阅读说明：本技术 光学器件和光学器件的制造方法 (Optical device and method for manufacturing optical device ) 是由 长能重博 森岛哲 于 2018-12-19 设计创作，主要内容包括：根据实施例的光学器件的制造方法包括：氢加注步骤,向含有Ge的玻璃部件加注氢；激光照射步骤,将来自飞秒激光器的激光会聚到加注有氢的玻璃部件中,该激光具有引起玻璃部件的光致折射率变化的能量,且具有10kHz以上的重复频率；以及聚光点移动步骤,使激光的聚光点位置相对于玻璃部件移动。重复激光照射步骤和聚光点移动步骤以在玻璃部件中形成连续的折射率变化区域。(The method of manufacturing an optical device according to the embodiment includes: a hydrogen filling step of filling hydrogen into the glass member containing Ge; a laser irradiation step of condensing laser light having energy for causing a change in the photoinduced refractive index of a glass member and having a repetition frequency of 10kHz or more, from a femtosecond laser into the glass member into which hydrogen has been injected; and a condensed point moving step of moving the condensed point position of the laser light relative to the glass member. The laser irradiation step and the focal point moving step are repeated to form continuous refractive index change regions in the glass member.)

1. A method of manufacturing an optical device, comprising:

a hydrogen filling step of filling hydrogen into the glass member containing Ge;

a laser irradiation step of irradiating a laser beam from a femtosecond laser into the glass member to which the hydrogen is added, the laser beam having energy to cause a photoinduced refractive index change of the glass member and having a repetition frequency of 10kHz or more; and

a condensed point moving step of moving a condensed point position of the laser beam with respect to the glass member,

repeating the laser irradiation step and the focal point moving step to form a continuous refractive index change region in the glass member.

2. The method of manufacturing an optical device according to claim 1,

the glass member contains B.

3. The method of manufacturing an optical device according to claim 1 or 2,

the laser beam has a wavelength of 400nm to 540 nm.

4. The method of manufacturing an optical device according to claim 1 or 2,

the laser beam has a wavelength of 800nm or less.

5. The method for manufacturing an optical device according to any one of claims 1 to 4,

in the hydrogen filling step, the glass member is placed in a hydrogen atmosphere of 10atm or more.

6. An optical device manufactured by the manufacturing method of an optical device according to any one of claims 1 to 5,

the glass member is quartz glass, phosphate glass, halide glass, or sulfide glass.

7. An optical device manufactured by the manufacturing method of an optical device according to any one of claims 1 to 5,

the refractive index change of the continuous refractive index change region is greater than 0.02.

Technical Field

The present invention relates to an optical device and a method of manufacturing the optical device.

This application claims priority to japanese patent application No.2018-002656, filed on 11/1/2018, which is incorporated herein by reference in its entirety.

Background

In the technical field such as optical network communication, as cloud services expand, the size of data centers and the capacity of communication data are also rapidly increasing. As an example, for example, the formation of an optical IC based on silicon photonics and the application of a multi-core fiber (hereinafter referred to as "MCF") as a high-density optical wiring are being studied. MCF is attracting attention as a next-generation large-capacity optical fiber because MCF can be used as a means for avoiding an allowable limit due to fiber fusion caused by a high-power beam incident on the optical fiber by space division multiplexing. However, in order to employ an optical member such as an MCF, it is essential to employ a technique of connecting between adjacent MCFs or a technique of connecting each core portion of an MCF to a plurality of single-core optical fibers. As a member capable of connecting between such optical members, for example, a thin coupler, a grating coupler, or the like can be used. In particular, from the viewpoint of productivity and design flexibility, the manufacture of a three-dimensional optical waveguide device in which an optical waveguide is formed in glass by laser drawing (laser drawing) is attracting attention.

