quantum yield of the reaction in terms of material design. Further, since the cartridge filter protects against ambient light and light decoloration during reproduction, the cartridge is indispensable, and there are problems in portability and cost.

Patent Document 4 proposes a method of recording a photochromic compound long wavelength absorber by two-photon absorption photoisomerization to a short wavelength absorber. In this proposal, the long-wavelength absorber has a larger two-photon absorption face area than the short-wavelength absorber and enables high-sensitivity recording, and the two-photon absorption reduces and records the absorption of the long-wavelength absorber. Reproduction is performed by detecting a decrease in extinction coefficient or refractive index due to recording. The recording wavelength and the reproduction wavelength are different.
However, in this proposal, a ring-closed body (long wavelength absorption) is recorded by photoisomerization to a ring-opened body (short wavelength absorption) by two-photon absorption, and recording / reproduction at the same wavelength can be performed by utilizing the change in optical characteristics. Can not. In addition, since the photochromic compound is a reversible material, there is a problem in that the photochromic compound is photo-decolored by ambient light or detection light, resulting in poor storage stability and repeated durability.

Patent Document 5 proposes a method of recording and reproducing molecular glass material by imparting fluorescence by three-photon absorption. In this proposal, recording occurs due to the formation of a fluorescent structure by three-photon absorption. Regeneration is performed by detecting the presence or absence of fluorescence. Recording and reproduction can be performed at the same wavelength.
However, in this proposal, because of the three-photon absorption, recording is possible only with a light source having a smaller absorption cross-sectional area than that of two-photon absorption and having an ultra-high density optical power, and naturally there is a limit to high-speed recording.

Patent Document 6 proposes a method for recording and reproducing a photochromic compound by photoisomerization by two-photon absorption. In this proposal, recording is performed by generating a new absorption band different from the maximum absorption wavelength of two-photon absorption. Regeneration is performed by detecting an increase or decrease in the absorption coefficient of near-infrared light. Recording / reproduction cannot be performed at the same wavelength.
However, in this proposal, recording / reproduction at the same wavelength is impossible, and since the photochromic compound is a reversible material, it is light-discolored to ambient light and detection light, resulting in poor storage stability and repeated durability. There is a problem.

In Patent Document 7, Patent Document 8, and Patent Document 9, recording / reproduction is performed by a change in optical characteristics due to some reaction of a reactive compound using two-photon absorption in a mixed recording material of a two-photon absorption compound and a reactive compound. A method has been proposed. In these proposals, recording is performed by causing a change in optical characteristics by a reaction utilizing two-photon absorption. Reproduction is performed by detecting the increase or decrease of the extinction coefficient due to recording or the increase or decrease of the refractive index. Normally, recording / reproduction cannot be performed at the same wavelength, but the linear absorption characteristics of the reaction product should be controlled. Is possible.
However, in these proposals, the recording-like reaction occurs in the unrecorded portion by the ambient light, and the remaining unrecorded material undergoes the same reaction by the reproducing light in the recording portion, so that the storage stability and the repeated durability are inferior. In addition, since the reaction product that changes the optical characteristics is based on a normal equilibrium reaction, there is a limit to high-speed recording.

Patent Document 10 discloses a method in which a coupling compound between a two-photon absorption site and a reactive species generation site is cleaved by two-photon absorption, and recording / reproduction is performed by a change in optical characteristics due to some reaction of the generated reactive species. Proposed. In this proposal, recording is performed by causing a change in optical characteristics by a reaction utilizing two-photon absorption. In the reproduction, an increase or decrease in extinction coefficient due to recording or an increase or decrease in refractive index is detected. Normally, recording / reproduction cannot be performed at the same wavelength, but it is possible by controlling the linear absorption characteristics of the reaction product.
However, in this proposal, a reaction similar to recording occurs due to ambient light in the unrecorded portion, and a similar reaction occurs due to reproduction light in the remaining unrecorded material in the recorded portion, so that storage stability and repeated durability are poor. In addition, since the reaction product that changes the optical characteristics is based on a normal equilibrium reaction, there is a limit to high-speed recording.

In addition, as a three-dimensional optical recording medium using a two-photon absorption material, a method of reading with fluorescence using a fluorescent substance for recording and reproduction (see Patent Document 11 and Patent Document 12), absorption or fluorescence with a photochromic compound. A reading method (see Patent Document 13 and Patent Document 14) has been proposed.
However, none of these proposals provide a specific two-photon absorption material, and the two-photon absorption compounds that are presented abstractly use two-photon absorption compounds with extremely low two-photon absorption efficiency. In addition, there are problems in non-destructive reading, long-term storage stability of recording, S / N ratio of reproduction, etc., examples of specific materials that can realize this, and examples of disclosure of optical function addition and detection methods There is no.

  Therefore, even in prior art documents, a two-photon absorption material that can efficiently detect optical functions (absorption spectrum, refractive index, change in polarization state, light emission characteristics, photoelectric characteristics, etc.) by two-photon absorption and can detect with light of the same wavelength In addition, there is no specific disclosure of a method for providing the optical function and a method for detecting the optical function.

JP 2003-308634 A JP 2004-277416 A JP 2004-39909 A JP 2004-39909 A JP-T-2004-534849 JP 2005-517769 Gazette JP 2005-71570 A JP 2006-78876 A JP 2006-289613 A Japanese Patent Laid-Open No. 2007-17785 JP-T-2001-524245 Special table 2000-512061 gazette Special table 2001-522119 gazette Special table 2001-508221 gazette

  An object of the present invention is to solve the above-described problems and achieve the following objects. In other words, the present invention induces optical functions (absorption spectrum, refractive index, change in polarization state, light emission characteristics, photoelectric characteristics, etc.) with high sensitivity by two-photon absorption, and the change can be detected with detection light of the same wavelength. Two-photon absorption material which is an organic material having a large two-photon absorption cross section, and an optical function imparting method, optical function detection method, optical recording / reproducing method, optical recording material, and three-dimensional optical recording using the two-photon absorption material The purpose is to provide a medium.

