JPH11295770A - Optical element and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the degradation of the optical input/output end faces of an optical element by forming the optical element by organic optical crystal provided with oppositely arranged optical incident end face and optical emission end face and a protective film composed of carbon and formed on the optical incident end face and optical emission end face. SOLUTION: The organic optical crystal 106 is arranged so as to make the incident end face 106a face a vapor deposition source 105 on an evaporation dish 101 and the vapor deposition source 105 is heated and evaporated by heating the evaporation dish 101 or the like. Then, the organic optical crystal 106 is arranged so as to make the emission end face 106b face the vapor deposition source 105 on the evaporation dish 101 and the vapor deposition source 105 is heated and evaporated by heating the evaporation dish 101 or the like. Thus, the protective film 107 is vapor deposited on the incident end face 106a and emission end face 106b of the organic optical crystal 106. Thus, the optical element for which the protective film 107 composed of the carbon in an amorphous shape is formed by vapor deposition on the respective incident and emission end faces 106a and 106b of the organic optical crystal 106 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element used as an optical signal processing element or an optical storage element, and a method for manufacturing the same.

[0002]

2. Description of the Related Art A nonlinear optical crystal can be used as an optical element in which, when laser light is incident, an emitted light having a component different from that of the incident light is obtained due to the interaction. For example, by applying the characteristic that the refractive index changes according to the intensity of incident light, nonlinear optical crystals such as all-optical switches and optical modulators, which are ultra-high speed and low energy consumption, are products that will revolutionize the information and communication field. Enable development. In addition, there is a possibility that a semiconductor material can be used as a material of an optical computer having a performance exceeding that of a current computer by utilizing an amplification effect of a nonlinear optical crystal.

As this nonlinear optical crystal, for example, organic optical crystals such as 2-methyl-4-nitroaniline and benzene derivatives have been found to have higher effects than inorganic crystals, and have attracted attention. Organic optical crystals made of those organic compounds having delocalized conjugated electrons have excellent characteristics such as large nonlinear optical characteristics based on the ease of movement of electrons and fast response.

[0004]

However, an optical element made of an organic optical crystal has a problem that its incident end face is easily damaged or oxidized and deteriorated by laser light. An organic material has a lower melting point and a higher sublimation property than an inorganic material, and easily reacts with oxygen or water in the air.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to suppress the deterioration of the light input / output end face of an optical element made of an organic optical crystal.

[0006]

An optical element according to the present invention comprises:
The organic optical crystal was provided with a light incident end face and a light output end face that were disposed to face each other, and a protective film made of carbon was formed on the light incident end face and the light output end face. Therefore, the light incident end face is in a state of being sealed by the protective film made of carbon. In the method of manufacturing an optical element according to the present invention, a protective film made of carbon is vapor-deposited on the light incident end face and the light output end face formed so as to face the organic optical crystal. Therefore, the light input / output end face is sealed by the deposited protective film.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 First, a first embodiment of the present invention will be described. FIG. 1 is an explanatory diagram for describing manufacturing of an optical element according to Embodiment 1 of the present invention. In the first embodiment, as shown in FIG.
The chamber 102 that forms a vacuum vessel provided with the above is used. The inside of the chamber 102 can be evacuated by a vacuum pump 103. The chamber 102 is configured so that an argon gas can be introduced from a gas cylinder 104. An evaporation source 105 is placed on the evaporating dish 101, and an organic optical crystal 106 is arranged to face the evaporation source 105.

