JP2002228868A - Manufacturing method of photonic crystal waveguide - Google Patents

Abstract

(57) [Abstract] [Problem] Even when mass-producing waveguides having the same structure,
Provided is a method for manufacturing a photonic crystal waveguide having a low manufacturing cost and a small variation in characteristics of each waveguide. A plurality of solid first rod members (2, 2,...) And a plurality of second rod members (3, 3,...) Having inner and outer portions having different refractive indices are prepared. , And a plurality of second rod members 3,
Are formed on the bundle end face by the first rod members 2, 2,... And the second rod members 3, 3,.
After bundling the rod material bundle 4 so as to form a predetermined lattice pattern by the inner portion of the rod material, the rod material bundle 4 is thinned by heating and stretching to produce a fibrous body, and the fibrous body is formed. A photonic crystal waveguide is manufactured by slicing to a predetermined thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a photonic crystal waveguide (hereinafter referred to as "PC (photonic crystal) waveguide").

[0002]

2. Description of the Related Art As shown in FIG. 9A, a PC waveguide is formed by regularly arranging a large number of dielectric pillars b on a substrate a as shown in FIG. A region having a photonic crystal structure in which a refractive index periodically changes in two dimensions formed by regularly arranging a large number of air rods d, d,. Having an optical waveguide region formed by a defect array surrounded by the structural region, and propagating and outputting only those having a wavelength confined by the photonic crystal structure region among the light incident on the optical waveguide region, It is known as a device that enables sharp bending of light.

For example, a PC waveguide of the air rod type shown in FIG. 9B is surrounded by a region having a photonic crystal structure constituted by an air rod as shown in FIG. 10A or 10B. Formed T-branch or Y
A device for splitting light having a branch type optical waveguide region into two, a coupler having an X-shaped optical waveguide region as shown in FIGS. 10 (c) and (d), and FIGS. 10 (e) and (f). And the like.

The function of such a PC waveguide depends on its photonic crystal structure. For example, as shown in FIG. 11 (a), the PC waveguide has a structure in which air rods are arranged so as to form a square lattice. Thing, FIG. 11 (b)
As shown in FIG. 11, there is a structure in which air rods are arranged so as to form a triangular lattice, and as shown in FIG. 11C, a structure in which air rods are arranged so as to form a honeycomb lattice.

The air rod type P
The C waveguide has a quartz (SiO ₂ ) layer f provided on a substrate e as shown in FIG.
Is applied, and after exposure to an electron beam in a periodic pattern as shown in FIG. 12B, development is performed as shown in FIG. 12C (electron beam lithography), and FIG.
As shown in the figure, quartz (Si
Are formed by forming air rods h, h,... On exposed portions of the O ₂ ) layer f, and finally removing the resist g as shown in FIG.

However, in this method, it is difficult to process an air rod having a diameter of submicron with high precision. For example, if the diameter of the air rod differs between the upper part and the lower part, the photonic crystal structure may have a predetermined shape. It does not fulfill the function of.

On the other hand, Japanese Patent Application Laid-Open No. 11-218627 discloses a method for manufacturing a PC waveguide in which a slab optical waveguide comprising a lower clad layer, a core layer and an upper clad layer is formed on a substrate, and then an electron beam is formed. , SOR (synchrot
(ron orbital radiation) Selectively irradiate the core layer with any one of light, ultraviolet light and near-infrared light through the upper cladding layer, and change the refractive index by the photo-induced effect to form a high-refractive region in a lattice array. A photonic crystal structure is disclosed in which a refractive index change region (photonic crystal structure region) having high precision dimensions and uniform dimensions of each part in the depth direction is manufactured. It is described that it is possible.

[0008]

However, in any of the above-described methods for manufacturing a PC waveguide, manufacturing is performed for each PC waveguide. Therefore, when mass-producing PC waveguides having the same structure, the manufacturing cost increases. In addition, there is a problem that the characteristics of the PC waveguides tend to vary.

SUMMARY OF THE INVENTION The present invention has been made in view of the foregoing, and has as its object to reduce the manufacturing cost and reduce the PC cost even when mass-producing a PC waveguide having the same structure.
It is an object of the present invention to provide a method of manufacturing a PC waveguide in which variations in characteristics of each waveguide are small.

