JPH05334880A - Method for storing information and device therefor - Google Patents

Abstract

PURPOSE:To realize a storage device which has a large capacity and whose access speed and data transfer speed are high by utilizing a photochemical hole burning(PHB) phenomenon. CONSTITUTION:To a storage medium 1 having the PHB phenomenon, the light of a light source 2 having a single or plural frequencies having band width being narrower than the band width of an absorption line is radiated selectively and simultaneously by a secondary space modulator 4 and a condensing system 5, and information is stored in parallel in a spatial dimension and a wavelength dimension. Also, the light generated from the light source 2 is radiated onto the storage medium 1, while making wavelength scan by a wavelength scanner 3, the light after transmission in a single or plural specific positions on the storage medium 1 is detected by a condensing system 6 and a two-dimensional detector 8, and the stored information is reproduced in parallel. In this regard, a cooling means 7 cools the storage medium 1 to an arbitrary temperature extending from a liquid helium temperature to a room temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength division multiplexing optical memory, and more particularly to an information storage method and apparatus using the photochemical hole burning phenomenon at extremely low temperatures.

[0002]

2. Description of the Related Art In the coming 21st century, there will be a literal multimedia society in which various kinds of information such as voice, data, characters and moving images are exchanged through a common network. In order to realize such a society, in addition to the construction of a broadband network, it is indispensable to develop an information storage device having a large capacity and a high access speed and a high data transfer speed. Comparing the current magnetic disk device and optical disk device,
The former is superior to the latter in access speed and data transfer speed, but is inferior to the latter in terms of storage capacity. Therefore, neither device has the required performance for future information storage devices.

Therefore, in the current optical disk apparatus which is a heat mode memory for storing information by using laser light as a heat source, the storage density is increased by shortening the wavelength of the laser, the capacity is increased by arranging a large number of optical disks, and the optical disk Efforts are being made to meet future demands for information storage devices by increasing the access speed by increasing the rotation speed and increasing the data transfer speed by using the multi-head, but it is said that the limit will be reached at the end of this century. .. Further, by arranging a large number of optical discs, the storage capacity of the entire device increases, but the storage capacity per optical disc is limited, so when information that spans two or more optical discs is required, There was a problem that it took a long time for the user to actually retrieve the information.

As an information storage method that has received a great deal of attention in recent years, there is an information storage method utilizing the photochemical hole burning (PHB) phenomenon. This information storage method is photon mode storage that uses light as it is to store information, and realizes a new type of high-speed, large-capacity information storage device by selecting an appropriate reaction system and its characteristic "wavelength multiple storage". Is expected (eg WEMoerner ed., “Persiste
nt Spectral Hole-Burning ”Science and Application
s, Springer-Verlag (1988)).

The principle of the information storage method utilizing the PHB phenomenon will be described with reference to FIG. For example, in a system in which guest molecules such as dye molecules are dispersed in a matrix such as a transparent polymer or rigid glass, the absorption spectrum is broadened by the essential width (uniform width: Δω _h ) of the electronic state of the molecule,
Inhomogeneous spread (inhomogeneous width: Δω _i ) caused by subtle differences in the interaction between individual guest molecules and the matrix
Indicates. Here, in a sufficiently low temperature state, Δω _h
<< Δω _i Therefore, when an absorber having the above-mentioned structure is irradiated with light having a narrow wavelength width, only the molecules of the energy sites that can resonantly absorb the energy of the irradiation light are selectively excited. , By causing a chemical reaction,
A hole is formed by shifting the absorption of the molecule to another wavelength range. The presence / absence of holes can represent "1" and "0" of the data bit.

In order to realize an information storage device using the above-described information storage method, technological development on both sides of the storage medium and the optical system is indispensable.

In storage media, research and development of PHB memory materials based on an optical gate type electron transfer reaction capable of non-destructive reading and high speed writing have been advanced, and materials capable of writing in several ns to several tens of ns have been found (for example, , TPCart
er et al., J. Phys. Chem., 91 , 3998 (1987), WEMoerne
r et al., Appl.Phys.Lett., 50 , 430 (1987), WEMoer
ner et al., Appl. Phys. Lett., 50 , 430 (1987) and H. Su.
zuki et al., Jpn.J.Appl.Phys., 29 , 1146 (1990)).