By the way, as the organic optical crystal 106,
There are the following. That is, 3-methyl-4-nitropyridine-1-oxide (POM), N- (4-nitrophenyl) -L-prolinol (NPP), N-
(Nitrophenyl) -N-methylaminoacetonitrile (NPAN), 4-N, N-dimethylamino-2-acetamido-4-nitroaniline (DAN), 2-cycloacetylamino-5-nitropyridine (COANP),
3,9-dinitro-5a, 6,11a, 12-tetrahydro- [1,4] benzoxazino [3,2-b]
[1,4] Benzoxazine (DNBB), 4′-nitropandylidene-3-acetamino-4-methoxyaniline (MNBA), (−) 4- (4′-dimethylaminophenyl) -3- (2′- Hydroxypropylamino)
Cyclobutene-3,4-dione (DAD), 2-methoxy-5-nitrophenol (MNP), 3,5-dimethyl-1- (4-nitrophenyl) pyrazole (DMN
P), 2-adamantylamino 5-nitropyridine (A
ANP), 3-nitroaniline (m-NA), 2-methyl-4-nitroaniline (MNA), 3-methyl-
(2,4-dinitrophenyl) -aminopropanoate (MAP), 4-isopropylcarbamoylnitrobenzene (PCNB), dimethylaminostilbazolium (DAST), 4-nitrodimethylaniline (NDM)
A), 2- (N-prolinol) -5-nitropyridine (PNP), dicyanovinylanisole (DIVA),
Stilbazolium-P-toluenesulfonic acid (SPT
S), N-methoxymethyl-4-nitroaniline (MM
NA), 3-aminophenyl (m-AP) and the like.

First, a vapor deposition source 105 made of, for example, amorphous carbon powder is placed on an evaporating dish 101. Further, an organic optical crystal 106 is arranged in the chamber 102. Further, the inside of the chamber 102 is evacuated to a predetermined degree of vacuum by the vacuum pump 103. It is not always necessary to evacuate the chamber. Here, the organic optical crystal 106 has, for example, a length of 5
A rod-shaped DMNP single crystal of mm was used. And X
The second harmonic generation (SHG) phase matching azimuth from a wavelength of 1.55 μm was obtained by line analysis, and the light input / output surface was determined. In addition, the determined surfaces were polished and used as an incident end surface 106a and an outgoing end surface 106b.

[0010] First, the organic optical crystal 106 is arranged such that the incident end face 106a faces the evaporation source 105 placed on the evaporating dish 101. And evaporating dish 1
For example, by heating 01, the evaporation source 105 is heated and evaporated. As a result, first, the organic optical crystal 1
A protective film 107 is deposited on the incident end face 106a of the reference numeral 06. Next, the organic optical crystal 106 is arranged such that the emission end face 106b faces the evaporation source 105 placed on the evaporating dish 101. Then, the evaporation source 105 is heated and evaporated by heating the evaporation dish 101 or the like. As a result, the protective film 107 is also deposited on the emission end face 106b of the organic optical crystal 106. Here, the protective film 107
The thickness may be about 10 to 500 nm, which is a thickness that does not hinder light transmission.

As described above, an optical element is produced in which the protective film 107 made of amorphous carbon is formed on the incident end face 106a and the output end face 106b of the organic optical crystal 106 by vapor deposition. FIG. 1 shows a state in which the protective film 107 is formed on the incident end face 106a.
According to the first embodiment, the formed optical element has a high-temperature and high-humidity resistance and a light resistance because the input and output end faces of the optical signal are sealed by the protective film. It can be improved.

FIG. 2 is a characteristic diagram showing characteristics of the optical element. The solid line shows the change of the relative transmittance with time, and the broken line shows the relative S
The change with time of the HG effect is shown. Here, FIG.
Is the protective film (100 nm thick) according to the first embodiment.
m) shows the case of the formed optical element. Also,
FIG. 2B shows the case of a conventional optical element without a protective film. As is apparent from FIG. 2, the protective film according to this embodiment can be made to have a state in which almost no change with time occurs.

FIG. 3 shows a continuous signal light (wavelength 1....).
FIG. 4 is a characteristic diagram showing characteristics of the optical element when irradiated with a laser beam of 55 μm and a power density of 4 GW / cm ² ). The solid line shows the change over time of the relative transmittance, and the broken line shows the change over time of the relative SHG effect. Here, FIG. 3A shows a case of the optical element in which the protective film (100 nm in thickness) according to the first embodiment is formed. FIG. 3 (b)
Shows the case of a conventional optical element without a protective film.
As is clear from FIG. 3, even when the signal light is continuously irradiated, the protection film according to the present embodiment can make the state hardly change with time.

