JP2003043273A - Photonic crystal waveguide and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact photonic crystal waveguide which is small and low in loss and to provide a method for manufacturing the waveguide. SOLUTION: The refractive index of a region 5 which is not irradiated with a ultraviolet laser beam spot becomes relatively higher an a waveguide is formed by forming a lowered refractive index region 4 in a matrix pattern by making a part, which is not made into an optical path of a polymer layer for photo bleaching, directly irradiated with a lot of ultraviolet laser beam spots with prescribed spaces S1 and S2, thus a compact waveguide having low loss is obtained without using a conventional photolithography or a etching process.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a photonic crystal waveguide and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, research using photonic crystals has been actively conducted as a technique for realizing a micro optical circuit. Photonic crystals are said to be artificial materials that have unique optical properties, such that they do not allow light of a certain wavelength to pass through at all, or the refractive index of light changes significantly with a slight change in wavelength.

13 (a) to 13 (f) are external perspective views of the photonic crystal.

FIG. 13A shows an air gap type structure, which is formed by wet etching.
Indicates a deep diffraction grating structure and is formed by dry etching. Both FIGS. 13A and 13B are one-dimensional photonic crystals. FIG. 13C shows a vertical hole type structure,
It is formed by dry etching anodization and is shown in FIG.
(D) shows a pillar structure, which is formed by dry etching selective growth. Both (c) and (d) of FIG. 13 are two-dimensional photonic crystals. FIG. 13E shows an oblique hole type structure, which is formed by dry etching.
(F) shows a building block structure, which is formed by pasting. Both (e) and (f) of FIG. 13 are three-dimensional photonic crystals. The arrow in the figure indicates the traveling direction of light.

Among these photonic crystals, FIG.
The two-dimensional photonic crystal shown in (c) and (d) is typically one in which holes or columns are formed on a substrate. FIG.
The three-dimensional photonic crystals shown in (e) and (f) have a three-dimensional mosaic structure, and there are a stack of rectangular crystals and a stack of small spheres. That is,
When the difference in refractive index between the two types of media is large and the periodic structure satisfies certain conditions, light of a specific wavelength cannot be transmitted at all, and light from the outside cannot enter the crystal and is reflected. This range of wavelength is called the photonic bandgap.

FIG. 14 is an external view showing another conventional example of a photonic crystal.

This is because a plurality of refractive index changing regions 52 are formed in a plane direction at a predetermined interval in a quartz glass film 51 formed on a Si substrate 50, and the refractive index changing regions are formed in the refractive index changing regions. Area where the area 52 does not exist (hereinafter referred to as “absent area”)
Say. ) 53, the optical fiber 54-
The optical signal 55-1 from 1 is passed from one end face (lower side in the figure) of the lack region 53 through the lack region 53 and the optical signal 55-2 from the other end face (upper side in the diagram) through the optical fiber 54-2. It is a photonic crystal waveguide that is taken out.

On the other hand, with the progress of optical interconnection technology, a method of parallel optical transmission between devices by means of fiber has entered a practical stage. As a next-generation system, in-board or LS
A method for parallel transmission of optical signals between I-chips has been studied in earnest. In order to realize this parallel transmission method, it is necessary to use a waveguide as a transmission line instead of an optical fiber. As this waveguide, a polymer waveguide using a polymer material is considered to be promising.

Since a polymer waveguide using a polymer material can be easily manufactured by a low temperature process, it is superior to a waveguide using a glass material in terms of cost reduction and large size. It is believed to be promising. Such a polymer waveguide is formed by coating a polymer solution dissolved in an organic solvent on various substrates by a spin coating method, an extrusion coating method or the like, and then heating at a low temperature (≦ 300 ° C.) to form a polymer film. After obtaining a high-refractive-index polymer pattern for a core having a substantially rectangular cross-section using a photolithography or etching process, a low-refractive-index polymer film is formed so as to cover the core pattern.

Further, as a technique for patterning a photoresist film, a method has been developed in which an ultraviolet laser beam is directly irradiated onto the photoresist film without using a photomask to expose the photoresist film in a desired pattern. ing.

[0011]

However, the above-mentioned conventional optical circuit using the photonic crystal is still in the research stage, and there are many problems to be solved. In addition, polymer waveguides also have many problems for practical use. These issues are shown below.

(1) A structure capable of easily manufacturing a photonic crystal and a manufacturing method thereof have not been found yet.

(2) Also, a low-loss photonic crystal type optical circuit has not been found.

(3) As the top data of the loss of the polymer waveguide, 0.1 dB / cm has been reported so far, but this value still has a large loss as compared with the glass waveguide.
It is not an alternative candidate for glass waveguides. It is difficult to reduce the loss to 0.1 dB / cm or less by the conventional polymer waveguide structure and manufacturing method.

The first reason why it is difficult to reduce the loss is that scattering loss due to roughness of the side surface of the core is extremely large among the losses of the polymer waveguide. As a countermeasure against this, it is conceivable to apply a method of directly irradiating the photoresist film with an ultraviolet laser beam onto the photoresist film in a desired pattern without using a photomask for patterning the photoresist film. .

However, since the pattern must be used as a mask for etching after that, side surface roughness is inevitably caused by etching, and as a result, it is difficult to reduce the loss.

The second reason why it is difficult to reduce the loss is that there is an absorption loss depending on the absorption groups (CH group, OH group) peculiar to the polymer material. As a measure to reduce this absorption loss, attempts have been made to fluorinate or deuterate polymers, but there are problems such as deterioration of heat resistance and difficulty of film formation. Not obtained.

(4) Solder is used when hybrid mounting electronic parts, electronic circuits, optical parts, optical circuits, etc. on the front surface or the back surface of the waveguide, and further inside. However, at present, a waveguide using a polymer material, which can be expected to have a low loss characteristic (about 0.2 dB / cm) to some extent, has poor heat resistance, and the solder reflow temperature (Au / Sn solder reflow temperature:> 2
It is difficult to withstand 80 ° C), and when mounted and processed at a temperature of 280 ° C or higher, the refractive index of the polymer used for the waveguide will change, and the optical characteristics of the waveguide will change drastically. I can not do it.

On the contrary, a waveguide using a polymer material, which is expected to have heat resistance, has a problem in practical use because of large loss and polarization dependence.

Therefore, an object of the present invention is to solve the above problems and provide a small-sized and low-loss photonic crystal waveguide and a manufacturing method thereof.

[0021]

In order to achieve the above object, the photonic crystal waveguide of the present invention is provided with a low refractive index layer on a substrate, and a high refractive index is provided on the surface or inside of the low refractive index layer. Is provided with a polymer layer for photobleaching, and an ultraviolet laser beam having a wavelength in the vicinity of the absorption wavelength of the polymer layer is irradiated at a predetermined interval in the plane direction of the polymer layer to reduce the refractive index. A photonic crystal waveguide in which the index reduction region is formed in a matrix,
A part of the low-refractive-index area is missing, and the missing pattern formed by the missing area consists of straight lines, curved patterns, or a combination thereof in the plane direction of the polymer layer. It propagates along the inside of the polymer layer.