For such three-dimensional optical waveguide devices based on laser drawing which have been published so far, glass materials, dopants, amounts of dopants, and irradiation conditions of a femtosecond laser (up to 800nm) based on Ti: S are being studied. For example, according to non-patent document 1, a laser beam is irradiated to a material containing TiO₂The phosphoric acid-based glass of (1) has a refractive index change (difference in refractive index between the substrate and the laser irradiated region) Δ n in the glass of about 0.015 (three-dimensional optical waveguide device fabrication).

CITATION LIST

Patent document

Patent document 1: japanese patent application laid-open No. H9-311237

Patent document 2: japanese patent application laid-open No. H10-288799

Non-patent document

Non-patent document 1: masakiyo Tonoike, "The result of The finished national project on" High-efficiency Processing Technology for 3-D Optical Devices in GLASS ", NEW GLASS Vol.26, No.3,2011, pp.33-44

Non-patent document 2: L.Williams et al, "ENHANCED UVPHOTOSENSITIVITY IN BORONCOPED GERMANOSILICATECIFERS", ELECTRONICS LETTERS,7th January,1993, Vol.29, No.1, pp.45-47

Non-patent document 3: greene et al, "Photoselective Reaction of H2 with German silicate Glass", LEOS'94(1994), Vol.2, PD-1.2, pp.125-126

Non-patent document 4: junji Nishii et al, "ultraviet-radiation-induced chemical reactions through one-and two-photon adsorption process in GeO2-SiO2 glasses", OPTICS LETTERS, Vol.20, No.10, May 15,1995, pp.1184-1186

Disclosure of Invention

The method for manufacturing an optical device according to the present invention includes at least a hydrogen filling step, a laser irradiation step, and a focal point moving step. Repeating the laser irradiation step and the focal point moving step to form a continuous refractive index change region in the glass member to be irradiated with the laser. Specifically, in the hydrogen filling step, hydrogen is filled into the Ge-containing glass member. In the laser irradiation step, a laser beam from a femtosecond laser is condensed into a glass member doped with hydrogen. Note that the laser beam from the femtosecond laser has energy that causes a light-induced refractive index change of the glass member, and has a repetition frequency of 10kHz or more. In the focal point moving step, the position where the glass member is placed and/or the position of the focal point of the laser beam are continuously or intermittently changed, and the focal point of the laser beam is moved within the glass member.

Drawings

Fig. 1 is a flowchart for describing a manufacturing method of an optical device according to an embodiment of the present disclosure.

Fig. 2 is a diagram showing the structure of a manufacturing apparatus that performs the manufacturing method of the optical device shown in fig. 1.

FIG. 3 is a graph showing different materials (SiO) for forming mainly glass parts₂、GeO₂、B₂O₃) A graph of the measurement results of the transmittance change with respect to the wavelength of the incident light beam for each of the above.

Detailed Description

[ problem to be solved by the present disclosure ]

The present inventors have studied a conventional method for manufacturing an optical waveguide device and found the following problems. That is, even with the method disclosed in non-patent document 1, the maximum variation in refractive index is about Δ n of 0.015, and the optical confinement is weak. Inevitably, the radius of curvature of the optical waveguide formed in the glass increases, so that it is necessary to increase the size of the obtained optical device (such as a three-dimensional optical waveguide device) (the size of the optical device increases). Further, in the method disclosed in non-patent document 1, the irradiation time of the femtosecond laser beam to the glass material necessary to obtain a desired increase in refractive index needs to be extended, it is difficult to increase the scanning speed of the femtosecond laser beam, and the manufacturing time becomes correspondingly long, which leads to an increase in manufacturing cost.

The present invention has been made to solve the above-described problems, and an object thereof is to provide a manufacturing method of an optical device capable of forming a high refractive index region in glass, capable of realizing a reduction in size of an optical device such as a three-dimensional optical waveguide device, and capable of realizing a reduction in manufacturing cost, and an optical device obtained by the manufacturing method of the optical device.

[ Effect of the present disclosure ]

According to the present invention, a high refractive index region can be formed inside glass, and the size of an optical device such as a three-dimensional optical waveguide device can be reduced.