As a result of intensive studies by the present inventors in order to solve the above problems, it has been found that the above problems can be solved by a two-photon absorption material having specific optical characteristics. That is, the present invention provides a two-photon absorption having a first linear absorption band in the vicinity of the maximum absorption wavelength of two-photon absorption and a second linear absorption band in a longer wavelength region than the first linear absorption band. Use materials.
The two-photon absorption material absorbs two-photons by a two-photon excitation wavelength, causes a chemical change by the light energy, and as a result, induces an optical characteristic change of a second linear absorption band in a long wavelength region, The optical properties at the two-photon excitation wavelength change.
As a result, the two-photon can change the optical function (absorption spectrum, refractive index, polarization state change, light emission characteristic, photoelectric characteristic, etc.) with high sensitivity by two-photon absorption, and the change can be detected with detection light of the same wavelength. It has been found that an absorbing organic material can be obtained.
Further, a two-photon absorption material having the above characteristics is used as a three-dimensional optical memory material, and a two-photon excitation wavelength is set as a recording and reproducing wavelength, so that two-photon absorption optical recording and optical reproduction at the same wavelength are possible. It was found that can be realized.

The present invention is based on the above findings by the present inventors, and means for solving the above problems are as follows. That is,
<1> having a first linear absorption band in the vicinity of the maximum absorption wavelength of two-photon absorption and a second linear absorption band in a longer wavelength range than the first linear absorption band, and by two-photon absorption The two-photon absorption material is characterized in that optical characteristics of the second linear absorption band are changed.
<2> The two-photon absorption material according to <1>, wherein the changing optical characteristic is any one of an extinction coefficient, a refractive index, a fluorescence intensity, and a fluorescence wavelength.
<3> The refractive index (n) of the second linear absorption band at the two-photon absorption excitation wavelength is 1.65 or more, and the extinction coefficient (k) is 0.05 or less. <1> to <2 > The two-photon absorption material according to any one of the above.
<4> The two-photon absorption material according to any one of <1> to <3>, wherein the two-photon absorption cross-sectional area is 200 GM (× 10 ⁻⁵⁰ cm ⁴ · s · molecule ⁻¹ · photon ⁻¹ ) or more. is there.
<5> The two-photon absorption material according to any one of <1> to <4>, wherein the conjugated bond has a chemical structure moiety linked in a cyclic manner.
<6> The two-photon absorption material according to any one of <1> to <5>, which is an azaannulene compound.
<7> The two-photon absorption material according to any one of <1> to <5>, which is an annulene compound.
<8> The two-photon absorption material according to any one of <1> to <5>, which is an anurenone compound.
<9> An optical function is imparted to the two-photon absorption material according to any one of <1> to <8> by changing the optical characteristics of the second linear absorption band according to the two-photon absorption excitation wavelength. It is the optical function provision method characterized.
<10> The two-photon absorption material according to any one of <1> to <8>, wherein the optical characteristics of the second linear absorption band are changed by the two-photon absorption excitation wavelength, and detection is performed at the same wavelength. This is a characteristic optical function detection method.
<11> The information is recorded on the two-photon absorption material according to any one of <1> to <8> by changing the optical characteristics of the second linear absorption band according to the two-photon absorption excitation wavelength. This is an optical recording method.
<12> The optical property of the second linear absorption band is changed by the two-photon absorption excitation wavelength to the two-photon absorption material according to any one of <1> to <8>, and information is reproduced by reproduction light having the same wavelength. An optical reproduction method characterized by reproducing the light.
<13> An optical recording material comprising the two-photon absorption material according to any one of <1> to <8>.
<14> A three-dimensional optical recording medium capable of recording and reproducing in the depth direction with respect to incident light in a recording layer containing the two-photon absorption material according to any one of <1> to <8>.

  According to the present invention, conventional problems can be solved, and two-photon absorption induces optical functions (absorption spectrum, refractive index, polarization state change, light emission characteristics, photoelectric characteristics, etc.) with high sensitivity, and the same wavelength. Two-photon absorption cross-sectional organic material having a large two-photon absorption cross-section that can be detected by the detection light of the two-photon absorption method, an optical function imparting method using the two-photon absorption material, an optical function detection method, an optical recording / reproducing method, An optical recording material and a three-dimensional optical recording medium can be provided.

(Two-photon absorption material)
The two-photon absorption material of the present invention has a first linear absorption band in the vicinity of the maximum absorption wavelength of two-photon absorption and a second linear absorption band in a longer wavelength region than the first linear absorption band. In addition, the optical characteristics of the second linear absorption band are changed by two-photon absorption.

The two-photon absorption material means a material that can excite molecules at a wavelength in a non-resonant region, and has a real excited state at an energy level twice that of the photon used for excitation at this time. To do.
The two-photon absorption phenomenon is a kind of third-order nonlinear optical effect, in which a molecule absorbs two photons at the same time and transitions from a ground state to an excited state. Since Bredas et al. Elucidated the relationship between molecular structure and mechanism in 1998 (Science, 281, 1653 (1998)), research on materials having two-photon absorption ability has been progressing in recent years.
However, the transition efficiency of such two-photon simultaneous absorption is extremely lower than that of one-photon absorption and requires extremely high power density photons. It has been confirmed that an ultra-short pulse laser of about femtosecond such as a mode-locked laser having high intensity (light intensity at the maximum emission wavelength) is used.
The transition efficiency of two-photon absorption is proportional to the square of the applied photoelectric field (the two-photon absorption square characteristic). For this reason, when a laser is irradiated, two-photon absorption occurs only at a position where the electric field strength is high at the center of the laser spot, and no two-photon absorption occurs at a portion where the electric field strength is weak at the peripheral portion. In the three-dimensional space, two-photon absorption occurs only in a region where the electric field strength at the focal point where the laser light is collected by the lens is large, and no two-photon absorption occurs in the region outside the focal point because the electric field strength is weak. Compared to the linear absorption of one photon where excitation occurs at all positions in proportion to the intensity of the applied photoelectric field, the two-photon absorption is excited only at a pinpoint inside the space due to this square characteristic. Therefore, the spatial resolution is significantly improved.