In addition to the above structure, the beam spot diameter of the ultraviolet laser beam used in the photonic crystal waveguide of the present invention is preferably 2 μm or less.

In addition to the above structure, the shape of the refractive index decreasing region of the photonic crystal waveguide of the present invention is preferably substantially circular.

In addition to the above structure, it is preferable that the refractive index decreasing region of the photonic crystal waveguide of the present invention has straight portions arranged in parallel at desired intervals.

In addition to the above structure, the wavelength of the ultraviolet laser used in the photonic crystal waveguide of the present invention is preferably in the range of 250 nm to 445 nm.

In addition to the above structure, it is preferable that a continuous wave laser or a pulse laser is used as the ultraviolet laser used in the photonic crystal waveguide of the present invention.

In addition to the above structure, the width of the non-irradiated region of the photonic crystal waveguide of the present invention which is not irradiated with the ultraviolet laser beam and the width of the refractive index lowered region are 0.1 μm or more and 4 μm or more.
It is preferably m or less.

In addition to the above constitution, the polymer layer for photobleaching of the high refractive index of the photonic crystal waveguide of the present invention has a polysilane compound, a polysilane compound added with a silicone compound, a silicone compound and a photo-acid generator,
Alternatively, a nitrone-added silicone compound or the like is preferably used.

In addition to the above structure, the refractive index lowering region of the photonic crystal waveguide of the present invention is formed in each of the photobleaching polymer layers laminated on at least two layers on the substrate, and 3 in the polymer layer. It is preferable that an optical path or an optical circuit for dimensionally propagating light is formed.

In addition to the above structure, the photonic crystal waveguide of the present invention is an ultrashort pulse obtained by shifting the absorption wavelength of the polymer layer to the long wavelength side on the surface or inside of the polymer layer which is not irradiated with the ultraviolet laser beam and becomes the light propagation layer. It is preferable that the laser beam is condensed and irradiated to increase the refractive index of the polymer layer.

In addition to the above structure, holes may be formed in the refractive index decreasing region of the photonic crystal waveguide of the present invention.

The method of manufacturing a photonic crystal waveguide of the present invention comprises a low refractive index layer forming step of forming a low refractive index layer on a substrate, and a high refractive index polymer for photobleaching on the low refractive index layer. Polymer layer forming step of forming a layer, low refractive index region formation by irradiating an ultraviolet laser beam on both sides of the light propagation region so as to secure a light propagation region of a desired width from above the polymer layer, and forming a low refractive index region The process consists of:

The method of manufacturing a photonic crystal waveguide of the present invention comprises a low refractive index layer forming step of forming a low refractive index layer on a substrate, and a high refractive index polymer layer for photobleaching on the low refractive index layer. Forming a polymer layer, a low-refractive-index region forming step of irradiating an ultraviolet laser beam on both sides of the light-propagating region so as to secure a light-propagating region of a desired width from above the polymer layer to form a low-refractive-index region An upper clad layer forming step of forming a lower refractive index upper clad layer on the polymer layer,
It consists of

The method of manufacturing a photonic crystal waveguide according to the present invention comprises a low refractive index layer forming step of forming a low refractive index layer on a substrate, and a high refractive index polymer layer for photobleaching on the low refractive index layer. Forming a polymer layer, forming an upper clad layer having a low refractive index on the polymer layer, forming an upper clad layer on both sides of the light propagating region so as to secure a light propagating region of a desired width from above the polymer layer. A low-refractive-index region forming step of irradiating an ultraviolet laser beam onto the low-refractive-index region
It consists of

In addition to the above structure, in the method of manufacturing the photonic crystal waveguide of the present invention, it is preferable that the low refractive index region is formed by scanning the laser beam at least once.

In addition to the above structure, in the method of manufacturing a photonic crystal waveguide of the present invention, a straight line pattern, a curved line pattern, and a combination pattern of the regions not irradiated with the ultraviolet laser beam are formed on the substrate or the laser beam. It may be formed by relative movement of either one.

In addition to the above-mentioned constitution, in the method for producing a photonic crystal waveguide of the present invention, a polysilane compound, a polysilane compound and a silicone compound, or a silicone compound and a photo-acid generator are used in the high refractive index polymer layer for photobleaching. It is preferable to use the added one, the nitrone-added silicone compound, or the like.

In addition to the above structure, in the method of manufacturing the photonic crystal waveguide of the present invention, at least two layers of the laser direct writing waveguide may be laminated on the substrate.

In addition to the above structure, in the method of manufacturing the photonic crystal waveguide of the present invention, a hole may be formed in a region where the refractive index is lowered by irradiating an ultraviolet laser beam having a desired diameter.

According to the present invention, a large number of ultraviolet laser beam spots in the vicinity of the absorption wavelength of the polymer layer (including a wavelength equal to the absorption wavelength) are directly irradiated to a portion of the polymer layer for photobleaching which is not used as an optical path at predetermined intervals. As a result, the regions where the ultraviolet laser beam spot is not irradiated have a relatively high refractive index and the waveguides are formed by forming the regions in which the refractive index is lowered in a matrix shape. A small-sized and low-loss waveguide can be formed without using.

If, for example, a polysilane compound is used as the photobleaching polymer layer, the polymer layer is irradiated with a deep UV ultraviolet laser beam having a wavelength of 266 nm, whereby the refractive index after irradiation is changed with respect to the refractive index before irradiation. Can be reduced by about 8% at the maximum in the relative refractive index difference. As the ultraviolet laser, the third harmonic (wavelength 266 nm) of an ultrashort pulse laser oscillating at a wavelength of 800 nm is used, and the pulse width is set to 1000 fs or less,
Since extremely large energy can be obtained within the pulse width, it is possible to form holes in the refractive index lowering region formed in a matrix in the plane direction at a predetermined interval, and to realize a larger refractive index changing structure. Therefore, it becomes possible to realize an even smaller photonic crystal waveguide. The control of punching can be performed by the average output value of the laser beam, the pulse width, the repetition frequency, the moving speed of the substrate, and the like.

Since the ultraviolet laser beam can be narrowed down to 2 μm or less, the photonic band gap structure is formed by arranging minute regions having a low refractive index by irradiation of the ultraviolet laser beam in a matrix at a predetermined interval. It is possible to realize a photonic crystal waveguide in which a pattern in which a minute region is missing is provided in a band-shaped band-like structure and an optical signal is propagated in the pattern. Moreover, the wavelength of the polysilane compound film is 1.3 μm,
At 1.55 μm, the propagation loss is as low as 0.1 dB / cm or less, so that a low-loss photonic crystal waveguide can be realized.

