JP4348347B2 - Method for producing glass optical waveguide film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a glass optical waveguide film by which the glass optical waveguide film having little distribution in the refractive index and being uniform is manufactured. <P>SOLUTION: In the method for manufacturing the glass optical waveguide film, comprising forming a deposited layer of glass fine particles by directly blowing and depositing the glass fine particles onto a substrate 11 arranged on a rotary turn table 31 by a burner 21 for synthesizing the glass fine particles and then converting the deposited layer into transparent glass at a high temperature, the temperature distribution of the substrate or the turn table is previously formed in accordance with the relative velocity of the burner and the substrate by controlling the temperature of a heat source so that the temperature of the substrate becomes constant when the glass fine particles are deposited. <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

Description

  The present invention relates to a method for producing a glass optical waveguide film that is a component of a waveguide type optical component.

Research and development of optical communication systems using the optical wavelength division multiplexing (WDM) system, which can communicate high-capacity information including images and video at ultra-high speed, due to recent advances in hardware and software related to personal computers and the development of the Internet Commercial introduction has begun mainly in the United States. Among the optical components that make up such an optical communication system, an optical splitter that combines and splits light, an optical star coupler, an optical wavelength multiplexer / demultiplexer that multiplexes and demultiplexes light of different wavelengths, and an optical switch that switches optical paths and so on. As an implementation form of these optical components, a bulk type, an optical fiber type, and a waveguide type are known.
The waveguide type can be realized by applying LSI manufacturing technology and forming optical waveguides on a flat substrate in a lump to realize the optical circuit function. Compared to the bulk type that combines prisms and lenses and the optical fiber type that processes the optical fiber itself. In addition to being excellent in integration, mass productivity, and stability, a large-scale circuit configuration can be realized.

  Silica-based glass optical waveguides fabricated on substrates such as silicon and quartz are made of other materials because they have good compatibility with silica-based optical fibers and can form stable and highly reliable optical circuits. Development of practical optical components is progressing compared to waveguides. Since a high-quality optical waveguide can be formed on a large substrate of 4 to 6 inches, a large scale such as a 144 × 144 star coupler, a 128-wave optical multiplexer / demultiplexer composed of an arrayed waveguide grating, a 16 × 16 thermo-optic switch, etc. A circuit is realized.

A method for producing a quartz optical waveguide will be described (see FIG. 1).
(a) A glass fine particle layer 12a for a lower clad layer mainly composed of SiO ₂ and a glass fine particle for a core layer by a flame hydrolysis reaction of a glass forming raw material gas mainly composed of SiCl ₄ on a substrate 11 (for example, a silicon substrate). Layers 13a are formed sequentially.
(b) The glass fine particle layers 12a and 13a are heated together with the substrate 11 in an electric furnace to form a transparent glass, thereby forming a glass optical waveguide film composed of the lower cladding layer 12b and the core layer 13b. Alternatively, only the lower cladding layer 12b may be formed on the substrate 11 first, and then the core layer 13b may be formed thereon. The core layer 13b is doped with GeO ₂ , TiO ₂ or the like in order to make the refractive index higher than that of the lower cladding layer 12b.
(c) Unnecessary portions of the core layer 13b are removed by reactive ion etching to form a ridge-shaped core 13c.
(d) An upper clad layer 14b (glass optical waveguide film) having a refractive index equivalent to that of the lower clad layer 12b is produced so as to cover the core 13c. The upper clad layer 14b is produced again by a flame hydrolysis reaction. The glass fine particle layer 14a for the upper clad layer is formed and heated in an electric furnace to form a transparent glass.

The lower cladding layer 12b, the core layer 13b, and the upper cladding layer 14b, which are glass optical waveguide films, include GeO ₂ (source gas GeCl ₄ ), TiO ₂ (source gas TiCl ₄ ), as dopants in addition to SiO _{2 as} the main component. A dopant such as B ₂ O ₃ (source gas BCl ₃ ) or P ₂ O ₅ (source gas PCl ₃ ) is appropriately contained. These dopants are for adjusting the softening temperature and refractive index of glass. B ₂ O ₃ and P ₂ O ₅ are mainly used for adjusting the softening temperature, and GeO ₂ and TiO ₂ are used mainly for the core. It is used to adjust the refractive index of the.

Formation (deposition) of the glass particle layer in the glass optical waveguide film manufacturing method is performed using a glass particle deposition apparatus E shown in FIGS.
FIG. 2 is a diagram showing a configuration of a glass particle deposition apparatus for producing a glass optical waveguide film, and FIG. 3 is a diagram showing a glass particle synthesis burner.
The glass particle deposition apparatus E includes a glass particle synthesis burner unit 20, a turntable unit 30, and a control unit 40. The glass fine particle synthesis burner unit 20 includes a glass fine particle synthesis burner 21 (hereinafter referred to as “burner 21”), a raw material gas supply device 22 for supplying a glass forming raw material gas such as SiCl _{4 to the} burner 21 and supplying hydrogen and oxygen. A gas pipe group 23 connecting the burner 21 and the source gas supply device 22, an exhaust pipe 24, an exhaust gas processing device 25, and an exhaust hose 26 connecting the exhaust pipe 24 and the exhaust gas processing device 25 are configured. In FIG. 3, symbol F indicates an oxyhydrogen flame. When this oxyhydrogen flame F is exposed to the substrate 11, glass fine particles are deposited on the substrate 11 (at the same time, the temperature of the substrate 11 also rises).
The turntable unit 30 includes a turntable 31, a drive device 32 that rotationally drives the turntable 31, and a burner / exhaust pipe moving device 33. The turntable unit 30 is provided with a heat source (not shown) by a heater for heating the turntable 31 below the turntable 31, and a thermocouple is disposed as a temperature sensor between the heat source and the turntable 31. An optical thermometer is arranged as a temperature sensor above the turntable 31 (not shown). In FIG. 2, the symbol O indicates the rotation axis of the turntable 31.