On the other hand, as an information storage device utilizing the PHB phenomenon, a device for accessing a storage medium with a laser beam by an optical deflector based on an acousto-optic device and a galvanometer mirror (FM Schellenberg et al., Appl. Opt., 25 , 3207 (1986)
And a device for accessing a storage medium with a laser beam by means of an optical deflector based on two acousto-optic elements (N. Asai
et al., Jpn.J.Appl.Phys., 31 , 699 (1992)) was proposed.

[0009]

However, in the former device, the access time is about 2 ms which is the driving time of the galvano mirror, which is 10 times faster than the current optical disk device, but the writing in the PHB storage medium is There is a problem that it is too slow as the potential of speed and the access speed of the storage device in the future. Further, in the latter device, since only the optical deflector based on the non-mechanical acousto-optic device is used as the optical deflector, the access time can be shortened to the order of μs, but the deflection angle is small. There is a problem that a wide area cannot be accessed, and the potential of the writing speed of the PHB storage medium and the access speed of future storage devices are still too slow.

In view of the above conventional problems, the present invention provides a PHB.
An object of the present invention is to provide an information storage method and a device thereof, which utilizes a phenomenon and has a large capacity and a high access speed and a high data transfer speed.

[0011]

Means for Solving the Problems In order to achieve the above-mentioned object, the present invention has a memory having a non-uniform absorption line caused by the fact that guest molecules are dispersed in a matrix and the interaction between the guest molecules and the matrix is different. A single or a plurality of arbitrary positions on the medium are selectively and simultaneously irradiated with light having a single or a plurality of frequencies having a bandwidth narrower than the bandwidth of the absorption line, and in the spatial dimension and the wavelength dimension. A photochemical reaction is caused in the guest molecules in parallel to store information, and a single or a plurality of arbitrary positions on the storage medium having a bandwidth narrower than the bandwidth of the absorption line. Information stored by irradiating light having a plurality of frequencies selectively and simultaneously while performing wavelength scanning, and from light after passing through a single or a plurality of specific positions on the storage medium Information storage method of reproducing in parallel,
And a storage medium having a non-uniform absorption line generated due to different interaction between the guest molecule and the guest molecule dispersed in the matrix, and a single storage medium having a bandwidth narrower than that of the absorption line. Alternatively, a light source for generating light of a plurality of frequencies, a wavelength scanner for performing wavelength scanning of the light source, and a single or a plurality of arbitrary positions on the storage medium to selectively and selectively emit light from the light source. A two-dimensional spatial modulator and a first focusing system for simultaneously irradiating, a cooling means for cooling the storage medium, and a light after passing through a single or a plurality of specific positions on the storage medium. A two-dimensional detector for simultaneously two-dimensionally detecting and a second light-collecting system are provided, and in writing and reading information, the light from the light source is the two-dimensional spatial modulator and the first light-collecting system. By the memory Suggest configuration information storage device so that it can be irradiated in parallel in a single or a plurality of selectively and simultaneously spatial dimension and wavelength dimension at an arbitrary position on the body.

[0012]

In the photon mode memory in which laser light is used as it is, in contrast to the heat mode memory in which laser light is used as a heat source, various properties of light can be positively utilized as they are. Particularly, in an optical memory using the PHB phenomenon, the spatial parallelism and wavelength parallelism of light can be utilized. In this case, the degree of parallelism is the product of the spatial parallelism indicating the degree of spatial parallelism and the wavelength parallelism indicating the degree of wavelength parallelism, that is, (spatial parallelism) × (wavelength parallelism) (hereinafter, the total It is referred to as the degree of parallelism.). According to the method of the present invention, by utilizing this parallelism, the data transfer rate can be increased at the maximum by the total parallel degree. According to the device of the present invention,
Since no mechanical movement such as rotation of the galvanometer mirror or storage medium is used, the access speed can be increased.

[0013]

1 shows an embodiment of the present invention, in which 1 is a storage medium, 2 is a light source, 3 is a wavelength scanner, and 4 is 2
A dimensional spatial modulator, 5 and 6 are light collecting systems, 7 is a cooling means, and 8 is a two-dimensional detector.

The storage medium 1 is composed of a matrix and guest molecules dispersed therein, and exhibits nonuniform absorption lines because the interaction between the matrix and the guest molecules is different. Any guest molecule may be used as long as it is capable of wavelength multiplexing storage,
Several nanoseconds to several 1 such as PHB memory materials based on photo-gate type electron transfer reaction capable of non-destructive reading and high speed writing
It is desirable that the material can be written in 0 ns (for example, TP Carter et al., J. Phys. Chem., 91 , 3998 (198
7), WEMoerner et al., Appl.Phys.Lett., 50 , 430 (19
87), WEMoerner et al., Appl.Phys.Lett., 50, 430
(1987) and H.Suzuki et al., Jpn.J.Appl.Phys., 29, 11
46 (1990)).

