JPH03266830A - Optical recording material with multiple wavelength - Google Patents

Abstract

PURPOSE:To make it possible to set wavelength for recording in a wavelength region from a visible region to a near IR region by using a specified guest dye and a prescribed matrix. CONSTITUTION:A guest dye causing photochemical or photophysical hole burning is dispersed in a matrix to form an optical recording material. A cyanine dye represented by formula I is used as the guest dye and an amorphous solid compatible with the dye and having transparency in the hole burning region of the dye, e.g., PVA is used as the matrix. In the formula I, A<+> is a group represented by formula II, III, etc., B is a group represented by formula IV, V, etc., each of X and Y is O, S, etc., each of R1 and R2 is H or alkyl, n is 0-3 and Z<-> is an anion. A compd. represented by formula IV may be used as the cyanine dye.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a wavelength multiplexed optical recording material based on photochemical hole burning or photophysical hole burning.

[Prior art and problems to be solved by the invention] Wavelength multiplexing optical recording systems that utilize photochemical hole burning (hereinafter referred to as PHB) or photophysical hole burning (hereinafter referred to as NPHB) are far superior to current optical disk recording systems. It is attracting attention as an ultra-high-density, ultra-large-capacity recording method.

However, only a few organic pigments that express PHB or NPHB have been discovered so far, such as metal-free porphyrins, quinizarins, some oxazine pigments, and xanthine pigments (R, M,Macfarlaneand R,M,5
Helby, J. Lum1n, 36 (1987
) 179-207)n For this reason, the wavelength range that can be recorded is discretely limited, and therefore there is a problem that the recording wavelength cannot be freely selected.

On the other hand, a method has been devised to increase the recording capacity by multiplexing recording layers and doping each layer with a dye that causes hole burning at different wavelengths [Kiyoshi Yoshimura et al., No. 49]
Proceedings of the Academic Conference of Japan Society for Applied Physics, P872 (198
8) Ko. However, in this case as well, since the types of dyes are limited as described above, the number of layers cannot be increased, and there is a problem that the recording wavelength range is limited.

By the way, in wavelength multiplexed optical recording, a laser light source that can sweep the wavelength at high speed is required, and for this purpose, it is preferable to use a semiconductor laser. For example, the current practical and typical semiconductor laser is a GaA1As laser, and its oscillation wavelength range is around 700 to 800 nm in the near-infrared region, so PH8 dye or NPHB that causes hole burning in the oscillation wavelength range of such semiconductor lasers
Pigments are preferred. However, there are almost no examples of research on PH8 dyes or NPHB dyes that cause hole burning in the near-infrared region.

Therefore, an object of the present invention is to provide a wavelength multiplexing method that can set various recording wavelengths in a wide range of wavelengths from the visible region to the near-infrared region, and in particular can perform recording in the oscillation wavelength region of various semiconductor lasers. The purpose of the present invention is to provide optical recording materials.

[Means for Solving the Problems] In order to achieve the above object, the present inventors have extensively searched for dye compounds that cause hole burning.

As a result, we found that ionic cyanine dye compounds generally cause hole burning. Moreover, these ionic cyanine-based dye compounds change the type of heterocycle in this compound, or change the petro atom constituting the heterocycle into 01S1S eS" C(CR3) 2
- By changing to CH-CH-, or by changing the value of n in general formula (I) between 0 and 3, the carbon chain length between A'' and B in this compound can be changed. By doing so, the wavelength range in which hole burning occurs can be arbitrarily set over a wide wavelength range from the visible region to the near-infrared region. We found that hole burning also occurs in the oscillation wavelength range.

The present invention was made based on such knowledge, and the present invention provides a wavelength-multiplexed optical recording device in which a guest dye that causes PHB (photochemical hole burning) or NPHB (photophysical hole burning) is dispersed in a matrix. In the material, the guest dye has the general formula (I) A"-(CH=CH)n-CH=B (I)-[In the general formula (I), A" is the formula (AI) (formula (A : ) ~(As), X is 0, S, Se,
=C(CH3)2 or -CH=CH-, and R1 is hydrogen or an alkyl group), B is selected from the group consisting of formula (formula (BL) to (Bto), where Y is 0. S, 5e=
C(CH3)t or -CH=CH-, R2 is hydrogen or an alkyl group), n is 0.1.2 or 3, and Z- is a -valent anion A cyanine dye compound represented by the above wavelength, which is an amorphous solid that is compatible with the matrix or the guest dye and is transparent at least at a wavelength that causes hole burning of the guest dye. This paper focuses on multiple optical recording materials.

