JP3925209B2 - Manufacturing method of waveguide - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a waveguide.
[0002]
[Prior art]
FIG. 9A is a conceptual diagram showing a conventional waveguide manufacturing method, FIG. 9B is a plan view of a waveguide to which the manufacturing method shown in FIG. 9A is applied, and FIG. (c) is a figure which shows the refractive index distribution in the 9c-9c line cross section of the waveguide shown in FIG.9 (b).
[0003]
In FIG. 9C, the horizontal axis indicates the refractive index, and the vertical axis indicates the position of the waveguide in the width direction (position on the 9c-9c line).
[0004]
An ultrashort pulse laser beam 2-1 is condensed by a lens 3 and irradiated (arrow 2-2) in a transparent glass block 1 containing at least one kind of refractive index control additive, thereby making the irradiated portion have a high refractive index. Modification to a light layer, that is, the light propagation layer 4 is performed.
[0005]
The pulse width of the ultrashort pulse laser beam 2-2 is as narrow as 200 femtoseconds or less.
[0006]
The glass block 1 is moved in a direction perpendicular to the ultrashort pulse laser beam 2-2 (arrow 5 direction) while irradiating the glass block 1 with such an ultrashort pulse laser beam 2-2 at a fast repetition frequency of about 200 kHz. By doing so, the light propagation layer 4 having a desired shape is formed.
[0007]
[Problems to be solved by the invention]
However, the conventional waveguide described above has the following problems.
[0008]
(1) Although it is easy to form a light propagation layer having a high refractive index by irradiation with an ultrashort pulse laser beam, the interface of the light propagation layer is uneven in the power density distribution in the laser beam spot, the fluctuation of the laser beam, the pulse A waveguide having a large light scattering loss is disturbed by the low repetition frequency of the width, the non-uniformity of the moving speed of the stage for moving the glass block, and a practical waveguide has not yet been obtained.
[0009]
(2) When a curved waveguide with a small radius of curvature is formed, the light scattering loss is greatly increased, and light such as branching, merging, demultiplexing, and multiplexing with low loss as realized by conventional waveguides. It is difficult to obtain a signal processing circuit.
[0010]
Accordingly, an object of the present invention is to solve the above problems and provide a method for manufacturing a waveguide with low light scattering loss.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the invention described in claim 1 is directed to irradiating and condensing an ultrashort pulse laser beam onto a transparent body containing at least one kind of refractive index control additive, and to make an ultrashort pulse laser beam or transparent. In a method of manufacturing a waveguide in which a light propagation layer is formed by making the refractive index of a condensing part higher than the refractive index of a transparent body by relatively moving the body, the wavelength of the ultrashort pulse laser beam is in the range of 250 nm to 1600 nm. Yes, with a pulse width of 1000 femtoseconds or less and 30 femtoseconds or more, and a repetition frequency of 300 kHz or less and 50 kHz or more . After condensing and irradiating the ultrashort pulse laser beam, a transparent body is formed on the light propagation layer. further condensing the carbon dioxide gas laser beam having a wavelength absorbed, in which irradiates.
[0013]
The method for manufacturing a waveguide according to claim 2 includes, in addition to the structure according to claim 1, at least one element that lowers the melting point, such as Ge, P, and B, as an additive for refractive index control, It is preferable to use SiO ₂ glass having a content of 8 mol% or more and 30 mol% or less.
[0014]
Method for producing a waveguide according to claim 3, in addition to the configuration according to claim 1 or 2, it is preferable to use a laser beam oscillates continuously as carbon dioxide laser beam.
[0015]
Method for producing a waveguide according to claim 4, in addition to the configuration according to any one of claims 1 to 3, as a carbon dioxide laser beam, has a recessed shape the power density distribution of the center portion, a substantially TEM Those having the ₀₁ mode are preferably used.
[0017]
Method for producing a waveguide according to claim 5, in addition to the configuration according to any one of claims 1 to 4, further irradiating the carbon dioxide gas laser beam in a region other than the light propagation layer of transparent body, by condensing A photonic bandgap structure having a large number of holes may be formed.