[ description of embodiments of the present disclosure ]

First, the details of embodiments of the present disclosure will be separately listed and described.

(1) As one aspect, a method of manufacturing an optical device according to the present disclosure includes at least a hydrogen filling step, a laser irradiation step, and a focal point moving step. Repeating the laser irradiation step and the focal point moving step to form a continuous refractive index change region in the glass member to be irradiated with the laser. Specifically, in the hydrogen filling step, hydrogen is filled into the Ge-containing glass member. The glass member doped with hydrogen is preferably a glass containing no dopant other than Ge or a glass doped with B and Ge. In the laser irradiation step, a laser beam from a femtosecond laser is condensed into a glass member doped with hydrogen. Note that the laser beam from the femtosecond laser has energy that causes a light-induced refractive index change of the glass member, and has a repetition frequency of 10kHz or more. In the focal point moving step, the position where the glass member is placed and/or the position of the focal point of the laser beam are continuously or intermittently changed, and the focal point of the laser beam is moved within the glass member.

Note that "photo-induced refractive index change" herein refers to a change in refractive index in glass caused by light irradiation such as a laser beam. Further, the "refractive index change" is defined by a refractive index maximum difference Δ n of the refractive index in the light irradiation region where the refractive index change has been generated with respect to the refractive index of the region other than the light irradiation region. The refractive index change Δ n in the glass caused by the light irradiation is a combination of a refractive index change Δ np (hereinafter, referred to as "pressure-induced refractive index change") caused by pressure (compressive stress and/or tensile stress) remaining in the glass and a refractive index change Δ nd (hereinafter, referred to as "structure-induced refractive index change") caused by a bond defect of a dopant material occurring in the glass or a composition variation in the glass.

The pressure-induced refractive index change Δ np is generated by, for example, laser irradiation that increases the density of a specific region in the glass as described in non-patent document 1, and Δ np has a maximum value of about 0.015. Further, the structure-induced refractive index change Δ nd is generated by, for example, a refractive index increasing mechanism used in the manufacture of the fiber grating or the like described in non-patent documents 2 to 4.

In patent documents 1 and 2, quartz-based glass doped with a photosensitive material Ge is irradiated with a femtosecond laser to generate a large refractive index change Δ n (═ Δ np + Δ nd), but the refractive index change is about 0.02, which is insufficient. To further increase the change in refractive index Δ n, it is necessary to fill H before irradiation₂。

Irradiation of Ge-containing and H-doped laser beam from femtosecond laser₂The glass member of (1) increases the refractive index change Δ n of the laser beam irradiation region (light-induced region) and accelerates the formation of the refractive index change Δ n. In other words, both the pressure-induced refractive index change Δ np and the structure-induced refractive index change Δ nd are generated in the laser beam irradiation region, and at this time, H₂The injection makes it possible to further increase the structure-induced refractive index change Δ nd, thereby forming a larger refractive index change Δ n (increasing the light confinement efficiency). As a result, the radius of curvature in the refractive index change region (optical waveguide region) formed in the glass member can be designed to be small, so that the size of the obtained optical device can be reduced. Furthermore, the selection of an appropriate dopant makes it possible to reduce the manufacturing time.

(2) As an aspect of this embodiment, the glass part may contain element B. Further, as an aspect of the present embodiment, the refractive index change of the refractive index change region is preferably more than 0.02. As an aspect of the present embodiment, the wavelength of the laser beam from the femtosecond laser is preferably in the range of 400nm to 540nm, or below 800 nm. In this case, both the pressure-induced refractive index change Δ np and the structure-induced refractive index change Δ nd can be generated at the same position inside the glass member irradiated with the laser beam from the femtosecond laser.

(3) As one aspect of this embodiment, in the hydrogen filling step, the glass member is preferably placed in a hydrogen atmosphere of 10atm or more.