The light source 2 emits light of a single or a plurality of frequencies having a bandwidth narrower than the bandwidth of the above-mentioned nonuniform absorption line, and the wavelength scanner 3 performs wavelength scanning. The two-dimensional spatial modulator 4 and the light converging system 5 selectively and simultaneously irradiate the light from the light source 2 to a single position or a plurality of arbitrary positions on the storage medium 1. The two-dimensional spatial modulator 4 includes, for example, a liquid crystal spatial modulator, a photoelectric fusion element (QCS effect element), a non-linear etalon, etc., but features such as parallelism, response speed, input sensitivity, contrast, operating wavelength and memory property. It can be used properly according to.

The cooling means 7 is for cooling the storage medium 1 and can cool the storage medium 1 to any temperature from liquid helium temperature to room temperature. The two-dimensional detector 8 and the condenser system 6 simultaneously two-dimensionally detect the light after passing through a single or a plurality of specific positions on the storage medium 1. Specifically, a photodiode array or CCD
A detector may be considered.

In writing and reading information, the light from the light source 2 is selectively moved to a single or a plurality of arbitrary positions on the storage medium 1 by the two-dimensional spatial modulator 4 and the condensing system 5. Moreover, it is configured such that irradiation can be performed in parallel in the space dimension and the wavelength dimension at the same time.

A detailed description will be given below. First, metal-free tetraphenylporphyrin (hereinafter abbreviated as TPP) and 9-bromoanthracene (hereinafter abbreviated as 9-ABr) in a chloroform solution of commercially available polymethylmethacrylate (hereinafter abbreviated as PMMA). .) Has a dry concentration of 5 × 10 ⁻³ M and 5 ×, respectively.
After adding it to 10 ^-2 M, it was cast on a transparent glass substrate at 50 to 60 ° C under nitrogen gas atmosphere all day and night, and further, the pressure was reduced to 1 by a rotary pump under reduced pressure.
The solvent was completely removed by leaving it at 50 ° C. for two days and nights to obtain a film having a thickness of about 50 μm.

Light (wavelength: 645.00 nm, pulse width: 30 ns, band width: 500 kHz) obtained by cooling the storage medium 1 to the temperature of liquid helium and making the ring dye laser light excited by Ar laser into a pulse shape by the AO modulator is used. 1 pulse (irradiation energy: 20 μJ / cm ² ) and pulsed Ar laser light by an AO modulator (wavelength: 514.5
nm, pulse width: 30 ns) 1 pulse (irradiation energy: 50 μJ / cm ² ) is made into coaxial light, and it is made into 5 parallel light rays equivalent through the spatial light modulator 4 made of ferroelectric liquid crystal. The aperture was narrowed down to 5 μmφ and the positions A, B, C, D and E of the storage medium 1 were simultaneously irradiated as shown in FIG.

Next, a ring dye laser beam excited by an Ar laser is pulsed by an AO modulator (wavelength: 645.02).
nm, pulse width: 30 ns, band width: 500 kHz)
1 pulse (irradiation energy: 20 μJ / cm ² ),
Spatial light modulation consisting of a ferroelectric liquid crystal using 1 pulse of pulsed light (wavelength: 514.5 nm, pulse width: 30 ns) of Ar laser light pulsed by an AO modulator (irradiation energy: 50 μJ / cm ² ). Equivalent four parallel light beams were made to pass through the device 4, narrowed down to 5 μmφ by the condensing system 5, and irradiated at positions A, E, F and G of the storage medium 1 at the same time.

Next, the ring dye laser light is passed through the spatial light modulator 4 to the positions A, B, C, D, on the storage medium 1.
Equivalent to 7 parallel rays corresponding to E, F, G, and narrowed down to 5μmφ by the condensing system 5, wavelength from 644.98nm
Scanning up to 645.04 nm shows that the wavelength of the ring dye laser light irradiated at the same time as the Ar laser light is shown in FIG.
As shown in (b), formation of holes was confirmed in the Q ₁ absorption band of TPP.