Utilizing this characteristic, research on a three-dimensional memory for recording bit data by causing a spectral change, a refractive index change or a polarization change by two-photon absorption at a predetermined position of a recording medium has been advanced. Since two-photon absorption occurs in proportion to the square of the intensity of light, a memory using two-photon absorption can reduce the spot size compared to a memory using one-photon absorption, and super-resolution recording. Is possible. In addition, from the characteristics of high spatial resolution derived from this square characteristic, development for applications such as a light limiting material, a cured material of a photo-curing resin for stereolithography, and a fluorescent dye material for a two-photon fluorescence microscope is being promoted.
Furthermore, in the case of inducing two-photon absorption, it is possible to use a short-pulse laser in the near-infrared region that has a longer wavelength than the wavelength region in which the linear absorption band of the compound exists and does not have absorption. Since the near-infrared light of the so-called transparent region, which does not have a linear absorption band of the compound, is used, the excitation light can reach the inside of the sample without being absorbed or scattered, and because of the square characteristic of the two-photon absorption, Since pinpoints can be excited with high spatial resolution, two-photon absorption and two-photon emission are also expected in photochemotherapy applications such as two-photon contrast and two-photon photodynamic therapy (PDT) in biological tissues. In addition, research on upconversion lasing has been reported from the viewpoint of a wavelength conversion device because photons with higher energy than the energy of incident photons can be extracted by using two-photon absorption and two-photon emission.

Here, basic optical characteristics of the two-photon absorption material of the present invention are shown in FIG.
From the result of FIG. 1, the two-photon absorption material of the present invention has a first linear absorption band in the vicinity of the maximum absorption wavelength of two-photon absorption and a second linear absorption band in a longer wavelength region. I understand.
The two-photon absorption material of the present invention having such optical characteristics absorbs two-photons by the two-photon excitation wavelength, causes a chemical change by the light energy, and induces a change in the optical characteristics of the second linear absorption band. . As a result, the optical function can be switched at the two-photon excitation wavelength corresponding to the optical characteristic change of the second linear absorption band.
As the reaction mode for inducing the light function, both a heat mode and a photon mode are possible. The reaction rate and the contrast ratio of the change are large, and the former is preferably a thermochromic reaction or a thermal decomposition reaction, and the latter is A photochromic reaction is preferred.
Examples of the optical function include an extinction coefficient, a refractive index, a change in polarization state, a light emission characteristic, and a photoelectric characteristic, and can be changed with high sensitivity by two-photon absorption, and the change can be detected at the same wavelength. Detection is possible with light.
Furthermore, a system that performs optical recording / reproduction by using a two-photon absorbing material having this characteristic as a three-dimensional optical recording material and changing the optical characteristics of the second linear absorption band by two-photon absorption is a two-photon having the same wavelength. A three-dimensional optical memory capable of absorbing optical recording / reproduction is made possible. In the three-dimensional optical memory system, from the viewpoints of downsizing of the apparatus and ease of detection, the changing optical characteristics are preferably an extinction coefficient, a refractive index, and fluorescence characteristics (fluorescence intensity or fluorescence wavelength).

Here, an example of an optical constant (an extinction coefficient, a refractive index) is shown as an optical function. The optical constant spectrum of the porphyrin compound represented by the following structural formula (i) is shown in FIG.
However, in the structural formula (i), Me represents a methyl group, and Et represents an ethyl group.

  From the result of FIG. 3, there is no linear absorption (corresponding to k in FIG. 3) in the wavelength region after 750 nm indicating the two-photon absorption of the compound represented by the structural formula (i). It can be seen that the refractive index (corresponding to n in FIG. 3) still shows a large value due to the influence of electronic polarization due to linear absorption. When the compound is caused to absorb two-photons in a wavelength region of 750 nm or more and the compound is decomposed, it is easily assumed that a large refractive index change occurs in this wavelength region.

Here, the refractive index of a normal organic compound is approximately 1.5, whereas the two-photon absorption material of the present invention has a refractive index (n of the second linear absorption band at the two-photon absorption excitation wavelength). ) Is preferably 1.65 or more, and more preferably 1.7 or more. When the refractive index (n) is less than 1.65, a sufficient amount of change in refractive index may not be obtained. In addition, if the second linear absorption band has an absorption capability at the two-photon excitation wavelength, the effective light quantity of the two-photon excitation is impaired. Therefore, it is preferable that there is no absorption, and the extinction coefficient (k) of the second linear absorption band is 0.05 or less is preferable and 0.03 or less is more preferable. When the extinction coefficient (k) exceeds 0.05, a large two-photon absorption cross section may not be obtained.
Here, the refractive index (n) and the extinction coefficient (k) can be measured, for example, by spectroscopic ellipsometry.

The two-photon absorption cross-sectional area of the two-photon absorption material is preferably 200 GM (× 10 ⁻⁵⁰ cm ⁴ · s · molecule ⁻¹ · photon ⁻¹ ) or more, and more preferably 500 GM or more. If the two-photon absorption cross-section is less than 200 GM, sufficient two-photon absorption ability cannot be obtained, and an expensive high-power laser may be required as an excitation light source for inducing two-photon absorption.
Here, the two-photon absorption cross-sectional area can be measured as follows using, for example, a two-photon absorption cross-sectional measurement system shown in FIG.
Measurement light source: femtosecond titanium sapphire laser (wavelength: 720 nm to 920 nm, pulse width: 100 fs, repetition: 80 MHz, optical power: 800 mW)
Measurement method: Z scan method (light source wavelength: 780 nm to 900 nm, cuvette inner diameter: 1 mm, measurement light power: about 500 mW, repetition frequency: 80 MHz, objective lens: f = 75 mm, condensing diameter: ˜40 μm)
A Z-scan measurement was performed by placing a quartz cell filled with a sample solution in the focused optical path portion and moving the position along the optical path.

The transmittance was measured, and the nonlinear absorption coefficient was determined from the result by the following theoretical formula (I).
T = [ln (1 + I0L0β)] / I0L0β (I)
In the theoretical formula (I), T is transmittance (%), I0 is excitation light density [GW / cm ² ], L0 is sample cell length [cm], and β is nonlinear absorption coefficient [cm / GW]. Represent.

The two-photon absorption cross section σ2 was determined from the determined nonlinear absorption coefficient by the following formula (II).
σ2 = 1000 × hνβ / NACβ (II)
In the formula (II), the unit of σ2 is 1GM = 1 × 10 ⁻⁵⁰ cm ⁴ · s · photon ⁻¹ , h is Planck's constant [J · s], and ν is the frequency of incident laser light [ s ⁻¹ ], NA is Avogadro's number, and C is the solution concentration [mol / L].