The glass fine particle layer is formed on the substrate 11 by (a) supplying a glass forming raw material gas such as SiCl _{4 to} the burner 21 having a multi-tube structure, and in an oxyhydrogen flame F composed of oxygen gas and hydrogen gas. Glass fine particles are synthesized by the flame hydrolysis reaction that occurs, and (b) the synthesized glass fine particles are sprayed onto the surface of the substrate 11 placed on the turntable 31 together with the oxyhydrogen flame. The glass fine particles not attached to the substrate 11 are discharged from the exhaust pipe 24 together with the unreacted raw material gas and the exhaust gas such as hydrogen chloride gas generated by the flame hydrolysis reaction, and are detoxified by the exhaust gas processing device 25. The

  Here, the burner 21 deposits the glass fine particle layer on the entire surface of the substrate 11, so that the turntable 31 on which the substrate 11 is arranged is rotated at a constant rotational speed by the driving device 32. The burner 21 is linearly reciprocated at a speed proportional to the reciprocal 1 / r of the position radius coordinate r of the burner 21 on the turntable 31 rotated at a constant rotational speed by the burner / exhaust pipe moving device 33. These controls are intensively performed by the control unit 40. The glass fine particle layer is a portion indicated by reference numerals 12a, 13a, and 14a in FIG. Incidentally, FIG. 4 shows an example of the direction in which the burner 21 moves.

  As described above, the glass optical waveguide film can be formed on a large substrate having a diameter of 4 to 6 inches by the method for producing the glass optical waveguide film in which the glass fine particle layer is formed, and the large-scale optical circuit as described above can be formed. As a result, a large number of small-scale optical circuits can be manufactured on the same substrate, thereby improving productivity.

However, in a large-scale circuit, as the circuit size increases, there is a tendency that the difference between the characteristics of the manufactured circuit and the theoretical characteristics increases, and the desired performance cannot be obtained. Further, in a small-scale circuit, the circuit characteristics may differ depending on the position of the substrate, and there is an inconvenience that the number of circuits that satisfy the required performance is suppressed and the yield is lowered. In particular, this inconvenience occurs remarkably in an optical circuit made of a glass optical waveguide film having a core layer doped with GeO ₂ . This is because the refractive index profile of the core layer that affects the circuit performance occurs on the order of 10 ⁻⁴ or more.

The refractive index distribution in the glass optical waveguide film formed on the same substrate 11 mainly occurs corresponding to the radial direction on the turntable. This is because (1) the dopant content such as GeO ₂ in the glass fine particle layer formed on the substrate greatly depends on the temperature of the substrate 11 during the glass fine particle deposition (dependence of the dopant content on the substrate temperature) And (2) the temperature of the substrate 11 when the glass particles are deposited increases on the inner peripheral side of the turntable where the passing speed of the oxyhydrogen flame is relatively slow, and the acceleration of the oxyhydrogen flame is relatively high. This is considered to be due to the fact that the lower turntable outer periphery becomes lower (longer or shorter exposure time to the oxyhydrogen flame F). Therefore, as the substrate 11 becomes larger, the refractive index distribution of the glass optical waveguide film formed on the substrate 11 becomes larger.

Figure 5 is a substrate temperature dependence of the GeO ₂ content that have been reported, it can be seen that the content of GeO ₂ in the glass particles is significantly dependent on the substrate temperature. TiO ₂ and B ₂ O ₃ have also been investigated, and TiO ₂ has almost no substrate temperature dependence, but B ₂ O ₃ has been reported to have a tendency similar to that of GeO _2. (Kawauchi et al. Japan. J. Appl. Phys, vol. 19, pp. L69-L71 (1980), vol. 19, pp. 2047-2054 (1980)). As for P ₂ O ₅ , it has been experimentally confirmed that the P ₂ O ₅ content in the glass fine particles tends to decrease as the substrate temperature rises.

  In view of the above, an object of the present invention is to provide a method for producing a glass optical waveguide film that produces a uniform glass optical waveguide film with a small variation in refractive index. In particular, an object of the present invention is to provide a method for producing a glass optical waveguide film that reduces the refractive index distribution in the direction corresponding to the radial direction on the turntable.

In order to solve the above-mentioned problems, the present invention (Claim 1) provides a glass fine particle by a glass fine particle synthesis burner that is movable from the outer periphery of the turn table to the central rotation axis (O) direction on a substrate arranged on a rotating turn table. This is a method for producing a glass optical waveguide film in which glass is directly sprayed and deposited to form a glass fine particle layer, which is then transparently vitrified at a high temperature.
And, when the relative speed of the substrate with respect to the glass fine particle synthesis burner changes, the temperature of the substrate or the turntable is controlled by controlling the temperature of a heat source disposed on the turntable to heat the substrate. A distribution is formed in advance in accordance with the relative speed of the glass fine particle synthesis burner and the substrate at a position in the substrate or the turntable so that the temperature of the substrate during glass fine particle deposition is constant. Features.
Here, the glass fine particle synthesis burner moves from the outer periphery of the turntable toward the rotation axis direction of the turntable (including the reverse direction). This includes the case of moving in a deviated direction. It also includes the case of moving across the turntable.