As described above, a photonic crystal waveguide is formed by directly irradiating a photobleaching polymer layer with an ultraviolet laser beam to draw a desired pattern without using photolithography and etching processes. Since the photonic crystal waveguide is manufactured, it is possible to manufacture a photonic crystal waveguide with extremely small scattering loss depending on the structural nonuniformity.

Furthermore, three-dimensional CAD (Computer Aided Des
ign), it is possible to form a three-dimensional optical circuit in the laminated polymer layer made of a polysilane compound.

Further, from the viewpoint of the manufacturing method, it is a very simple manufacturing method in which a polymer solution is applied by a spin coating method and a polymer layer is formed by heating, and cost reduction can be expected.

For the polymer layer for photobleaching, a polysilane compound, a polysilane compound and a silicone compound,
Alternatively, a silicone compound and a photoacid generator may be used. In the photonic crystal waveguide having a holed structure, the waveguide is subjected to a heat treatment at a temperature higher than 300 ° C. to promote the mineralization, whereby absorption groups (CH group, OH group) unique to the polymer material are obtained. It is possible to reduce the absorption loss depending on. Also Au / Sn
Solder reflow temperature (Au / Sn solder reflow temperature:>
Since it can withstand 280 ° C.), it becomes possible to hybridly mount an electronic component, an electronic circuit, an optical component, an optical circuit, etc. on the front surface or the back surface of the waveguide, and further inside.

Further, if a pulsed laser beam is used as the ultraviolet laser beam as described above, the refractive index of the polymer layer can be lowered with a low average output laser beam power without being thermally damaged by the irradiated polymer layer. You can In addition, since the ultraviolet laser beam is pulsed compared to a continuous wave, it has a high light intensity momentarily but a low average intensity, so even for a thick polymer layer in a short time, the refractive index in the depth direction is increased. The changes can be made uniform. That is, it becomes possible to realize a waveguide in a short time. The degree of change in the refractive index in the depth direction can be controlled by adjusting the power of the laser beam and the moving speed of the workpiece (or either the laser beam). Further, the same region may be irradiated with the laser beam a plurality of times.

Further, by adjusting the beam spot diameter of the laser beam, the width of the region where the refractive index is lowered and the width of the light propagation region can be controlled.

Further, the wavelength of the ultraviolet laser is selected from the wavelength band in which the polymer layer absorbs it and changes its refractive index, but it is preferable to select the maximum absorption wavelength. When a laser having a wavelength deviated from the maximum absorption wavelength is used, excessive power is required to compensate for the deviation.

Another feature of the present invention is that since no photomask is used, the waveguide manufacturing cost can be significantly reduced. In particular, the cost for producing various optical circuits having different optical circuit patterns can be drastically reduced and can be produced in a short time, so that the total cost performance can be drastically improved.

Furthermore, the present invention can be realized by irradiating a laser beam while in-line monitoring the change of the characteristic of the optical circuit, and the optical characteristic can be improved by trimming.

Further, since the polymer layer whose refractive index is changed by laser beam irradiation has a substantially flat surface, even if an upper clad layer is formed thereon, the surface can also have a flat surface. As a result, electronic components, electronic circuits, optical components, optical circuits, etc. can be mounted on the upper surface with high dimensional accuracy.

An ultrashort pulsed laser beam on the long wavelength side whose wavelength deviates from the absorption wavelength of the polymer is collected on the surface of or inside the missing pattern region where the ultraviolet laser beam is not irradiated, and the refractive index of the region is irradiated. May have a high refractive index. The wavelength of the ultrashort pulsed laser beam is selected from the range of 600 nm to 1600 nm, the pulse width is selected from the range of several thousand fs to several tens fs, and the pulse repetition frequency is selected from the range of 10 Hz to 200 kHz. The average output is preferably selected from the range of several tens mw to several hundred mw. Increasing the refractive index of the missing pattern region in this way improves the confinement of light in that region, that is, the light propagation layer, and the organic matter in the light propagation layer is further improved by irradiation with the ultrashort pulsed laser beam. It can be removed to be inorganic, and can be modified into a light propagation layer having a high density and a small number of light scattering centers.

[0054]

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

FIG. 1A is a side view showing an embodiment of a waveguide to which the method for manufacturing a photonic crystal waveguide of the present invention is applied, and FIG. 1B is a top view.

This waveguide comprises a low refractive index layer 2 on a substrate 1.
And a photobleaching polymer layer 3 is formed on the low refractive index layer 2. Polymer layer 3
An ultraviolet laser beam having a desired diameter D is radiated in the inside of the refractive index lowering region 4 in a matrix form at predetermined intervals S1 and S2 in the surface direction (vertical and horizontal in FIG. 1B) from 4-1-1. Four
-9-17, the refractive index lowering region 4 is missing in the matrix structure, and the missing pattern is from the end face of one of the waveguides (left side in FIG. 1B) to the other (FIG. 1
The straight line pattern 5 is formed toward the end face on the right side in (b). The optical signal propagates in the polymer layer 3 along the missing pattern 5 as shown by arrows 6 to 7.

Since this waveguide can reduce the spot size D of the ultraviolet laser beam to 2 μm or less, it is preferable that the diameter of the refractive index decreasing region 4 upon irradiation with the ultraviolet laser beam is also 2 μm or less. It is also preferable that the periodic intervals of the refractive index lowering regions 4 be 2 μm or less. The width of the missing linear pattern of the refractive index lowering region 4 is 4
It is preferable that the thickness is less than or equal to μm. These structural parameters can be determined in consideration of the single mode propagation condition, the relative refractive index difference between the polymer layer 3 and the refractive index lowering region 4, and the photonic bandgap condition. As described above, in the refractive index lowering region 4, if, for example, a polysilane compound is used as the photobleaching polymer layer, the polymer layer is irradiated with a Deep UV ultraviolet laser beam having a wavelength of 266 nm to obtain a refractive index before irradiation. On the other hand, it is possible to realize a maximum refractive index difference of about 8% after irradiation. Further, as an ultraviolet laser for forming the refractive index lowering region 4 configured in a matrix, a wavelength of 800 n
The third harmonic (wavelength 26
6 nm) and the pulse width is 1000 fs or less, an extremely large energy can be obtained within the pulse width, so that the refractive index decreasing region 4 formed in a matrix can be perforated. In this case, a larger refractive index changing structure can be realized, and an even smaller photonic crystal waveguide can be realized. The control of perforation can be performed by the average output value of the ultrashort pulse laser beam, the pulse width, the repetition frequency, the moving speed of the substrate, and the like. The thickness of the polymer layer 3 is preferably 6 μm or less in consideration of the single mode propagation condition.