The present invention will be explained in detail below.

The wavelength multiplexed optical recording material of the present invention is PHB or NPHB.
The guest dye is dispersed in a matrix, and the guest dye is selected from among the cyanine dye compounds represented by the general formula (I).

General formula (I) is represented by A''-(CH=CH)n-CH=B (I), and A+ located at one end of general formula (I) is
It is selected from the above eight partial structural formulas (A,) to (A8) in which the nitrogen atom in the heterocycle is positively charged. By appropriately selecting these partial structural formulas (A1) to (A8), the hole burning wavelength of the cyanine dye compound can be varied.

In partial structural formulas (A1) to (A8), X is 0, S,
, Se, =C(CH3)p or -CH=CH-, and by appropriately selecting X from these,
The hole burning wavelength of the cyanine dye compound can be varied in various ways.

In the partial structural formulas (A) to (A8), R1 is hydrogen or an alkyl group, and the alkyl group is not particularly limited in the number of carbon atoms, but an alkyl group having about 1 to 6 carbon atoms is preferable. . This is because when the length of the alkyl group exceeds about 6 carbon atoms, the zero phonon component with a sharp width decreases.

Next, in general formula (I), B located at the other end of the above A+ with a carbon chain interposed is a moiety of the above 10 types in which the nitrogen atom in the heterocycle is not charged. It is selected from structural formulas (B1) to (B). By appropriately selecting these partial structural formulas (B1) to (BIO), the hole burning wavelength of the cyanine dye compound can be varied.

In partial structural formulas (B1) to (BIO), Y is 0, S
, Se, =C(CH3)2 or -CH=CH-, and by appropriately selecting Y from these,
The hole burning wavelength of the cyanine dye compound can be varied in various ways.

In the partial structural formulas (Bt) to (Boo), R2 is hydrogen or an alkyl group, and the alkyl group is not particularly limited in the number of carbon atoms;
Approximately 6 is suitable.

In general formula (I), n is 0.1.2 or 3, and the length of the carbon chain between A'' and B is determined by the number of n. As mentioned above, n is 0. However, 1 or more is preferable.The reason is that when n is O, both terminal groups A'
This is because the interaction between B and B becomes stronger, causing the sharp zero phonon holes to diminish and wide phonon side holes to become noticeable, which is undesirable in terms of recording density and signal-to-noise ratio. By selecting the number n in the range of 0 to 3, the hole burning wavelength of the cyanine dye compound can be varied.

In general formula (I), the counter anion Z-
Any monovalent anion may be used as the anion, but preferred examples include p-toluenesulfonate ion, iodine ion, perchlorate ion, and bromine ion. However, it is necessary to select Z- in consideration of solubility depending on the type of organic solvent used. Particularly preferred are p-toluenesulfonic acid ion and iodine ion because of their high solubility.

In the cyanine dye compound of general formula (I), A+,
B as (A1) to (A8) and (B1) to (BIO
), and X in A゛,
Y in B is O and 5SSe, respectively.

By appropriately selecting from =C(CH3) 2, -CH=CH-, and by appropriately selecting the number of n in the range of 0 to 3, the hole burning wavelength of the cyanine dye compound can be variously changed. be able to. An example of wavelength change when ethanol glass is used as a matrix is shown in Table 1 below.

As is clear from Table 1, in the cyanine dye compound of formula (I), A" is A, , R1 in A is E
t, B is B, , R2 in B is Et.