According to the present invention (Claim 2), in the invention of Claim 1, by further controlling the temperature of the heat source, the temperature distribution of the substrate or the turntable is increased on the outer peripheral side of the turntable, and the inner peripheral side It is also possible to form a glass optical waveguide film by forming the glass fine particle layer in advance so as to be low and forming a glass fine particle layer and then forming a transparent glass at a high temperature.
In other words, by controlling the temperature of the heat source in consideration of the difference in exposure time of the oxyhydrogen flame by the burner, the temperature distribution of the substrate or turntable can be determined by the relative velocity of the substrate and burner at the position in the substrate or turntable. It is formed in advance so as to almost match.

  According to the present invention, since the refractive index variation of the glass optical waveguide film produced on the substrate can be reduced, the deviation from the theoretical characteristics becomes small in a large-scale circuit laid out on the entire surface of the substrate, which is high. Performance can be realized. In addition, in a plurality of small-scale circuits formed on the same substrate, variation in characteristics between circuits is reduced, and yield can be increased. Realization of a large-scale high-functional circuit makes it possible to construct a more advanced optical communication system, and the improvement in the yield of small-scale circuits can reduce the cost of components, greatly contributing to the economics of general-purpose systems. .

Hereinafter, although an embodiment of the present invention is described in detail, the present invention is not limited to the following embodiment.
In this embodiment, (a) the first embodiment (reference example) in which the relative speed between the burner and the substrate is controlled to be substantially constant, and (b) the temperature of the substrate or the turntable by the heat source is set to the relative temperature between the burner and the substrate. A second embodiment in which the control is substantially matched to the speed, (c) a third embodiment (reference example) in which the raw material supply amount is controlled to be almost matched to the relative speed of the burner and the substrate, and (d) the first The description will be divided into a fourth embodiment (reference example) in which the third to third embodiments are arbitrarily combined.

<< First embodiment (reference example) >>
In the first embodiment (reference example), the relative speed of the burner 21 and the substrate 11 disposed on the turntable 31 is controlled to be substantially constant regardless of where the burner 21 is located on the turntable 31. This is a method for producing a glass optical waveguide film. The glass fine particle deposition apparatus E used in the first embodiment (reference example) is the same as that described in the prior art (see FIGS. 2 and 3). Therefore, the description of the glass fine particle deposition apparatus E is omitted.

In the first embodiment (reference example), the relative speed between the burner 21 and the substrate 11 is controlled to be substantially constant regardless of the position on the turntable 31 (on the substrate 11). That is, the difference between the relative speeds of the burner 21 and the substrate 11 between the outer peripheral portion and the inner peripheral portion of the turntable that occurs when the turntable 31 rotates at a constant speed is determined according to the position of the burner 21 on the turntable 31. The problem is solved by changing the rotation speed (rpm) of the table 31. As a result, the exposure time to the oxyhydrogen flame F is almost the same at any position on the substrate 11, and the temperature rise of the substrate 11 when the glass particles are deposited by the oxyhydrogen flame F can be made substantially constant.
Accordingly, it is possible to dope GeO ₂ and other dopants having substrate temperature dependency, whose content in the glass particles is greatly influenced by the temperature of the substrate 11 at the time of deposition of the glass particles, at a predetermined concentration with high accuracy. As a result, the refractive index distribution of the glass optical waveguide film formed on the substrate 11 can be made uniform regardless of the position on the substrate 11 (refractive index variation can be eliminated). Moreover, the film thickness of the glass fine particle layer formed can also be made constant. In addition, a glass fine particle layer is heated with an electric furnace etc., and is transparently vitrified at high temperature.

  Here, as a method for producing a glass optical waveguide film in which the relative speed between the burner 21 and the substrate 11 is controlled to be substantially constant, in the first embodiment (reference example), the burner 21 is positioned on the inner peripheral side of the turntable 31. The rotation speed can be increased when the rotation is performed, and the rotation speed can be decreased when the rotation position is positioned on the outer peripheral side.

In this way, if the relative speed between the burner 21 and the substrate 11 is made substantially constant, the moving speed in the tangential direction (tangential speed) of the turntable 31 at the position of the burner 21 is the inner peripheral side and the outer peripheral side of the turntable 31. In particular, when the moving speed of the burner 21 is slower than the tangential speed of the turntable 31, the relative speed of the burner 21 and the substrate 11 is substantially the tangential speed of the turntable 31. The relative speed of the burner 21 and the substrate 11 can be made substantially constant by controlling the rotational speed only by the position of the burner 21 on the turntable 31 regardless of the moving speed of the burner 21.
Accordingly, the temperature rise of the substrate 11 due to the oxyhydrogen flame F is constant at any position of the substrate 11, and the temperature of the substrate 11 during the deposition of the glass fine particles can be made constant, thereby refraction of the glass optical waveguide film formed on the substrate 11. The rate distribution can be made uniform regardless of the position on the substrate 11.
In the present embodiment (reference example), the glass optical waveguide film refers to the lower clad layer 12b, the core layer 13b, the upper clad layer 14b, or any combination of these layers shown in FIG. The same in the embodiment and the reference example).

<< Second Embodiment >>
The second embodiment is a method for producing a glass optical waveguide film in which the temperature of the substrate 11 or the turntable 31 by a heat source is controlled in accordance with the relative speed of the burner 21 and the substrate 11 disposed on the turntable 31. . The glass fine particle deposition apparatus E used in the second embodiment can apply the apparatus in the first embodiment (reference example) (see FIGS. 2 and 3). Therefore, the description of the glass fine particle deposition apparatus E is omitted. In the second embodiment, the heat source is provided below the turntable 31.