For the substrate 1, glass, ceramics, plastics, semiconductors, ferroelectrics, composite materials of glass and plastic, and combination materials of the above materials can be used.

The low-refractive index layer 2 includes SiO ₂ , SiO ₂ to which at least one refractive index control dopant such as Ge, P, Ti, B, Zn, Sn, Ta, and F is added, a polymer layer, an organic layer. And an inorganic composite layer can be used.

For the photobleaching polymer layer 3, a polysilane compound, a polysilane compound containing a silicone compound, a silicone compound plus a photoacid generator, a nitrone-containing silicone compound, or the like is used.

First, the polysilane compound applicable to the present invention will be described.

As the polysilane compound used in the present invention, a linear type and a branched type can be used. The branched type and the linear type are distinguished by the bonding state of Si atoms contained in polysilane. That is, with the branched polysilane, the number (bond number) bonded to the adjacent Si atoms is
It is a polysilane containing 3 or 4 Si atoms.

On the other hand, the linear polysilane is S
The number of bonds of the i atom to the adjacent Si atom is 2. Usually, it is bonded to a hydrocarbon group, an alkoxy group or a hydrogen atom in addition to the Si atom.

Such a hydrocarbon group has a carbon number of 1
An aliphatic hydrocarbon group which may be substituted with halogen of 10 to 10 and an aromatic hydrocarbon group of 6 to 14 carbon atoms are preferable.
Specific examples of the aliphatic hydrocarbon group include a methyl group, a propyl group, a butyl group, a hexyl group, an octyl group, a decyl group, a trifluoropropyl group, a nonafluorohexyl group and the like, and a cyclohexyl group and methylcyclohexyl group. Examples thereof include alicyclic ones such as groups.

Specific examples of the aromatic hydrocarbon group include:
Examples thereof include a phenyl group, p-tolyl group, biphenyl group and anthracyl group. Examples of the alkoxy group include those having 1 to 8 carbon atoms. Specific examples include a methoxy group, an ethoxy group, a phenoxy group and an octyloxy group. Of these, a methyl group and a phenyl group are particularly preferable in view of ease of synthesis.

In the case of a branched polysilane, the adjacent S
The number of Si atoms having 3 or 4 bonds with i atoms is more preferably 2% or more of the total number of Si atoms in the branched polysilane. If less than 2% or linear polysilane has high crystallinity, microcrystals are easily generated in the film, which causes light scattering, and light transparency is easily deteriorated.

The polysilane used in the present invention is produced by a polycondensation reaction by heating a halogenated silane compound to 80 ° C. or higher in the presence of an alkali metal such as sodium in an organic solvent such as n-decane or toluene. be able to. It can also be synthesized by an electrolytic polymerization method or a method using metal magnesium and metal chloride.

The branched polysilane is composed of an organotrihalosilane compound, a tetrahalosilane compound, and a diorganodihalosilane compound, and the organotrihalosilane compound and the tetrahalosilane compound account for 2 mol% or more of the total amount. The desired branched polysilane is obtained by heating and polycondensing the halosilane mixture.

Here, the organotrihalosilane compound serves as a Si atom source whose number of bonds to adjacent Si atoms is 3, and one tetrahalosilane compound is adjacent S atom.
It becomes a Si atom source having 4 bondings with i atoms. In addition,
The network structure can be confirmed by measuring an ultraviolet absorption spectrum and a nuclear magnetic resonance spectrum of silicon.

The halogen atom contained in each of the organotrihalosilane compound, the tetrahalosilane compound and the diorganodihalosilane compound used as the raw material of the polysilane is preferably a chlorine atom. Examples of the substituent other than the halogen atom which the organotrihalosilane compound and the diorganohalosilane compound have include a hydrocarbon group, an alkoxy group or a hydrogen atom.

Next, as the silicone compound added to the polysilane compound of the present invention, one represented by the chemical formula 1 is used.

[0072]

[Chemical 1]

However, in the chemical formula 1, R1 to R12 are an aliphatic hydrocarbon group which may be substituted with a halogen having 1 to 10 carbon atoms or a glycidyloxy group, and 6 to 12 carbon atoms.
Of aromatic hydrocarbon groups and alkoxy groups having 1 to 8 carbon atoms, which may be the same or different. a, b, c and d are integers including 0, and a +
b + c + d ≧ 1 is satisfied. Specific examples of the aliphatic hydrocarbon group contained in this silicone compound include alicyclic groups such as a methyl group, a propyl group, a butyl group, a hexyl group, an octyl group, a decyl group, a trifluoropropyl group, and a glycidyloxypropyl group. The following are listed.
Further, specific examples of the alkoxy group include a methoxy group, an ethoxy group, a phenoxy group, an octyloxy group, a ter-butoxy group and the like. The types of R1 to R12 and the values of a, b, c, and d are not particularly important and are not particularly limited as long as they are compatible with polysilane and an organic solvent and the film is transparent. In consideration of compatibility, it is preferable that the polysilane used has the same group as the hydrocarbon group. For example, when a phenylmethyl type polysilane is used as the polysilane, it is preferable to use the same phenylmethyl type or diphenyl type silicone compound.

At least 2 of R1 to R12
A silicone compound having two or more alkoxy groups in one molecule, one of which is an alkoxy group having 1 to 8 carbon atoms, can be used as a cross-linking material. Examples thereof include methylphenyl methoxy silicone and phenyl methoxy silicone containing 15 to 35 wt% of alkoxy groups. The molecular weight is 100
A value of 00 or less, preferably 3000 or less is suitable.

In order to reduce light absorption due to CH groups and OH groups in the film, polysilane compounds and silicone compounds are deuterated, or at least a part thereof is halogenated.
In particular, if a fluorinated product is used, the light loss due to the absorbing group can be significantly reduced. As a result, it is possible to realize a polymer film having low wavelength loss and low optical loss, and it is possible to expand the application to a wide range for high-performance waveguide type optical components and optical devices.

Further, by using a crosslinkable or alkoxy group-containing silicone compound, the silicone compound can be uniformly added to the branched polysilane compound and is easily soluble in an organic solvent such as toluene. It becomes a nanometer level ultrafine particle solution, and by using a polymer solution, a uniform structure or film without light scattering centers can be formed.

Next, a method of forming a polymer layer on the low refractive index element 2 will be described.

A polymer compound is dissolved in an organic solvent to obtain a polymer solution, and the polymer solution is applied onto the low refractive index layer 2 by a spin coating method or an extrusion coating method. Then, prebaking is performed in the temperature range of 80 ° C. to 150 ° C. for about 20 to 40 minutes. Then from 200 ℃ to 30
Post-baking is performed for about 20 to 60 minutes in the temperature range of 0 ° C. to form a polymer layer. The pre-baking and post-baking may be carried out by continuously performing the temperature raising, constant temperature holding, temperature raising, constant temperature holding, and temperature lowering steps in a programmable temperature control type electric furnace.

