JPH05297511A - Wavelength multiplex recording medium and wavelength multiplex recording method using this medium - Google Patents

Abstract

PURPOSE:To stabilize characteristic, to improve a recording state and to enable the execution of recording with high efficiency by executing good recording and reproducing without deterioration by stepwise two photon excitation in the wavelength multiplex recording medium and wavelength multiplex recording method utilizing a light hole burning phenomenon. CONSTITUTION:The wavelength multiplex recording medium is obtd. by dispersing zinc tetraphenyl porphine and adamantane bromide into a supporting material or dispersing dyestuff which has zinc tetraphenyl porphine skeleton and is introduced with electron acceptors as the substitution group into the supporting material. Information signals are recorded by stepwise two photon excitation on the wavelength multiplex recording medium.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength multiplex recording medium using the photochemical hole burning phenomenon (PHB phenomenon) and a wavelength multiplex recording method using the same, and particularly recording is performed by stepwise two-photon excitation. The present invention relates to a wavelength multiplexing recording medium and a wavelength multiplexing recording method using the same.

[0002]

2. Description of the Related Art The principle of wavelength multiplexing recording utilizing photochemical hole burning is shown by a light absorbing dye dispersed in a transparent medium at an extremely low temperature, as described in, for example, JP-A-53-99735. It is to form a sharp depression (hole) by irradiating a narrow band laser beam in one of two wide absorption bands (nonuniform absorber). A large number of holes can be formed in the nonuniform absorption band by gradually changing the wavelength of laser light to be applied. Theoretically, it is said that 10 ² to 10 ³ holes can be formed in one non-uniform absorption band. If the presence or absence of these holes is used for bit recording, the amount of information per spot Is expected to be able to increase dramatically.

[0003]

By the way, since the optical hole-burning materials, which have been extensively researched in the past, perform recording by a photochemical reaction by one-photon excitation, there is no threshold for recording and read-out light is used. It has the essential problem of destroying records.

In order to solve this, a photochemical hole-burning material of stepwise two-photon excitation (optical gate type) which uses a photochemical reaction that occurs from a high excited state generated by simultaneously irradiating two wavelengths of light has been studied. There is. In the stepwise two-photon excitation method, the recording is not destroyed only by the light of one wavelength, and the recording is not deteriorated by the reading light.

As the photochemical hole-burning material of the stepwise two-photon excitation system, a material system in which recording is performed by an electron transfer reaction between molecules has the highest degree of freedom in material selection and is promising for improving recording characteristics. However, photochemical hole burning actually occurs only in those having a specific molecular structure, and even if it has a degree of freedom, it is largely restricted in selecting a material system. Therefore, an electron acceptor or an electron donor is added to a material system that does not cause photochemical hole burning by itself to impart photochemical electron transfer reactivity, and is used as a photochemical hole burning material.

However, many electron acceptor materials are in liquid form, and the wavelength multiplexing recording medium prepared by dispersing the electron acceptor and the light absorbing dye in a transparent medium has a problem in stability of characteristics. is there. Furthermore, in the above wavelength multiplexing recording medium, it is necessary to efficiently transfer electrons to the electron acceptor in order to cause the photochemical hole burning phenomenon, and therefore, the concentration of the electron acceptor is increased to make it excessive. There is also a problem that the wavelength multiplexing recording medium becomes fragile.

Therefore, the present invention has been proposed in view of such circumstances, and it is possible to perform good recording and reproduction without deterioration by stepwise two-photon excitation, and the characteristics are stable. An object of the present invention is to provide a wavelength multiplex recording medium which is in a good recording state and can perform recording with high efficiency, and a wavelength multiplex recording method using the same.

[0008]

Means for Solving the Problems As a result of earnest studies over a long period of time, the inventors of the present invention have achieved the above-mentioned object, and as a result,
Recording and reproduction are performed by stepwise two-photon excitation by using zinc tetraphenylporphine as a light absorbing dye and adamantane bromide which is a solid at room temperature as an electron acceptor and dispersing them in a transparent medium which is a supporting material. Therefore, it has been found that a wavelength division multiplexing recording medium having a stable property can be obtained.

The present invention has been completed based on the above findings, and zinc tetraphenylporphine is used as a light absorbing dye (photosensitive material), and adamantane bromide is used as an electron acceptor, and these are used as supporting materials. It is characterized by being dispersed. At this time, the electron acceptor may be present in excess of the light absorbing dye, and is usually in large excess with respect to the light absorbing dye.