With n constant as 1, both Y in XSB in ○ are 0, S, Se, -C(CH3)2, -CH=CH
-, the hole burning wavelength of the cyanine dye compound is changed to 510 nm, 595 nm, 608 nm, and 586 nm, respectively, using ethanol glass as the matrix.
nm, can be around 645 nm (see samples N001 to 5 in Table 1) n Also, change n from 1 to 2, and change both X in A4 and Y in B to 0, S, Se, =C(CH3)2, -CH=
When changed to CH-, the hole burning wavelength of the cyanine dye compound using ethanol glass as a matrix becomes 610 nm, 698 nm, 708 nm, respectively.
676nm, 737nm (see sample No. 6 to 10 in Table 1) In this way, when A゛R,, XSB, R2, and Y are the same, when n is 2, It is clear that the hole burning wavelength shifts to the longer wavelength side than when n is 1 (for example, Table 1
Sample No. 1 and Sample No. inside.

6)n Also, change n from 2 to 3, and set both X in A and Y in B to 0,5SSe, =C(CH3)2, -CH=
When changed to CH-, the hole burning wavelength of the cyanine dye compound using ethanol glass as a matrix changes to 710 nm, 795 nm, 803 nm, and 770 nm.
, around 850 nm (Sample No. in Table 1).

11-15) In this way, A= , R, , X, B5
When R2 and Y are the same, when n is 3, when n is 2
It is clear that the hole burning wavelength shifts to the longer wavelength side than when the sample No.
Compare Sample No. 6 with Sample No. 11) n Preferred specific examples of the compound of general formula (I) include the following.

C,H.

r e (to) IH7 (Hereinafter in the margin) In addition, the wavelength multiplexing optical recording material of the present invention may contain other hole burning compounds other than the cyanine dye compound of the general formula (1), within a range that does not impede the object of the present invention. ingredients (e.g.
Known hole-burning dye compounds) and other additive components can also be used together as guest dyes.

Other hole burning dyes that may be used as desired include, for example, various phthalocyanines such as tetraphenoxyphthalocyanine, various porphyrins such as tetraphenylporphyrin, chlorins such as tetraphenylchlorin, and various dihydroxy compounds such as quinizaline. Examples include quinones and various tetrazines such as dimethyl-8-tetrazine.

Next, the matrix in which the guest dye is dispersed will be explained. As this matrix, any amorphous solid can be used as long as it is compatible with the guest dye and is transparent at least at a wavelength that causes hole burning of the guest dye. For example, polyvinyl alcohol (PVA), polymethyl methacrylate (PMMA)
, polystyrene (PS), polyvinyl chloride (PV)
C), organic amorphous polymers such as polyvinyl carbazole (PVCz), or n-
Examples include alcohols, organic solvents such as chrycerol, ethylene glycol, methyltetrahydrofuran (MTHF), etc., or those obtained by cooling and solidifying mixtures thereof, as well as silica glass and alumina glass obtained by a sol-gel method. Among these matrices, a hydrogen bonding amorphous matrix in which molecules are hydrogen bonded is preferable. This is because the guest dye represented by the general formula (I) exhibits particularly high hole burning efficiency in such a hydrogen-bonding matrix. Furthermore, among the hydrogen-bonding matrices, organic polymers having hydroxyl groups in side chains, such as PVA, are desirable. because,
This is because when the matrix is an organic polymer having a hydroxyl group in a side chain, the retention characteristics of holes recorded at a low temperature after increasing the temperature are high.

Note that the matrix materials may be used alone or in combination of two or more, if necessary.

The wavelength multiplexing optical recording material of the present invention can be obtained by dispersing the cyanine dye compound represented by the general formula (I) as an essential component in the matrix. At this time, usually one type of the dye compound may be dispersed in the matrix, but if desired, a plurality of dye compounds that do not interfere with each other may be appropriately selected and dispersed.

In other words, each dye compound has its own wavelength of light that exhibits a hole-burning phenomenon, but if the relationship that at least that wavelength is not absorbed by another dye is satisfied, two or more types of dyes can be used as necessary. Compounds may be used in combination.

In this case, as a standard that the dye is not absorbed by another dye compound, for example, as a rough guide, the absorbance ratio at that wavelength is 1/1,000 or less.

The concentration of the guest dye dispersed in the matrix is preferably 10'' to 10-5M (mo 1/1). If the concentration is too high, the hole burning efficiency will decrease, and if the concentration is too low, the optical density will decrease. This is because the recording signal-to-noise ratio decreases.A density of about 10-3 to 10-4 M is particularly preferable.

