JP2002311277A - Production method for glass waveguide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method for a glass waveguide, by which the glass waveguide having low-loss stable characteristics can be provided. SOLUTION: The light propagating part of a high refraction factor is formed by converging a femto-sec laser pulse 2 at a position almost in the 1/2 thickness of a transparent glass pane 1. Since the light propagating parts 5 of the high refraction factor are continuously formed inside the transparent glass pane 1 by relatively moving this transparent glass pane 1 and the focal point of the femto-see laser pulse 2, even when thermal distortion caused by laser radiation is remained in the transparent glass pane 1, since the waveguide has an almost symmetric structure, polarization dependency hardly occurs.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a glass waveguide.

[0002]

2. Description of the Related Art By condensing and irradiating a femtosecond laser pulse beam on the surface of a glass plate or inside the glass plate, the refractive index of the irradiated minute region is increased, and the high refractive index region is formed. A method of realizing a waveguide through which light propagates by continuously forming a glass plate in the X, Y, or Z directions has been proposed.

FIG. 8A is a cross-sectional view when a waveguide is formed in synthetic quartz glass, FIG. 8B is a cross-sectional view when a waveguide is formed in fluoride glass, and FIG. FIG. 3 is a cross-sectional view when a waveguide is formed in optical glass.

FIGS. 8A and 8B show that the thickness of the waveguides 20a to 20c changes depending on the type of glass.

FIG. 9A is a cross-sectional view showing a case where a laser beam is moved in parallel to the surface of a sample and irradiated.
(B) is a cross-sectional view when the laser beam is moved along the surface of the sample while being moved perpendicularly to the surface of the sample and irradiated.

FIGS. 9A and 9B show that the waveguides 21a and 21b are formed according to the movement of the focal point of the laser beam. That is, when the laser beam is moved in parallel along the surface of the sample, a linear waveguide 21a is formed (FIG. 9A), and the surface of the sample is moved while moving the laser beam perpendicularly to the surface of the sample. In the case of moving along the flow path, a wavy waveguide 21b is formed.
(B)).

[0007]

However, the above-described method of forming a waveguide is a stage at which the principle method has been confirmed, and there are a number of problems for practical use as a waveguide. The prospect is not yet available. (1) Very short pulse width (several tens of femtoseconds (fs)
Since a laser beam having a large output (hundreds of billions to several billions of watts) is irradiated to the glass plate during several hundred fs), a slight thermal distortion remains in the glass plate, and this distortion is dependent on the polarization. A waveguide structure with a defect is formed. (2) Since the waveguide structure is asymmetric, the light propagation characteristics tend to fluctuate with temperature changes. (3) Low loss characteristics are not realized. There was a problem.

An object of the present invention is to solve the above-mentioned problems and to provide a method of manufacturing a glass waveguide capable of obtaining a glass waveguide having low loss and stable characteristics.

[0009]

In order to achieve the above object, a method of manufacturing a glass waveguide according to the present invention is to focus a femtosecond laser pulse beam on a transparent glass plate at a position having a thickness of about 1/2. At the same time, the focal point of the femtosecond laser pulse beam and the transparent glass plate are relatively moved along the surface direction of the transparent glass plate to continuously form a light transmission layer having a high refractive index.

In addition to the above configuration, the method of manufacturing a glass waveguide according to the present invention further comprises:
0 nm to 2400 nm, the pulse width is several tens femtoseconds to several hundred femtoseconds, and the number of repetitions is several tens Hz to several hundreds H.
z, the average output is preferably 10 mW to several hundred mW, and the focused spot diameter is preferably several μm to several tens μm.

In addition to the above structure, the method for manufacturing a glass waveguide of the present invention is characterized in that, as the transparent glass plate, quartz glass having an extremely low hydroxyl group, athermal glass having a thermal expansion coefficient of substantially zero, or quartz glass or athermal glass having a high melting point is used. It is preferable to use one containing at least one kind of dopant for controlling the refractive index.

In addition to the above structure, the method of manufacturing a glass waveguide according to the present invention is characterized in that the shape of the high-refractive-index light propagation layer in the transparent glass plate has a desired thickness and width, at least a straight line, a curve, and both. It is preferable to irradiate a femtosecond laser pulse beam so as to include a pattern including a directional coupler type pattern and a Y-branch type pattern.

In addition to the above structure, the method for manufacturing a glass waveguide according to the present invention is characterized in that a dopant for lowering the refractive index such as F or B is previously provided on the entire transparent glass plate or on the outer periphery of the irradiation part of the femtosecond laser pulse beam. And it is preferable to irradiate with a femtosecond laser pulse beam.