(4) An optical device according to the present disclosure is manufactured by any one of the above embodiments or a combination of the embodiments. In particular, as one aspect of the optical device, the glass member is preferably quartz-based glass, phosphate-based glass, halide glass, or sulfide glass.

As described above, each aspect listed in the "description of the embodiments of the present disclosure" applies to all the remaining aspects or all combinations of the remaining aspects.

[ details of embodiments of the present disclosure ]

Hereinafter, specific examples of the optical device and the method of manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the present invention is not limited to these examples and is intended to be defined by the claims and is intended to include all modifications within the scope of the claims and their equivalents. Further, in the description of the drawings, the same members are denoted by the same reference numerals, and redundant description will be omitted.

Fig. 1 is a flowchart for describing a manufacturing method of an optical device according to an embodiment of the present disclosure. Further, fig. 2 is a diagram showing the structure of a manufacturing apparatus that executes the manufacturing method of the optical device shown in fig. 1.

The manufacturing apparatus shown in fig. 2 includes a femtosecond laser 20, a laser driver 25 that drives the femtosecond laser 20, a condensing optical system (condenser) 30, an XYZ stage 40, a stage driver 45 that drives the XYZ stage 40, and a controller 50 that controls the actions of the respective members.

The laser driver 25 controls the power and repetition frequency of a pulsed laser beam (hereinafter, referred to as "femtosecond laser beam") output from the femtosecond laser 20 according to an instruction from the controller 50. This allows the femtosecond laser 20 to output a femtosecond laser beam having a pulse width of several hundred femtoseconds or less. In particular, a femtosecond laser beam whose pulse width is set to several hundred femtoseconds or less is effective because its peak power can reach 10⁵W is more than W. Further, the repetition frequency of the femtosecond laser beam output is preferably 10kHz or more in order to smooth the refractive index and structure of the optical waveguide formed in the glass material. On the device placement surface of the XYZ stage 40, a glass member 10 to be an optical device is placed. The glass member 10 contains Ge so as to generate a pressure-induced refractive index change Δ np and a structure-induced refractive index change Δ nd by laser beam irradiation. More specifically, glass member 10 is doped with a material other than GeGlass doped with B and Ge. The glass is quartz glass, phosphate glass, halide glass or sulfide glass. H is to be₂Pre-filled into the glass part. The femtosecond laser beam output from the femtosecond laser 20 is condensed into the glass member 10 (condensed point position 35) placed on the XYZ stage 40 by the condensing optical system 30, which causes the refractive index change region 15 (optical waveguide) to be formed in the glass member 10.

The stage driver 45 drives the XYZ stage 40 according to instructions from the controller 50 to move the device placement surface of the XYZ stage 40 along the X axis, the Y axis, or the Z axis. Such a structure allows the focal point position 35 of the femtosecond laser beam to be relatively moved with respect to the glass member 10. The controller 50 controls the action of each of the laser driver 25 and the stage driver 45 as described above, thereby forming the refractive index variation region 15 (manufacturing of an optical waveguide device serving as an optical device) having a desired pattern (corresponding to the shape of an optical waveguide projected on an XY plane containing information in the depth direction of the Z axis) in the glass member 10.

Next, a manufacturing method of an optical device according to the present embodiment in which the manufacturing apparatus configured as described above is used to manufacture an optical device (an optical device according to the present embodiment) will be described with reference to a flowchart of fig. 1. Note that in the following description, a case of manufacturing a three-dimensional optical waveguide device (optical device) that forms an optical waveguide (refractive index change region) having a desired pattern will be described as an example.