[0018]
According to the present invention, after forming a light propagation layer by condensing and irradiating an ultrashort pulse laser beam on a transparent body containing at least one kind of refractive index control additive, the wavelength that is absorbed by the transparent body in the light propagation layer condensing the carbon dioxide gas laser beam having, by irradiating, it is possible to change the refractive index distribution in the width direction of the light propagation layer with the refractive index control additives of the light propagation layer is thermally diffused, the light propagation Since the refractive index distribution in the longitudinal direction of the layer and its peripheral part is made uniform, the scattering loss of signal light in the light propagation layer is reduced.
[0019]
By using at least one additive that lowers the melting point such as Ge, P, and B as the refractive index control additive and using SiO ₂ glass with a content of 8 mol% or more and 30 mol% or less, light propagation The refractive index control additive in the layer can be easily thermally diffused to change the refractive index distribution in the width direction of the light propagation layer and to make the refractive index distribution in the longitudinal direction of the light propagation layer and its peripheral part uniform. it can. That is, since the interface between the core layer as the light propagation layer and the cladding layer as the transparent body on the side surface of the core layer can be smoothed, low scattering loss characteristics can be obtained. In addition, when it exceeds 30 mol%, mismatching with a thermal expansion coefficient with the substrate occurs, and polarization dependency appears, so 30 mol% or less is preferable.
[0020]
As Les Zabimu the oscillation wavelength having a wavelength of absorbing refractive index control additives transparent body comprising at least one wavelength is the use of the carbon dioxide gas laser beam of 10.6μm band, depending on the irradiation conditions of the ultrashort pulse laser Since the output power can be selected and adjusted from a wide range, a waveguide with low scattering loss can be easily manufactured.
[0021]
By using a continuously oscillating laser beam as a laser beam having a wavelength that is absorbed by a transparent body containing at least one additive for controlling the refractive index, the unevenness of the light propagation layer formed by the pulsed laser beam is lengthened. Can be made uniform.
[0022]
As a power density distribution of a laser beam having a wavelength that is absorbed by a transparent body containing at least one kind of refractive index control additive, a substantially TEM ₀₁ mode laser beam with a recessed central portion is used, so that the center of the light propagation layer is It is possible to make uniform the structure non-uniformity in the peripheral part of the light propagation layer with little change in the refractive index of the part.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0024]
FIG. 1A is a conceptual diagram showing an embodiment of a method for manufacturing a waveguide according to the present invention, and FIG. 1B is a cross-sectional view taken along line 1b-1b of the waveguide shown in FIG. FIG. 1C is a diagram showing a refractive index distribution in the cross section taken along line 1c-1c in FIG. In FIG. 1C, the horizontal axis indicates the refractive index, and the vertical axis indicates the position on the 1c-1c line or the position on the 1c′-1c ′ line (position in the width direction) of the waveguide.
[0025]
A method for manufacturing a waveguide will be described with reference to FIG.
[0026]
10 transparent glass block containing an additive for controlling the refractive index (14 mol% GeO ₂ and 10 mol% P ₂ O ₅ co-added in SiO ₂ glass, thickness: 0.5 mm) Ultra-short pulse laser beam (wavelength: 800 nm, average output: 100 mW, pulse width: 160 femtoseconds, pulse repetition frequency: 200 kHz) 11-1 inside the lens (region having a depth of 0.1 mm from the surface) is 6 μm by the lens 12 The glass block 10 is focused and irradiated as indicated by an arrow 11-2 while the glass block 10 is focused on and irradiated with a beam spot at a speed of 100 μm / s, for example, in a direction orthogonal to the ultrashort pulse laser beam 11-1 (arrow 13 direction). It is possible to form the light propagation layer 14 having a high refractive index by moving the layer with the above. The substantially in synchronism with the ultrashort pulse laser beam 11-1 ultrashort pulse carbonated gas laser beam so as to follow later in the laser beam 11-1 (wavelength: 10.6 [mu] m band, continuous wave output: 5W) 15-1 to By holding and irradiating with a beam spot having a diameter of about 12 μm by the lens 16 as shown by an arrow 15-2, the refractive index distribution shape of the light propagation layer 14 is expanded from a solid line L1 to a broken line L2. The light propagation layer 17 can be obtained.