[0010]

According to the present invention, a plurality of solid first rod members and a plurality of second rod members each having an inner portion and an outer portion having mutually different refractive indices are prepared and provided on the bundle end surface. After a first rod material and a second rod material are bundled to form a predetermined waveguide pattern by the first rod material and a predetermined lattice pattern by an inner portion of the second rod material, to produce a rod material bundle The rod bundle is made thin by wire drawing to produce a fibrous body, and the fibrous body is sliced to a predetermined thickness to produce a PC waveguide.

Specifically, the present invention is a method of manufacturing a PC waveguide, comprising: a first solid rod material; a second rod material having inner and outer portions having different refractive indices from each other; A plurality of the first rod members and a plurality of the second rod members are formed by forming a predetermined waveguide pattern on the bundle end surface with the first rod members, and After bundling a rod material bundle by forming a predetermined lattice pattern by the inner portion, the rod material bundle is reduced in diameter by heating and stretching to produce a fibrous body, and the fibrous body is formed to a predetermined thickness. A photonic crystal waveguide is manufactured by slicing the substrate.

According to the above configuration, the first rod member and the second rod member
The rod material bundle constituted by the rod material is heated and drawn to form a fibrous body, and the fibrous body is several μm
The PC waveguide is manufactured by slicing to a thickness of 〜 to several tens of μm. If the fibrous body has a length of 1 m, it is possible to obtain a large number of PC waveguides having the same structure in the number of thousands to tens of thousands. As a result, the productivity is improved and the manufacturing cost is extremely reduced as compared with the case where each PC waveguide is manufactured. Moreover, similar to an optical fiber obtained by drawing a preform, the difference in structure of a fibrous body obtained by heating and drawing is extremely small in units of several meters. The variation in the characteristics of each PC waveguide is extremely small.

Here, as a configuration of the second rod material, quartz (SiO ₂ ) to which germanium (Ge) which is a component for increasing the refractive index is added to one of the inner portion and the outer portion.
And a rod material made of pure (SiO ₂ ), and one of the inner part and the outer part added with fluorine (F) or boron (B) which is a component for lowering the refractive index. rod material formed by formed by (SiO ₂₎ and the other is pure silica (SiO _2), one of the inner portion and the outer portion is formed with a germanium (Ge) silica was added (SiO ₂₎ and The other is a rod material formed of quartz (SiO ₂ ) to which fluorine (F) or boron (B) is added, and the outer portion is quartz (SiO ₂ ) to which germanium (Ge) is added, or fluorine (F) or boron (B). ) Is added to quartz (SiO ₂ ) or pure quartz (SiO ₂ ). If you have The present invention is not limited to. Further, the refractive index of the first rod material and the respective refractive indexes of the inner portion and the outer portion of the second rod material are independent, and the three members may have mutually different refractive indexes. The inner part or the outer part of the first rod material and the second rod material may have the same refractive index. Further, the outer shape of the cross section of the inner portion of the second rod member is not particularly limited, such as a circle or an ellipse.

The waveguide pattern is not particularly limited, and may be a Y-branch type, a T-branch type, or the like.

The lattice pattern is not particularly limited as long as it constitutes a photonic crystal structure after drawing, and examples thereof include a triangular lattice, a cubic lattice, and a honeycomb lattice.

Further, the first rod material and the second rod material may be filled in a cylindrical support pipe to form a rod material bundle. According to such a configuration, since both rod members are constrained by the support tube, the movement of each rod member is restricted, and the heat stretching process is facilitated.

[0017]

As described above, according to the present invention,
The rod material bundle constituted by the first rod material and the second rod material is heated and stretched to form a fibrous body, and the fibrous body is sliced to a thickness of several μm to several tens μm to obtain a PC. When a fibrous body is 1 m long, a large number of thousands to tens of thousands of Ps having the same structure are produced.
Since a C waveguide can be obtained, the productivity can be improved and the manufacturing cost can be extremely reduced as compared with the case where each PC waveguide is manufactured. In addition, since the difference in the structure of the fibrous body obtained by the heat drawing process is extremely small in units of several meters, it is possible to minimize the variation in the characteristics of each PC waveguide obtained by slicing the same fibrous body. it can.