In addition to the above configuration, the method of manufacturing a glass waveguide according to the present invention controls the refractive index of the high-refractive-index light propagation layer by adjusting the pulse width and average output of a femtosecond laser pulse beam. Is preferred.

In addition to the above configuration, in the method of manufacturing a glass waveguide of the present invention, it is preferable to form at least one different refractive index region having a different refractive index in the middle of a high refractive index light propagation layer.

In addition to the above configuration, in the method of manufacturing a glass waveguide of the present invention, it is preferable that the shape of the different refractive index region is spherical.

In addition to the above structure, the method for manufacturing a glass waveguide according to the present invention is characterized in that at least one rare earth element is added in advance to the entire transparent glass plate or to the outer periphery of the irradiation part of the femtosecond laser pulse beam. Irradiation with a pulse beam is preferred.

In the method of manufacturing a glass waveguide of the present invention, in addition to the above structure, it is preferable that a transparent glass plate containing a dopant for controlling the refractive index is manufactured by a sol-gel method or a flame deposition method.

According to the present invention, a light transmitting portion having a high refractive index is formed by condensing a femtosecond laser pulse at a position approximately half the thickness of a transparent glass plate. By relatively moving the transparent glass plate and the focal point of the femtosecond laser pulse, a high-refractive-index light propagation layer is continuously formed in the transparent glass plate. Even if the distortion remains, the waveguide has a substantially symmetrical structure, so that polarization dependency hardly occurs.

Further, according to the present invention, even if the environmental temperature changes, the waveguide has a substantially symmetric structure, so that the optical characteristics hardly change.

Further, according to the present invention, by using a quartz glass plate having an extremely low hydroxyl group as the transparent glass plate,
It is possible to obtain a low-loss, wide-band glass waveguide with extremely small absorption loss due to hydroxyl groups in a wavelength of 1.39 μm.

Further, according to the present invention, a temperature-independent waveguide can be realized by using athermal glass having a thermal expansion coefficient of substantially zero (for example, crystallized glass manufactured by Nippon Electric Glass).

By using the glass waveguide of the present invention to constitute an optical signal processing circuit such as an optical directional coupler, an optical demultiplexer, an optical multiplexer, an optical star coupler, etc. Is hardly changed, and low loss and low polarization characteristics can be realized.

Further, according to the present invention, by using a transparent glass plate containing at least one kind of high melting point refractive index controlling dopant which is hardly diffused by laser irradiation, these dopants can be irradiated by laser irradiation. The oxide can be changed to a uniform and dense oxide, and the relative refractive index difference between the laser-irradiated portion and the laser non-irradiated portion can be increased.

Further, according to the present invention, since the transparent glass plate contains dopants such as F and B which lower the refractive index in the entire transparent glass plate, these dopants have a low melting point, so that they can be easily irradiated by laser irradiation. The light diffuses and moves to the non-laser-irradiated portion, and the relative refractive index difference between the light propagation layer and the glass containing the low-refractive-index dopant can be further increased. Further, F has an effect of reacting with a hydroxyl group in the transparent glass plate at a high temperature to act as a dehydrating acid group, thereby realizing a waveguide having a lower hydroxyl group.

Furthermore, according to the present invention, a waveguide grating, an optical resonator, and the like are formed by forming at least one different refractive index region having a different refractive index in the middle of a high refractive index light propagation layer. be able to. This different refractive index region can be realized by adjusting the pulse width and average output of the femtosecond laser pulse beam. It is possible to realize an optical resonator, an optical filter, and the like by forming a different refractive index region into a spherical shape and forming a plurality of spherical different refractive index regions at predetermined intervals in the light propagation direction of the transparent glass plate. it can.

Furthermore, according to the present invention, by using at least one rare earth element added to the entire transparent glass plate or the laser irradiation area, active functions such as an optical amplifier and laser oscillation can be achieved. The optical component having the function described above can be realized. That is, a transparent glass plate to which a rare earth element is added is formed by a sol-gel method (or a flame deposition method + a method of dipping a rare earth element compound dissolved in alcohol + a high temperature heating method), and the like. By irradiating a half-thick position with a femtosecond laser pulse beam, it is possible to increase the refractive index and to achieve a uniform distribution of the rare earth element in the irradiation region. By inputting pumping light together with signal light to such a waveguide, an active functional circuit such as high gain optical amplification and high output optical oscillation can be realized.

