JP2003128429A - Optical element and method of manufacturing it, optical fiber and method of manufacturing it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical element which exhibits a function of a photonic crystal by alternately arranging a quartz glass and one of a non-quartz glass and an organic substance having a nonlinear optical property in cycles of a wavelength of light and is provided with various functions resulted with the non-quartz glass and the organic substance having the nonlinear optical property. SOLUTION: The optical element is provided with a base part 101 having a plurality of parallel rectangular plates of quartz glass which project vertically from one plane of a sheet of the glass in cycles of 10-10<5> nm, and with filled parts 102 between parallel plates of quartz glass of the base part 101 being filled with a tellurite glass.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element in which silica glass is combined with at least one of non-silica glass and an organic material, a manufacturing method thereof, an optical fiber and a manufacturing method thereof.

[0002]

2. Description of the Related Art In recent years, with the development of information society, a high-speed and large-capacity communication system is required. As such a communication system, an optical communication system using an optical fiber has been put into practical use. In this optical communication system, various optical elements such as amplifiers and filters are used to perform amplification, conversion, and other various processing of optical signals.
Recently, much research has been conducted to use photonic crystals for such optical elements.

A photonic crystal has a dielectric constant of 2
An artificial crystal in which more than one kind of substance is arranged at a period of the wavelength of light. Since this photonic crystal has a non-propagable light wavelength region called a photonic band gap, it can control spontaneous emission light that was conventionally uncontrollable, and has large dispersion and anisotropy. It is expected that it can also be used as a polarizer or a filter.

The optical characteristics of the photonic crystal are as follows:
It depends on the difference in the dielectric constants of two types of materials that are arranged periodically.

[0005]

However, since the structure of the photonic crystal is fine and complicated, until now, a periodic structure was produced using a semiconductor such as Si or GaAs or SiO ₂ , and another substance was used. Most of them use air as. In particular, the photonic crystal in the shape of an optical fiber is only one in which pores are periodically arranged in the bulk of silica glass. Since such an optical fiber has low mechanical strength and is largely deformed by temperature change, it is difficult to exhibit stable optical characteristics.

The present invention has been made in view of the above circumstances, and an object of the present invention is to make silica glass, non-silica glass, and / or at least one of organic substances having nonlinear optical characteristics within a wavelength range of light. To provide an optical element and an optical fiber, which are arranged alternately in a periodical manner to exert the function of a photonic crystal and to which various optical functions derived from non-quartz glass and organic substances having nonlinear optical characteristics are added. is there.

[0007]

In order to achieve the above object, the invention of claim 1 provides in at least one direction quartz glass, glass containing a substance other than quartz as a main component, and nonlinear optical characteristics. An optical element is characterized in that at least one of the organic substances contained therein is alternately arranged at a cycle of 10 to 10 ⁵ nm.

Here, the glass containing a substance other than quartz as a main component is a glass in which the most abundant component in the composition is a substance other than quartz. For example, a glass containing TeO ₂ as a main component is used. Light glass, bismuth glass, chalcogenide glass, fluoride glass and the like can be mentioned. Further, an organic substance having a nonlinear optical property is one that has a function of converting the optical property from incident light to outgoing light in a nonlinear manner, and in a polymer, Poly (methylmet
hacrylate), Poly [4,4 '-(1-methylethylidene) bispheny
lterephthalate], Poly [4,4 '-(1-phenylethylidene) bis
phenylterephthalate], etc., in the side chain type polymer, Poly (m
ethylmethacrylate-co-diazo-dye-substituted methacr
ylate), Disperse Red DR1 (cis and trans forms) for dyes, and 4-dimethyl for organic optical crystals.
amino-N-methylstylbazorium-tosylate (DAST),
4'-nitrobenzylidene-3-acetamino-4-methoxyaniline
(MNBA), (-) 2- (a-methylbenzylamino) -5-nitropy
ridine (MBANP) etc. can be mentioned.

According to the structure of the invention of claim 1, since the photonic crystal is composed of quartz glass and at least one of the non-quartz glass and the organic substance having nonlinear optical characteristics, the periodic structure is the same. However, the optical characteristics of the photonic crystal can be changed by selecting the dielectric constant of non-quartz glass or organic material. Further, various optical characteristics possessed by non-quartz glass and organic substances can be further added. Here, the periodical arrangement of the quartz glass and the non-quartz glass or the organic substance may be only one direction, and at that time, it becomes a one-dimensional arrangement, and if the periodic arrangement is planar, it becomes a two-dimensional arrangement. If so, it will be a three-dimensional arrangement. Note that the periodic arrangement may have some defects or may have different periods depending on the place and direction.