  The two-photon absorption material of the present invention is not particularly limited, and any material having the above-described two-photon absorption ability and the necessary light absorption characteristics can be used. Among these, the two-photon absorption material having a structural portion in which conjugated bonds are connected in a ring is absorbed in both near-ultraviolet and visible wavelengths by electronic interaction of two transition moments orthogonal to each other in the plane. The azaannulene compound (porphyrin derivative, azaporphyrin derivative), an annulene compound, and an anurenone compound are particularly preferable because of their ability to exhibit basic optical characteristics of the two-photon absorption material of the present invention.

  Hereinafter, the azaannulene compound (porphyrin derivative, azaporphyrin derivative), the annulene compound, and the annurenone compound suitable as the two-photon absorption material of the present invention will be specifically described.

-Porphyrin derivative (1)-
However, in the general formula (1), R _{1 to} R ₄ may be the same as or different from each other, and may be a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group. And X _{1 to} X ₈ representing either a substituted or unsubstituted acyl group may be the same as or different from each other, and may be a hydrogen atom, a halogen atom, a nitro group, a cyano group, Any of hydroxyl group, carboxyl group, substituted or unsubstituted alkyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted aryl group, substituted or unsubstituted amino group, and substituted or unsubstituted acyl group Represents.
M is a divalent, trivalent, or tetravalent metal atom that may have two hydrogen atoms, oxygen atoms, or halogen atoms, or (OR ₅ ) p, (OSiR ₆ R ₇ R ₈ ) q , (OPOR ₉ R ₁₀ ) r, and (OCOR ₁₁ ) s may be represented by a metal atom. R _{5 to} R ₁₁ may be the same as or different from each other, and each represents a hydrogen atom, a substituted or unsubstituted aliphatic hydrocarbon group, or an aromatic hydrocarbon group.
p, q, r, and s each represent an integer of 0 to 2.

-Porphyrin derivative (2)-
In a porphyrin derivative having a structure in which four pyrrol rings which may have a substituent are bonded via a carbon atom which may have a substituent or are directly bonded, the four pyrrol rings are connected. The total number of carbon atoms that may have a substituent is four, and at least one is a porphyrin derivative in which a pyrrole ring is directly bonded without a carbon atom.
In the general formula (2), R _{1 to} R ₈ and X _{1 to} X ₄ may be the same as or different from each other, and are a hydrogen atom, a halogen atom, a nitro group, a cyano group, or a hydroxyl group. , A carboxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryl group, a substituted or unsubstituted amino group, and a substituted or unsubstituted acyl group. Represent.
M is a divalent, trivalent, or tetravalent metal atom that may have two hydrogen atoms, oxygen atoms, or halogen atoms, (OR ₉ ) p, (OSiR ₁₀ R ₁₁ R ₁₂ ) q, It represents any of metal atoms that may have (OPOR ₁₃ R ₁₄ ) r and (OCOR ₁₅ ) s. R _{9 to} R ₁₅ may be the same as or different from each other, and each represents a hydrogen atom, a substituted or unsubstituted aliphatic group, or an aromatic hydrocarbon group.
p, q, r, and s each represent an integer of 0 to 2.

-Azaporphyrin derivatives-
In the azaporphyrin derivative represented by the above general formula (1) having a structure in which four pyrrol rings which may have a substituent are bonded via a carbon atom or a nitrogen atom which may have a substituent, An azaporphyrin derivative in which at least one of the atoms optionally having a substituent connecting the four pyrrol rings is a carbon atom and a nitrogen atom.
However, in the general formula (3), R _{1 to} R ₄ may be the same as or different from each other, and represent either a nitrogen atom or a carbon atom, and at least one of these. Represents a nitrogen atom.
X ^{1 to} X ⁸ may be the same or different from each other, and may be a hydrogen atom, a halogen atom, a nitro group, a cyano group, a hydroxyl group, a carboxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted group. It represents any of a substituted alkoxy group, a substituted or unsubstituted aryl group, a substituted or unsubstituted amino group, and a substituted or unsubstituted acyl group.
M is a divalent, trivalent, or tetravalent metal atom that may have two hydrogen atoms, oxygen atoms, or halogen atoms, (OR ₅ ) p, (OSiR ₆ R ₇ R ₈ ) q , (OPOR ₉ R ₁₀ ) r, and (OCOR ₁₁ ) s may be represented by any of the metal atoms. R _{5 to} R ₁₁ may be the same as or different from each other, and each represents a hydrogen atom, a substituted or unsubstituted aliphatic group, or an aromatic hydrocarbon group.
p, q, r, and s each represent an integer of 0 to 2.

As M in the azaannulene compounds of the general formulas (1) to (3), specifically, Ib group, IIa group, IIb group, IIIa group, IVa group, IVb group, Vb group, VIb group, VIIb group, There are Group VIII metals, oxides of these metals, halides of these metals, or hydroxides of these metals, and further, those having substituents on the above metals. Examples of the metals include Cu, Zn, Mg, Al, Ge, Ti, Sn, Pb, Cr, Mo, Mn, Fe, Co, Ni, In, Pt, Pd, etc. are mentioned, and examples of the oxide include TiO, VO, etc., halogen the _{product, AlCl, GeCl 2, SiCl 2} , FeCl, SnCl 2, InCl and the like, and as the hydroxide _{Al (OH), Si (OH} ) 2, Ge (OH) 2, Sn (OH _2, and the like.
Further, when the metal has a substituent, the metal includes Al, Ti, Si, Ge, Sn, etc. Examples of the substituent include an aryloxyl group, an alkoxyl group, a trialkylsiloxyl group, and a triaryl. Examples include a siloxyl group, a trialkoxysiloxyl group, a triaryloxysiloxyl group, a trityloxyl group, and an acyloxyl group.

-Anurene derivatives-
However, in said general formula (4), R < ₁ > -R < ₈ > and R < ₉ > -R < ₁₂ > may mutually be the same and may differ, a hydrogen atom, a substituted or unsubstituted alkyl group, One of a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted amino group is shown.