Here, the organic solvent used in this embodiment is a hydrocarbon type having 5 to 12 carbon atoms, a halogenated hydrocarbon type, an ether type, or the like. Examples of hydrocarbons are pentane, hexane, heptane, cyclohexane, n-decane, n-dodecane, benzene, toluene, xylene,
Methoxybenzene or the like can be used. Examples of halogenated hydrocarbons include carbon tetrachloride, chloroform,
1,2-dichloroethane, dichloromethane, chlorobenzene and the like can be used. As examples of ether type, diethyl ether, dibutyl ether, tetrahydrofuran, etc. can be used. Further, as a polymer material for photobleaching, as an organic solvent for a silicone compound containing a nitrone compound, as described above,
Pegmia may be used. The photobleaching polymer material must be a material that is soluble in organic solvents.

Next, a method of irradiating the polymer layer produced by the above-mentioned method with an ultraviolet laser beam to form the region 4 having a low refractive index will be described.

The ultraviolet laser has an oscillation wavelength of 266.
nm laser (third harmonic laser of mode-locked femtosecond laser using titanium-doped sapphire crystal of 800 nm wavelength), Dee with oscillation wavelength of 266 nm
p UV ultraviolet laser, He with an oscillation wavelength of 325 nm
A −Cd laser, a third harmonic laser of a YAG laser having an oscillation wavelength of 355 nm, a semiconductor laser having an oscillation wavelength of 400 nm, a He—Cd laser having an oscillation wavelength of 442 nm, or the like can be used. The oscillation output may be continuous wave or pulse oscillation.

As an example of the polymer layer, a polymer solution for photobleaching is prepared by dissolving a polymer obtained by adding 50 wt% of a silicone compound to a branched polymethylphenylsilane compound having a branching degree of 20% in an organic solvent toluene. This polymer solution was applied onto the low refractive index layer 2 (SiO ₂ layer, film thickness of about 10 μm) on the substrate 1 (quartz glass substrate), prebaked at 150 ° C. for 20 minutes, and then at 200 ° C.
Post-baking was performed for 30 minutes to obtain a polymer layer having a thickness of about 5 μm. The oscillation wavelength of 442 nm H on this polymer layer
An e-Cd laser (continuous wave power value on the polymer layer surface: about 5 mw) is held at a laser beam spot diameter of about 1.6 μm, and the laser is periodically turned on while moving the substrate 1 at a speed of 100 μm / s. , M while repeating OFF
Regions 4-1-1 to 4- in the polymer layer 3 on the substrate 1 on which the low-refractive index layer 2 of m × 50 mm is formed are changed to low-refractive index.
9-17 was formed. As a result, the relative refractive index difference Δ between the polymer layer 3 and the region 4 having a low refractive index could be set to about 5%. The diameter and the interval of the region 4 were both about 1.5 μm. The width of the missing linear pattern was about 3 μm.

Next, as a modified example, the substrate 1 is
As a result of lowering the refractive index only at a moving speed of 50 μm / s, the relative refractive index difference Δ could be 6.5%.

From these results, it was found that lowering the refractive index can be promoted by increasing the energy in the laser beam irradiation portion. In addition, 325 nm, which is close to the maximum absorption wavelength range of polysilane compounds in ultraviolet light
Alternatively, if a laser having another oscillation wavelength of 266 nm is used, the refractive index can be further lowered.

FIG. 2A is a side view showing another embodiment of the waveguide to which the method for manufacturing a photonic crystal waveguide of the present invention is applied, and FIG. 2B is a top view.

This waveguide is a buried waveguide in which the same layer as the low refractive index layer 2, that is, the upper clad layer 8 is formed on the polymer layer 3 which causes a change in the refractive index.

The low refractive index layer 2 and the upper cladding layer 8 may be made of the following materials. That is, a polymer obtained by adding 50 wt% of a silicone compound to a branched polymethylphenylsilane compound having a branching degree of 20% is dissolved in toluene as an organic solvent to prepare a polymer solution for photobleaching, and this solution is preliminarily exposed to ultraviolet rays (150%).
w About 1 light emitted from the mercury xenon lamp is transmitted through the image fiber bundle with a diameter of 20 mm and output.
Irradiation at a distance of 0 cm, the output is about 1200 mw / c
m ² ) for 135 minutes to lower the refractive index (the refractive index at a wavelength of 632.8 nm is lowered from 1.645 to 1.62 before irradiation with ultraviolet rays), and this solution is applied onto the substrate 1, It is obtained by prebaking at 150 ° C. for 20 minutes and then post-baking at 200 ° C. for 20 minutes to obtain a polymer layer for the low refractive index layer 2. The upper clad layer 8 is also formed by the same method. The ultraviolet laser beam irradiation may be performed by forming a laser beam on the polymer layer 3 after forming the upper cladding layer 8. This waveguide has the same effect as the waveguide shown in FIGS. 1 (a) and 1 (b).

FIG. 3A is a side view showing another embodiment of the waveguide to which the method for manufacturing a photonic crystal waveguide of the present invention is applied, and FIG. 3B is a top view.

In this waveguide, an ultraviolet laser beam is condensed and irradiated in the photobleaching polymer layer 3 to form a substantially spherical low refractive index region (a polymer region having a lowered refractive index or a hole). Area). This low refractive index region is formed by focusing and irradiating an ultra-ultraviolet ultrashort pulse laser beam having a pulse width of 1000 fs or less. This waveguide has the same effect as the waveguide shown in FIGS. 1 (a) and 1 (b).

FIG. 4A is a side view showing another embodiment of the waveguide to which the method for manufacturing a photonic crystal waveguide of the present invention is applied, and FIG. 4B is a top view.

Also in this waveguide, the ultraviolet laser beam is focused and irradiated in the vicinity of the surface in the photobleaching polymer layer 3 and is irradiated with a substantially spherical low refractive index region (a polymer region having a lowered refractive index or a hole). The open area) is formed.

This waveguide has the same effect as the waveguide shown in FIGS. 1 (a) and 1 (b).

FIG. 5 (a) is a side view showing another embodiment of the waveguide to which the method for manufacturing a photonic crystal waveguide of the present invention is applied, and FIG. 5 (b) is a top view.

This waveguide has an upper clad layer 8 formed on the upper surface of the waveguide shown in FIGS. 3 (a) and 3 (b).

This waveguide has the same effect as the waveguide shown in FIGS. 1 (a) and 1 (b).

FIG. 6A is a side view showing another embodiment of the waveguide to which the method for manufacturing a photonic crystal waveguide of the present invention is applied, and FIG. 6B is a top view.