The period of the alternating arrangement is 10 to 10 ⁵ nm.
Therefore, the photonic crystal can be used for light of all wavelengths from ultraviolet light to infrared light. For light in the wavelength range used for optical communication, a period of 10 ² to 10 ⁴ nm is preferable.

The functions of light conversion of non-quartz glass or organic substances having non-linear optical characteristics, which cannot be obtained by quartz, include wide-band light amplification and a large degree of change in refractive index due to ultraviolet irradiation (high light-induced change in refractive index). Examples include optical nonlinear characteristics and high Raman gain. Among them, the fiber grating can be easily manufactured by utilizing the high light-induced change in refractive index. Examples of optical nonlinear characteristics include the generation of second harmonics using the local crystal structure of tellurite glass and the refractive index change characteristics (used for optical switches) of organic optical crystals depending on the intensity of input light. Can be mentioned as. A high-performance Raman amplifier can be manufactured by using high Raman gain. Also, by setting the difference between the refractive index value of quartz glass and the refractive index value of non-quartz glass or organic matter according to the wavelength of light used, the reflection, transmission, and refraction characteristics of light can be freely controlled to It can be a coupling element or an optical branching element.

Next, in the invention of claim 2, a step of alternately arranging the silica glass and the air layer in at least one direction at a cycle of 10 to 10 ⁵ nm, and a substance other than quartz in the air layer. And a step of introducing at least one of a glass as a main component and an organic substance having nonlinear optical characteristics.

According to the manufacturing method of the second aspect of the invention, the optical element of the first aspect can be easily manufactured. Further, if only the periodic structure of quartz glass is manufactured first, the air layer is formed. Since non-quartz glass or an organic substance to be filled can be arbitrarily selected and introduced later, various types of optical elements can be easily manufactured in a short time at low cost. Here, as the method of introducing the non-quartz glass or the organic substance, a method of introducing the liquid non-quartz glass or the organic substance by utilizing the capillary phenomenon or the pressure difference of suction or pressurization is preferable.

Next, the invention of claim 3 is directed to an optical fiber whose main constituent material is silica glass.

Further, a large number of functional optical paths extending in the fiber axis direction and comprising at least one of a glass containing a substance other than quartz as a main component and an organic material having nonlinear optical characteristics are provided. It is assumed that the fibers are arranged so as to have a two-dimensional periodic structure of 10 to 10 ⁵ nm in the cross section of the fiber.

Here, the two-dimensional periodic structure is a structure which is periodically arranged in every direction of the plane, and the periods may be different in different directions.

According to the third aspect of the present invention, the optical fiber of the present invention has a shape of an optical fiber and is a photonic crystal composed of at least one of quartz glass, non-quartz glass and an organic substance. The strength is almost the same as that of quartz glass, and it can be easily joined with a normal quartz optical fiber, and can be easily used as an optical component for an optical communication system. Further, since the optical fiber is made of at least one of quartz glass, non-quartz glass, and organic matter, the volume change with respect to temperature change is small and stable. Further, as in claim 1, since the period of alternately arranging the quartz glass, the non-quartz glass and at least one of the organic substances is 10 to 10 ⁵ nm, all of the photonic crystals from ultraviolet light to infrared light can be obtained. It is possible to correspond to the light of the wavelength. For light in the wavelength range used for optical communication, a period of 10 ² to 10 ⁴ nm is preferable.

Next, the invention of claim 4 is based on claim 3, wherein the functional optical paths are arranged at different periods in two directions orthogonal to each other in the cross section of the fiber.

According to the structure of the invention of claim 4, birefringence occurs in the cross section of the fiber, so that the fiber is a polarization maintaining fiber. That is, the optical fiber of the invention of claim 4 is an optical fiber in which polarization preservation is added to the effect of claim 3.

Next, in the invention of claim 5, in claim 3, the functional optical path has a plurality of kinds of different constituent materials, and the distribution of the refractive index in two directions orthogonal to each other in the cross section of the fiber. Are arranged so that they are different from each other.

With the structure of the fifth aspect of the present invention, birefringence occurs in the cross section of the fiber, so that the fiber is a polarization maintaining fiber. That is, the optical fiber of the invention of claim 5 is an optical fiber in which polarization preservation is added to the effect of claim 3. The refractive index is an index representing the optical aspect of the dielectric constant.

Here, a plurality of kinds of functional optical paths having different constituent materials are arranged so as to be different in two directions in which the refractive index distribution is orthogonal in the cross section of the optical fiber, that is, the constituent materials are different. As a result, a plurality of types of functional optical paths having different refractive indices are arranged so that the distributions are different for each functional optical path in two directions orthogonal to each other in the optical fiber cross section.
That is, the refractive index distributions are different in the two orthogonal directions. In other words, in the cross section of the optical fiber, the refractive index distribution is arranged so as to be non-axisymmetric (when rotated by 90 degrees) with respect to the central axis, that is, when the optical fiber is rotated by 90 degrees around the central axis. In addition, the refractive index distribution before rotation is different from the refractive index distribution after rotation.