[0027]
In the periphery of the light propagation layer 14 only by irradiation with the ultrashort pulse laser beam 11-2, fluctuation of the ultrashort pulse laser beam 11-2, disturbance due to the ultrashort pulse laser beam 11-2, and movement of the glass block 10 are performed. Concavities and convexities were generated due to speed fluctuations and the like, but the peripheral portion of the light propagation layer 17 can be made smooth after irradiation with the carbon dioxide laser beam 15-2 (FIG. 1 (b)).
[0028]
Further, the refractive index distribution of the light propagation layer 14 can be extended to the light propagation layer 17 by irradiation with the carbon dioxide laser beam 15-2, and the refractive index of the light propagation layer 17 can be slightly lowered (FIG. 1). (C) Refractive index distribution: solid line L1 and broken line L2). It can be considered that this is caused by the diffusion of part of GeO ₂ and P ₂ O ₅ in the glass block 10 from the light propagation layer 14 toward the periphery thereof by irradiation with the carbon dioxide laser beam 15-2. it can.
[0029]
Here, a waveguide was prototyped by the same method as described above using a glass block in which 15 mol% of GeO ₂ and 10 mol% of B ₂ O ₃ were co-added to SiO ₂ . As a result, compared with the case shown in FIGS. 1A to 1C, the refractive index decrease in the central portion of the light propagation layer was reduced, and the refractive index in the peripheral portion of the light propagation layer was greatly decreased. This is considered to be due to the influence of the diffusion of B ₂ O ₃ to the periphery of the light propagation layer.
[0030]
Examples of the refractive index control additive to be added into the glass block 10 include PbO, Zn, ZrO _{2 and the} like in addition to B ₂ O ₃ , but GeO ₂ and P ₂ O ₅ are more effective. It is desirable to add more than 8 mol% of these additives. By increasing the amount of the additive, it becomes easy to perform the refractive index control and the structural homogenization step by irradiation with the carbon dioxide laser beam 15-2 behind.
[0031]
2 (a) and 2 (b) are conceptual diagrams showing another embodiment of the waveguide manufacturing method of the present invention.
[0032]
This is because the ultrashort pulse laser beam 11-1 is focused on the glass block 10, the light propagation layer 14 is formed by irradiation (FIG. 2A), and the carbon dioxide gas laser beam 15 having a wavelength absorbed in the glass block 10. The light propagation layer 17 is controlled by controlling the refractive index distribution in the width direction of the light propagation layer 14 by condensing and irradiating -1 and making the refractive index distribution in the longitudinal direction of the light propagation layer 14 and its peripheral part uniform. The manufacturing method which performed the shaping | molding process process (FIG.2 (b)) to perform separately is shown.
[0033]
Thus, by performing in separate steps, control of the refractive index distribution in the width direction of the light propagation layer 14 by the carbon dioxide laser beam 15-2 having a wavelength absorbed by the glass block 10 shown in FIG. It is possible to speed up the light propagation layer 14 and the processing time for uniformizing the shape of the refractive index distribution in the longitudinal direction of the peripheral portion thereof by increasing the output of the carbon dioxide laser beam 15-1. This is because, for example, some carbon dioxide lasers have an output of several W to several hundred W, and high-speed machining can be realized by increasing the output.
[0034]
FIG. 3 is a conceptual diagram showing another embodiment of the waveguide manufacturing method of the present invention.
[0035]
This is an example using a laminate in which a transparent layer 10a containing a refractive index control additive is formed on a substrate 18. As the substrate 18, a semiconductor substrate such as Si, GaAs, or InP, a glass substrate such as quartz or Pyrex (registered trademark), a ferroelectric substrate such as LiNbO ₃ or LiTaO ₅ , a magnetic material substrate such as ceramics or alumina, or a plastic substrate Etc. can be used. In particular, since the interface of the substrate 18 is not heated to a high temperature by irradiation with the ultrashort pulse laser beams 11-2 and 15-2, various substrates as described above can be used.