This waveguide is a photonic crystal waveguide in which the optical signal 6 is bent at a right angle and propagated in the direction of the arrow 7 as an optical path in which the missing portion is bent at a right angle as 5-1 and 5-2. . This waveguide has the same effect as the waveguide shown in FIGS. 1 (a) and 1 (b).

FIG. 7 is a top view showing another embodiment of a waveguide to which the method for manufacturing a photonic crystal waveguide of the present invention is applied.

In this waveguide, the missing portion is formed in a Y shape 5-1 and
By providing like 5-2, 5-3, 5-4, 5-5, the optical signal 6 is branched and propagated in two directions 6-1 and 6-2, and arrows 7-1 and 7- are used. It shows a branched waveguide structure which is configured to emit light in two directions.

This waveguide has the same effect as the waveguide shown in FIGS. 1 (a) and 1 (b).

FIG. 8A is a side view showing another embodiment of a waveguide to which the method for manufacturing a photonic crystal waveguide of the present invention is applied, and FIG. 8B is a side view of FIG. 8b-8b
8C is a cross-sectional view taken along the line 8C-8C in FIG. 8A.
It is a line sectional view.

This waveguide is formed by stacking two photobleaching polymer layers 3-1 and 3-2, and a missing portion 5-in the upper photobleaching polymer layer 3-2.
The incident light is made to enter and propagate in the inside of No. 1 and is bent at a right angle into the missing portion 5-2 in the photobleaching polymer layer 3-1 at the lower part and propagated, and is emitted as shown by an arrow 7. It is a thing. That is, this waveguide is a three-dimensional optical waveguide. Incidentally, 4a-1-1 to 4a-13-21, 4
Reference numerals b-1-1 to 4b-12-21 represent refractive index lowering regions, respectively.

In addition to the above-mentioned two layers, a three-dimensional optical circuit can be realized by stacking photobleaching polymer layers in a multi-layered manner and providing a missing portion region in each polymer layer. That is, the optical signal can be bent and propagated at right angles or oblique directions in the depth direction of the laminated polymer layer, or can be propagated by being optically coupled between the respective polymer layers.

FIG. 9 is a top view showing another embodiment of a waveguide to which the method for manufacturing a photonic crystal waveguide of the present invention is applied.

An optical signal 6 is supplied to this waveguide by arrows 6-1 and 6-.
2, 6-3, 6-4, 6-5, 6-6, 6-7, 7 so as to propagate the photobleaching polymer layer 3
The cutout portion is formed in a zigzag shape.

This waveguide also has the same effect as the waveguide shown in FIGS. 1 (a) and 1 (b).

FIG. 10A is a side view showing another embodiment of the waveguide to which the method for manufacturing a photonic crystal waveguide of the present invention is applied, and FIG. 10B is a top view.

A plurality of waveguides (9 waveguides in the figure) are provided on the substrate 1.
Layers, but not limited to. ) The photobleaching polymer layers 3-1 to 3-9 are laminated, and the low refractive index regions 4 are provided in the respective layers so as to form a photonic bandgap structure at predetermined intervals in the plane direction. The bleaching polymer layer 3-5 has a linear pattern missing portion 5.

Then, the optical signal is made incident in the direction of the arrow 6 in the linear pattern 5 and is outputted in the direction of the arrow 7. This waveguide has the same effect as the waveguide shown in FIGS. 1 (a) and 1 (b).

In this embodiment, the missing portion is provided only in the photobleaching polymer layer 3-5. However, the missing portion is provided in each of the polymer layers, and the total thickness of these layers is 3%.
Dimensional light propagation or a three-dimensional optical circuit may be formed.

FIG. 11A is a side view showing another embodiment of a waveguide to which the method for manufacturing a photonic crystal waveguide of the present invention is applied, and FIG. 11B is a side view of FIG. 11A. 11
It is a b-11b sectional view.

FIGS. 1A, 1B to 10A,
In the embodiment shown in (b), the low refractive index region 4 has a diameter D.
However, in the present embodiment, the width W
The photonic bandgap structure is formed by using a linear structure having a, the width Wa of which is 2 μm or less, and the interval S3 between the linear portions 4L is also 2 μm or less. The low-refractive-index linear portion 4L may be a hole or may be solid. This waveguide is also shown in FIG.
The same effect as the waveguide shown in (b) can be obtained.

FIG. 12 is a top view showing another embodiment of a waveguide to which the method for manufacturing a photonic crystal waveguide of the present invention is applied.

This waveguide has a notch so that the optical signal is bent at a right angle from the direction of arrow 6 to the direction of arrow 7 and propagated. That is, a plurality of L-shaped linear portions 4La having a low refractive index are arranged in parallel and are separated so that a portion 5 for propagating an optical signal is formed. This waveguide has the same effect as the waveguide shown in FIGS. 1 (a) and 1 (b).

The present invention is not limited to the above embodiment.

For example, 2% of a photoacid generator (paramethoxystiltriazine with a melting point of 192 ° C. and a maximum absorption length of 77 nm) is added to a polysilane compound containing a silicone compound.
It is also possible to use a polymer layer containing 5% to 5%. In this case, the waveguide loss tended to increase somewhat, but the uniformity of the pattern in the depth direction of the low refractive index change region due to the irradiation of the ultraviolet laser beam was further improved, and a rectangular core layer with higher dimensional accuracy was obtained. Could be realized. It was found that a triazine-based photoacid generator is preferable.

An ultraviolet blocking layer may be provided on the upper cladding layer 6 so that the refractive index of the core layer 5 does not change for a long period of time.

Various kinds of polysilane compounds, silicone compounds, triazine compounds, photoacid generators and the like can be applied. For example, a branched polysilane compound having a branching degree of 2% or more is preferable as the polysilane compound from the viewpoint of optical transparency. The photoacid generator is preferably a triazine type,
Among them, those having high light transparency at long wavelengths and those having high melting points are preferable. The silicone compound is also preferably one having a high light transparency and a high melting point.

Further, an ultrashort pulsed laser beam having a wavelength deviating from the absorption wavelength of the above-mentioned polymer is collected and irradiated on the surface or inside of the missing portion which is not irradiated with the ultraviolet laser beam and becomes the light propagation layer. The refractive index of the core layer may be increased.

The wavelength of the ultrashort pulsed laser beam is 6
In the range of 00 nm to 1600 nm (preferably 800 n
m wavelength), the pulse width is selected from the range of several thousand fs to several tens fs, and the pulse repetition is selected from the range of 10 Hz to 200 kHz. The average output is preferably selected from the range of several tens mw to several hundred mw. Increasing the refractive index of the core layer to 16 as described above further strengthens the confinement of light in the core layer, and the organic matter in the core layer is further removed by the irradiation with the ultrashort pulsed laser beam to make it inorganic. In addition, the core layer can be modified into a highly homogeneous core layer having a high density and a small number of light scattering centers. It should be noted that the narrower the pulse width of the laser beam, the higher the energy within the pulse width becomes, and the higher refractive index can be realized without any thermal damage.