Next, in the invention of claim 6, in claim 3, the composition of the substance constituting the functional optical path is changed in the longitudinal direction of the fiber.

According to the configuration of the invention of claim 6, claim 3
In addition to the above effect, it is possible to add a function such as modulation in the direction in which light propagates. Here, the fact that the composition of the substance forming the functional optical path changes in the longitudinal direction of the fiber means that the concentration changes or the combination of compositions changes.

Next, in the invention of claim 7, in any one of claims 3 to 6, the functional optical path has a periodic refractive index changing structure in the fiber axis direction.

According to the structure of the invention of claim 7, since the functional optical path has a periodic refractive index changing structure in the axial direction of the fiber, that is, a fiber grating, in addition to the effect of claim 3, The optical fiber has a function of reflecting a specific wavelength or transmitting a specific wavelength as a fiber grating. Here, since the non-quartz glass or the organic substance having nonlinear optical characteristics has a large degree of change in refractive index due to irradiation with ultraviolet rays, that is, has a high light-induced change in refractive index, it can be easily used as a fiber grating.

Next, the invention of claim 8 is the invention according to any one of claims 3 to 7, further comprising a coating layer which covers the entire circumference and has heat resistance equal to or higher than the melting point of the constituent material of the functional optical path. And

Here, the coating layer having heat resistance equal to or higher than the melting point of the constituent material of the functional optical path means a coating layer whose melting point, thermal decomposition temperature or thermal deterioration temperature is equal to or higher than the melting point of the constituent material of the functional optical path. That is, at the temperature at which the heat resistance is exhibited, the coating layer protects the optical fiber and blocks direct contact with external objects such as air. Specific examples thereof include heat resistant resins such as polyimide, polyamide imide, fluororesin and aromatic polyamide, and metals such as Al and Cu.

According to the structure of the invention of claim 8, at least one of the non-quartz glass and the organic substance having nonlinear optical characteristics is melted at a high temperature and introduced into the pores extending in the axial direction of the quartz optical fiber to form a composite. Even when the optical fiber is formed, the coating layer does not melt or decompose, and the protective function as the coating layer can be achieved even after the introduction of non-quartz glass or an organic substance having nonlinear optical characteristics. In particular, by maintaining the covering function at high temperature, it is possible to prevent the quartz glass from deteriorating under wet heat.

Next, a ninth aspect of the present invention is a step of drawing an optical fiber preform made of quartz glass while forming a large number of pores extending in the fiber axis direction, and a molten state in the pores. A method of manufacturing an optical fiber, comprising: a glass having a substance other than quartz as a main component or an organic substance having nonlinear optical characteristics, which is introduced by using a pressure difference.

Here, the drawing means forming an optical fiber or an optical fiber intermediate body in which the core portion of the optical fiber is a pore by heating and melting the optical fiber preform and stretching it.

According to the manufacturing method of the ninth aspect, an optical fiber intermediate body made of quartz having a large number of pores extending in the fiber axis direction is formed in advance, and suction and pressurization are applied to the pores. The optical fiber according to any one of claims 3 to 8 can be easily manufactured by introducing a fused non-quartz glass or an organic substance having nonlinear optical characteristics by a method utilizing a pressure difference using at least one of them. . Further, since the parts other than the core part of the optical fiber are formed in advance, various kinds of optical fibers can be prepared by changing the kind of non-quartz glass or organic material having nonlinear optical characteristics to be introduced into the core in the step of forming the functional optical path. It can be manufactured easily, at low cost, and in a short time. Since silica glass has a very high melting point, silica glass retains the shape of an optical fiber intermediate at the melting point of non-silica glass or an organic substance having non-linear optical characteristics, and has non-quartz glass or non-linear optical characteristics. It is possible to easily introduce an organic substance.

Further, as a method for forming a quartz optical fiber intermediate body having pores extending in the axial direction, for example, a method of forming an axial hole in an optical fiber preform and then drawing it,
Examples include a method in which a quartz rod and a tube are bundled, melted and adhered to form a base material, and then drawn. When the molten non-quartz glass or the organic substance having the nonlinear optical characteristic is introduced into the optical fiber intermediate, the optical fiber intermediate is kept at a temperature substantially the same as the melting point of the non-quartz glass or the organic substance having the nonlinear optical characteristic. It is preferable that the non-quartz glass and the organic substance having nonlinear optical characteristics are cooled and solidified on the way and are not introduced further into the future.