The manufacturing method of an optical device according to the present embodiment includes a preparation step and an optical waveguide manufacturing step. First, in a preparation step, a glass member 10 (for example, parallel plate glass) to be a three-dimensional optical waveguide device is prepared, and the glass member 10 is temporarily placed in a chamber. In the case where the glass member 10 is placed, 100% hydrogen gas is introduced into the chamber, and the pressure in the chamber is maintained at 10atm or more. The hydrogen filling period ranges from one day to half a year. This allows hydrogen to be charged into the glass member 10 (step ST 10). Note that, when the optical waveguide manufacturing step is not performed immediately after the hydrogen filling step in step ST10, the hydrogen-filled glass member 10 is kept at a temperature of-10 ℃ or lower to suppress hydrogen from escaping from the glass member 10 (step ST 15). Note that step ST15 (low temperature keeping step) is performed during the period shown by points a and B in fig. 1.

In the optical waveguide manufacturing step, an optical waveguide (refractive index changing region 15) having a desired pattern is formed in the glass member 10 to which hydrogen is added. Specifically, immediately after step ST10, the glass part 10 to which hydrogen has been added is placed on the device placement surface of the XYZ stage 40 and irradiated with a femtosecond laser beam (step ST 20). The controller 50 controls the laser driver 25 to cause the femtosecond laser 20 to output the femtosecond laser beam having energy to cause the light-induced refractive index change of the glass member 10 and having a repetition frequency of 10kHz or more. The femtosecond laser beam output from the femtosecond laser 20 is condensed into the glass member 10 by the condensing optical system 30 to cause a photoinduced refractive index change in the vicinity of a condensing point position 35 (light condensing region) of the femtosecond laser beam. When the predetermined portion of the glass member 10 has been irradiated with the laser light, the controller 50 controls the stage driver 45 to move the position of the glass member 10 placed on the device placing surface of the XYZ stage 40 (step ST 30). As described above, in the condensed point moving step (step ST30), the position where the glass member 10 is placed and/or the condensed point position 35 of the femtosecond laser beam are continuously or intermittently changed, so that the condensed point position 35 of the femtosecond laser beam is moved within the glass member 10.

Note that the laser irradiation step in step ST20 and the condensed point moving step in step ST30 are repeated, that is, the operation control of the laser driver 25 and the operation control of the stage driver 45 performed by the controller 50 are repeated under a fixed condition or under a changed condition while returning to point C in fig. 1 until a previously designed optical waveguide pattern is formed in the glass member 10 (step ST 40). When the optical waveguide (refractive index change region 15) is formed in the glass member 10 (step ST40), the glass member 10 is subjected to aging treatment to keep Δ n constant for a long time, and the glass member 10 is annealed to remove residual hydrogen (step ST 50). Through the above steps (steps ST10 to ST50 or steps ST10 to ST50 including step ST15), a three-dimensional optical waveguide device is obtained.

Next, details of the laser irradiation step (step ST20) for manufacturing the three-dimensional optical waveguide device will be described.

First, in order to manufacture a three-dimensional optical waveguide device, it is required that a laser beam be condensed to a glass member serving as a substrate. That is, by moving the light converging region (including the focal point position 35) of the laser beam relative to the glass member (scanning the laser converging region) while increasing the refractive index in the light converging region, a refractive index changing region having a desired pattern is formed in the glass member. In order to form such a refractive index change region having a desired pattern, a laser light source and a condensing optical system are required as an irradiation system, and a movable stage that operates in cooperation with the condensing optical system is required. In the example shown in fig. 2, there are provided a femtosecond laser 20 serving as a laser light source and a laser driver 25, a condenser serving as a condensing optical system 30, and an XYZ stage 40 serving as a movable stage and a stage driver 45. The controller 50 controls the action of each member.

The mechanism of increasing the refractive index in the glass member by converging the laser beam to the glass member is classified into the following two mechanisms.

The first mechanism is a refractive index increasing mechanism using a Ti: S laser (femtosecond laser having a wavelength of 800nm or less). According to the refractive index increasing mechanism using the Ti: S laser, high-pressure plasma is generated in the glass member where the laser is condensed. In the laser convergence region of the glass member, dynamic compression caused by the impact of the high-pressure plasma generates and propagates pressure waves outward, thereby making the glass in the laser convergence region loose (coarse). Further, after laser irradiation, elastic confinement applies a compressive stress to the center of the laser-condensed region, so that a high-density glass region is formed in the glass member. At this time, the refractive index change Δ n in the high-density glass region is about 0.015 (see non-patent document 1). The change in refractive index caused by the first mechanism corresponds to a pressure-induced change in refractive index Δ np.