-Anurenone derivative-

In the general formulas (5) and (6), R _{1 to} R ₁₆ may be the same as or different from each other, and each represents a hydrogen atom and a substituted or unsubstituted alkyl group. .

In the general formulas (1) to (6), examples of the unsubstituted alkyl group include linear or branched alkyl groups. Examples of substituted alkyl groups include hydroxy-substituted alkyl groups, carboxy-substituted alkyl groups, amino-substituted alkyl groups, halogen atom-substituted alkyl groups, phenyl-substituted alkyl groups, and alkoxy-substituted alkyl groups.
Examples of the alkyl group include methyl, ethyl, n-propyl, n-butyl, isobutyl, n-pentyl, neopentyl, isoamyl, 2-methylbutyl, n-hexyl, and 2-methyl. Pentyl group, 3-methylpentyl group, 4-methylpentyl group, 2-ethylbutyl group, n-heptyl group, 2-methylhexyl group, 3-methylhexyl group, 4-methylhexyl group, 5-methylhexyl group, 2 -Ethylpentyl group, 3-ethylpentyl group, n-octyl group, 2-methylheptyl group, 3-methylheptyl group, 4-methylheptyl group, 5-methylheptyl group, 2-ethylhexyl group, 3-ethylhexyl group, Primary alkyl group such as n-nonyl group, n-decyl group, n-dodecyl group; isopropyl group, sec-butyl group, 1-ethyl group Pyl group, 1-methylbutyl group, 1,2-dimethylpropyl group, 1-methylheptyl group, 1-ethylbutyl group, 1,3-dimethylbutyl group, 1,2-dimethylbutyl group, 1-ethyl-2-methyl Propyl group, 1-methylhexyl group, 1-ethylheptyl group, 1-propylbutyl group, 1-isopropyl-2-methylpropyl group, 1-ethyl-2-methylbutyl group, 1-propyl-2-methylpropyl group, 1-methylheptyl group, 1-ethylhexyl group, 1-propylpentyl group, 1-isopropylpentyl group, 1-isopropyl-2-methylbutyl group, 1-isopropyl-3-methylbutyl group, 1-methyloctyl group, 1- Secondary alkyl groups such as ethylheptyl group, 1-propylhexyl group, 1-isobutyl-3-methylbutyl group; Tertiary alkyl groups such as thiol group, tert-hexyl group, tert-amyl group, tert-octyl group; cyclohexyl group, 4-methylcyclohexyl group, 4-ethylcyclohexyl group, 4-tert-butylcyclohexyl group, 4- ( 2-ethylhexyl) cyclohexyl group, bornyl group, isobornyl group, cycloalkyl group such as adamantane group, and the like.

Specific examples of the compound represented by the general formula (1) include, but are not limited to, the following compounds.
In the above formula, Et represents an ethyl group.

Specific examples of the compound represented by the general formula (2) include, but are not limited to, the following compounds.

Specific examples of the compound represented by the general formula (3) include, but are not limited to, the following compounds.

Specific examples of the compound represented by the general formula (4) include, but are not limited to, the following compounds.
In the above formula, tBu represents a tertiary butyl group.

Specific examples of the compound represented by the general formula (5) include, but are not limited to, the following compounds.
In the above formula, Et represents an ethyl group.

Specific examples of the compound represented by the general formula (6) include, but are not limited to, the following compounds.
In the above formula, Et represents an ethyl group.

  In addition, thermomaterials and photochromic materials that absorb in different wavelength ranges depending on the isomer, the short-wavelength absorption isomer has a two-photon absorption ability, and the long-wavelength absorption isomer has a short wavelength due to the two-photon absorption energy. Materials that isomerize to absorption isomers can also be used.

  FIG. 4 shows a change in absorption spectrum of a salicylidene aniline type thermochromic material as the photochromic material. Both isomer mixed systems of the photochromic material satisfy the necessary light absorption characteristics of the present invention, and those having this characteristic and exhibiting two-photon absorption can be used similarly.

  The two-photon absorption material of the present invention can be applied directly on the substrate by using a spin coater, roll coater, bar coater or the like, or cast as a film, and then laminated to the substrate by a usual method, Thereby, it can be set as a two-photon absorption optical recording material.

The two-photon absorption material of the present invention can be applied to various devices by itself or in a thin film mixed with various resins, or in bulk. For example, in an optical disk, the thin film is in contact with a substrate, and examples of the substrate material include polyethylene terephthalate, polycarbonate, polymethyl methacrylate, polyester, polyvinyl alcohol, and glass.
In the case of stacking, the surface of the thin film is in contact with the intermediate layer (partition layer). Specific examples of the intermediate layer include polyolefins such as polypropylene and polyethylene; plastic films such as polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyethylene terephthalate, and cellophane films, and various photocurable resins.

(Optical function application method)
The optical function imparting method of the present invention imparts an optical function to the two-photon absorption material of the present invention by changing the optical characteristics of the second linear absorption band according to the two-photon absorption excitation wavelength.
The changing optical characteristic is preferably one of an extinction coefficient, a refractive index, a fluorescence intensity, or a fluorescence wavelength.
Examples of the optical function include an absorption spectrum, a refractive index, a change in polarization state, light emission characteristics, and photoelectric characteristics.

(Optical function detection method)
In the optical function detection method of the present invention, the optical characteristics of the second linear absorption band are changed by the two-photon absorption excitation wavelength in the two-photon absorption material of the present invention, and detection is performed at the same wavelength.
The changing optical characteristic is preferably one of an extinction coefficient, a refractive index, a fluorescence intensity, or a fluorescence wavelength.
Examples of the optical function include an absorption spectrum, a refractive index, a change in polarization state, light emission characteristics, and photoelectric characteristics.

(Optical recording method)
The optical recording method of the present invention records information in the two-photon absorption material of the present invention by changing the optical characteristics of the second linear absorption band according to the two-photon absorption excitation wavelength.
The changing optical characteristic is preferably one of an extinction coefficient, a refractive index, a fluorescence intensity, or a fluorescence wavelength.