By the way, in forming the protective film 107,
If a large amount of oxygen or moisture is present in the atmosphere, the evaporation source 1
There is a case where the vapor of 05 reacts with them, and a good deposited film (protective film 107) may not be formed in some cases. For this reason, when the inside of the chamber 102 is kept in a higher vacuum state, the protective film 107 formed by vapor deposition can be in a good carbon film state. In addition, by performing vapor deposition in a state of being evacuated as described above, the presence of oxygen or water vapor between the formed protective film and the light input / output end face can be suppressed.

The above-described vapor deposition may be performed in a state where the inside of the chamber 102 is in an argon gas atmosphere. That is, the chamber 102 is controlled by the vacuum pump 103.
After evacuating the inside to a high vacuum, a predetermined amount of argon gas may be supplied from the gas cylinder 104 into the chamber 102, and the above-described vapor deposition may be performed in this state. By doing so, the protective film 107 formed by vapor deposition can be made into a good graphite film state without applying a very high vacuum.

If the vacuum state is too high, the organic optical crystal 106 may sublimate in some cases, and the mirror surfaces of the incident end face 106a and the outgoing end face 106b cannot be maintained. However, as described above, by introducing the argon gas into the chamber 102, the sublimation can be suppressed and the protective film 107 formed by vapor deposition can be in a good carbon film state. In addition to the argon gas atmosphere, another inert gas such as helium gas, neon gas, krypton gas, and xenon gas may be used.

Embodiment 2 In this embodiment 2, as shown in FIG. 4, a chamber 402 constituting a vacuum vessel having therein graphite electrodes 401a and 401b each having a distal end disposed close to each other is used. The inside of this chamber 402 can be evacuated by a vacuum pump 403. Also, this chamber 40
2 is configured such that an argon gas can be introduced from a gas cylinder 404. Then, the graphite electrode 40
1a and 401b are configured to be able to apply a higher voltage than the high voltage power supply 405.

First, an organic optical crystal 406 is arranged in a chamber 402. Also,
The inside of the chamber 402 is 10 ⁻⁶ T by the vacuum pump 403.
Evacuate to a vacuum degree of orr or less. It is not always necessary to evacuate the chamber. Here, the organic optical crystal 406 is, for example, a rod-shaped NP having a length of 5 mm.
A P single crystal was used. Then, by X-ray analysis, a wavelength of 1.5
The SHG phase matching azimuth from 5 μm was determined, and the light input / output surface was determined. The determined surfaces were polished and used as an incident end surface 406a and an outgoing end surface 406b.

First, the incident end face 406a is opposed to the graphite electrodes 401a and 401b.
An organic optical crystal 406 is arranged. And the high voltage power supply 40
5, a high voltage is applied between the graphite electrodes 401a and 401b so that the graphite electrodes 401a and
An electric discharge is caused between the near-end portions of the contact 01b.
Thus, first, a protective film 407 made of graphite is deposited on the incident end face 406a of the organic optical crystal 406.

Next, the organic optical crystal 406 is arranged so that the emission end face 406b faces the graphite electrodes 401a and 401b. Then, similarly, a high voltage is applied between the graphite electrodes 401a and 401b by the high-voltage power supply 405, so that the protective film 407 is also deposited on the emission end face 406b. Here, the protective film 407 to be deposited
Should have a thickness of about 10 to 500 nm, and a thin film that does not hinder light transmission.

As described above, an optical element in which the graphite protective film 407 is formed on the incident end face 406a and the output end face 406b of the organic optical crystal 406 is manufactured. In FIG. 4, the protective film 407 is formed on the incident end face 406a.
Is formed. According to the second embodiment, the formed optical element has a state in which the input and output end faces of the optical signal are sealed by the protective film. , High temperature and high humidity resistance,
Light resistance can be improved.

In the formation of the protective film 407, if a large amount of oxygen, moisture, or the like is present in the atmosphere, the vapor generated from the graphite electrodes 401a and 401b may react with them, and a good vapor deposition film (protective film) may be formed. Membrane 40
7) may not be formed. For this reason, chamber 4
The inside of the protective film 407 formed by vapor deposition is set to a higher vacuum state as in the second embodiment.
Can be in a good graphite film state. However, it is not always necessary to evacuate.