The inventors of the present invention also used stepwise two-photon excitation by using a zinc tetraphenylporphine derivative having an electron acceptor as a substituent as a light absorbing dye and dispersing these in a transparent medium as a supporting material. According to the above, it has been found that it is possible to obtain a wavelength division multiplexing recording medium capable of recording / reproducing, having stable characteristics, and capable of recording with high efficiency.

The present invention has been completed based on the above findings, and a dye having a zinc tetraphenylporphine skeleton as a light absorbing part and having an electron acceptor introduced as a substituent is dispersed in a support material. It is characterized by That is, as shown in chemical formula 1,
As long as it is a zinc tetraphenylporphine derivative having one or more electron acceptors represented by Formula A as a substituent, an optional substituent represented by B in Formula 1 may be present.

[0012]

[Chemical 1]

The electron acceptor represented by A in the chemical formula 1 is represented by the general formula-(C
H ₂₎ linear alkyl halide derivatives represented by _n Br, 2─ bromoethyl carboxyl, 3─ formula ─COO- (CH ₂ such bromopropyl carboxyl group) _n B
Examples of the linear halogenated alkylcarboxyl derivative represented by r include 2-bromoethylcarbonyl, 3-bromopropylcarbonyl group and other general formulas: linear halogenated alkylcarbonyl derivatives represented by CO— (CH ₂ ) _n Br, and the like. Be done.

On the other hand, the supporting material (dispersion medium) in which the light absorbing dye and the electron acceptor are dispersed is an optically transparent substance which does not absorb in the absorption region of the light absorbing dye,
Any material can be used as long as it can uniformly disperse the light absorbing dye and does not cause cracks at extremely low temperatures, but an amorphous medium is used to widen the nonuniform absorption band. In order to reduce the width of the hole, it is important to design the combination and structure of the light absorbing dye and the supporting material so that the interaction with the phonon is reduced. Further, in a system where the interaction between the light absorbing dye and the supporting material is strong, side holes are generated and the SN ratio of the signal is deteriorated. Therefore, it is necessary to select a system having a weak interaction as much as possible.

The supporting material is selected in consideration of such conditions, and it is selected from the group consisting of ethanol-methanol, organic glass such as tetrahydrofuran and glycerol, n.
Although a crystalline medium such as alkane can be used, a polymer material such as polystyrene, polyethylene, polyvinyl alcohol or polymethacrylate is preferable in view of the stability of the manufactured wavelength division multiplexing recording medium at room temperature.

The supporting substance and the light absorbing dye or electron acceptor are mixed at a predetermined ratio to form a wavelength multiplexing recording medium. In this case, the concentration of the light absorbing dye is the concentration of the light absorbing dye when dispersed in the supporting substance. It may be set to such a ratio that the molecule-molecule interaction of the absorbing dye can be neglected, and normally, the light absorbing dye is 10 ^-6 to 10 ^-1 mol% of the whole.

Furthermore, the above-described wavelength-division multiplex recording medium in which zinc tetraphenylporphine and adamantane bromide are dispersed in a support material and a zinc tetraphenylporphine skeleton as a light absorbing part, and an electron acceptor as a substituent are An information signal is recorded by a stepwise two-photon excitation on a wavelength-division multiplex recording medium in which the introduced dye is dispersed in a supporting material.

[0018]

[Function] Zinc tetraphenylporphine (light absorbing dye)
In a wavelength multiplexing recording medium in which adamantane bromide (electron acceptor) is dispersed in a support material, adamantane bromide that is solid at room temperature is used as an electron acceptor, so that the characteristics are stable. When the wavelength-multiplexed recording medium is cooled to an extremely low temperature and the wavelength-selective light and the gate light are simultaneously irradiated, the information signal is recorded by the optical hole burning phenomenon due to the stepwise two-photon excitation. Information is read by irradiating only the wavelength-selective light, and photochemical hole burning does not occur by irradiating only the wavelength-selective light, and the recorded state is maintained.

Further, in a wavelength division multiplexing recording medium having a zinc tetraphenylporphine skeleton as a light absorbing part and a dye having an electron acceptor introduced as a substituent dispersed in a support material, the electron acceptor is substituted. Since it is bound to a light-absorbing dye as a group, it is not necessary to add an electron acceptor separately, and it is easy to prepare a wavelength-multiplexed recording medium, and the characteristics are stable, and recording can be performed efficiently. .. When the wavelength-multiplexed recording medium is cooled to an extremely low temperature and the wavelength-selective light and the gate light are simultaneously irradiated, the information signal is recorded by the optical hole burning phenomenon due to the stepwise two-photon excitation.
Information is read by irradiating only the wavelength-selective light, and photochemical hole burning does not occur by irradiating only the wavelength-selective light, and the recorded state is maintained.