[0018]

(Embodiment 1) Hereinafter, a method for manufacturing a PC waveguide according to Embodiment 1 of the present invention will be described step by step.

[0019] <Preparation Step> quartz and one of (SiO ₂₎ made of a cylindrical support tube, quartz (SiO ₂₎ made cylindrical and a plurality of the solid rod (first rod member) in a quartz ( SiO
₂ ) Prepare a plurality of cylindrical capillaries (second rod material). Here, the capillary and the solid rod have the same outer diameter. Further, the capillary has a structure in which the outer portion is formed of quartz (SiO ₂ ) and has a relatively high refractive index, and the inner portion is formed as a hole and has a relatively low refractive index.

<Rod bundle forming step> As shown in FIG.
The solid rods 2, 2,... And the capillaries 3, 3,. At this time, the solid rods 2, 2,... Form a Y-branch type waveguide pattern at the bundle end face, and the holes of the capillaries 3, 3,. . The gaps formed between the solid rods 2, 2,... And the capillaries 3, 3,... Located in the outermost layer and the inner wall of the support tube 1 are filled with a filler such as SiO ₂ powder. Make sure that no misalignment occurs.

<Heating Stretching Step> The rod material bundle 4 is stretched by heating to produce a fibrous body 5 having a fibrous diameter. At this time, the adjacent solid rods 2, the capillaries 3, the solid rods 2 and the capillaries 3, the outermost solid rods 2 and the capillaries 3 and the support tube 1 are fused and integrated with each other. Become. As shown in FIG.
Are made into a Y-branched solid portion 6a formed by solid rods 2, 2,... And a large number of pores 6b formed by capillaries 3, 3,. , 6b,... And a covering portion 7 covering the waveguide forming portion 6 formed by the support tube 1.

<Slicing Step> As shown in FIG. 3, the fibrous body 5 is processed into a prismatic shape by using a precision processing cutter or the like, and then sliced to a thickness of several μm to several tens μm and guided. The waveguide main body 8 is manufactured. Then, the sliced waveguide main body 8 is washed with a solvent (ethanol, acetone, dichloromethane, or the like) to remove cutting chips. At this time, ultrasonic cleaning may be performed instead of or in addition to cleaning with a solvent. The waveguide body 8 manufactured in this manner includes an optical waveguide region 9 formed in a Y-branch type defect row corresponding to the solid portion 6a of the fibrous body 6,
Air rods 10a, 1 corresponding to the pores 6b of the fibrous body 6
Are arranged so as to form a triangular lattice, and a photonic crystal structure region 10 in which the refractive index periodically fluctuates two-dimensionally.

<Upper and Lower Cladding Arrangement Steps> As shown in FIG. 4, the waveguide body 8 is made of quartz (SiO.sub.2) to which fluorine (F) or boron (B), which is a component for lowering the refractive index, is added. ₂ ) PC waveguide 1 as a device for splitting Y-branch type light into two by being integrated by being sandwiched between upper clad 11 and lower clad 12 formed of plates.
3 are configured. At this time, the waveguide main body 8 and each of the upper clad 11 and the lower clad 12 may be integrated using an adhesive. The adhesive is made of quartz (SiO ₂ ) or the upper clad 1 forming the waveguide body 8.
1 and the lower clad 12 preferably have a refractive index similar to that of quartz (SiO ₂ ) to which fluorine (F) or boron (B) is added. For example, a commercially available ultraviolet-curable resin adhesive is preferably used. Can be used.