As described above, the present invention has the following effects.

(1) In the present invention, a photonic crystal waveguide is formed by directly irradiating a photobleaching polymer layer with an ultraviolet laser beam to draw a desired pattern without using conventional photolithography and etching processes. It is designed to be configured. If, for example, a polysilane compound is used as the photobleaching polymer layer, by irradiating the layer with a deep UV ultraviolet laser beam having a wavelength of 266 nm, the refractive index after irradiation is relative to the refractive index before irradiation. The difference can be lowered by about 8% at the maximum. Also, as an ultraviolet laser, a wavelength of 80
By using the third harmonic (wavelength of 266 nm) of an ultrashort pulse laser oscillating at 0 nm and setting the pulse width to 1000 fs or less, extremely large energy can be obtained within the pulse width, so that the matrix structure is adopted. It is possible to form a hole in the refractive index lowering region, to realize a larger refractive index changing structure, and to realize an even smaller photonic crystal waveguide. The control of punching can be performed by the average output value of the laser beam, the pulse width, the repetition frequency, the moving speed of the substrate, and the like.

(2) Since the ultraviolet laser beam can be narrowed down to 2 μm or less, minute regions having a low refractive index due to the irradiation of the ultraviolet laser beam are periodically arranged in a matrix to form a photonic bandgap structure. It is possible to realize a photonic crystal waveguide in which a pattern in which a minute region is missing is provided in a band-gap structure having a circular shape and an optical signal is propagated in the pattern. Moreover, the wavelength of the polysilane compound film is 1.3 μm and 1.55 μm.
At m, the propagation loss is 0.1 dB / cm or less, which is a low loss, so that a low-loss photonic crystal waveguide can be realized.

(3) Since a photonic crystal waveguide is formed by directly irradiating a photobleaching polymer layer with an ultraviolet laser beam to form a desired pattern without using photolithography and etching processes. It is possible to manufacture a photonic crystal waveguide with extremely small scattering loss depending on the structural nonuniformity.

(4) Three-dimensional CAD (Computer Aided Des)
ign), it is possible to form a three-dimensional optical circuit in the laminated polymer layer made of a polysilane compound.

(5) From the viewpoint of the manufacturing method, since the polymer layer can be formed by applying the polymer solution by the spin coating method and heating, it is a very simple manufacturing method, and cost reduction can be expected. You can

(6) For the photobleaching polymer layer, a polysilane compound, a polysilane compound, a silicone compound, or a mixture of a silicone compound and a photoacid generator can be used. In addition, in the photonic crystal waveguide having a structure with a hole,
By carrying out heat treatment at a higher temperature to promote mineralization, absorption groups (CH group, O
The absorption loss depending on the (H group) can be reduced. Further, since it can withstand the Au / Sn solder reflow temperature (Au / Sn solder reflow temperature:> 280 ° C.), it can be used for electronic parts, electronic circuits, optical parts, optical circuits, etc. on the front surface or the back surface of the waveguide. Can be implemented as a hybrid.

(7) If the pulse laser beam is used as the ultraviolet laser beam as described above, the refractive index of the polymer layer is lowered with a low average output laser beam power without being thermally damaged by the irradiated polymer layer. Can be made. In addition, by using a pulse compared to a continuous wave, the average intensity is low while having a high light intensity momentarily, so that even for a thick polymer layer, the change in the refractive index can be made uniform in the depth direction. Can be generated. That is,
It becomes possible to realize a waveguide in a short time. Note that the degree of change in the refractive index in the depth direction can be controlled by adjusting the power of the laser beam and the moving speed of the workpiece (or one of the laser beams). Further, the same region may be irradiated with the laser beam a plurality of times.

(8) The width Wc of the refractive index lowering region can be controlled by adjusting the beam spot diameter of the laser beam.

(9) The wavelength of the ultraviolet laser is selected from the wavelength band in which the polymer layer absorbs and changes its refractive index, but it is preferable to select the maximum absorption wavelength. When a laser having a wavelength deviated from the maximum absorption wavelength is used, excessive power is required to compensate for the deviation.

Another feature of the present invention is that since no photomask is used, the waveguide manufacturing cost can be significantly reduced. In particular, the cost for producing various optical circuits having different optical circuit patterns can be drastically reduced and can be produced in a short time, so that the total cost performance can be drastically improved.

(10) The characteristics of the optical circuit can be changed by irradiating the laser beam while in-line monitoring, and the optical characteristics can be improved by trimming.

(11) Since the polymer layer whose refractive index is changed by laser beam irradiation has a substantially flat surface, even if an upper clad layer is formed on the polymer layer, the surface also has a flat surface. it can. As a result, electronic components, electronic circuits, optical components, optical circuits, etc. can be mounted on the upper surface with high dimensional accuracy.

(12) The ultrashort pulsed laser beam having a wavelength deviating from the absorption wavelength of the polymer is condensed on the surface of or inside the missing pattern region where the ultraviolet laser beam is not irradiated, and the region is refracted. The refractive index may be increased. The wavelength of the ultrashort pulsed laser beam is selected from the range of 600 nm to 1600 nm, the pulse width is selected from the range of several thousand fs to several tens fs, and the pulse repetition frequency is from 10 Hz to 200 kHz.
Select from the range of z. The average output is preferably selected from the range of several tens mw to several hundred mw. Increasing the refractive index of the missing pattern region in this way improves the confinement of light in that region, that is, the light propagation layer, and the organic matter in the light propagation layer layer is irradiated by the ultrashort pulsed laser beam irradiation. It can be further removed to be inorganicized, and can be modified into a light propagation layer having a high density and a small number of light scattering centers.

[0135]

In summary, according to the present invention, the following excellent effects are exhibited.

It is possible to provide a small-sized and low-loss photonic crystal waveguide and a method for manufacturing the same.

[Brief description of drawings]

FIG. 1A is a side view showing an embodiment of a waveguide to which a method for manufacturing a photonic crystal waveguide of the present invention is applied, and FIG. 1B is a top view.

FIG. 2A is a side view showing another embodiment of the waveguide to which the method for manufacturing a photonic crystal waveguide of the present invention is applied, and FIG. 2B is a top view.

FIG. 3A is a side view showing another embodiment of a waveguide to which the method for manufacturing a photonic crystal waveguide of the present invention is applied, and FIG. 3B is a top view.

FIG. 4A is a side view showing another embodiment of a waveguide to which the method for manufacturing a photonic crystal waveguide of the present invention is applied, and FIG. 4B is a top view.