The above-described vapor deposition may be performed in a state where the inside of the chamber 402 is in an argon gas atmosphere. That is, the chamber 402 is operated by the vacuum pump 403.
After evacuating the inside to a high vacuum, a predetermined amount of argon gas may be supplied from the gas cylinder 404 into the chamber 402, and the above-described vapor deposition may be performed in this state. By doing so, the protective film 407 formed by vapor deposition can be in a good graphite film state without applying a very high vacuum. If the vacuum state is too high, the organic optical crystal 406 may sublime in some cases, and the mirror surface state of the incident end face 406a and the output end face 406b may not be maintained. However, as described above, by introducing an argon gas into the chamber 402, the sublimation is suppressed and the protective film 40 formed by vapor deposition is formed.
7 can be in a good carbon film state.

Third Embodiment Next, a third embodiment of the present invention will be described. FIG. 5 is an explanatory diagram for describing manufacturing of an optical element according to Embodiment 3 of the present invention. In Embodiment 1 described above, amorphous carbon powder is used as the vapor deposition source. In Embodiment 3, however, fullerene is used as vapor deposition source 505 as shown in FIG.

That is, in Embodiment 3, FIG.
As shown in (a), a chamber 502 constituting a vacuum container having an evaporating dish 501 inside is used, and the inside of the chamber 502 can be evacuated by a vacuum pump 503. Chamber 50
2 was configured so that argon gas could be introduced from the gas cylinder 504. Then, the evaporation source 50 on the evaporation dish 501
As No. 5, fullerene powder was used. As shown in FIG. 5B, the fullerene is a molecule in which, for example, 60 carbons 511 are bonded in a spherical shape. Not only fullerenes composed of 60 carbons but also powders of fullerenes composed of 70 carbons may be used, or a mixture thereof may be used.

First, an organic optical crystal 506 is disposed in the chamber 402. Also,
After the inside of the chamber 502 is evacuated to a high vacuum by the vacuum pump 503, a predetermined amount of argon gas is supplied from the gas cylinder 504 into the chamber 502, and the inside of the chamber 502 is replaced with argon gas. Here, the organic optical crystal 506
For example, a rod-shaped AANP single crystal having a length of 5 mm was used. Then, the SHG phase matching direction from a wavelength of 1.55 μm was determined by X-ray analysis, and the light input / output surface was determined. The determined surfaces were polished and used as an incident end surface 506a and an outgoing end surface 506b.

First, the organic optical crystal 506 is arranged such that the incident end face 506a faces the evaporation source 505 placed on the evaporating dish 501. And evaporating dish 5
For example, by heating 01, the evaporation source 505 is heated and evaporated. As a result, first, the organic optical crystal 5
A protective film 507 is deposited on the incident end face 506a of the reference numeral 06. Next, the organic optical crystal 506 is arranged such that the emission end face 506b faces the evaporation source 505 placed on the evaporating dish 501. Then, the evaporation source 505 is heated and evaporated by heating the evaporation dish 501 or the like. Thus, a protective film 507 is deposited on the emission end face 506b of the organic optical crystal 506. Here, the protective film 507 is
The thickness may be about 50 to 500 nm, which is a thickness that does not hinder light transmission.

As described above, an optical element in which the protective film 507 made of fullerene is formed on the incident end face 506a and the output end face 506b of the organic optical crystal 506 is manufactured. In FIG. 5, the protective film 50 is formed on the incident end face 506a.
7 shows a state in which No. 7 is formed. According to the third embodiment, the formed optical element has a high-temperature and high-humidity resistance and a light resistance because the input and output end faces of the optical signal are sealed by the protective film. It can be improved.

FIG. 6 shows a continuous signal light (wavelength 1.55 μm).
FIG. 9 is a characteristic diagram showing characteristics of the optical element when irradiated with m laser light and a power density of 6 GW / cm ² ). The solid line shows the change over time of the relative transmittance, and the broken line shows the change over time of the relative SHG effect. Here, FIG. 6A shows a case of the optical element in which the protective film according to the third embodiment is formed. FIG. 6B shows a case of a conventional optical element having no protective film.

As is clear from FIG. 6, even if the signal light is continuously irradiated, the protection film according to the present embodiment makes it possible to make the state hardly change with time. In the case of the third embodiment, a stronger laser beam is irradiated as compared with the case shown in FIG.
Almost similar results have been obtained. That is, it is understood that the optical element having the protective film according to the third embodiment has more improved light resistance.