In the second embodiment, the glass by the oxyhydrogen flame F caused by the difference in the relative speed between the burner 21 and the substrate 11 generated depending on whether the burner 21 is located on the outer peripheral side or the inner peripheral side of the turntable 31. The difference in temperature rise of the substrate 11 during the deposition of the fine particles is controlled so that the temperature of the substrate 11 during the deposition of the fine glass particles becomes constant by controlling the heat source.
That is, when the rotational speed of the turntable 31 is constant, the temperature of the substrate 11 is relatively increased by the oxyhydrogen flame F on the inner peripheral side of the turntable 31 where the relative speed between the substrate 11 and the burner 21 is decreased. On the other hand, on the outer peripheral side of the turntable 31 where the relative speed between the substrate 11 and the burner 21 is increased, the temperature of the substrate 11 is relatively lowered by the oxyhydrogen flame F. In the method for producing a glass optical waveguide film according to the second embodiment, the temperature of the substrate 11 at the time of depositing the glass particles is not different depending on the position on the substrate 11 by controlling the heat source provided below the turntable 31. Like that.

The heat source is controlled by controlling the temperature of the substrate 11 or the turntable 31 substantially in accordance with the relative speed of the substrate 11 with respect to the burner 21, or the temperature distribution of the substrate 11 or the turntable 31 by the heat source is controlled by the substrate 11 or the turntable. This is performed by controlling in accordance with the relative speed of the burner 21 and the substrate 11 at a position within 31.
Thus, GeO ₂ and other substrate temperature-dependent dopants whose content in the glass particles is greatly influenced by the temperature of the substrate 11 during the deposition of the glass particles can be doped with a predetermined concentration with high accuracy. Thus, the refractive index distribution (refractive index variation) of the glass optical waveguide film formed on the substrate 11 can be made uniform regardless of the position on the substrate 11.

According to the manufacturing method based on the control in which the temperature of the substrate 11 or the turntable 31 by the heat source is substantially matched to the relative speed between the burner 21 and the substrate 11, when the relative speed between the substrate 11 and the burner 21 decreases or increases, Since the temperature of the substrate 11 under F rises or falls, it is controlled by the heat source so that the temperature of the substrate 11 or the turntable 31 is lowered or raised, and the temperature of the substrate 11 during the deposition of the glass particles is made substantially constant. To do. Thereby, the refractive index distribution in the substrate 11 can be made uniform.
Further, the temperature distribution of the substrate 11 or the turntable 31 by the heat source is controlled in accordance with the relative speed of the burner 21 and the substrate 11 at a position in the substrate 11 or the turntable 31 in the same manner at the time of depositing the glass particles. The temperature of the substrate 11 can be made substantially constant.

  If the temperature of the substrate 11 or the turntable 31 by the heat source is controlled so as to be high when the burner 21 is located on the outer peripheral side of the turntable 31 and low when it is located on the inner peripheral side, the position of the burner 21 is When the relative speed between the burner 21 and the substrate 11 when positioned on the outer peripheral side is higher than that when positioned on the inner peripheral side, the temperature of the substrate 11 when depositing the glass particles can be made substantially constant.

Further, in the second embodiment, when the rotational speed of the turntable 31 is constant, at least the tangential speed of the turntable 31 at the position of the burner 21 is such that the burner 21 is on the inner peripheral side of the turntable 31. Compensates for the temperature rise of the substrate 11 due to the oxyhydrogen flame F during the deposition of glass particles caused by the difference in the tangential speed of the turntable 31 when the position at the outer peripheral side is faster than the position at the position. Therefore, the temperature of the substrate 11 can be made substantially constant even if the exposure time to the oxyhydrogen flame F is different when depositing the glass particles. Thereby, the refractive index variation of the glass optical waveguide film formed on the substrate 11 can be made uniform regardless of the position on the substrate 11.
In particular, in the case of the second embodiment, when the moving speed of the burner 21 is slower than the tangential moving speed of the turntable 31, the relative speed of the substrate 11 and the parner 21 is approximately the tangential speed of the turntable 31. Therefore, the heat source can be controlled only by the position radius coordinates of the turntable 31 of the burner 21 regardless of the moving speed of the burner 21, and the temperature of the substrate 11 when depositing the glass particles can be made more constant. Forming the temperature distribution of the substrate 11 or the turntable 31 by the heat source so as to be higher on the outer peripheral side of the turntable 31 and lower on the inner peripheral side is the same as sequentially controlling the heat source at the position of the burner 21. In addition, the temperature of the substrate 11 when the glass fine particles are deposited can be made substantially constant.

<< 3rd Embodiment (reference example) >>
The third embodiment (reference example) is a method for producing a glass optical waveguide film in which the amount of raw material supplied is controlled substantially in accordance with the relative speed of the substrate 11 with respect to the burner 21. The glass fine particle deposition apparatus E used in the third embodiment (reference example) can apply the apparatus in the first embodiment (reference example) (see FIGS. 2 and 3). Therefore, the description of the glass fine particle deposition apparatus E is omitted. In the third embodiment (reference example), the raw material supply device 22 is provided with a gas flow rate controller (not shown).

In the third embodiment (reference example), the difference in dopant content in the glass particles due to the difference in temperature rise of the substrate 11 resulting from the difference in relative speed between the burner 21 and the substrate 11 during the deposition of the glass particles is determined as the raw material supply. Compensating by controlling the amount, the content of the substrate temperature-dependent dopant in the glass fine particles is made constant, and the refractive index distribution of the glass optical waveguide film formed on the substrate 11 is made constant.
That is, the supply amount of raw material is controlled on the assumption that a difference in temperature rise occurs on the substrate 11.