The method for dispersing the dye compound in the matrix is not particularly limited, and various methods such as known methods can be used as long as the dye compound can be uniformly dispersed at an appropriate concentration.

Examples of this dispersion method include a compatible method that does not use any solvent other than the organic solvent for the matrix, a solution method that uses a solvent, and a mechanical mixing method that uses a solvent or dispersion promoter as necessary. I can do it.

Examples of the above-mentioned compatibilizing method include a method in which a dye compound serving as a guest dye is dissolved or melted in the matrix as it is or is made to be compatible with the matrix and uniformly dispersed.

As a specific example of the solution method, a dye compound and a matrix such as an organic polymer are mixed as a solution in a solvent that dissolves both at the predetermined ratio, and after mixing, a thin film is formed by a spin coding method or a casting method. Examples include a method in which the solvent is sufficiently removed by drying, air drying, and, if necessary, heating and vacuum drying, or a method in which the solvent is removed by air drying, vacuum drying, etc., and then heat molding is carried out as appropriate.

A specific example of the mechanical mixing method includes a method of mechanically kneading a dye compound into a matrix of an organic polymer or the like softened by heating.

In addition, various methods can be applied, such as a method in which a dye compound is coexisted during the manufacturing process of a matrix such as an organic polymer (for example, during solid phase polymerization into a polymer).

In the manner described above, the optical recording material of the present invention can be obtained. The optical recording material of the present invention can be molded into any desired shape depending on the purpose of use and put into practical use.

When obtaining a desired recording medium using the optical recording material of the present invention, at least one recording layer made of the optical recording material may be provided. That is, the recording layer may be one layer (single layer), or may be a multilayer recording layer having two or more recording layers made of the optical recording material of the present invention, or at least one layer as desired. A multilayer recording layer may be formed by laminating a recording layer made of the optical recording material of the present invention and at least one recording layer made of another optical recording material.

Note that, as described above, by constructing the one or more recording layers of the optical recording material of the present invention containing a dye compound having a desired hole burning wavelength, hole burning in the resulting recording medium can be improved. The recording wavelength can be freely selected from a wide range from the visible region to the near-infrared region.

Further, as described above, by providing two or more recording layers made of the optical recording material of the present invention and using dye compounds having different hole-burning wavelengths in each layer, the hole-burning recording wavelength of the recording medium can be improved. The settings can be freely combined over a wide range from the visible region to the near-infrared region.

[Example code] Hereinafter, the present invention will be specifically explained with reference to Examples.

In the following examples, an argon laser-excited ring dye laser was used as the light source for hole burning. In addition, all observations of hole spectra were performed by measuring transmission spectra using monochromatic Xe lamp light using a spectrometer.

Example 1 Formula % Formula %) 2 mg was dissolved in 20 ml of ethanol, and the concentration was 1Xl0-4.
A solution of M was obtained. This solution was sealed in an optical cell with an optical path length of 1 mm, cooled and solidified in a cryostat, and then heated to a temperature of 5 mm.
Wavelength 586. llnm, intensity 80μW/cr
A laser beam of I was irradiated for 90 seconds to cause hole burning. It was confirmed that a sharp zero phonon hole with a half width of about 0.06 nm was generated in the transmitted light spectrum.

Example 2 A solution of formula 10-4M was obtained. This solution was sealed in an optical cell with an optical path length of 1 mm, cooled and solidified in a cryostat, and then heated to a wavelength of 676 nm at a temperature of 5K.

Hole burning was performed by irradiating laser light with an intensity of 40 μW/c♂ for 90 seconds. Figure 1 shows the shape of the hole as seen in the transmitted light spectrum. From Figure 1, the half width is 0.
It was confirmed that a sharp zero phonon hole of about 04 nm was generated.