Next, in the invention of claim 10, in the step of forming the functional optical path according to claim 9, a plurality of the plurality of pores are selectively sealed and the remaining pores are melted. Glass having a substance other than quartz in a state of being a main component or an organic substance having nonlinear optical characteristics, a step of introducing by using a pressure difference, and releasing the sealing, to the unsealed pores, It is assumed that the method includes a step of introducing a glass having a substance other than quartz in a molten state different from that of the introduced substance as a main component or an organic substance having nonlinear optical characteristics by using a pressure difference.

According to the manufacturing method of the tenth aspect of the present invention, it is possible to easily form the functional optical paths having different constituent materials at arbitrary positions of the optical fiber.

[0036]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

First Embodiment FIG. 1 is a perspective view of an optical element 100 according to the first embodiment. The optical element 100 includes a comb-shaped base portion 101.
And a filling portion 102 that fills the gap of the base portion 101.

The base portion 101 is a piece of quartz glass.
A plurality of rectangular quartz glass plates are arranged vertically from one side of the plate.
It sticks out in parallel at regular intervals and is attached to both quartz glass plates.
The vertical cross section is comb-shaped. Parallel above
The quartz glass plate of 10 to 10^Fivearranged with a period of nm
ing. This cycle is the same as the light incident on the optical element 100.
1/2 to almost the same length. Therefore, ultraviolet
10-4 × 10 when applied to light²nm period and
However, when applied to visible light, 1.9 × 10²~ 8x
10²nm period and when applied to infrared light,
3.8 x 10²-10 ^FiveThe period may be nm. Also,
The thickness of the quartz glass plates arranged in parallel is not particularly limited
Is 1/4 to 3/4 of the array period, the optical element 10
0 is easy to manufacture and functions as a photonic crystal
Is also preferable because it sufficiently exhibits.

The filling portion 102 may be made of at least one of glass containing a substance other than quartz as a main component and an organic substance having nonlinear optical characteristics. Here, tellurite containing TeO ₂ as a main component is used. It is made of glass.

Next, a method of manufacturing the optical element 100 of this embodiment will be described.

First, the base portion 101 is formed of quartz glass. The base portion 101 may be formed by scraping off quartz glass by etching or the like, or may be formed by joining quartz glass plates. After forming the base portion 101 in which quartz glass and air layers are alternately and periodically arranged, the base portion 10 is added to the molten tellurite glass.
The lower part is immersed with the surface showing the comb tooth shape of 1 facing upward, the upper surface side is sucked, and the tellurite glass is sucked up. When the tellurite glass is introduced into almost the entire air layer of the base portion 101, the base portion 101 is pulled up from the molten tellurite glass to solidify the tellurite glass in the filling portion 102, and the optical element 100 is completed.

The optical element 10 thus completed
0 functions as a photonic crystal when light is made incident in the periodic alternating arrangement direction of quartz glass and tellurite glass. Further, optical characteristics such as wide band light amplification and high Raman gain of the tellurite glass of the filling portion 102 can be used.

The optical element 100 of this embodiment has a simple structure and is entirely filled with glass, so that the strength is high.
Easy to handle. Further, due to the periodic structure of quartz glass and tellurite glass, it has the function of a photonic crystal and also has various optical characteristics of tellurite glass. In the manufacturing method according to the present embodiment, the base portion 1 in which quartz glass and air layers are alternately and periodically arranged in advance.
By forming 01, it is possible to arbitrarily select the type of non-quartz glass or an organic substance having nonlinear optical characteristics to be introduced into the air layer. Therefore, the difference in refractive index from the quartz glass can be freely selected, and the properties of the photonic crystal can be controlled. Further, the optical characteristics of the substance of the filling portion 102 can be freely selected. Further, since the molten tellurite glass is introduced into the base portion 101 by suction, it can be easily manufactured.

-Embodiment 2- FIG. 2 is a diagram showing a part of a cross section of an optical fiber 10 according to a second embodiment. The optical fiber 10 has a circular cross section, and a large number of functional optical paths 2 are periodically arranged in a clad 1 made of quartz glass. The outer surface of the clad 1 is covered with a coating layer (not shown). ).