[0020]

EXAMPLES The present invention will be described below based on concrete experimental results. Example 1 In this example, polymethylmethacrylate (PMMA molecular weight 9 × 10 ⁴ ) was used as a support material (dispersion medium material).
Was used, and zinc tetraphenylporphine (light absorbing dye) and adamantane bromide (electron acceptor) dispersed therein were used as a sample. The proportion of the light absorbing dye contained in the sample is 2 × 10 ⁻³ mol% in the PMMA ratio, and the proportion of the electron acceptor is 44 mol% in the PMMA ratio. These were cast from the solution and hot pressed to prepare three plate-shaped samples having a thickness of 0.5 mm, which were referred to as Samples 1 to 3.

By the way, in a wavelength multiplex recording medium in which zinc tetraphenylporphine (light absorbing dye) and adamantane bromide (electron acceptor) are dispersed in a support material,
Zinc tetraphenylporphine is photoexcited by wavelength-selective light, transitions from the excited singlet state to the lowest triplet state, and is irradiated with gate light (465 nm) in this state, the energy of the gate light (2.79 eV) It is considered that the transition to the high triplet state corresponding to the, where electron transfer to adamantane bromide occurs, and holes are generated.

Therefore, the samples 1 to 3 were irradiated with laser light. The intensity of the wavelength-selective light was fixed at 16 mW / cm ² , and irradiation was performed while changing the wavelength. The sample 1 was irradiated with only the wavelength selection light, and the samples 2 and 3 were irradiated with the wavelength selection light and the gate light at the same time. The result is shown in Figure 1.
Shown in. The results shown in FIG. 1 are obtained by parallelly comparing the spectra obtained when the samples are irradiated with the wavelength selection light and the gate light.

The result of the sample 2 is shown by b in FIG. 1, and the gate light whose intensity is 8 mW / cm ² at the same time as the wavelength-selective light at a position of 16830 cm ^-1 (the position shown by an arrow A in the drawing) in the drawing. Was irradiated for 10 minutes, and a gate light having an intensity of 24 mW / cm ² was simultaneously irradiated for 10 minutes at the position of 16769 cm ⁻¹ in the figure (position indicated by arrow B in the figure). The result of Sample 3 is shown by c in FIG. 1, and at the position of 16842 cm ⁻¹ (the position shown by an arrow C in the drawing) in the drawing, the gate light whose intensity is 56 mW / cm ² is simultaneously emitted for 10 minutes. Irradiated. From these results, it is understood that as the intensity of the gate light increases, the generated holes become deeper, and the reaction between zinc tetraphenylporphine excited to a high triplet state and adamantane bromide occurs. Further, the result of Sample 1 which is not irradiated with the gate light is shown by a in FIG. 1, and only the wavelength selective light is irradiated for 30 minutes at the position of 16754 cm ⁻¹ (the position shown by the arrow D in the drawing) in the drawing. did. Comparing the results of Sample 1 and Sample 3, the gate ratio (ratio of the depth of generated holes) is 30.
As described above, it can be seen that holes are hardly generated only by the wavelength selective light. Therefore, in the wavelength-multiplexed recording medium in which zinc tetraphenylporphine is used as the light absorbing dye, adamantane bromide is used as the electron acceptor, and these are dispersed in the supporting material, the optical hole burning phenomenon due to stepwise two-photon excitation is confirmed. Was done.

Example 2 In this example, a dye having a zinc tetraphenylporphine skeleton as a light absorbing part in the molecule and an electron acceptor bonded as a substituent, as shown in Chemical formula 2, An example in which zinc tetrakis (4- (2-bromoethylcarboxy) phenyl) porphine is used as a light absorbing dye will be described.

[0025]

[Chemical 2]

The above zinc tetrakis (4- (2-bromoethylcarboxy) phenyl) porphine was synthesized from zinc tetrakis (4-carboxyphenyl) porphine which is a light absorbing dye and ethylene bromohydrin which is an electron acceptor. Polymethylmethacrylate (PMMA molecular weight 9 × 10 ⁴ ) was used as a support material (dispersion medium), and zinc tetrakis (4- (2-bromoethylcarboxy) phenyl) porphine dispersed therein was used as a sample. .. The ratio of the light absorbing dye contained in the sample is PMMA
The ratio is 2 × 10 ^-3 mol%, and the ratio of electron acceptor is 4 in PMMA ratio.
It is 4 mol%. These were cast from the solution and hot pressed to prepare a plate-shaped sample having a thickness of 0.5 mm, which was referred to as Sample 4.