[0028]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is an explanatory view showing one embodiment of a method for manufacturing a glass waveguide according to the present invention.

In the method of manufacturing the present glass waveguide, the femtosecond laser pulse beam 2 is condensed at a position having a thickness of about の in the transparent glass plate 1 and the focal point of the femtosecond laser pulse beam 2 Transparent glass plate 1 with glass plate 1
Is relatively moved along the surface direction of the light transmitting layer 5 having a high refractive index.
Are formed continuously.

In irradiating the transparent glass plate 1 with the femtosecond laser pulse beam 2, the wavelength of the femtosecond laser pulse beam 2 is 200 nm to 2400 nm, the pulse width is several tens fs to several hundred fs, and the number of repetitions is It is several tens Hz to several hundred Hz, and the average output is 10 mW to several hundred mW.
It is preferable that the focused spot diameter is several μm to several tens μm.

As described above, the thickness of the transparent glass plate 1 is approximately 1 /
By condensing the femtosecond laser pulse beam 2 at the position 2, a light propagation portion having a high refractive index is formed. By relatively moving the transparent glass plate 1 and the focal point of the femtosecond laser pulse 2, the light-transmitting layer 5 having a high refractive index is continuously formed in the transparent glass plate 1. Even if thermal distortion due to laser irradiation remains, the polarization dependence is unlikely to occur because the waveguide has a substantially symmetric structure.

In the following, specific numerical values will be described.
The present invention is not limited to this.

As a transparent glass plate 1 shown in FIG. 1, a very low hydroxyl group quartz glass plate (1200 ° C. of SiCl ₄ and O ₂₎
(An anhydrous quartz glass plate having a thickness of 0.5 mm) produced by the high-temperature reaction described above. While continuously moving the transparent glass plate 1 in the direction of arrow 6 at a constant speed, the transparent glass plate 1 is placed inside the glass plate substantially at the center of the thickness t (0.5 mm) of the transparent glass plate 1 (that is, at the position of t / 2). Femtosecond laser pulse beam 2
Was collected by the lens 3.

Here, the femtosecond pulse laser pulse beam 2 has a wavelength of 800 nm, a pulse width of 100 fs,
A femtosecond laser pulse beam having a repetition frequency of 220 kHz and an average output of 200 mW was used. As a result, FIG.
As shown in the figure, a light propagation layer 5 having a high refractive index and a substantially circular cross-sectional shape (about 10 μm in diameter) is continuously provided in a position substantially at half the thickness direction of the transparent glass plate 1 in the length direction of the transparent glass plate 1. Could be formed.

The refractive index of the high-refractive-index light propagation layer 5 could be changed by the moving speed of the transparent glass plate 1 in the direction of arrow 6. That is, as the moving speed of the transparent glass plate 1 is lower, the refractive index of the light propagation layer 5 can be increased,
The higher the moving speed of the transparent glass plate 1, the lower the refractive index of the light propagation layer 5 can be. When the moving speed of the transparent glass plate 1 was in the range of 1 mm / sec to 10 mm / sec, the relative refractive index difference between the light propagation layer 5 and the quartz glass plate 1 could be changed from about 0.5% to about 0.06%. (This is a value roughly calculated from the near-field pattern at the exit end of the waveguide, and He-Ne laser light having a wavelength of 632.8 nm was used as light propagating into the waveguide.) Wavelengths of a waveguide having a relative refractive index difference of about 0.5% are 1300 nm and 1550 nm.
As a result of measuring the light propagation loss at 0.03 dB / cm,
0.02 dB / cm was obtained. In addition, there was almost no difference in propagation loss between the TE wave and the TM wave.
For comparison, a commercially available water-containing quartz glass plate (thickness 0.5
mm), the light propagation loss at a wavelength of 1300 nm and a wavelength of 1550 nm of a waveguide having a light propagation layer formed near the surface layer was measured to be 0.09 dB / cm.
12 dB / cm, each having a large loss,
Loss at 1550 nm increased due to the effect of hydroxyl groups.

FIG. 2 is an explanatory view showing another embodiment of the method for manufacturing a glass waveguide of the present invention.

The glass waveguide shown in FIG. 2 was prepared by high temperature (1200 ° C.) reaction with SiCl ₄ and TiCl ₄ and O _2, with TiO ₂ doped anhydrous quartz glass plate, substantially at the center of the transparent glass plate 1 The light propagation layer 5 having a high refractive index is formed on the substrate. This glass waveguide was also able to realize a waveguide having a larger relative refractive index difference as the moving speed of the glass plate 1 in the direction of the arrow 6 was slower. The relative refractive index difference is shown in FIG.
The maximum was about 0.8%, which was larger than the case of the glass waveguide shown in FIG.