The functional optical path 2 extends in the axial direction of the optical fiber 10 and is 10 in the cross section of the optical fiber 10.
It is arranged so as to have a two-dimensional periodic structure of -10 ⁵ nm. The two-dimensional periodic structure in this embodiment is a planar lattice structure whose minimum unit is an equilateral triangle, and the distance between the centers of adjacent functional optical paths 2 is 10 to 10 ⁵ nm. This distance is 1 / the wavelength of the light incident on the optical element 100.
2 to almost the same length. Therefore, this distance is 10 to 4 × 10 ² nm when applied to ultraviolet light, and 1.9 × 10 ² to 8 × 10 ² n when applied to visible light.
m, and when applied to infrared light, 3.8 × 10 ² ~
It may be 10 ⁵ nm. Further, the functional optical path 2 is Te
It consists of tellurite glass with O ₂ as the main component,
TeO ₂ is preferably contained in an amount of 50 mol% or more, and other components include BaO, Bi ₂ O ₃ and Na ₂
O, Li ₂ O, it may be mentioned ZnO, K ₂ O or the like.
In the present embodiment, for example, BaO (20 mol%)-Zn
Tellurite glass having a composition of O (20 mol%)-TeO ₂ (60 mol%) can be used. Further, Er is added to the functional optical path 2 in order to impart a light amplification function. A rare earth element other than Er, such as Pr or Nd, may be added. The diameter of the functional optical path 2 is
Although not particularly limited, 1/4 to 3/4 of the distance between the centers of the adjacent functional optical paths 2 is preferable.

The quartz glass forming the clad 1 may contain Ge, B or the like in order to adjust the refractive index and other characteristics. Further, the diameter of the clad 1 is not particularly limited, but it is preferable that it is the same as that of other optical fibers for transmission and light sources.

The coating layer is made of a polyimide resin which is a heat resistant resin having a melting point of over 300 ° C., and the coating thickness is preferably 0.01 to 50 μm.

Next, a method of manufacturing the optical fiber 10 of this embodiment will be described.

FIG. 3 is a sectional view of the base material of the optical fiber 10. This base material is formed by bundling a large number of quartz glass tubes 3 having a hole 4 in the center. Diameter of quartz glass tube 3 and hole 4
The diameter of is set to be the same in all quartz glass tubes 3.

Then, the base material is drawn. That is,
The base material is heated and melt-stretched, and a coating layer is further provided to form an optical fiber intermediate body 12 as shown in FIG. At this time, the quartz glass tubes 3 are melted and joined to each other, the boundary disappears, and a large number of pores 6 extending in the fiber axis direction are simultaneously formed in the entire optical fiber intermediate body 12.

Next, as shown in FIG. 2, in the step of forming the functional optical path, the molten tellurite glass is introduced into a large number of pores 6 of the optical fiber intermediate body 12 to form the functional optical path 2, and the optical path is formed. The fiber 10 is completed.

The tellurite glass is introduced into the pores 6 by using an introduction device 20 as schematically shown in FIG. The introduction device 20 includes a constant temperature bath 21 and a suction device 22, and the constant temperature bath 21 and the suction device 22 are connected by a tube 23. The tellurite glass 25 is melted in the constant temperature bath 21. A melting device 24 is installed. The tellurite glass 25 is introduced into the optical fiber intermediate body 12 by using the introducing device 20 as follows.

First, the optical fiber intermediate body 12 having a large number of pores 6 shown in FIG. 4 is placed in the constant temperature bath 21. One end of the optical fiber intermediate body 12 is inserted into the molten tellurite glass 25, and the other end is inserted into the constant temperature bath 21.
It is inserted into the suction port 26 provided on the wall of the. Suction port 26
Is connected to the suction device 22 via a tube 23.

After the optical fiber intermediate body 12 is set in this way, the temperature in the constant temperature bath 21 is made substantially the same as the melting point of the tellurite glass 25, and the suction device 22 is operated to move the tellurite glass 25 to the optical fiber intermediate body. 12 is sucked into the pores 6. Since the ambient temperature is kept almost the same as the melting point of the tellurite glass 25, the tellurite glass 2
5 is sucked in the pores 6 without solidifying.
When the suction is completed up to a predetermined point, the temperature in the constant temperature bath 21 is lowered to solidify the tellurite glass 25 introduced into the optical fiber 10 and then the operation of the suction device 22 is stopped. Then, both ends of the optical fiber 10 are taken out from the molten tellurite glass 25 and the suction port 26, respectively, and the optical fiber 10 itself is taken out from the constant temperature bath 21,
The introduction process ends. During this process, the heat-resistant coating layer covers the entire periphery of the clad 1, and therefore plays a role of coating during and after the introduction of the tellurite glass 25.
Therefore, the surface of the clad 1 is not directly contacted with air to be deteriorated or collided in the apparatus to be damaged.

In the optical fiber 10 of the present embodiment, the signal light passes through the plurality of functional optical paths 2 made of tellurite glass and the surrounding cladding 1 made of quartz. Therefore, the dispersion of the optical fiber 10 is made of quartz glass. And each dispersion of tellurite glass will be synthesized. That is, the optical fiber 10 has a function as a dispersion control element. Of course, it also has a function of a photonic crystal and optical characteristics peculiar to tellurite glass.