(Light regeneration method)
In the optical reproduction method of the present invention, the optical characteristics of the second linear absorption band are changed by the two-photon absorption excitation wavelength in the two-photon absorption material of the present invention, and information is reproduced by reproduction light of the same wavelength.
The changing optical characteristic is preferably one of an extinction coefficient, a refractive index, a fluorescence intensity, or a fluorescence wavelength.

(Optical recording material)
The optical recording material of the present invention contains the two-photon absorption material of the present invention, and the two-photon absorption material of the present invention is used alone, mixed with various resins, or mixed with a photocurable resin.
Accordingly, the use requirement of the two-photon absorption material of the present invention is that the material is mixed with various resins or glass, or the interface of the two-photon absorption material layer is in contact with various resins or glass. In other words, the two-photon absorption material of the present invention is in contact with various resins or glass at the micro level or the macro level.

  Specifically, a recording layer can be formed by applying a composition containing at least the two-photon absorption material of the present invention and, if necessary, a resin and a solvent on a substrate.

By said substrate is meant any natural support or synthetic support, preferably one that can be present in the form of a flexible film, a rigid film, a sheet or a plate.
Examples of the material of the substrate include polyethylene terephthalate, resin-primed polyethylene terephthalate, polyethylene terephthalate subjected to flame or electrostatic discharge treatment, cellulose acetate, polycarbonate, polymethyl methacrylate, polyester, polyvinyl alcohol, and glass. The substrate may be provided with tracking guide grooves and address information in advance.

The resin is not particularly limited and may be appropriately selected depending on the intended purpose. For example, polymethyl acrylate, polycarbonate, epoxy resin, polystyrene, polyester resin, vinyl resin, cellulose, aliphatic hydrocarbon resin, natural Examples thereof include rubber, sterene butadiene resin, chloroprene rubber, wax, alkyd resin, and rosin.
The solvent used can be removed by evaporation during drying. For this evaporation removal, heating or reduced pressure may be used.

Further, a protective layer (intermediate layer) for blocking oxygen and preventing interlayer crosstalk may be formed on the two-photon absorption optical recording material.
The protective layer (intermediate layer) is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include polyolefins such as polypropylene and polyethylene; polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyethylene terephthalate or cellophane film. A plastic film or plate such as the above may be attached by electrostatic adhesion, lamination using an extruder, or the like, or the polymer solution may be applied. Further, a glass plate may be bonded. Further, an adhesive or a liquid substance may be present between the protective layer and the recording layer and / or between the base material and the recording layer in order to improve airtightness. Furthermore, a protective groove (intermediate layer) between recording layers may be provided with tracking guide grooves and address information in advance.

<Application to two-dimensional multilayer optical memory using two-photon absorption material>
Recently, networks such as the Internet and high-definition TV are rapidly spreading. In addition, HDTV (High Definition Television) will soon be broadcast, and there is an increasing demand for a large-capacity recording medium for easily and inexpensively recording image information of 50 GB or more, preferably 100 GB or more for consumer use. Furthermore, for business use such as computer backup use and broadcast backup use, an optical recording medium capable of recording large-capacity information of about 1 TB or more at high speed and at low cost is required. Under such circumstances, the conventional two-dimensional optical recording medium such as DVD ± R is about 25 GB at most even if the recording / reproducing wavelength is shortened due to the physical principle, and is sufficiently large enough to meet future demands. It cannot be said that capacity can be expected.

Under such circumstances, a three-dimensional optical recording medium has attracted attention as an ultimate high-density, high-capacity recording medium. Three-dimensional optical recording media can be recorded in dozens or hundreds of layers in the three-dimensional (film thickness) direction, resulting in tens or hundreds of times the ultra-high density and ultra-high capacity of conventional two-dimensional optical recording media. Try to achieve the record. In order to provide a three-dimensional optical recording medium, it is necessary to be able to access and write at an arbitrary place in the three-dimensional (film thickness) direction. As a means for this, a method using a two-photon absorption material and holography (interference) There is a method of using. In a three-dimensional optical recording medium using a two-element absorbing material, so-called bit recording can be performed over tens or hundreds of times based on the physical principle described above, and higher density recording is possible, which is exactly the ultimate. It can be said that this is a high-density, high-capacity optical recording medium.
As a three-dimensional optical recording medium using a two-photon absorption material, a method of reading with fluorescence using a fluorescent substance for recording and reproduction (refer to JP-A-2001-524245 and JP-A-2000-512061), photochromic compounds A method of using and reading with absorption or fluorescence (refer to Japanese Patent Publication No. 2001-522119 and Japanese Patent Publication No. 2001-508221) has been proposed.
However, none of these proposals provide a specific two-photon absorption material, and the two-photon absorption compounds presented abstractly use two-photon absorption compounds with extremely low two-photon absorption efficiency. ing.
Further, since the photochromic compounds used in these prior art documents are reversible materials, there are problems in nondestructive reading, long-term storage stability of recording, S / N ratio of reproduction, and the like, which are practical as optical recording media. It cannot be said that it is a method. In particular, in terms of nondestructive reading, long-term storage stability of recording, etc., it is preferable to reproduce by changing the reflectance (refractive index or absorptance) or emission intensity using an irreversible material, but a two-photon having such a function. There was no example that specifically disclosed the absorbent material.

  JP-A-6-28672 and JP-A-6-118306 disclose a recording apparatus, a reproducing apparatus, a reading method, and the like that three-dimensionally records by refractive index modulation. There is no description of a method using a three-dimensional optical recording material.

As described above, the reaction is caused using the excitation energy obtained by non-resonant two-photon absorption, and as a result, the emission intensity when light is irradiated at the laser focus (recording) part and the non-focus (non-recording) part. If modulation is possible with a method that cannot be rewritten, it is possible to cause emission intensity modulation with extremely high spatial resolution in any place in three-dimensional space, and it can be applied to three-dimensional optical recording media that are considered to be the ultimate high-density recording medium. It becomes possible. Furthermore, non-destructive reading is possible, and since it is an irreversible material, good storage stability can be expected and it is practical.
However, the currently available two-photon absorption compounds have a low two-photon absorption capability, so that a very high-power laser is required as a light source and a long recording time is required. In particular, in order to use it in a three-dimensional optical recording medium, it is essential to construct a material that can perform recording with a high sensitivity and a difference in luminous ability by two-photon absorption in order to achieve a high transfer rate. For that purpose, the difference between the two-photon absorption compound that can absorb two-photons with high efficiency and generate an excited state, and the two-photon absorption optical recording material using a two-photon absorption compound excited state in some way. A material containing a recording component that can efficiently form a thin film is effective, but such a material has hardly been disclosed so far, and it is desired to construct such a material.
Also, in order to realize a small and inexpensive two-photon absorption three-dimensional optical recording system, recording is performed by efficiently inducing optical functions (absorption spectrum, refractive index, change in polarization state, fluorescence characteristics) by two-photon absorption. A two-photon absorption material that can be reproduced with reproduction light of the same wavelength is promising, but a specific material example and optical recording / reproduction technology that can realize this are not disclosed.