Example 3 1, 3. 3. 1', 3'
3'-hexamethyl-2,2'-(4,5,4'
, 5'-dibenzo) indodicarbocyanine verchlorate (NK-2929, Japan Photosensitive Color Research Institute)
1.2 mg was dissolved in 20 ml of ethanol, and the concentration was expressed as 1.3. 3. 1'3'3'
-hexamethyl-2,2'-(4,5,4'5'
-dibenzo) indodicarbocyan Verchlorate (NK-2014, Nippon Kanko Shokuryoku Kenkyusho) 1.2 μl was dissolved in 20 ml of ethanol to obtain a solution with a concentration of 1×10 −4 M. This solution was sealed in an optical cell with an optical path length of 1 mm, cooled and solidified in a cryostat, and then heated to a temperature of 5K with a wavelength of 778. Onm, intensity 90μW/cnl
A laser beam was irradiated for 100 seconds to cause hole burning. The half width in the transmitted light spectrum is 0. It was confirmed that a sharp zero phonon hole of about 05 nm was generated.

Example 4 The same cyanine dye compound 1 used in Example 1
．． 20 ml of an aqueous solution of 2 mg dissolved in 100 ml of water,
An aqueous solution of 5 g of PVA dissolved in 100 ml of water was mixed. After casting this mixed solution, 72
Air dry for 1 hour, dry under reduced pressure at 80℃ for 24 hours, dye density 1X
A PVA membrane with l0-4M and a thickness of 100 μm was obtained. The membrane was placed in a cryostat at a temperature of 6. In OK,
A laser beam having a wavelength of 590° Onm and an intensity of 70 ttW/ctA was irradiated for 100 seconds to cause hole burning. It was confirmed that a sharp zero phonon hole with a half width of about 0.06 nm was generated in the transmitted light spectrum.

[Effects of the Invention] As explained above, according to the present invention, by appropriately selecting and using the cyanine dye compound represented by the formula (I), a wide wavelength range from the visible region to the near-infrared region can be obtained. A wavelength multiplexing optical recording material has been provided which allows recording wavelengths to be set in various ways, and in particular allows recording in the oscillation wavelength range of various semiconductor lasers.

[Brief explanation of drawings]

FIG. 1 is a transmitted light spectrum diagram showing hole burning of the optical recording material of Example 2.

Claims (2)

[Claims] (1) In a wavelength multiplexing optical recording material in which a guest dye that causes photochemical hole burning or photophysical hole burning is dispersed in a matrix, the guest dye has the general formula (I) A^+-(CH=CH)_n -CH=B(I)Z^- [In the general formula (I), A^+ is the formula (A_1) ▲ There are mathematical formulas, chemical formulas, tables, etc.
2) ▲There are mathematical formulas, chemical formulas, tables, etc.▼, (A_3)▲There are mathematical formulas, chemical formulas, tables, etc.▼, (A_
4) ▲There are mathematical formulas, chemical formulas, tables, etc.▼, (A_5)▲There are mathematical formulas, chemical formulas, tables, etc.▼, (A_
6) ▲There are mathematical formulas, chemical formulas, tables, etc.▼, (A_7)▲There are mathematical formulas, chemical formulas, tables, etc.▼, (A_
8) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In formulas (A_1) to (A_8), X is O, S, Se, =
C(CH_3)_2 or -CH=CH-, and R_
1 is hydrogen or an alkyl group) and B is selected from the group consisting of formula (B_1)
2) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (B_3)▲There are mathematical formulas, chemical formulas, tables, etc.▼, (B_
4) ▲There are mathematical formulas, chemical formulas, tables, etc.▼, (B_5)▲There are mathematical formulas, chemical formulas, tables, etc.▼, (B_
6) ▲There are mathematical formulas, chemical formulas, tables, etc.▼, (B_7)▲There are mathematical formulas, chemical formulas, tables, etc.▼, (B_
8) ▲There are mathematical formulas, chemical formulas, tables, etc.▼, (B_9)▲There are mathematical formulas, chemical formulas, tables, etc.▼, (B_
1_0) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In formulas (B_1) to (B_1_0), Y is O, S, Se
, =C(CH_3)_2 or -CH=CH-,
R_2 is hydrogen or an alkyl group), n is 0, 1, 2 or 3, and Z^- is a monovalent anion]; A wavelength multiplexing optical recording material, wherein the matrix is an amorphous solid that is compatible with the guest dye and is transparent at least at a wavelength that causes hole burning of the guest dye. (2) The wavelength multiplexed optical recording material according to claim (1), wherein the matrix is a hydrogen bonding amorphous solid in which molecules are hydrogen bonded.