  As a method for controlling the raw material supply amount, (1) a control method for changing the substrate temperature-dependent dopant supply amount itself, and (2) a variation in the substrate temperature-dependent dopant content is supplied. A control method that effectively changes the content of the dopant by controlling the supply amount of at least one of a plurality of raw materials, and (3) supplying a change in refractive index caused by a change in the dopant content that depends on the substrate temperature. There is a control method in which at least one supply amount of a plurality of raw materials is controlled so that the refractive index becomes constant.

  In this third embodiment (reference example), as a method for producing a glass optical waveguide film in which the raw material supply amount is controlled in accordance with the relative speed of the substrate 11 with respect to the burner 21, in this third embodiment (reference example), the raw material supply amount of the turntable 31 The glass optical waveguide film can be manufactured by controlling the position so as to be different when positioned on the inner peripheral side and when positioned on the outer peripheral side.

In this way, if the raw material supply amount is controlled substantially in accordance with the relative speed of the substrate 11 with respect to the burner 21, the relative speed between the burner 21 and the substrate 11 is such that the position of the burner 21 on the turntable 31 is the outer peripheral side and the inner peripheral side. Even when different, the refractive index variation (refractive index distribution) of the glass optical waveguide film 11 formed on the substrate 11 can be made substantially constant. In addition, when the tangential speed of the turntable 31 at the position of the burner 21 is different between the outer peripheral side and the inner peripheral side, the variation in dopant content caused by the difference in the tangential speed of the turntable 31 is compensated. Therefore, the refractive index distribution of the glass optical waveguide film formed on the substrate 11 can be made substantially constant.
In particular, when the moving speed of the burner 21 is slower than the tangential speed of the turntable 31, the relative speed of the substrate 11 and the burner 21 is substantially the tangential speed of the turntable 31. Regardless, the raw material supply amount can be controlled only by the turntable position radius coordinates of the burner 21, and the refractive index distribution of the glass optical waveguide film formed on the substrate 11 can be made more constant.

<< 4th Embodiment (reference example) >>
By arbitrarily combining the above three controls, the content of the glass fine particle dopant depending on the substrate temperature during deposition can be adjusted with higher accuracy.
As a combination mode, 1 “rotational speed control + temperature control”, 2 “rotational speed control + raw material supply amount control”, 3 “rotational speed control + temperature control + raw material supply amount control”, 4 “temperature control + raw material supply” Volume control "is raised. At this time, the contribution ratio of each control can be arbitrarily adjusted.

Hereinafter, the present invention will be further described based on examples (see FIGS. 1 to 8). The present invention is not limited to the following examples.
<< Example 1 (reference example) >>
Example 1 (reference example) corresponds to the first embodiment (reference example). That is, in the glass particle deposition apparatus E, the rotation speed of the turntable 31 is controlled so that the relative speed between the burner 21 and the substrate 11 is constant regardless of the position of the burner 21, and a glass particle layer is formed on the substrate 11. Thereafter, the glass optical waveguide film to be transparent vitrified is produced.

(Lower cladding layer)
A 6-inch silicon substrate was used as the substrate 11, and a plurality of the substrates 11 were arranged on a turntable 31 having an effective diameter of 1 m. A glass fine particle layer 12a for the lower cladding layer was formed under the following conditions.
(1) Source gas supply rate: SiCl ₄ 100 cc / min, BCl ₃ 5 cc / min, PCl ₃ 5 cc / min
(2) Substrate temperature by heat source (when not deposited); 600 ° C
(3) Burner moving speed; conditions shown in Fig. 6 (a)
(4) Rotation speed of the turntable; condition of FIG. 6 (b) The movement speed of the burner 21 is adjusted so that the burner 21 spirals on the turntable 31 and draws a locus with almost equal intervals. The moving speed of the burner 21 and the rotational speed of the turntable 31 are changed so as to be proportional to the inverse 1 / r of the burner position radius coordinate r from the rotation axis O of the turntable 31. I let you. Therefore, the relative speed between the burner 21 and the substrate 11 is mainly the tangential speed of the turntable 31, and the relative speed is substantially constant regardless of the position of the burner 21. The burner 21 was moved only half a reciprocation from the outside to the inside. In Example 1 (reference example), the movement direction of the burner 21 is substantially the M2 direction in FIG. 4 (the same applies to all examples and comparative examples described below).

  After transparent vitrification, the refractive index was measured up to 4 digits after the decimal point using the prism coupler method in a matrix at intervals of 5 mm, and they were consistent within a measurement error of 0.0001. On the other hand, the glass optical waveguide film (lower clad layer) of the comparative example manufactured by the conventional technique in which the rotation speed of the turntable is constant (10 rotations / min) has a refractive index variation of 0.0002, and according to the present invention. Refractive index variation was reduced. The manufacturing conditions of this comparative example are the same as those of Example 1 (reference example) except that the rotation speed is constant.