As described above, in the optical fiber 10 of this embodiment, since the functional optical path 2 is made of tellurite glass and the clad 1 is made of silica glass, the function of the photonic crystal and the broadband optical amplification and the like can be obtained. It has a light conversion function and has the same fiber strength as silica glass fiber. It is also stable against temperature changes. The connection with the silica-based optical fiber for transmission can be made firmly by welding the clads together. Further, since polyimide, which is a heat-resistant resin, is used for the coating layer, the coating layer can withstand the high temperature in the manufacturing process, prevent the optical fiber 10 from deteriorating under heat and humidity, and prevent fiber breakage.

In the manufacture of this optical fiber 10, the molten tellurite glass 25 is introduced by suction into the axially extending pores 6 formed in the optical fiber 10 in advance, so that the manufacturing is easy. If the optical fiber 10 having the pores 6 is formed in advance, the composition and additives of the tellurite glass in the functional optical path 2 portion can be arbitrarily changed, so that many kinds of optical fibers 10 can be easily manufactured. It can be manufactured at low cost and in a short time.

-Embodiment 3- FIG. 6 is a view showing a part of a cross section of the optical fiber 10 according to the third embodiment. In this embodiment, the minimum unit of the plane lattice of the two-dimensional periodic structure is a square. Embodiment 2
Is different only in the plane lattice structure, the material and manufacturing method,
Functions and the like are the same. The wavelength of light at which the function of the photonic crystal is exerted is determined by this plane lattice structure and its period.

-Embodiment 4- FIG. 7 is a view showing a part of a cross section of an optical fiber 10 according to Embodiment 4. As shown in FIG. In the present embodiment, the minimum unit of the plane lattice having the two-dimensional periodic structure is rectangular. That is, the functional optical path 2 is perpendicular to the cross section of the optical fiber 10.
They are arranged in different directions with different periods. The second embodiment is different from the second embodiment only in the plane lattice structure, and the material and manufacturing method are the same. In addition to the function of the second embodiment, it has a polarization conservation function. The wavelength of the light that exhibits the function of the photonic crystal is determined by this plane lattice structure and its period. However, since the period differs depending on the direction, the optical fiber 10 of the present embodiment uses the photonic light for polarized light of two wavelengths. Work as a crystal.

-Fifth Embodiment FIG. 8 is a view showing a part of a cross section of the optical fiber 10 according to the fifth embodiment. In this embodiment, the two-dimensional periodic structure is the same as that of the third embodiment, but the functional optical paths 2a arranged on a specific straight line have a different refractive index from the material with which the other functional optical paths 2 are filled. The material is filled. for that reason,
The refractive index distributions are arranged differently in two directions orthogonal to each other in the cross section of the optical fiber 10 and have a polarization preserving function. Further, since the functional optical paths 2 and 2a are filled with two kinds of materials, the optical fiber 10 has each optical characteristic that these materials have.

The method of manufacturing the optical fiber 10 of the present embodiment is the same as that of the second embodiment up to the point of forming the optical fiber intermediate body 12 having a large number of pores 6 extending in the axial direction. Next, the pores 6 arranged on a specific straight line are sealed, and the first tellurite glass is introduced into the remaining pores 6 by the device shown in FIG. The sealing of the pores 6 may be performed on the end portion side to be inserted into the tellurite glass or on the opposite end portion. Also, both ends may be sealed. After introducing the first tellurite glass, the sealing is released and the second tellurite glass having a different composition and a different refractive index from the first tellurite glass is introduced into the sealed pores 6. Then, the optical fiber 10 of this embodiment is completed. In this manufacturing process, it is preferable that the first tellurite glass has a higher melting point than the second tellurite glass.

-Sixth Embodiment- FIG. 9 is a view showing a part of a cross section of an optical fiber 10 according to a sixth embodiment. The optical fiber 10 has four types of functional optical paths 31 to 34 having different diameters. Also,
The two-dimensional periodic structure is the same as in the second embodiment. In the center of the cross section of the optical fiber 10, one functional optical path 31 having the largest diameter is arranged, six functional optical paths 32 having the second largest diameter are arranged around it, and the third functional optical path 32 is further arranged around it. Twelve large-diameter functional optical paths 33 are arranged, and the remaining small-diameter functional optical paths 34 are arranged.

The optical fiber 10 of this embodiment has a wider wavelength band of light that functions as a photonic crystal than that of the second embodiment. Other functions, manufacturing methods, etc. are the same as those in the second embodiment.
Is the same as.