Note that the laser wavelength used may be about 800nm as described above, or may be in the range of 400nm to 540 nm. In the wavelength range of 800nm or less, a laser (e.g., Ti: S laser) that outputs a stable laser beam can be used. The effectiveness of the wavelengths from 400nm to 540nm will be described later. However, with the first mechanism (Δ n generation method using high-pressure plasma) in which the refractive index change is generated from the high-pressure plasma, it is difficult to further increase the refractive index change Δ n. Therefore, in the present embodiment, a Δ n generation method for a fiber grating (second mechanism) is employed.

In the second mechanism, the silicon substrate will be doped with GeO₂Etc. are put into a high-pressure atmosphere of hydrogen so as to charge hydrogen into the glass member. Subsequently, the hydrogen-filled glass part was irradiated with a UV laser of about 250 nm. The reason for using the UV laser of about 250nm is that the UV laser cuts off such as GeO₂Bonds of the doping material (bond defects of the doping material) and due to H₂And Ge, Si, and O vary in composition to cause high density change of the glass (see non-patent document 3 and non-patent document 4 described above). Further, by the action of the element B, the formation of the refractive index change Δ n is accelerated, and the refractive index change Δ n thus generated becomes about 0.01 (see the above-mentioned non-patent document 2 and non-patent document 4). The change in refractive index resulting from the second mechanism corresponds to a structure-induced change in refractive index Δ nd.

According to the present embodiment, it is expected that the combination of the first mechanism that produces the pressure-induced refractive index change Δ np in the glass member and the second mechanism that produces the structure-induced refractive index change Δ nd in the glass member produces a refractive index change (light-induced refractive index change) Δ n of more than 0.02 at the maximum. As described above, according to the present embodiment, since a larger refractive index change can be generated in the glass member than in the related art, that is, the light confinement efficiency of the high refractive index region (optical waveguide) formed in the glass member can be improved, the size of the optical device such as the three-dimensional optical waveguide device can be reduced. This also makes it possible to increase the manufacturing speed.

(wavelength of laser beam)

A glass member manufactured as an optical device according to the present embodiment, for example, applied to the above-described three-dimensional optical waveguide device needs to contain a dopant uniformly in the entire glass. Therefore, unlike, for example, fiber gratings, it is not possible to use optical gratings such as GeO₂The dopant dopes only the region (core) where an increase in refractive index is desired. When completely irradiated with a UV beam with GeO doping₂Etc., even in the case of constructing an irradiation optical system capable of condensing a light beam to a desired position, the UV light beam is absorbed immediately after entering the glass member; therefore, the required energy cannot be concentrated in the light converging region of the UV beam. Even if the required energy can be concentrated in the light converging region of the UV beam, the refractive index will increase over the entire region extending from the incident surface of the glass member to the light converging region of the UV beam, which makes it difficult to form a desired optical waveguide in the glass member.

Therefore, according to the present embodiment, two-photon absorption equivalent to energy having a wavelength of about 250nm is used instead of the UV beam. That is, according to the present embodiment, a laser beam having a high peak power with a wavelength of about 500nm is made incident on the glass member to increase the photon density in the laser condensing region of the glass member. When the probability of two-photon absorption increases as described above, a dopant material (such as GeO)₂Etc.) is cut by energy having a wavelength of about 250nm, and thus may cause composition variations. Here, in order to increase the photon density in the laser light condensing region, the focal length of the condenser is preferably 100mm or less. Further, as the condenser, an achromatic lens capable of suppressing chromatic aberration generated by a multi-wavelength component of the short pulse laser is effective. When the wavelength of the irradiation beam is 800nm or more, three or more photon absorptions must be efficiently generated; therefore, the condenser preferably has an f of 100mm or less.