[Core layer]
Next, the silicon substrate 11 was newly placed on the turntable 31, and the glass fine particle layer 13a for the core layer was formed under the following conditions such as the raw material gas flow rate.
(1) Source gas supply rate: SiCl ₄ 100 cc / min, BCl ₃ 6 cc / min, PCl ₃ 6 cc / min, GeCl ₄ 12 cc / min
(2) Substrate temperature by heat source (undeposited); same condition as in lower cladding layer
(3) Burner moving speed; 10/3 times the moving speed condition in the lower cladding layer
(4) Turntable rotation speed; same condition as in lower clad layer

  After transparent vitrification, the refractive index was measured in the same manner as the lower cladding layer. As a result, the refractive index variation was 0.0003. On the other hand, the refractive index of the glass optical waveguide film (core layer) of the comparative example manufactured by the conventional technique in which the rotation speed of the turntable 31 is constant (10 rotations / minute) is in the direction corresponding to the radial direction of the turntable 31. , And increased toward the outer peripheral side by 0.0018 (that is, refractive index variation 0.0018). The manufacturing conditions of this comparative example are the same as those of Example 1 (reference example) except that the rotation speed is constant.

[Upper clad layer]
The silicon substrate 11 was newly placed on the turntable 31, and the upper clad layer glass fine particle layer 14a was formed under the following conditions such as the raw material gas flow rate.
(1) Source gas supply rate: SiCl ₄ 100 cc / min, BCl ₃ 10 cc / min, PCl ₃ 10 cc / min
(2) Substrate temperature by heat source (undeposited); same condition as in lower cladding layer
(3) Burner moving speed; 2/3 times the moving speed condition in the lower cladding layer
(4) Turntable rotation speed; same condition as in lower clad layer

  After the transparent vitrification, the refractive index of the upper cladding layer 14b was measured in the same manner as the lower cladding layer 12b and the core layer 13b, and the refractive index variation was 0.0001 within the measurement error. On the other hand, the refractive index of the glass optical waveguide film (upper clad layer) of the comparative example manufactured under the same conditions as in Example 1 (reference example) except that the rotation speed of the turntable is constant (10 rotations / min) is Corresponding to the radial direction of the turntable 31, it increased by 0.0003 toward the outer peripheral side.

According to the present invention, the refractive index variation can be reduced as compared with the comparative example according to the prior art, but the film thickness variation can also be reduced. Specifically, the film thickness variation of the produced glass optical waveguide films of the lower clad layer 12b, the core layer 13b, and the upper clad layer 14b is a comparative example with respect to the average film thicknesses of 20 μm, 6 μm, and 30 μm, respectively. Although it was about 8%, it became 3% or less in the present invention. In the comparative example, since the rotational speed of the turntable 31 is constant, the deposition speed varies in proportion to r depending on the position of the burner 21, and in order to correct this, the burner moving speed is proportional to 1 / r, and the spiral Although the uniform trajectory interval was made proportional to 1 / r, in the present invention, the trajectory interval can be made equal, so that the uniformity can be further improved.
In Example 1 (reference example), each glass optical waveguide film layer was prepared separately. However, after forming the glass fine particle layer 12a for the lower cladding layer and before forming into the transparent glass, the glass for the core layer was formed. A method for producing a glass optical waveguide film in which the fine particle layer 13a is formed and both the glass fine particle layers 12a and 13a are simultaneously formed into transparent glass may be used.

Example 2
In Example 2, the heat source is controlled in accordance with the second embodiment, that is, the relative speed of the burner 21 and the substrate 11, or a temperature distribution substantially matched with the relative speed is formed by the heat source, and the heat source is formed on the substrate 11. This corresponds to a method for producing a glass optical waveguide film that is formed into a transparent glass after forming a glass fine particle layer. In this embodiment, the lower part of the turntable 31 is divided into five regions in the radial direction, heaters serving as heat sources are respectively arranged, and the temperature distribution of the turntable 31 when not deposited without supplying the raw material gas of glass fine particles is the turntable. It was made to become high toward the outer peripheral side of 31 radial directions.

The solid line in FIG. 7 is a calculated value of the temperature distribution on the turntable 31 that is substantially matched to the relative speed of the burner 21 and the substrate 11, and the white circles are obtained when the power supplied to the heater is adjusted to match this calculated value. Measurement temperature. The temperature was measured at the midpoint of each heater. The temperature on the substrate 11 is 5 ° C. lower than the temperature on the turntable 31.
The manufacturing conditions of each glass optical waveguide film (lower clad layer 12b, core layer 13b, upper clad layer 14b) in Example 2 are the conventional techniques shown in Example 1 (reference example) except for the temperature distribution of the turntable 31. Is the same as the manufacturing conditions of the comparative example (constant rotational speed). As in Example 1 (reference example), the lower cladding layer 12b, the core layer 13b, and the upper cladding layer 14b were formed on different substrates 11, respectively.

  The refractive index variations of the glass optical waveguide films corresponding to the prepared lower clad layer 12b, core layer 13b, and upper clad layer 14b are 0.0001, 0.0005, and 0.0001, respectively. The refractive index variation of the glass optical waveguide film according to the comparative example, which is the prior art shown in FIG. 3, is reduced compared to 0.0002, 0.0018, and 0.0003. In addition, the film thickness variation in Example 2 was almost the same as that in the comparative example.

  The heater adjustment in Example 2 was performed by measuring the temperature of the substrate 11 under the oxyhydrogen flame F with an optical pyrometer, but the temperature of the substrate 11 during the deposition of the glass particles cannot be measured accurately. Can adjust the heat source (heater supply power) based on the refractive index variation of the produced glass optical waveguide film and FIG.