According to the method of manufacturing the PC waveguide 13 having the above structure, the rod material bundle 4 composed of the solid rods 2, 2,... And the capillaries 3, 3,. The PC waveguide 13 is manufactured from the waveguide main body 8 which is sliced into a thickness of several μm to several tens μm after processing the fibrous body 5 into a prismatic shape as the body 5,
If the length of the fibrous body 5 is 1 m, it is possible to obtain a large number of PC waveguides 13 having the same structure of several thousand to several tens of thousands, so that the productivity is better as compared with the case where each PC waveguide is manufactured. And the production cost becomes extremely low. Moreover,
Similar to the optical fiber obtained by drawing the preform, the difference in the structure of the fibrous body 5 obtained by heating and drawing is extremely small in units of several meters. The variation in the characteristics of each PC waveguide 13 is extremely small.

Since the solid rods 2, 2,... And the capillaries 3, 3,... Are filled into the cylindrical support tube 1, the rod material bundle 4 is formed.
3 is restrained by the support tube 1, the movement of each of the rod members 2, 3 is regulated, and the heating and stretching process is facilitated.

In the first embodiment, the solid rod 2
Is used to form a Y-branch type waveguide pattern. However, the present invention is not limited to this.
It may be one in which a U-shaped waveguide pattern is formed.

In the first embodiment, the capillaries 3, 3,...
The PC waveguide 13 in which 0a, 10a,... Are arranged so as to form a triangular lattice is manufactured, but the present invention is not particularly limited to this. Or a honeycomb lattice may be arranged. In this case, since the square lattice pattern and the honeycomb lattice pattern are not formed by the closest packing of the capillaries, the shape of the lattice pattern can be maintained by filling a filler such as a quartz rod between the capillaries.

In the first embodiment, the capillary 3 is used as the second rod material having the inner portion and the outer portion having different refractive indexes. However, the present invention is not limited to this, and the outer portion may be made of germanium. (Ge) silica was added (SiO ₂₎ or fluorine (F) or boron (B) quartz added with capillary and the inner portion is formed by (SiO ₂₎ is formed in the pores, of the inner portion and the outer portion Either one is made of quartz (SiO ₂ ) to which germanium (Ge) which is a component for increasing the refractive index is added, and the other is pure (S
The rod material formed of iO ₂ ), and one of the inner and outer portions is formed of quartz (SiO ₂ ) to which fluorine (F) or boron (B) which is a component for lowering the refractive index is added, and pure silica rod material formed by (SiO _2), one is formed by a germanium (Ge) silica was added (SiO ₂₎ and the other is fluorine (F) or boron inner portion and the outer portion ( A rod material made of quartz (SiO ₂ ) to which B) is added may be used.

In the first embodiment, the solid rod 2
Pure silica has been a (SiO ₂₎ made of things, a component that raises the refractive index of germanium (Ge) silica was added fluorine is a component lowering the (SiO ₂₎ made of one or refractive index (F) Or boron (B) -added quartz (Si
O ₂ ).

In the first embodiment, the fibrous body 5 is processed into a prism and then sliced to produce the waveguide body 8. However, the present invention is not limited to this.
As shown in FIG. 5, first, the fibrous body 5 may be sliced to form a disc-shaped body 14, and the rectangular plate-shaped waveguide body 8 may be cut out from the center. However, Embodiment 1
The method indicated by is preferred because the productivity becomes better.

In the first embodiment, the waveguide body 8
Are sandwiched between the upper and lower claddings 11 and 12 to improve the handleability of the PC waveguide 13 and are not an essential component of the PC waveguide.

(Embodiment 2) Waveguide bodies having various waveguide patterns as shown in FIGS. 10A to 10F are manufactured by the same manufacturing method as in Embodiment 1.

Then, as shown in FIG. 6, each waveguide main body 8 is made into one unit, and is placed on a lower substrate 15 made of a quartz (SiO ₂ ) plate to which fluorine (F) or boron (B) is added. Waveguide bodies 8, 8, having a predetermined waveguide pattern
Are arranged in combination, and the upper substrate is covered from above to form a large-sized PC waveguide in which the waveguide patterns of the respective waveguide main bodies 8 are connected. At this time, as shown in FIG. 7, an optical waveguide region 9 such as a corner of the waveguide main body 8 is formed.
The waveguide main bodies 8, 8 adjacent to each other are arranged on the basis of alignment markers 16, 16 provided at places where optical influence is not exerted on the optical waveguides to prevent their positional deviation. The marker 16 may be made of colored glass, air holes (voids), quartz columns, or the like.
In the case of the waveguide main body 8 in which the photonic crystal structure region is formed by the air rod, the air rod or the optical waveguide region can be the marker 16. Further, instead of the marker, similarly to the power monitoring method at the time of fusion splicing an optical fiber, light is made to enter from the waveguide end of one waveguide main body 8 and the light is incident at the waveguide end of the other waveguide main body. Positioning may be performed so that the intensity of the emitted light is maximized. In addition, each waveguide main body 8 and each of the upper substrate and the lower substrate 15 are bonded and integrated in the same manner as in the first embodiment.