[0036]
FIG. 4 is a conceptual diagram showing another embodiment of the waveguide manufacturing method of the present invention.
[0037]
This is an example in which the light propagation layers 14a and 17a are formed on the surface of the transparent layer 10a containing the refractive index control additive. In this embodiment, control of the refractive index distribution in the width direction of the light propagation layer 14a by the carbon dioxide laser beam 15-2 irradiated after the irradiation with the ultrashort pulse laser beam 11-2, and the light propagation layer 14a and its peripheral portion are performed. It becomes easier to make the light propagation layer 17 by uniforming the refractive index distribution in the longitudinal direction. That is, since the light propagation layer 14a is formed on the surface of the transparent layer 10a, the diffusion rate of the refractive index control additive by irradiation with the carbon dioxide laser beam 15-2 can be increased, and the light propagation layer 14a. And the process of making the refractive index distribution in the longitudinal direction of the periphery thereof more uniform.
[0038]
FIG. 5A is a schematic view of a laser beam used for manufacturing the waveguide of the present invention, and FIG. 5B is a diagram showing the power density in the radial direction of the laser beam shown in FIG. FIG. 5C is a diagram showing the power density distribution three-dimensionally. In FIG. 5B, the horizontal axis indicates the radial position of the laser beam, and the vertical axis indicates the power density.
[0039]
This uses the TEM ₀₁ mode laser beam 19-1 as the carbon dioxide laser beam 15-1, and the laser beam 19-1 is converged by the lens 16 (arrow 19-2).
[0040]
If a TEM ₀₁ mode laser beam 19-2 having a recessed central portion is used as shown in FIG. 5C, the light propagation layer is not significantly changed without significantly changing the refractive index distribution in the central portion of the light propagation layer 14 (14a). The light propagation layer 17 (17a) having a uniform shape can be realized by improving the non-uniformity of the refractive index distribution in the longitudinal direction of 14a and its peripheral part.
[0041]
6A is a conceptual diagram showing another embodiment of the waveguide manufacturing method of the present invention, and FIG. 6B is a cross-sectional view taken along the line 6b-6b of the waveguide shown in FIG. It is the figure which superimposed the refractive index distribution and the refractive index distribution in a 6b'-6b 'line cross section. In FIG. 6B, the horizontal axis indicates the refractive index, and the vertical axis indicates the position (position in the thickness direction) on the 6b-6b line or 6b′-6b ′ line of the waveguide.
[0042]
In the manufacturing method shown in FIG. 6A, the TEM ₀₁ mode laser beam 19-1 having the power density distribution shown in FIG. 5C is irradiated with the ultrashort pulse laser beam 11-2 on the transparent layer 10a. In this method, the formed light propagation layer 14 is further irradiated.
[0043]
A refractive index distribution as shown by a solid line L3 in FIG. 6B is formed by irradiation with the laser beam 11-2, and a refractive index distribution as shown by a broken line L4 in FIG. 6B by irradiation with the laser beam 19-2. become.
[0044]
Even with such a manufacturing method, a waveguide with low light scattering loss can be obtained.
[0045]
The present invention is not limited to the embodiment described above.
[0046]
First, as the rear laser beams 15-1 and 19-1, a laser beam in a vacuum ultraviolet region or an ultraviolet region, for example, an excimer laser beam can be used in addition to the carbon dioxide laser beam. In addition to continuous oscillation, a pulsed laser may be used. In this case, the thermal influence is reduced.
[0047]
An optical directional coupler, an optical Y branch circuit, a ring resonator, an optical filter circuit, an optical switch circuit, and the like as conventionally known are configured by using a waveguide to which the waveguide manufacturing method of the present invention is applied. May be. Moreover, you may comprise the optical signal processing circuit using a linear pattern, a curvilinear pattern, or the pattern which combined these as a light propagation layer.