By the way, in a wavelength multiplexing recording medium in which zinc tetrakis (4- (2-bromoethylcarboxy) phenyl) porphine is dispersed in a support material, the zinc tetraphenylporphine skeleton is photoexcited by wavelength-selective light and excited singlet. By transitioning from the state to the lowest triplet state, irradiation with gate light (465 nm) in this state causes a transition to a higher triplet state corresponding to the energy (2.79 eV) of the gate light, and there It is considered that holes are generated by electron transfer to ethylene bromohydrin which is a substituent.

Therefore, the sample 4 was irradiated with laser light. The intensity of the wavelength selection light was 8 mW / cm ^2, and the generation of holes was observed depending on the presence or absence of the gate light. The results are shown in Figure 2.

The position at 16927 cm ^{-1 in} the figure (arrow E in the figure
(The position indicated by the arrow) is irradiated with only the wavelength-selective light for 10 minutes, and at the position of 16943 cm ^-1 in the figure (the position indicated by the arrow F in the figure), the gate light having the intensity of 112 mW / cm ² is simultaneously emitted for 10 minutes. Irradiated. From these results, the holes generated in the presence of gate light become deeper, and the electron transfer reaction from the zinc tetraphenylporphine skeleton, which is a light absorbing part excited to a high triplet state, to the electron accepting part in the molecule occurs. I understand that The position of 16927Cm ^-1 (position indicated by arrow E) and the gate ratio (the ratio of the depth of the formed holes) at position (in the drawing the position indicated by the arrow F) in the figure 16943Cm ^-1 is 10 or more Therefore, it can be seen that holes are hardly generated only by the wavelength-selective light. Therefore,
Zinc tetrakis (4- (2-
In the wavelength multiplexing recording medium in which bromoethylcarboxy) phenyl) porphine was dispersed in the support material, the optical hole burning phenomenon due to stepwise two-photon excitation was confirmed.

[0030]

As is clear from the above description, in the wavelength multiplexing recording medium in which zinc tetraphenylporphine and adamantane bromide of the present invention are dispersed in a support material, it is necessary to combine it with a solid support material at room temperature. As a result, it is possible to provide a wavelength multiplexing recording medium that is solid at room temperature and has a stable characteristic and a good recording state. Further, since the information signal is recorded on the wavelength-division multiplexed recording medium by stepwise two-photon excitation, it is possible to perform excellent recording and reproduction without deterioration.

Further, in the wavelength division multiplexing recording medium of the present invention in which a dye having a zinc tetraphenylporphine skeleton and having an electron acceptor introduced as a substituent is dispersed in a support material, the support material solid at room temperature By combining with, it is possible to provide a wavelength multiplexing recording medium that is solid at room temperature and has a stable recording characteristic and good recording state.
Since the sample preparation is easy because there is no need to add an electron acceptor separately, its industrial value is very high. In addition, it is possible to perform good recording / reproduction on the wavelength-division multiplexed recording medium without deterioration due to stepwise two-photon excitation.

[Brief description of drawings]

FIG. 1 is a characteristic diagram showing a spectrum when wavelength-selective light or wavelength-selective light and gate light are simultaneously applied to a wavelength-division multiplex recording medium of Example 1.

FIG. 2 is a characteristic diagram showing a spectrum when wavelength-selective light or wavelength-selective light and gate light are simultaneously applied to the wavelength-division multiplexing recording medium of Example 2.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobutoshi Asai 6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation (72) Inventor Takashi Iwamura 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo No. Sony Co., Ltd. (72) Inventor Junetsu Seto 6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Within Sony Co., Ltd.

Claims (5)

[Claims] 1. A wavelength division multiplexing recording medium comprising zinc tetraphenylporphine and adamantane bromide dispersed in a support material. 2. A wavelength division multiplexing recording medium having a zinc tetraphenylporphine skeleton and a dye having an electron acceptor introduced as a substituent, dispersed in a support material. 3. The electron acceptor is at least one of a linear halogenated alkyl derivative, a linear halogenated alkylcarboxyl derivative, and a linear halogenated alkylcarbonyl derivative.
The wavelength multiplexing recording medium according to claim 2, characterized in that it is of a type. 4. A wavelength multiplexing recording method, wherein an information signal is recorded by stepwise two-photon excitation on a wavelength multiplexing recording medium in which zinc tetraphenylporphine and adamantane bromide are dispersed in a support material. 5. A wavelength-multiplexed recording medium having a zinc tetraphenylporphine skeleton and having an electron acceptor introduced as a substituent introduced therein and dispersed in a support material, thereby providing an information signal by stepwise two-photon excitation. A wavelength division multiplexing recording method characterized by recording.