Further, TPP and 9-ABr were added to a commercially available chloroform solution of PMMA so that the concentrations when dried were 5 × 10 ⁻³ M and 5 × 10 ⁻² M, respectively, and then,
50 on a transparent glass substrate under a nitrogen gas atmosphere.
The solvent was completely removed by casting at -60 ° C for one day and one night and then for two days at 150 ° C under reduced pressure of a rotary pump to obtain a film having a thickness of about 50 µm.

This storage medium 1 is cooled to the temperature of liquid helium, and five visible light cw semiconductor lasers are arranged to form an array light source (wavelengths: 644.98 nm, 644.99 nm, 645.00 n).
m, 645.01 nm, 645.02 nm, irradiation energy: 20 μ
J / cm ² , irradiation time: 10 s, Ar laser light (wavelength: 514.5 nm, irradiation time: 10 s, irradiation energy:
50 μJ / cm ² ) as coaxial light, and 5 parallel light rays equivalent through the spatial light modulator 4 made of ferroelectric liquid crystal,
The light was focused to 5 μmφ by the condensing system 5, and the positions A, B, C, D, and E of the storage medium 1 were simultaneously irradiated as shown in FIG.

Next, the semiconductor laser light is made into five equivalent parallel light rays corresponding to the positions A, B, C, D and E of the storage medium 1 through the spatial light modulator 4, and the parallel light rays are made 5 by the focusing system 5.
When the wavelength was narrowed down to μmφ and the wavelength was scanned from 644.95 nm to 645.05 nm, the Q ₁ absorption band of TPP was detected as shown in FIG. 4 (b), corresponding to the wavelength of the semiconductor dye laser light irradiated at the same time as the Ar laser light. The formation of holes was confirmed.

[0025]

As described above, according to the present invention, it is possible to write or read information without using an optical deflector or a galvanometer mirror based on an acousto-optic device for accessing a storage medium as in the prior art. Light from a light source having a plurality of frequencies is selectively and simultaneously irradiated in parallel in a spatial dimension and a wavelength dimension on a single or plural arbitrary positions on a storage medium by a two-dimensional spatial modulator and a condensing system. Therefore, it is possible to realize a large-capacity information storage method utilizing the PHB phenomenon and having a high access speed and a high data transfer speed, and an apparatus thereof.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram of the principle of an information storage method using the PHB phenomenon.

FIG. 3 is a diagram showing an example of a writing position of information on a storage medium and wavelength-absorption intensity characteristics showing stored information at that time.

FIG. 4 is a diagram showing another example of a writing position of information on a storage medium and a wavelength-absorption intensity characteristic showing stored information at that time.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Storage medium, 2 ... Light source, 3 ... Wavelength scanner, 4 ... Two-dimensional spatial modulator, 5,6 ... Condensing system, 7 ... Cooling means, 8 ... Two-dimensional detector.

Claims (2)

[Claims] 1. A guest molecule is dispersed in a matrix,
A single or a plurality of arbitrary positions on the storage medium having a non-uniform absorption line caused by a different interaction between the matrix and the guest molecule, and a single band having a bandwidth narrower than the bandwidth of the absorption line. Alternatively, light having a plurality of frequencies is selectively and simultaneously irradiated to cause a photochemical reaction in the guest molecules in parallel in a space dimension and a wavelength dimension to store information, and a single or a plurality of information on the storage medium is stored. Is irradiated with light having a single or a plurality of frequencies having a bandwidth narrower than that of the absorption line selectively and simultaneously while performing wavelength scanning. An information storage method characterized in that stored information is reproduced in parallel from light that has passed through a plurality of specific positions. 2. A guest molecule is dispersed in a matrix,
A storage medium having a non-uniform absorption line caused by a different interaction between the matrix and the guest molecule, and a light source for generating light of a single or a plurality of frequencies having a bandwidth narrower than the bandwidth of the absorption line. A wavelength scanner for performing wavelength scanning of the light source, and a two-dimensional spatial modulator for selectively and simultaneously irradiating light from the light source to a single or a plurality of arbitrary positions on the storage medium. And a first condensing system, a cooling unit for cooling the storage medium, and 2 for simultaneously two-dimensionally detecting light that has passed through a single or a plurality of specific positions on the storage medium. A two-dimensional spatial modulator and a first light-collecting system, for writing and reading information, the two-dimensional spatial modulator and the first light-collecting system.
An information storage device characterized in that it can be selectively and simultaneously irradiated in parallel in the space dimension and the wavelength dimension to a single position or a plurality of arbitrary positions on the storage medium.