Here, preferred embodiments (specific examples) of the three-dimensional multilayer optical memory are shown. However, the present invention is not limited to these embodiments, and may have a structure capable of three-dimensional recording (recording in a plane and a film thickness direction). Any other structure may be used. A schematic diagram of the recording / reproducing system of the three-dimensional multilayer optical memory is shown in FIG. 2 (a), and a schematic sectional view of the recording medium is shown in the right diagram (b) of FIG.
In the optical recording medium of FIG. 2 (b), a recording layer using the two-photon absorption compound of the present invention on a flat support (substrate 1) and an intermediate layer (protective layer) for preventing crosstalk alternate. 50 layers are stacked on each other, and each layer is formed by spin coating.
The thickness of the recording layer is preferably 0.01 μm to 0.5 μm, and the thickness of the intermediate layer is preferably 0.1 μm to 5 μm. With this structure, it is possible to realize terabyte-class ultrahigh-density optical recording with the same disk size as the currently popular CD / DVD. Further, a substrate 2 (protective layer) similar to the substrate 1 or a reflective layer made of a highly reflective material is formed by a data reproduction method (transmission / or reflection type).

A single beam is used at the time of recording, and in this case, ultrashort pulse light of femtosecond order can be used. At the time of reproduction, it is also possible to use light having a wavelength different from that of the beam used for data recording or light of the same wavelength with low output. Recording and playback can be performed in either bit units or page units, and parallel recording / playback using a surface light source, a two-dimensional detector, or the like is effective in increasing the transfer rate.
Note that examples of the form of the three-dimensional multilayer optical memory similarly formed according to the present invention include a card form, a plate form, a tape form, and a drum form.

  In addition, it functions as the three-dimensional optical recording medium of the present invention by focusing on an arbitrary layer of the three-dimensional multilayer optical recording medium and performing recording and reproduction. Further, even if the layers are not separated by a protective layer (intermediate layer), three-dimensional recording in the depth direction is possible from the two-photon absorption dye characteristics.

According to the present invention, it is possible to realize a two-photon absorption material that induces an optical function with high sensitivity by two-photon absorption and can detect the change with detection light of the same wavelength, and a method for imparting and detecting the optical function, Practical applications (three-dimensional memory materials, etc.) using small and inexpensive lasers can be realized.
In addition, by using the two-photon absorption material of the present invention as a three-dimensional optical memory material and using the two-photon wavelength as the recording and reproduction wavelength, a three-dimensional optical memory capable of recording and reproducing two-photon absorption light at the same wavelength can be realized. It becomes.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1
A tetrahydrofuran solution of a diazaporphyrin derivative represented by the following structural formula (A) was prepared, and the two-photon absorption cross section was measured by the following two-photon absorption cross section evaluation method. The results are shown in Table 1.
However, Pr represents a propyl group.

<Measurement method of two-photon absorption cross section>
A schematic diagram of a two-photon absorption cross-section measurement system is shown in FIG.
Measurement light source: femtosecond titanium sapphire laser (wavelength: 720 nm to 920 nm, pulse width: 100 fs, repetition: 80 MHz, optical power: 800 mW)
Measurement method: Z scan method (light source wavelength: 780 nm to 900 nm, cuvette inner diameter: 1 mm, measurement light power: about 500 mW, repetition frequency: 80 MHz, objective lens: f = 75 mm, condensing diameter: ˜40 μm)
A Z-scan measurement was performed by placing a quartz cell filled with a sample solution in the focused optical path portion and moving the position along the optical path.

The transmittance was measured, and the nonlinear absorption coefficient was determined from the result by the following theoretical formula (I).
T = [ln (1 + I0L0β)] / I0L0β (I)
In the theoretical formula (I), T is transmittance (%), I0 is excitation light density [GW / cm ² ], L0 is sample cell length [cm], and β is nonlinear absorption coefficient [cm / GW]. Represent.

The two-photon absorption cross section σ2 was determined from the determined nonlinear absorption coefficient by the following formula (II).
σ2 = 1000 × hνβ / NACβ (II)
In the formula (II), the unit of σ2 is 1GM = 1 × 10 ⁻⁵⁰ cm ⁴ · s · photon ⁻¹ , h is Planck's constant [J · s], and ν is the frequency of incident laser light [ s ⁻¹ ], NA is Avogadro's number, and C is the solution concentration [mol / L].

Next, a tetrahydrofuran solution in which the compound represented by the structural formula (A) and polystyrene (weight average molecular weight = 2,000) are mixed at a mass ratio of 1/1 is prepared, and spin coated on a quartz substrate. A thin film having a thickness of about 1 μm was prepared. About the obtained thin film, the absorption spectrum, fluorescence intensity, and its optical constant (refractive index (n) and extinction coefficient (k)) were measured as follows. The results are shown in Table 2 and FIG.
Further, after the thin film was photo-degraded (xenon lamp 50,000 lux, left for 50 hours) and thermally deteriorated (120 ° C., left for 150 hours), the absorption spectrum, fluorescence intensity and optical constant (refractive index (n) and The extinction coefficient (k)) was measured. The results are shown in FIG.

<Measurement of absorption spectrum>
The absorption spectrum was measured with a spectrophotometer.
<Measurement of fluorescence intensity>
The fluorescence intensity was measured with a fluorometer.
<Measurement of optical constant (refractive index (n) and extinction coefficient (k))>
The refractive index (n) and extinction coefficient (k) were measured by spectroscopic ellipsometry.