(Embodiment 3) A plurality of waveguide bodies of the same type or different types are manufactured by the same manufacturing method as in the first embodiment.

Then, as shown in FIG. 8, a three-dimensional PC waveguide 13 is formed by laminating the plurality of waveguide bodies 8, 8,. The waveguide bodies 8 are bonded and integrated by the same method as in the first embodiment.

[Brief description of the drawings]

FIG. 1 is a front view of a bundle end surface of a rod material bundle.

FIG. 2 is a front view of a fiber end face of the fibrous body.

FIG. 3 is an explanatory diagram of a slicing step.

FIG. 4 is a perspective view of the photonic crystal waveguide manufactured in the first embodiment.

FIG. 5 is an explanatory diagram of a slicing step according to another embodiment.

FIG. 6 is an explanatory diagram of the method for manufacturing the photonic crystal waveguide according to the second embodiment.

FIG. 7 is a top view of the photonic crystal waveguide.

FIG. 8 is an explanatory diagram of the method for manufacturing the photonic crystal waveguide according to the third embodiment.

FIG. 9 is a perspective view of a photonic crystal structure.

FIG. 10 is an explanatory diagram showing an example of a waveguide pattern of a PC waveguide.

FIG. 11 is an explanatory diagram showing an example of a photonic crystal structure of a PC waveguide.

FIG. 12 is an explanatory view showing a conventional method for manufacturing a PC waveguide.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Support pipe 2 Solid rod 3 Capillary 4 Rod bundle 5 Fibrous body 6 Waveguide formation part 6a Solid part 6b Pores 7 Coating part 8 Disc body 8 Waveguide body 9 Optical waveguide area 10 Photonic crystal structure area 10a Air rod 11 Upper clad 12 Lower clad 13 PC waveguide 14 Disc-shaped body 15 Lower substrate 16 Marker a Substrate b Dielectric pillar c Glass plate d Air rod e Substrate f Quartz layer g Resist h Air rod

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tetsuya Yamamoto 4-3 Ikejiri, Itami-shi, Hyogo Mitsubishi Cable Industry Co., Ltd. Itami Works (72) Inventor Moriyuki Fujita 4-3 Ikejiri, Itami-shi, Hyogo Mitsubishi Cable Industries Inside the Itami Works (72) Inventor Masataka Nakazawa 2-3-1 Otemachi, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Hirokazu Kubota 2-3-1 Otemachi, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Inventor Satoru Kawanishi 2-3-1 Otemachi, Chiyoda-ku, Tokyo F-Term (in reference) 2H047 KA03 LA12 PA00 PA24 PA26 QA04 TA41

Claims (3)

[Claims] 1. A plurality of solid first rod members and a plurality of second rod members each having an inner portion and an outer portion having mutually different refractive indices are prepared. A rod material bundle is formed by bundling a plurality of second rod materials such that a predetermined waveguide pattern is formed by the first rod material on the bundle end surface and a predetermined lattice pattern is formed by an inner portion of the second rod material. After manufacturing, the rod material bundle is reduced in diameter by heating and stretching to produce a fibrous body, and the fibrous body is sliced to a predetermined thickness to produce a photonic crystal waveguide. A method for manufacturing a photonic crystal waveguide. 2. The method for manufacturing a photonic crystal waveguide according to claim 1, wherein the second rod material is a capillary. 3. The photonic crystal waveguide according to claim 1, wherein the first rod material and the second rod material are filled in a cylindrical support pipe to form the rod material bundle. Manufacturing method.