-Seventh Embodiment- FIG. 10 is a diagram schematically showing a part of a vertical cross section of an optical fiber 10 according to a seventh embodiment. In this embodiment, in the functional optical path 2 of the optical fiber 10 of the second embodiment, a periodic refractive index changing structure in the fiber axis direction, that is, a portion 36 having a high refractive index is provided.
The optical fiber 10 is provided with a structure in which the lower portions 35 and the lower portions 35 are alternately and periodically arranged. That is, the optical fiber 10 of the second embodiment is a fiber grating. Therefore, in the optical fiber 10 of this embodiment, the function of the fiber grating is added to the function of the optical fiber 10 of the second embodiment. The period of the fiber grating may be about the same as the wavelength of the incident light, or may be about two orders of magnitude longer than the wavelength. As a manufacturing method, after manufacturing the optical fiber 10 of the second embodiment, ultraviolet rays may be applied to the optical fiber 10 perpendicularly to the fiber axis direction through a mask having a grating pattern to manufacture the grating. Tellurite glass has a large degree of change in the refractive index only by irradiation with ultraviolet rays without being subjected to hydrogen treatment or the like, and a fiber grating can be easily manufactured.

The above embodiments are examples, and the present invention is not limited to these examples. The material forming the filling section 102 or the functional optical path 2 may be non-quartz glass other than tellurite glass. Also, this material is DAS
An organic substance having nonlinear optical characteristics such as T may be used. In the first embodiment, all the filling portions 102 may be filled with one kind of material, or may be filled with two or more kinds of materials. Further, the concentration of a certain substance in the material may be gradually changed. In the second embodiment, when the molten tellurite glass 25 is introduced into the pores 6, the melting device 24
Er may be added to the inside so that the Er concentration in the functional optical path 2 changes in the longitudinal direction of the fiber. Further, the material composition of the functional optical path 2 may be locally changed in the longitudinal direction of the fiber. In this case, the group velocity variable optical fiber 1 whose velocity changes depending on the wavelength of light.
It becomes 0. The shape of the pores 6 need not be a cylinder, but may be a polygonal column or an elliptic column.

In the manufacturing method of the second embodiment, the method of forming the pores 6 may be a method of forming a large number of holes in the axial direction in the cylindrical preform of quartz glass and drawing the wire. Further, the coating layer may be a metal coating obtained by immersing the optical fiber intermediate body 12 in a molten metal (for example, Al) during drawing. Further, the method of introducing the non-quartz glass or the organic substance having nonlinear optical characteristics into the pores 6 may be a method of applying pressure in the thermostat 21, or a combination of pressurization in the thermostat 21 and suction by the suction device 22. But it's okay.

In Embodiments 2 to 7, the minimum lattice unit of the two-dimensional periodic structure may be a parallelogram or the like, and may have different periods or defects locally or in a specific direction. In the fifth embodiment, the optical fiber 10 may have three or more types of functional optical paths 2 having different refractive indexes, and their distribution is not particularly limited.

[0068]

The present invention is carried out in the form as described above, and has the following effects.

Since the quartz glass and at least one of the non-quartz glass and the organic material having the non-linear optical characteristic are alternately arranged at a period of 10 to 10 ⁵ nm, a photonic crystal is formed, Its optical properties can be modified by the dielectric constant of non-quartz glass or organics. Further, various optical functions such as wide band optical amplification and high Raman gain possessed by non-quartz glass and organic substances can be exhibited.

Quartz glass and air layer are 10 to 10 ⁵ nm
Since the optical elements are manufactured by alternately arranging them in a cycle of, and introducing at least one of non-quartz glass and an organic substance having nonlinear optical characteristics into the air layer, the optical elements can be easily manufactured, and they are introduced later. It is possible to freely select the non-quartz glass or organic substance to be used, and it is possible to manufacture various kinds of optical elements in a short time and at low cost.

An optical fiber mainly made of silica glass has a large number of functional optical paths extending in the axial direction of the fiber and made of non-silica glass and an organic material having nonlinear optical characteristics. 10
Since it has a two-dimensional periodic structure of -10 ⁵ nm, the optical fiber functions as a photonic crystal having the same strength as that of the silica glass fiber, and the broadband optical amplification and high Raman gain of non-silica glass and organic substances. It is also possible to exert various optical functions such as. Further, it can be easily joined to a normal quartz optical fiber, and the rate of change in volume is small and stable with respect to temperature changes.

The functional optical paths of the optical fiber are arranged at different periods in two directions orthogonal to each other in the cross section of the fiber, or the functional optical paths of different materials are arranged so that the refractive index distributions are different in the two directions orthogonal to each other. Therefore, it also functions as a polarization maintaining optical fiber.

Molten non-quartz glass or an organic substance having nonlinear optical characteristics is introduced into a large number of pores extending in the axial direction of the fiber by utilizing a pressure difference, so that an optical fiber can be easily manufactured and If an optical fiber intermediate having a large number of pores is manufactured in advance, various types of optical fibers having functional optical paths having different material compositions can be manufactured at low cost in a short time.