When a dopant having a low melting point such as GeO ₂ or P ₂ O ₅ is used in addition to TiO ₂ , a very large relative refractive index difference cannot be obtained, and a high relative refractive index difference such as TiO ₂ or Nb ₂ O ₃ cannot be obtained. When a dopant having a melting point was used, a high relative refractive index difference was obtained. In FIGS. 1 and 2, single-mode and multi-mode waveguides can be manufactured by changing the diameter of a focused spot when a laser pulse beam is focused at substantially the center of the inside of the glass plate 1. Was.

FIG. 3B is a perspective plan view showing an embodiment of a waveguide type optical circuit to which the glass waveguide manufacturing method of the present invention is applied, and FIG. 3A is a plan view. 3 (c) is a right side view of FIG. 3 (b).

The optical circuits shown in FIGS. 3A to 3C are one-input, four-output optical couplers, and include three Y branch circuits 7-1,
7-2 and 7-3 are combined. This optical circuit cannot be realized only by moving the glass plate 1 once in the direction of arrow 6 as shown in FIG. 1, but as shown in FIG. 3 (b), →, →, →
, → can be realized by patterning.

This optical circuit converts the optical signal incident on the light propagation layer 5a-1 into the light propagation layers 5b-1, 5b-2, 5b-3, 5
This is an optical star coupler that is substantially equally distributed to b-4 and emitted.

This optical star coupler was manufactured by using the above-mentioned quartz glass plate having an extremely low hydroxyl group (thickness t: 0.5 mm, width w: 10 m).
m, length 1: 40 mm). The excess loss of this optical star coupler was 0.8 dB, the distribution variation was ± 0.4 dB, and the polarization dependent loss was 0.1 dB or less. Further, in the temperature range of -10 ° C to + 60 ° C, there was almost no increase or decrease in the polarization dependent loss.

FIG. 4B is a plan perspective view showing another embodiment of the waveguide type optical circuit to which the method for manufacturing a glass waveguide of the present invention is applied, and FIG. 4A is a plan view. 4) is a left side view, and FIG. 4 (c) is a right side view of FIG. 4 (a).

The optical circuits shown in FIGS. 4 (a) to 4 (c) are directional coupler type optical circuits, and like the optical circuits shown in FIGS. 3 (a) to 3 (c), are extremely low hydroxyl based quartz. Glass plate (thickness t:
0.5 mm, width w: 5 mm, length 1: 20 mm) 1.

As a result of trial production of a 3 dB coupler using this optical circuit, an excess loss of 0.3 dB, a branching ratio of 3 dB ± 0.4 dB,
A polarization dependent loss of 0.1 dB or less was obtained. Also, there was almost no increase or decrease in the polarization dependent loss when the temperature was in the range of -10 ° C to + 60 ° C.

FIG. 5 is an external perspective view showing another embodiment of a glass waveguide to which the method for manufacturing a glass waveguide of the present invention is applied.

This glass waveguide is formed by using a quartz glass plate of an extremely low hydroxyl group obtained by adding fluorine F to a transparent glass plate 1. Since F has a low melting point, it is easily diffused by laser irradiation. Therefore, the light propagation layer 5
And a high refractive index with a very high density. Since F is added to the transparent glass plate 1, the refractive index is low, and the relative refractive index difference from the light propagation layer 5 can be increased.

Here, as a result of actually evaluating the relative refractive index difference, a maximum of about 1.2% could be obtained. Also, the content of hydroxyl groups in the transparent glass plate 1 itself could be made lower than the content of the glass waveguide shown in FIG. 1 by adding F. Therefore, the light propagation loss of the glass waveguide shown in FIG. 5 was 0.02 dB / cm and 0.015 dB / cm at the wavelengths of 1300 nm and 1550 nm. Although boron B may be added to the transparent glass plate instead of F, it is inferior to F in terms of hygroscopicity.

FIG. 6B is a perspective plan view showing another embodiment of an optical circuit to which the method for manufacturing a glass waveguide according to the present invention is applied, and FIG. 6A is the left side of FIG. 6B. FIG.
FIG. 6C is a right side view of FIG.

The optical circuits shown in FIGS. 6A to 6C have spherical high-refractive-index light transmitting portions 9-1 to 9-11 in the middle of the high-refractive-index light transmitting layers 5a and 5b. The cascaded optical resonators 10 are arranged at desired intervals.