[0048]
Further, as shown in FIGS. 7A to 7C, a low refractive index layer 20 having a lower refractive index than that of the transparent body is formed on the upper surface of the transparent layer 10a made of a transparent body containing at least one kind of refractive index control additive. -1 is formed, the ultrashort pulse laser beam condensing, after irradiation, further condensing the carbon dioxide gas laser beam having a wavelength that is absorbed in the transparent body in the light propagation layer, by irradiating constitute a light propagation layer 17 (FIG. 7 (a)), a low refractive index layer 20-2 having a refractive index lower than that of the transparent body is formed on the lower surface of the transparent layer 10a, and an ultrashort pulse laser beam is condensed and irradiated, followed by light propagation. further condensing the carbon dioxide gas laser beam having a wavelength that is absorbed into the transparent body layer, by irradiating it may constitute the light propagation layer 17 (FIG. 7 (b)), or the upper and lower surfaces of the transparent layer 10a (FIG. 7 (C)) includes low refractive index layers 20-1 and 20-2 having a refractive index lower than that of the transparent body. Each form, condensing the ultrashort pulse laser beam was irradiated, further condensing the carbon dioxide gas laser beam having a wavelength that is absorbed in the transparent body in the light propagation layer, by irradiating constitute a light propagation layer 17 Also good.
[0049]
For example, the low refractive index layers 20-1 and 20-2 preferably include at least one kind of F, B, P, and the like.
[0050]
FIGS. 7A to 7C are structural views of other waveguides to which the waveguide manufacturing method of the present invention is applied.
[0051]
Furthermore, at least one more transparent body containing at least one additive for controlling the refractive index may be laminated, and a light propagation layer may be formed in each layer, and the light propagation layer propagates in each layer. You may form so that it may do. By doing in this way, further higher integration can be achieved, and multi-functionalization can also be expected.
[0052]
The wavelength of the ultrashort pulse laser beam can be selected from the range of 260 nm to 1600 nm in addition to 800 nm.
[0053]
Further, for example, polyimide, polysilane, silicone, epoxy resin or the like may be used as a transparent material containing at least one kind of refractive index control additive. The waveguide manufacturing method of the present invention may be applied to a photonic crystal structure as shown in FIGS.
[0054]
8A is a side view of a waveguide having a photonic crystal structure, FIG. 8B is a cross-sectional view taken along line 8b-8b of FIG. 8A, and FIG. 8C is a line 8c-8c. It is a figure which shows the refractive index distribution in a cross section. In FIG. 8C, the horizontal axis indicates the refractive index, and the vertical axis indicates the position (position in the width direction) of the waveguide on the 8c-8c line.
[0055]
A low refractive index layer 23 having a refractive index lower or substantially equal to that of the transparent layer 22 made of a transparent body is formed on the substrate 21, and the refractive index is higher than that of the low refractive index layer 23 on the low refractive index layer 23. Transparent having a structure in which a transparent layer 22 containing at least one kind of refractive index control additive is formed, and another low refractive index layer 24 having a refractive index lower than or substantially equal to that of the transparent layer 22 is formed on the transparent layer 22. A hole 25 having a diameter d (1 μm or less) is provided in a region of the transparent layer 22 where a light propagation layer is not formed so that a photonic band gap structure is formed vertically and horizontally at a desired interval s (1 μm or less). . The holes 25 can be formed by increasing the energy of the laser beams 15-2 and 19-2.
[0056]
An ultrashort pulse laser beam (not shown) having a wavelength in the range of 250 nm to 1600 nm, a pulse width of 1000 femtoseconds or more and 30 femtoseconds or more, and a repetition frequency of 300 kHz or less and 50 kHz or more in a region where the holes 25 are not formed. When the light propagation layer 26 is formed by increasing the refractive index of the condensing part by condensing and irradiating the light, a laser beam having a wavelength that is absorbed by the transparent body after condensing and irradiating the ultrashort pulse laser beam By condensing and irradiating, the refractive index control additive in the light propagation layer 26 is thermally diffused to change the refractive index distribution, and the shape of the periphery of the light propagation layer can be made uniform.