In addition, doping is prevented from materials (such as GeO)₂Etc.) there is an effective laser wavelength range from the standpoint of the wavelength absorbed and the energy to cut the bonds of the doped material. FIG. 3 is a graph showing different materials (SiO) for forming mainly glass parts₂、GeO₂、B₂O₃) A graph of the measurement results of the transmittance change with respect to the wavelength of the incident light beam for each of the above. Note that, in fig. 3, a wavelength range R1 between the line a 'and the line B' indicates a wavelength range corresponding to two-photon absorption, and a wavelength range R2 between the line a and the line B indicates an incident wavelength range.

For example, GeO₂One end of the band gap of (A) is opposite to that of (B)₂O₃Is located on the longer wavelength side, and GeO₂Absorbing up to about 400 nm. Therefore, the end on the shorter wavelength side of the incident wavelength range R2 is preferably equal to or higher than 400nm of the line a of which the material does not absorb light. Since the wavelength of 400nm is transparent to the material, the laser beam incident on the glass member is converged to a predetermined position in the glass member. Since the energy of two-photon absorption at 400nm wavelength is equivalent to about 200nm, B can be cut off₂O₃And GeO₂The bond of both. As a result, it can be seen that the laser beam having a wavelength of 400nm or more effectively causes the composition variation in the glass member. On the other hand, the condition of the limit (upper limit) of the longer wavelength side of the incident wavelength range R2 is an energy required to cut the bonds of all the dopant materials. In this case, since the wavelength of energy obtained by two-photon absorption is equal to or lower than B₂O₃270nm (limit on the longer wavelength side of the wavelength range R1), the limit (upper limit) on the longer wavelength side of the incident wavelength range R2 is required to be equal to or lower than 540 nm.

As can be seen from the above, for B₂O₃And GeO₂The laser beam incident on the glass member has a wavelength (incident wavelength) in the range of 400nm to 540nm, which is particularly effective. In addition, setting the wavelength of the laser beam to the range from 400nm to 540nm makes it possible to make the positions where both the pressure-induced refractive index change Δ np and the structure-induced refractive index change Δ nd are generated coincide with each other; therefore, as in the present embodiment, it is very effective in manufacturing a three-dimensional optical waveguide device or the like as an optical device.

Note that in the case of using laser beams having different wavelengths, in general, two types of laser beams having a wavelength of 450nm and a wavelength of 225nm are condensed by a condenser. When an achromatic lens is used as the condenser, it is difficult to completely eliminate chromatic aberration (condensed points of laser beams having respective wavelengths are different from each other). That is, since the refractive index change Δ np due to pressure and the refractive index change Δ nd due to structure occur in different regions in the glass member, it is difficult to design a highly precise optical waveguide (high refractive index region to be formed in the glass member).

Further, in addition to the laser beam irradiation selected based on the wavelength as described above, it is also effective to use a laser beam having a wavelength of about 800nm from a Ti: S laser to generate a refractive index change Δ np caused by pressure caused by plasma and a refractive index change Δ nd caused by a structure generated by multi-photon absorption more than two-photon absorption.

As a condition required for the laser light source, a fundamental wavelength and a wavelength conversion wavelength of a solid laser, a gas laser, a fiber laser, or the like having a pulse width narrower than 1 picosecond and having a high peak power are effective. In particular, it is effective that the pulse width is several hundred femtoseconds or less, because the peak power can be set to 10⁵W is more than W. Further, the repetition frequency of the pulse laser beam output from the laser light source is preferably 10kHz or more, thereby shortening the manufacturing time.

List of reference numerals

10 … … glass components; 15 … … refractive index changing region (optical waveguide); 20 … … femtosecond laser; 25 … … laser driver; 30 … … condenser optics (condenser); 40 … … XYZ stage; 45 … … drivers; and a 50 … … controller.