In the second embodiment, the temperature distribution of the turntable 31 is formed in advance. However, the heater is sequentially controlled so that the temperature corresponds to the position on the turntable 31 of the burner 21, or the temperature is monitored with an optical thermometer or the like. However, by sequentially controlling the heater, the temperature of the substrate 11 during the deposition of the glass particles can be made substantially constant. However, when the heaters are sequentially controlled, it is necessary to control in consideration of a delay from the heater control time until the temperature of the substrate 11 reaches a predetermined value, and the change in the relative speed between the burner 21 and the substrate 11 is It is desirable that the temperature of the substrate 11 be gentle enough to follow the temperature rise and fall of the heater.
In the second embodiment, the heater is arranged by dividing the radial direction of the turntable 31 into five regions. However, the number of divisions is increased or the heater structure is configured to generate heat according to a predetermined temperature distribution. Thus, a more desired temperature distribution can be formed.

<< Example 3 (reference example) >>
Example 3 (reference example) corresponds to the third embodiment (reference example). That is, a method for producing a glass optical waveguide film in which a raw material supply amount (raw material gas supply speed) is controlled substantially in accordance with the relative speed between the burner 21 and the substrate 11, and a glass fine particle layer is deposited on the substrate 11 and then transparent glass is formed. Is due to. In this example 3 (reference example), the glass optical waveguide film corresponding to the core layer 13b is prepared under the same conditions as in example 1 (reference example) except for the source gas supply speed and the rotation speed of the turntable 31. (In other words, only the supply amount of the raw material gas in the production conditions of the comparative example in Example 1 (reference example) was changed). The source gas supply speed is set to SiCl ₄ 100 cc / min, BCl ₃ 6 cc / min, and PCl ₃ 6 cc / min, and the rotation speed of the turntable is constant at 10 rev / min. Incidentally, the supply rate of GeCl ₄ is changed so that the supply amount increases toward the outer peripheral side in the radial direction of the turntable 31 as shown in FIG. 8, and almost matches the relative speed of the burner 21 and the substrate 11. Change.

  Here, the gas supply speed in FIG. 8 is that at the tip of the burner 21, but in consideration of the delay time from the gas flow controller (not shown) in the source gas supply device 22 to the tip of the burner 21, 40 controlled the gas flow controller. The refractive index variation of the glass optical waveguide film of the manufactured core layer 13b is 0.0003, which is smaller than the refractive index variation of the glass optical waveguide film according to the comparative example shown in Example 1 (reference example). .

In the third embodiment (reference example), only the core layer 13b is used. However, the gas supply rates of BCl ₃ and PCl ₃ may be similarly controlled for the lower cladding layer 12b and the upper cladding layer 14b. In Example 3 (reference example), only GeCl ₄ was controlled. However, since the change in the refractive index is small with respect to the change in the gas supply rate, it is combined with BCl ₃ or PCl _{3 which} is easy to use for fine adjustment of the refractive index. You can also. Furthermore, it is also possible to control the gas supply rate of the SiCl ₄ instead of changing the ratio of the GeCl ₄ in the source gas by controlling the gas feed rate of GeCl _4. However, when the supply amount of raw materials (for example, SiCl ₄ , BCl ₃ , PCl ₃ ) other than the dopant (mainly GeO ₂ ) whose content in the glass fine particles is changed, the softening temperature and the deposition rate are also changed. Therefore, it is desirable to control the supply amount of dopant as varied as possible (GeCl ₄ here).

<< Example 4 (reference example) >>
Example 4 (reference example) corresponds to a mode in which the rotation speed control and the raw material supply amount control are performed together in the fourth embodiment (reference example). That is, the rotational speed of the turntable 31 is controlled so that the relative speed between the burner 21 and the substrate 11 is substantially constant, and the raw material supply amount is controlled substantially in accordance with the relative speed between the burner 21 and the substrate 11. After the glass fine particle layer is formed on the glass optical waveguide film, the glass optical waveguide film is made into a transparent glass.

In this example 4 (reference example), the glass optical waveguide film forming conditions of the core layer 13b in example 1 (reference example) and the gas supply rate of PCl3 are substantially matched to the relative speed of the burner 21 and the substrate 11. The turntable 31 was controlled so as to increase on the inner peripheral side. The refractive index variation of the produced glass optical waveguide film was 0.0002, and the variation could be reduced compared to the refractive index variation of 0.0003 in the core layer formed in Example 1 (reference example). .
The heat source can also be controlled instead of changing the raw material supply amount (raw material gas supply speed). Incidentally, when the temperature of the substrate 11 on the inner peripheral side of the turntable 31 is set to be about 30 ° C. higher than that on the outer peripheral side and the temperature distribution is adapted to the relative speed between the substrate 11 and the burner 21, the refractive index variation is It was 0.0002.

As mentioned above, although embodiment and the Example of this invention were described, this invention is not necessarily limited to the said embodiment and Example of the said invention, The objective said to this invention was achieved, and this invention is achieved. Modifications can be made as appropriate within the scope of the effects.
The method for producing a glass optical waveguide film of the present invention can make the refractive index or film thickness uniform on the substrate, and also changes the refractive index and film thickness at a desired position on the substrate. Is also applicable.

For example, when changing the refractive index in the substrate plane, a manufacturing method in which the relative speed between the burner and the substrate is made constant, or a manufacturing method by controlling the temperature of the substrate or turntable by a heat source to substantially match the relative speed between the burner and the substrate. Thus, the substrate temperature at the time of depositing the glass particles may be made substantially constant, and the raw material supply amount may be controlled so as to obtain a desired refractive index.
In the case of using a method for producing a glass optical waveguide film in which the raw material supply amount is controlled in accordance with the relative speed of the burner and the substrate, the dopant content in the glass fine particles estimated from the raw material supply amount and the dopant in the actual glass fine particles are used. The ratio of the content changes almost in accordance with the relative speed of the burner and the substrate, that is, changes in accordance with the substrate temperature at the time of deposition. Just adjust.