In the above description, the case where the material composition of the protective film is one type is shown, but the present invention is not limited to this. A protective film may be formed by laminating films having different configurations in multiple layers. For example, the thickness of the carbon film to be formed is adjusted in consideration of the wavelength of the signal light to be used, the refractive index of the organic optical crystal, the refractive index of the carbon vapor deposition film, and the like. With the protective film described above, a non-reflective coating film can be formed.

[0032] In the above description, the amorphous carbon powder as the evaporation source, graphite, has been to use a fullerene powder consisting of C ₆₀ and C _70, not limited to this. Alternatively, a higher fullerene powder shown below may be used as the evaporation source. That is, C ₇₆ , C
₇₈ , _C80 , _C84 , _C86 , _C88 , and _C94 . Further, the following carbon compounds may be used as the evaporation source. That is, adamantane (C ₁₀ H ₁₆ ), diamantane (C ₁₄ H ₂₀ ), and dodecahedran (C ₂₀ H ₂₀ ) may be used. Further, carbon nanotubes may be used as the evaporation source. Moreover, C _{60-1,3-dioxolane} and C ₆₀ Br ₈ or the like may be vapor deposition source, a derivative of fullerene. By using them as vapor deposition sources, a protective film composed of each vapor deposition source can be formed.

[0033]

As described above, according to the present invention, an organic optical crystal having a light incident end face and a light output end face which are arranged opposite to each other, and a protective film made of carbon formed on the light incident end face and the light output end face. It consisted of. Therefore, the light incident end face is in a state of being sealed by the protective film made of carbon. In the method for manufacturing an optical element according to the present invention,
A protective film made of carbon was vapor-deposited on the light incident end face and the light output end face which were formed oppositely to the organic optical crystal. Therefore, the light input / output end face is sealed by the deposited protective film. As a result, according to the present invention,
Since the light input / output end face of the optical element does not directly come into contact with air and is not directly exposed to signal light irradiation, deterioration of the light input / output end face can be suppressed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram for describing manufacturing of an optical element according to Embodiment 1 of the present invention.

FIG. 2 is a characteristic diagram showing characteristics of an optical element.

FIG. 3 is a characteristic diagram showing characteristics of an optical element when signal light is continuously irradiated.

FIG. 4 is an explanatory diagram for describing manufacturing of an optical element according to Embodiment 2 of the present invention.

FIG. 5 is an explanatory diagram for describing manufacturing of an optical element according to Embodiment 3 of the present invention.

FIG. 6 is a characteristic diagram illustrating characteristics of an optical element when signal light is continuously irradiated.

DESCRIPTION OF SYMBOLS 101: evaporation dish, 102: chamber, 103: vacuum pump, 104: gas cylinder, 105: evaporation source, 106: organic optical crystal, 106a: incident end face, 106b: emission end face, 107: protective film.

Claims (9)

[Claims] 1. An organic optical crystal having a light incident end face and a light output end face opposed to each other, and a protective film made of carbon formed on the light incident end face and the light output end face. Optical element. 2. The optical element according to claim 1, wherein said protective film is made of amorphous carbon. 3. The optical element according to claim 1, wherein the protective film is made of graphite. 4. The optical element according to claim 1, wherein the protective film is made of fullerene. 5. A first step of preparing an organic optical crystal having a light incident end face and a light output end face which are disposed to face each other, and a second step of depositing a protective film made of carbon on the light incident end face and the light output end face. And a method for producing an optical element. 6. The method for manufacturing an optical element according to claim 5, wherein the vapor deposition is performed in an evacuated atmosphere. 7. The method for manufacturing an optical element according to claim 5, wherein the vapor deposition is performed in an inert gas atmosphere. 8. The method for manufacturing an optical element according to claim 5, wherein in the second step, the first and second optical elements are made of graphite.
A protective film made of carbon evaporated from the first or second electrode is vapor-deposited on the light input / output end face by applying a voltage between the electrodes to cause discharge. 9. The method for manufacturing an optical element according to claim 5, wherein in the second step, fullerene or a compound thereof is used as an evaporation source.