From the measurement results of the two-photon excitation wavelength and the two-photon absorption cross section showing the largest two-photon absorption in Table 1, and the absorption spectrum of FIG. 6, the compound represented by the structural formula (A) is an optical compound of the present invention. It was found to be a two-photon material with properties.
Further, from the results of FIG. 6 and Table 2, the absorption spectrum change, the fluorescence intensity change (relative value), and the optical constant change are generated by decomposing with the initial value of the two-photon absorption material and the energy obtained by the two-photon absorption. This shows a change in optical characteristics with the assumed substance, and that the change can be detected at the two-photon excitation wavelength (same wavelength).

(Example 2)
Evaluation similar to Example 1 was performed about the tetraaza porphyrin derivative represented by the following structural formula (B). The measurement results of the two-photon absorption cross section are shown in Table 1, the absorption spectrum change is shown in FIG. 7, and the fluorescence intensity change (relative value) and the optical constant change are shown in Table 2.

(Example 3)
Evaluation similar to Example 1 was performed about the porphyrin derivative represented by following Structural formula (C). The measurement results of the two-photon absorption cross section are shown in Table 1, the absorption spectrum change is shown in FIG. 7, and the fluorescence intensity change (relative value) change and the optical constant change are shown in Table 2.
However, in the formula, Pr represents a propyl group.

Example 4
Evaluation similar to Example 1 was performed about the anurenone derivative represented by Structural formula (D). The measurement results of the two-photon absorption cross section are shown in Table 1, and the fluorescence intensity change (relative value) and the optical constant change are shown in Table 2.

(Comparative Example 1)
As a conventional material, the same evaluation as in Example 1 was performed on a diallylethene derivative represented by the following structural formula (E). Table 1 shows the measurement results of the two-photon absorption cross section.

(Comparative Example 2)
As a material having a large two-photon absorption cross section, the same evaluation as in Example 1 was performed on a styryl derivative represented by the following structural formula (F). The measurement results of the two-photon absorption cross section are shown in Table 1, and the fluorescence intensity change (relative value) and the optical constant change are shown in Table 2.

From the results in Table 1, it was found that Examples 1 to 4 are two-photon absorption materials that are one or more orders of magnitude more sensitive than the conventional material (Comparative Example 1).

* N: Refractive index, k: extinction coefficient, decomposition rate:%, fluorescence intensity: relative value, x: fluorescence cannot be detected at the two-photon excitation wavelength Note that the amount of change in optical properties naturally depends on the decomposition rate, and the decomposition rate Depends on accelerated deterioration conditions (corresponding to laser irradiation conditions).

  From the results in Table 2, Examples 1 to 4 have larger optical properties than Comparative Example 2 (Δn to 0, which emits light in a short wavelength region and cannot detect fluorescence at a two-photon excitation wavelength) having a large two-photon absorption cross section. It turned out to show a change.

  The two-photon absorption material of the present invention induces an optical function with high sensitivity by two-photon absorption, and the change (extinction coefficient change, refractive index change, fluorescence intensity) can be detected with detection light having the same wavelength, By using the two-photon excitation wavelength as the recording and reproducing wavelength, it becomes possible to perform optical recording and reproduction at the same wavelength, and is suitably used for applications such as a three-dimensional optical memory material, a three-dimensional optical memory system, a light emitting element, and a photoelectric conversion element. .

FIG. 1 is a diagram showing the absorption characteristics of the two-photon absorption material of the present invention. FIG. 2 is a schematic diagram of a three-dimensional memory system. FIG. 3 is a diagram showing an optical constant spectrum of a porphyrin compound. FIG. 4 is a diagram showing an absorption spectrum of a salicylidene aniline-based thermochromic material. FIG. 5 is a schematic diagram showing a two-photon absorption cross-section measurement system. 6 is a graph showing an absorption spectrum of the diazaporphyrin compound of Example 1. FIG. 7 is a graph showing an absorption spectrum of the tetraazaporphyrin compound of Example 2. FIG. FIG. 8 shows the absorption spectrum of the porphyrin compound of Example 3.

Explanation of symbols

1 substrate 2 substrate

Claims (10)

It possesses a first linear absorption band at the maximum absorption wavelength near the two-photon absorption, and a second linear absorption band having a maximum at the longer wavelength range than said first linear absorption band, azaanulene compound, annulene A two-photon absorption material selected from either a compound or an anurenone compound ,
Two-photon absorption changes the optical properties of the second linear absorption band,
The optical properties,衰消coefficient, refractive index state, and are at least one of fluorescence intensity and fluorescence wavelength,
The change in optical properties, two-photon absorption material characterized detectable or renewable der Rukoto in two-photon absorption excitation wavelength.   The two-photon absorption material according to claim 1, wherein the refractive index (n) of the second linear absorption band at the two-photon absorption excitation wavelength is 1.65 or more and the extinction coefficient (k) is 0.05 or less. . The two-photon absorption cross-sectional area is 200 GM (× 10 ⁻⁵⁰ cm ⁴ · s · molecule ⁻¹ · photon ⁻¹ ) or more. The two-photon absorption material according to claim 1.   The two-photon absorption material according to any one of claims 1 to 3, wherein the two-photon absorption material has a chemical structure portion in which a conjugated bond is connected in a ring shape. An optical function imparting, wherein the two-photon absorbing material according to claim 1 is imparted with an optical function by changing an optical characteristic of a second linear absorption band according to a two-photon absorption excitation wavelength. Method. 5. The optical function detection according to claim 1, wherein the two-photon absorption material according to claim 1 is detected at the same wavelength by changing the optical characteristics of the second linear absorption band according to the two-photon absorption excitation wavelength. Method. 5. An optical recording method, wherein information is recorded on the two-photon absorption material according to claim 1 by changing optical characteristics of a second linear absorption band according to a two-photon absorption excitation wavelength. 5. The two-photon absorption material according to claim 1, wherein optical information of the second linear absorption band is changed by a two-photon absorption excitation wavelength, and information is reproduced by reproduction light having the same wavelength. An optical regeneration method . An optical recording material comprising the two-photon absorption material according to claim 1. A three-dimensional optical recording medium capable of recording and reproducing in the depth direction with respect to incident light in a recording layer containing the two-photon absorption material according to claim 1.