  For example, when changing the film thickness within the substrate surface, change the density of the burner locus on the turntable according to the film thickness, or pass the same locus multiple times in the method for producing a glass optical waveguide film of the present invention. You can change the number of passes. In order to change both the refractive index and the film thickness, these methods may be combined.

  In the above-described embodiment, the burner is only moved from the outside to the inside, but the same result can be obtained by moving the burner from the inside to the outside. In this case, it is important that the raw material supply speed is stable, and if there is a subtle time change, the refractive index changes according to the fluctuation, so it is better to increase the burner moving speed and reciprocate multiple times. good. However, since there are places where the trajectories intersect due to reciprocation, it is necessary to consider the position of the substrate arrangement on the turntable in order to reduce the film thickness variation.

  In the above-described embodiment, the trajectory of the burner on the turntable is made spiral, so that the burner moving speed is made sufficiently smaller than the tangential speed of the turntable, but the present invention is not limited to this. Even when the burner moving speed is increased, (1) the rotation speed of the turntable is controlled so that the relative speed of the burner and the substrate is almost constant, and (2) the heat source is adjusted to approximately match the relative speed of the burner and the substrate. (3) By controlling the raw material supply amount in accordance with the relative speed of the burner and the substrate, the refractive index variation is the same as in the example. It can be made as small as possible. Of course, it is also within the scope of the present invention to set the moving speed of the burner to a different speed between the vicinity of the outer peripheral portion and the inner peripheral portion of the turntable.

  The position on the turntable with respect to the burner, such as the “relative speed of the burner and the substrate” and “the trajectory of the burner on the turntable”, is the oxyhydrogen flame formed between the burner on the turntable and the exhaust pipe. It is desirable that the position is formed, and substantially the same effect can be obtained as the position of the burner tip on the turntable.

  The expression “almost” used in the above-mentioned “almost matches the relative speed of the burner and the substrate” and “the relative speed of the burner and the substrate is almost constant” is a control that accurately matches the relative speed of the burner and the substrate. This is because the refractive index variation, which is the effect of the present invention, can be reduced as compared with the prior art even if the control is not performed so that the relative speed of the burner and the substrate is accurately constant. For example, in Example 2, the temperature distribution of the turntable shown in FIG. 7 is set at the measurement point so that the temperature width 120 ° C. is proportional to the relative speed in the turntable range of a 6-inch substrate (150 mm). Between the measured values, a curve or waveform having a small amplitude is used instead of a straight line like the calculated temperature distribution. Even if the temperature range of 120 ° C. is reduced to 60 ° C., which is half of the turntable range of this 6-inch substrate (150 mm), for example, the refractive index variation of the core layer is 0.0010, which is greatly reduced compared to the conventional case. ing.

  In the embodiment of the present invention, the case where a glass fine particle layer of any one of a lower clad layer, a core layer and an upper clad layer is formed on a substrate and then transparent vitrification is described, but a plurality of glass fine particle layers are formed. Even when it is formed into a transparent glass, it belongs to the category of the present invention, and variation in refractive index can be reduced.

It is a figure which shows the preparation methods of the optical waveguide which consists of a glass optical waveguide film. It is a figure which shows the structure of the glass microparticle deposition apparatus for glass optical waveguide film preparation. It is a figure which shows a glass particulate synthesis burner. It is a figure which shows the example of the moving direction of a burner. It is a diagram showing a substrate temperature dependence of the content of GeO _2. It is a figure which shows the preparation conditions of the glass optical waveguide film in Example 1 (reference example) of this invention. (A) shows the moving speed of the burner, and (b) shows the rotational speed of the turntable. It is a figure which shows the temperature distribution on the turntable which arises at the time of non-deposition which is the preparation conditions of the glass optical waveguide film in Example 2 of this invention. Is a diagram showing a gas feed rate of Example 3 GeCl ₄ is produced conditions in Reference Example of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Glass optical waveguide 11 Substrate 12a Glass fine particle layer (glass fine particle layer) for lower clad layers
12b Lower cladding layer 13a Glass fine particle layer (glass fine particle layer) for core layer
13b Core layer 13c Core (core after ridge processing)
14a Glass fine particle layer for upper clad layer (glass fine particle layer)
14b Upper cladding layer 20 Glass particulate deposition burner 21 Glass particulate deposition burner (burner)
Reference Signs List 22 Material gas supply device 23 Gas piping group 24 Exhaust pipe 25 Exhaust gas treatment device 26 Exhaust hose 30 Turntable unit 31 Turntable 32 Drive device 33 Burner / exhaust pipe moving device 40 Control unit E Glass particulate deposition device O Rotating shaft

Claims (2)

A glass particle layer is formed by spraying glass particles directly onto a substrate placed on a rotating turntable by means of a glass particle synthesis burner that is movable from the outer periphery of the turntable to the central rotation axis direction. In the method for producing a glass optical waveguide film,
When the relative speed of the substrate with respect to the glass fine particle synthesis burner changes,
By controlling the temperature of a heat source disposed on the turntable to heat the substrate, the temperature distribution of the substrate or the turntable is changed to the glass fine particle synthesis burner at a position in the substrate or the turntable. Preliminarily forming in accordance with the relative speed of the substrate so that the temperature of the substrate during deposition of the glass fine particles is constant,
A method for producing a glass optical waveguide film characterized by the following. By controlling the temperature of the heat source, the temperature distribution of the substrate or the turntable is formed in advance so as to be high on the outer peripheral side of the turntable and low on the inner peripheral side,
The method for producing a glass optical waveguide film according to claim 1.

Images