[Brief description of drawings]

FIG. 1 is a perspective view of an optical element according to a first embodiment.

FIG. 2 is a cross-sectional view showing a part of a cross section of an optical fiber according to a second embodiment.

FIG. 3 is a cross-sectional view showing a part of a cross section of an optical fiber preform according to a second embodiment.

FIG. 4 is a cross-sectional view showing a part of a cross section of an optical fiber intermediate body according to a second embodiment.

FIG. 5 is a schematic view of a device for introducing tellurite glass.

FIG. 6 is a cross-sectional view showing a part of a cross section of an optical fiber according to a third embodiment.

FIG. 7 is a cross-sectional view showing a part of a cross section of an optical fiber according to a fourth embodiment.

FIG. 8 is a cross-sectional view showing a part of a cross section of an optical fiber according to a fifth embodiment.

FIG. 9 is a cross-sectional view showing a part of a cross section of an optical fiber according to a sixth embodiment.

FIG. 10 is a sectional view showing a part of a vertical section of an optical fiber according to a seventh embodiment.

[Explanation of symbols]

2,2a Functional optical path 6 pores 10 optical fibers 31-34 Functional optical path 100 optical elements

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tetsuya Yamamoto             4-3 Ikejiri, Itami City, Hyogo Prefecture Mitsubishi Electric Cable             Industrial Co., Ltd. Itami Works (72) Inventor Shinya Yamatori             4-3 Ikejiri, Itami City, Hyogo Prefecture Mitsubishi Electric Cable             Industrial Co., Ltd. Itami Works (72) Inventor Takayuki Komatsu             16-9 Minaminanakamachi, Nagaoka City, Niigata Prefecture (72) Inventor Takumi Fujiwara             2-7-7 Aobadai, Nagaoka City, Niigata Prefecture (72) Inventor Yasuhiko Kono             20-4 Minaminanakamachi, Nagaoka City, Niigata Prefecture F-term (reference) 2H047 KA02 PA01                 2H049 AA03 AA33 AA37 AA44 AA45                       AA59 AA62                 2H050 AA01 AB03 AC01                 4G021 HA01 HA05 LA02

Claims (10)

[Claims] 1. In at least one direction, quartz glass and at least one of glass containing a substance other than quartz as a main component and an organic substance having nonlinear optical characteristics are 10 to 10.
An optical element characterized by being arranged alternately at a cycle of 10 ⁵ nm. 2. A step of alternately arranging silica glass and an air layer in at least one direction at a period of 10 to 10 ⁵ nm, and glass and a non-linear optics containing a substance other than quartz as a main component in the air layer. And a step of introducing at least one of organic substances having characteristics. 3. An optical fiber whose main constituent material is silica glass, which is internally composed of at least one of glass extending in the fiber axis direction and containing a substance other than silica as a main component and an organic substance having nonlinear optical characteristics. It is provided with a large number of functional optical paths, and the functional optical paths are 10 to 10 in a fiber cross section.
An optical fiber, which is arranged so as to have a two-dimensional periodic structure of ⁵ nm. 4. The functional optical path according to claim 3, wherein the functional optical paths are orthogonal to each other in a cross section of the fiber.
An optical fiber characterized by being arranged in different directions with different periods. 5. The functional optical path according to claim 3, wherein a plurality of types of constituent materials different from each other are present, and the functional optical paths are arranged so that refractive index distributions are different in two directions orthogonal to each other in a fiber cross section. An optical fiber characterized in that 6. The optical fiber according to claim 3, wherein the composition of the substance forming the functional optical path changes in the longitudinal direction of the fiber. 7. The optical fiber according to claim 3, wherein the functional optical path has a refractive index changing structure that is periodic in the fiber axis direction. 8. The optical fiber according to claim 3, further comprising a coating layer that covers the entire circumference and has heat resistance equal to or higher than the melting point of the constituent material of the functional optical path. 9. An optical fiber preform made of quartz glass,
A step of drawing while forming a large number of fine pores extending in the fiber axis direction, and glass having a substance other than quartz in a molten state as a main component or an organic substance having nonlinear optical characteristics is used for the fine pores by using a pressure difference. And a step of forming a functional optical path to be introduced as a method of manufacturing an optical fiber. 10. The functional optical path forming step according to claim 9, wherein a plurality of the plurality of pores are selectively sealed and the remaining pores are filled with a substance other than fused quartz. A step of introducing glass as the main component or an organic substance having nonlinear optical characteristics by using a pressure difference, and releasing the sealing, and then opening the unsealed pores of a type different from that introduced above. A method of manufacturing an optical fiber, comprising the step of introducing a glass containing a substance other than quartz in a molten state as a main component or an organic substance having nonlinear optical characteristics by using a pressure difference.