By changing the refractive index of the cascaded optical resonator 10 in this manner, the resonance characteristics (bandwidth, finesse, etc.) of the optical resonator 10 can be adjusted. Also, the resonance characteristics can be adjusted by changing the size of the spheres, the spacing between the spheres, and the like of the spherical high-refractive-index light propagation portion.
Rare earth element ions (for example, E
(r, Nd, Sm, etc.), the wavelength and bandwidth of an optical amplifier and an optical oscillator can be controlled by utilizing the absorption and fluorescence characteristics unique to the rare earth element ions. The size and refractive index of the sphere of the light propagation portion, the interval between the spheres, and the like can be changed by adjusting the pulse width and average output of the femtosecond laser pulse beam.

FIG. 7 is an external perspective view showing another embodiment of a glass waveguide to which the method for manufacturing a glass waveguide of the present invention is applied.

The glass waveguide shown in FIG. 1 uses a transparent glass plate containing a rare earth element in the transparent glass plate 1, and the light propagation layer 11 also contains a rare earth element.

This glass waveguide is a waveguide for optical amplification or light oscillation, and the optical signal propagates along with the pumping light through the light propagation layer having a high refractive index. Erbium E as a rare earth element
r, niobium Nb, ytterbium Yb, samarium S
m, cerium Ce and the like.

The present invention is not limited to the above embodiment.

In FIG. 1, instead of moving the transparent glass plate 1, the laser pulse beam 2 may be continuously moved to form a light-transmitting layer having a high refractive index substantially at the center of the transparent glass plate 1. When a glass plate to which F is added as the transparent glass plate 1 is manufactured by using a sol-gel method or a flame deposition method, a glass plate to which a desired amount of dopant is added can be obtained with low loss.

The wavelength of the femtosecond laser pulse beam is
Wavelength band transmitting through a transparent glass plate, from 200 nm to 24
It can be selected from the range of 00 nm. Further, as the pulse width is smaller, the light output in the enhanced mode can be increased, and the refractive index of the light propagation layer 5 can be increased with less thermal damage.

When an athermal glass having a thermal expansion coefficient of substantially zero is used as the transparent glass plate, a temperature-independent waveguide type optical signal processing circuit can be realized. In addition, the irradiation of the femtosecond laser pulse beam can suppress a high temperature rise of the athermal glass, so that a light transmission layer having a high refractive index can be formed without deteriorating athermal characteristics.

Here, the glass waveguide to which the method for manufacturing a glass waveguide of the present invention is applied has the following effects. (1) Since a femtosecond laser pulse beam is condensed at a position approximately one-half of the thickness of the transparent glass plate to continuously form a high-refractive-index light propagation layer, light having little polarization dependence is generated. A signal processing circuit can be realized. In addition, it was found that the optical characteristics hardly changed even when the environmental temperature changed. (2) Quartz glass having an extremely low hydroxyl group as a transparent glass plate,
If quartz glass containing a high melting point dopant having an extremely low hydroxyl group is used, the absorption loss due to the hydroxyl group in the 1.39 μm wavelength band can be reduced, and from 1.3 μm to 1.3 μm.
A low-loss waveguide can be realized over the 55 μm band. If an athermal glass plate is used as the transparent glass plate, a high-refractive-index light propagation layer can be formed without deteriorating athermal characteristics, and a temperature-independent optical signal processing circuit (optical filter, optical multiplexer / demultiplexer) can be used. , An optical star coupler, etc.). (3) A glass plate in which a dopant for lowering the refractive index such as F is added to the entire transparent glass plate by a flame deposition method,
By manufacturing the transparent glass plate with a femtosecond laser pulse beam by a method such as a gel method or the like, a dopant can be diffused to obtain a waveguide having a high relative refractive index difference. (4) By forming at least one different refractive index region in the middle of the high-refractive-index light propagation layer, a waveguide grating, an optical resonator, or the like can be configured. (5) At least one rare earth element is added to the entire transparent glass plate or the laser-irradiated area.
A transparent glass plate manufactured by a gel method, a flame deposition method, or the like is irradiated with a femtosecond laser pulse beam, thereby realizing a high refractive index in a laser-irradiated region and a uniform distribution of a rare earth element. If the pump light is input to the waveguide thus obtained together with the signal light, high-gain optical amplification, high-output optical oscillation, and the like can be realized.