[0057]
In the above embodiment has been described in the case of moving the transparent member, the present invention is not limited thereto, form a light propagation layer by moving the ultrashort pulse laser beam and carbonic acid gas laser beam You may make it do.
[0058]
In the above, the present invention has the following effects.
[0059]
(1) As in the prior art, either an object to be irradiated or a laser beam is focused while irradiating and irradiating an ultrashort pulse laser beam on or inside a transparent body containing at least one kind of refractive index control additive. It is difficult to reduce the roughness of the side surface of the core layer by a method of patterning by relatively moving and forming a core layer having a high refractive index that becomes a light propagation layer. On the other hand, after the light propagation layer is formed by condensing and irradiating the ultrashort pulse laser beam as in the present invention, the light propagation is performed by condensing and irradiating the laser beam having a wavelength that is absorbed by the transparent body. The refractive index control additive in the layer is thermally diffused to change the refractive index distribution in the width direction of the light propagation layer and to make the shape of the refractive index distribution in the longitudinal direction of the light propagation layer and its peripheral part uniform. Can do. As a result, an ultra-low loss waveguide with low scattering loss can be obtained.
[0060]
(2) If a SiO ₂ glass containing at least one additive for lowering the melting point such as Ge, P, and B, such as 8 mol% to 30 mol%, is used as the refractive index control additive, the light propagation layer The refractive index control additive can be easily thermally diffused to change the refractive index distribution in the width direction, and the shape of the refractive index distribution in the longitudinal direction of the light propagation layer and its peripheral part can be made more uniform. . That is, since the interface between the core layer and the cladding layer on the side surface of the core layer can be smoothed, a waveguide with a lower scattering loss can be obtained.
[0061]
(3) If a carbon dioxide laser beam having a wavelength of 10.6 μm is used as a laser beam having a wavelength that is absorbed by a transparent body containing at least one kind of refractive index control additive, it depends on the irradiation condition of the ultrashort pulse laser beam. Since the output power can be selected and adjusted from a wide range, the above effect can be obtained more efficiently.
[0062]
(4) Concavities and convexities on the periphery of the light propagation layer formed by a pulsed laser beam by using a continuous oscillation laser beam as a laser beam having a wavelength that is absorbed by a transparent body containing at least one kind of refractive index control additive Can be made uniform in the longitudinal direction.
[0063]
(5) As a power density distribution of a laser beam having a wavelength that is absorbed by a transparent body containing at least one kind of refractive index control additive, a light propagation layer is formed by using a substantially TEM ₀₁ mode laser beam having a recessed central portion. The longitudinal non-uniformity of the peripheral part of the light propagation layer can be corrected with almost no change in the refractive index of the central part.
[0064]
(6) Various light-transmitting layers can be formed in a two-dimensional or three-dimensional manner using a linear pattern, a curved pattern, or a combination thereof in a transparent body containing at least one kind of refractive index control additive. An optical signal processing circuit can be formed.
[0065]
(7) As the light propagation layer, it is possible to form an optical signal processing circuit for branching and combining optical signals, or for demultiplexing and combining optical signals of various wavelengths. An optical signal processing circuit can be realized.
[0066]
(8) By forming at least one transparent body containing at least one kind of refractive index control additive on the substrate, various electric circuits, electronic components, optical circuits, light on, under or inside the substrate. An optical device mounted with elements and the like can be obtained.
[0067]
(9) By forming the light propagation layer in at least one of the layers, a highly integrated and multifunctional optical circuit can be realized.
[0068]
(10) By covering a transparent body containing at least one kind of refractive index control additive with a layer having a lower refractive index, an optical circuit with better light confinement by the light propagation layer, external environment (temperature change, humidity change) Etc.) can be realized.