5A is a side view showing another embodiment of a waveguide to which the method for manufacturing a photonic crystal waveguide of the present invention is applied, and FIG. 5B is a top view.

FIG. 6A is a side view showing another embodiment of the waveguide to which the method for manufacturing a photonic crystal waveguide of the present invention is applied, and FIG. 6B is a top view.

FIG. 7 is a top view showing another embodiment of a waveguide to which the method for manufacturing a photonic crystal waveguide of the present invention is applied.

FIG. 8A is a side view showing another embodiment of the waveguide to which the method for manufacturing a photonic crystal waveguide of the present invention is applied, and FIG. 8B is a sectional view taken along line 8b-8b of FIG. 8A. Is a figure,
FIG. 8C is a sectional view taken along line 8c-8c of FIG.

FIG. 9 is a top view showing another embodiment of the waveguide to which the method for manufacturing a photonic crystal waveguide of the present invention is applied.

10A is a side view showing another embodiment of the waveguide to which the method for manufacturing a photonic crystal waveguide of the present invention is applied, and FIG. 10B is a top view.

FIG. 11A is a side view showing another embodiment of the waveguide to which the method for manufacturing a photonic crystal waveguide of the present invention is applied, and FIG. 11B is a sectional view taken along line 11b-11b of FIG. 11A. It is a figure.

FIG. 12 is a top view showing another embodiment of the waveguide to which the method for manufacturing a photonic crystal waveguide of the present invention is applied.

13A to 13F are external perspective views of a photonic crystal.

FIG. 14 is an external view showing another conventional example of a photonic crystal.

[Explanation of symbols]

1 substrate 2 Low refractive index layer 3 Polymer layer for photobleaching 4-1-1 to 4-9-17 Refractive index decreasing region 5 straight line pattern 8 Upper clad layer

Claims (19)

[Claims] 1. A low refractive index layer is provided on a substrate, and a polymer layer for photobleaching having a high refractive index is provided on the surface or inside of the low refractive index layer, and the polymer layer is provided in the polymer layer. A photonic crystal waveguide in which a refractive index lowering region in which the refractive index is lowered by irradiating an ultraviolet laser beam having a wavelength near the absorption wavelength of the layer in the surface direction of the polymer layer at a predetermined interval is formed in a matrix. , A part of the refractive index decreasing region is missing, the missing pattern formed by the missing region is a straight line in the plane direction of the polymer layer,
A photonic crystal waveguide comprising a curved pattern or a combination thereof, wherein an optical signal propagates in the polymer layer along the missing pattern. 2. The photonic crystal waveguide according to claim 1, wherein the beam spot diameter of the ultraviolet laser beam is 2 μm or less. 3. The photonic crystal waveguide according to claim 1, wherein the refractive index lowering region has a substantially circular shape. 4. The photonic crystal waveguide according to claim 1, wherein the refractive index decreasing region has straight portions arranged in parallel at desired intervals. 5. The photonic crystal waveguide according to claim 1, wherein the wavelength of the ultraviolet laser is in the range of 250 nm to 445 nm. 6. The photonic crystal waveguide according to claim 1, wherein a continuous wave laser or a pulsed laser is used as the ultraviolet laser. 7. The width of the non-irradiated region not irradiated with the ultraviolet laser beam and the width of the refractive index lowered region are 0.1 μm.
The photonic crystal waveguide according to any one of claims 1 to 6, wherein the photonic crystal waveguide has a thickness of m or more and 4 μm or less. 8. The high-refractive-index photobleaching polymer layer is made of a polysilane compound, a polysilane compound containing a silicone compound, a silicone compound plus a photoacid generator, or a nitrone-containing silicone compound. The photonic crystal waveguide according to any one of claims 1 to 7. 9. The refractive index decreasing regions are respectively formed in at least two polymer layers for photobleaching laminated on the substrate, and optical paths for three-dimensionally propagating light in the polymer layers, Alternatively, the photonic crystal waveguide according to claim 1, wherein an optical circuit is formed. 10. The ultrashort pulsed laser beam shifted from the absorption wavelength of the polymer layer to the long wavelength side is condensed and irradiated on the surface or inside of the polymer layer which is not the ultraviolet laser beam and becomes the light propagation layer. The photonic crystal waveguide according to claim 1, wherein the polymer layer has a high refractive index. 11. The photonic crystal waveguide according to claim 1, wherein a hole is formed in the refractive index lowering region. 12. A low refractive index layer forming step of forming a low refractive index layer on a substrate, a polymer layer forming step of forming a high refractive index photobleaching polymer layer on the low refractive index layer,
A low refractive index region forming step of irradiating an ultraviolet laser beam on both sides of the light propagation region so as to secure a light propagation region of a desired width from above the polymer layer and forming a low refractive index region. A method for manufacturing a photonic crystal waveguide. 13. A low refractive index layer forming step of forming a low refractive index layer on a substrate, a polymer layer forming step of forming a high refractive index photobleaching polymer layer on the low refractive index layer, and the polymer. A low refractive index region forming step of forming a low refractive index region by irradiating an ultraviolet laser beam on both sides of the light propagation region so as to secure a light propagation region having a desired width from above the layer, and forming a low refractive index region on the polymer layer. An upper clad layer forming step of forming an upper clad layer having a refractive index, and a method of manufacturing a photonic crystal waveguide. 14. A low refractive index layer forming step of forming a low refractive index layer on a substrate, a polymer layer forming step of forming a high refractive index polymer layer for photobleaching on the low refractive index layer, said polymer An upper clad layer forming step of forming an upper clad layer having a low refractive index on the layer, irradiating an ultraviolet laser beam on both sides of the light propagation region so as to secure a light propagation region of a desired width from above the polymer layer. And a low-refractive-index region forming step of forming a low-refractive-index region by a photonic crystal waveguide. 15. The method of manufacturing a photonic crystal waveguide according to claim 12, wherein the refractive index lowering region is formed by at least one laser beam scanning. 16. The method according to claim 12, wherein a linear pattern, a curved pattern, and a combination pattern of the regions not irradiated with the ultraviolet laser beam are formed by relative movement of either the substrate or the laser beam. 15. The method for manufacturing the photonic crystal waveguide according to any one of 14. 17. A polysilane compound, a silicone compound added to a polysilane compound, a silicone compound and a photo-acid generator, or a nitrone-added silicone compound is used for the high refractive index polymer layer for photobleaching. Item 17. A method for manufacturing a photonic crystal waveguide according to any one of items 12 to 16. 18. The method for manufacturing a photonic crystal waveguide according to claim 12, wherein at least two layers of the laser direct writing waveguide are laminated on a substrate. 19. The method of manufacturing a photonic crystal waveguide according to claim 12, wherein a hole is formed in a region having a lowered refractive index by irradiating an ultraviolet laser beam having a desired diameter.