[0061]

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

It is possible to provide a method of manufacturing a glass waveguide that can obtain a glass waveguide having low loss and stable characteristics.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing one embodiment of a method for manufacturing a glass waveguide of the present invention.

FIG. 2 is an explanatory view showing another embodiment of the method for manufacturing a glass waveguide of the present invention.

FIG. 3B is a perspective plan view showing an embodiment of a waveguide type optical circuit to which the glass waveguide manufacturing method of the present invention is applied, and FIG. 3A is a left side view of FIG. FIG. 7C is a right side view of FIG.

FIG. 4B is a perspective plan view showing another embodiment of the waveguide type optical circuit to which the method for manufacturing a glass waveguide of the present invention is applied, and FIG. 4A is a left side view of FIG. (C) is a right side view of (a).

FIG. 5 is an external perspective view showing another embodiment of the glass waveguide to which the method for manufacturing a glass waveguide of the present invention is applied.

6B is a perspective plan view showing another embodiment of the optical circuit to which the method for manufacturing a glass waveguide of the present invention is applied, FIG. 6A is a left side view of FIG. (C) is (b)
FIG.

FIG. 7 is an external perspective view showing another embodiment of a glass waveguide to which the method for manufacturing a glass waveguide of the present invention is applied.

8A is a cross-sectional view when a waveguide is formed in a synthetic quartz glass, FIG. 8B is a cross-sectional view when a waveguide is formed in a fluoride glass, and FIG. It is sectional drawing in case a waveguide is formed.

FIG. 9A is a cross-sectional view of a case where a laser beam is moved in parallel to a surface of a sample to be irradiated, and FIG. 9B is a view along a surface of the sample while moving the laser beam perpendicular to the surface of the sample. It is sectional drawing at the time of moving and irradiating.

[Explanation of symbols]

 Reference Signs List 1 transparent glass plate 2 femtosecond laser pulse beam 3 lens 5 light propagation layer

Claims (10)

[Claims] 1. A femtosecond laser pulse beam is condensed at a position of approximately 1/2 thickness in a transparent glass plate,
A glass waveguide characterized in that a focal point of the femtosecond laser pulse beam and the transparent glass plate are relatively moved along a surface direction of the transparent glass plate to form a light transmission layer having a high refractive index continuously. Manufacturing method. 2. The femtosecond laser pulse beam has a wavelength of 200 nm to 2400 nm, a pulse width of several tens femtosecond to several hundred femtoseconds, and a repetition rate of several tens Hz.
To several hundred Hz, the average output is 10 mW to several hundred mW,
The method for manufacturing a glass waveguide according to claim 1, wherein the focused spot diameter is several μm to several tens μm. 3. The transparent glass plate includes quartz glass having an extremely low hydroxyl group, athermal glass having a thermal expansion coefficient of substantially zero,
3. The method of manufacturing a glass waveguide according to claim 1, wherein the quartz glass or the athermal glass contains at least one high-melting-point refractive index controlling dopant. 4. The shape of the high-refractive-index light propagation layer in the transparent glass plate has a desired thickness and width, and includes a pattern including at least a straight line, a curve and both, a directional coupler type pattern, and Y 4. The method of manufacturing a glass waveguide according to claim 1, wherein the femtosecond laser pulse beam is irradiated so as to include a branched pattern. 5. The whole of the transparent glass plate or the outer periphery of the irradiation part of the femtosecond laser pulse beam is doped with a dopant such as fluorine or boron to lower the refractive index in advance, so that the femtosecond laser pulse beam is emitted. The method for manufacturing a glass waveguide according to claim 3, wherein the irradiation is performed. 6. The glass according to claim 1, wherein a refractive index of the high-refractive-index light propagation layer is controlled by adjusting a pulse width and an average output of the femtosecond laser pulse beam. Waveguide manufacturing method. 7. The method of manufacturing a glass waveguide according to claim 1, wherein at least one different refractive index region having a different refractive index is formed in the middle of the high refractive index light propagation layer. 8. The method of manufacturing a glass waveguide according to claim 7, wherein the different refractive index region has a spherical shape. 9. The femtosecond laser pulse beam, wherein at least one rare earth element is added in advance to the entirety of the transparent glass plate or the outer periphery of the femtosecond laser pulse beam irradiation part, and the femtosecond laser pulse beam is irradiated. The method for producing a glass waveguide according to any one of the above. 10. The method of manufacturing a glass waveguide according to claim 3, wherein the transparent glass plate containing the dopant for controlling the refractive index is prepared by a sol-gel method or a flame deposition method.