[0069]
(11) A low-loss waveguide can be manufactured stably and with good reproducibility. Further, the refractive index distribution in the width direction of the manufactured waveguide can be easily adjusted. Furthermore, the uniformity in the longitudinal direction of the light propagation layer and its peripheral part can be further improved. Further, the above effect can be further enhanced by using a carbon dioxide laser or a continuously oscillating laser beam as the rear laser beam irradiated after the ultrashort pulse laser beam irradiation. Further, if a TEM ₀₁ mode laser beam is used as the power density distribution of the rear laser beam, the uniformity in the longitudinal direction of the light propagation layer and its peripheral portion can be improved.
[0070]
【The invention's effect】
In short, according to the present invention, it is possible to provide a method for manufacturing a waveguide with low light scattering loss.
[Brief description of the drawings]
1A is a conceptual diagram showing an embodiment of a method for manufacturing a waveguide according to the present invention, and FIG. 1B is a cross-sectional view taken along line 1b-1b of the waveguide shown in FIG. (C) is a figure which shows the refractive index distribution in the 1c-1c line cross section of (b).
FIGS. 2A and 2B are conceptual diagrams showing another embodiment of the waveguide manufacturing method of the present invention.
FIG. 3 is a conceptual diagram showing another embodiment of the waveguide manufacturing method of the present invention.
FIG. 4 is a conceptual diagram showing another embodiment of the waveguide manufacturing method of the present invention.
5A is a schematic diagram of a laser beam used for manufacturing the waveguide of the present invention, and FIG. 5B is a diagram showing the power density in the radial direction of the laser beam shown in FIG. (C) is a figure which shows a power density distribution in three dimensions.
6A is a conceptual diagram showing another embodiment of the waveguide manufacturing method of the present invention, and FIG. 6B is a refractive index of the waveguide shown in FIG. 6A taken along the line 6b-6b. It is the figure which superimposed the distribution and the refractive index distribution in a 6b'-6b 'line cross section.
7A to 7C are structural views of other waveguides to which the waveguide manufacturing method of the present invention is applied. FIG.
8A is a side view of a waveguide having a photonic crystal structure, FIG. 8B is a sectional view taken along line 8b-8b in FIG. 8A, and FIG. 8C is a refractive index at a section taken along line 8c-8c. It is a figure which shows distribution.
9A is a conceptual diagram showing a conventional waveguide manufacturing method, FIG. 9B is a plan view of a waveguide to which the manufacturing method shown in FIG. 9A is applied, and FIG. It is a figure which shows the refractive index distribution in the 9c-9c line cross section of the waveguide shown to b).
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Transparent body 11-1, 11-2 Ultrashort pulse laser beam 12, 16 Lens 14, 17 Light propagation layer 15-1, 15-2 Laser beam

Claims (5)

A transparent body containing at least one kind of refractive index control additive is irradiated and condensed with an ultrashort pulse laser beam, and the ultrashort pulse laser beam or the transparent body is relatively moved to change the refractive index of the condensing part. In the method for manufacturing a waveguide in which a light propagation layer is formed with a refractive index higher than that of the transparent body, the ultrashort pulse laser beam has a wavelength in the range of 250 nm to 1600 nm and a pulse width of 1000 femtoseconds or less and 30 femtoseconds. above, and the used as the repetition frequency is 300kHz or less 50kHz or more, the ultra-short pulse laser beam condensing, after irradiation, carbon dioxide laser beam having a wavelength that is absorbed into the transparent body to the light propagation layer A method of manufacturing a waveguide, further comprising condensing and irradiating. As the refractive index control additives, Ge, P, comprising at least one of elements lowering the melting point of B, etc., according to claim 1 in which the content of using 30 mol% or less of SiO ₂ glass 8 mol% A method of manufacturing a waveguide. Method for producing a waveguide according to claim 1 or 2 using the laser beam oscillates continuously as the carbon dioxide laser beam. As the carbon dioxide gas laser beam, it has a recessed shape the power density distribution of the center portion, the manufacturing method of the waveguide according to any one of claims 1 to 3, to use those having a substantially TEM ₀₁ mode. Guide according to any one of 4 to further the carbon dioxide gas laser beam in a region other than the light propagation layer of the transparent body irradiation, claim 1 of forming a photonic band gap structure with a large number of pores is condensed A method for manufacturing a waveguide.

Images