JP2002341393A - Manufacturing method for optical waveguide device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve productivity of a ridge type optical waveguide, to improve the stability of its optical characteristics and the stability of its shape, to prevent a process degenerating layer on the surface of the optical waveguide, and to control the angle of the flank of the ridge type optical waveguide to the main surface of a substrate. SOLUTION: In a method for manufacturing an optical waveguide device equipped with a substrate 1 and the ridge type optical waveguide 3 projecting on the main surface 1a of the substrate 1, the optical waveguide device is a second higher harmonic generating device and the ridge type optical waveguide has a dummy phase matching type cyclic polarization inversion structure and is formed by an abrasion processing method. Light having <=350 nm wavelength is preferably used as the light source for the abrasion processing and light having 150 to 300 nm wavelength is more preferably used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical waveguide device having a ridge type optical waveguide, which can be suitably used as a quasi phase matching type second harmonic generation device or an optical modulation device.

[0002]

2. Description of the Related Art A so-called ridge-type optical waveguide is expected in an optical modulator, an optical switching element and the like. Quasi-Phase-Matched (QPM) using an optical waveguide having a periodic domain-inverted structure formed on a single crystal of lithium niobate or lithium tantalate as a light source for a blue laser used in an optical pickup or the like. A second-harmonic-generation (SHG) device is expected. The second harmonic generation device is
A wide range of applications are possible, such as for optical disk memory, medical use, photochemistry, and various optical measurements.

Conventionally, as a method of forming a ridge-type structure, a mask pattern is transferred onto a substrate by photolithography, and portions other than the mask pattern are removed by, for example, a reactive ion etching (RIE) method. The method was common sense. In the case of an optical modulator that forms an electrode for applying an alternating electric field for modulation to a ridge type optical waveguide and modulates light intensity, phase, wavelength, etc.
It is theoretically known that as the ridge angle approaches 90 [deg.], The electric field correction coefficient increases and the drive voltage can be reduced (Japanese Patent Laid-Open No. 4-123018). JP-A-4-12
No. 3018 discloses that the ridge-type optical waveguide has a d / W
0.1 to 1.0, and the ridge angle is 90 °
By setting the angle to ± 10 °, an attempt is made to increase the electric field correction coefficient as much as possible.

[0004]

However, this method has the following problems. That is, in the reactive ion etching method, for example, when it is attempted to uniformly etch the entire 3-inch wafer to a depth of several μm, it takes a very long time, and the processing cost is high. In addition, since the substrate is irradiated with high-energy ions, the substrate is liable to be damaged, and a damaged layer is formed in an optical waveguide portion through which essential light passes, resulting in a change in characteristics such as a light refractive index. was there. When the simulation of the optical waveguide device is performed, the formation of such a processed deteriorated layer is not taken into consideration, so that the characteristics of the actual optical waveguide device are different from the results of the simulation and cause deterioration.

[0005] Further, in such a conventional optical modulator, there is a limit to the improvement of the electric field correction coefficient. That is, although the surface of the ridge-type optical waveguide is substantially flat and the side surface of the ridge-type optical waveguide is inclined, an electrode film for modulation is formed over the inclined side surface and the main surface of the epitaxial film. For this purpose, (Incorporated Association, IEICE document, OQE77-57, “Ridge type optical waveguide” 197
As discussed theoretically on October 24, 7),
When an alternating electric field for modulation is applied to the optical waveguide, the efficiency of modulation by this alternating electric field is lower than when the ridge angle is 90 °, and therefore the drive voltage is reduced.

The reason why the side surface of the ridge type optical waveguide is inclined is considered as follows. The ridge-type optical waveguide protrudes from the main surface of the epitaxial film. In this case, in order to increase the ratio d / W of the height d of the ridge-type optical waveguide to the width W, the ridge-type optical waveguide is elongated. For this purpose, it is necessary to etch the periphery of the ridge-type optical waveguide as deeply as possible. However, since the ratio of the etching rate between the substrate side and the mask is usually about 2 to 5: 1, in order to deeply etch the periphery of the ridge-type optical waveguide, a mask having a correspondingly large thickness is required. Must be used. However, when such a thick mask is used, the ridge angle θ becomes significantly smaller than 90 ° because the etching rate is reduced around the mask. For example, the height W of the ridge-type optical waveguide is 2 μm.
In this case, it was difficult to make the ridge angle θ close to 90 °.

An object of the present invention is to reduce the time required for forming a ridge-type optical waveguide when manufacturing an optical waveguide device having a substrate and a ridge-type optical waveguide protruding above the main surface of the substrate. Shortening the processing cost to reduce the damage to the substrate during this processing,
An object of the present invention is to prevent the formation of a damaged layer in the optical waveguide portion. Furthermore, the side surface of the ridge-type optical waveguide is made to approach in the direction perpendicular to the main surface of the substrate.

[0008]

Means for Solving the Problems A first aspect of the present invention is as follows.
A method for manufacturing an optical waveguide device, comprising: a substrate; and a ridge-type optical waveguide protruding above a main surface of the substrate, wherein the optical waveguide device is a second harmonic generation device; Has a quasi phase matching type periodically poled structure, and forms the ridge type optical waveguide by an ablation processing method. According to a second aspect of the present invention,
A method for manufacturing an optical waveguide device comprising a substrate and a ridge-type optical waveguide protruding above a main surface of the substrate, wherein the material of the substrate includes lithium niobate, lithium tantalate, and lithium niobate. The ridge-type photoconductor is formed using one or more oxide single crystals selected from the group consisting of lithium tantalate solid solution or one or more oxide single crystals selected from the group consisting of lithium potassium niobate and lithium potassium tantalate. The present invention relates to a method for manufacturing an optical waveguide device, wherein a waveguide is formed by an ablation method.

The present inventor has been studying a method of forming a ridge type optical waveguide on a substrate made of an oxide single crystal or the like. In this process, the substrate is directly connected to the substrate using an excimer laser. We have conceived of forming a ridge-type optical waveguide by ablation processing.

An excimer laser has a wavelength of 150 to 3
It is a laser beam in the ultraviolet region of 00 nm, and has a feature that the wavelength can be selected depending on the type of gas to be sealed. Ablation processing is a processing method in which high-energy light such as excimer laser light is applied to a material to be processed, thereby instantaneously decomposing and vaporizing a portion irradiated with light, thereby obtaining a target shape.

The present inventors have studied the use of an ablation processing technique using an excimer laser for forming a ridge-type optical waveguide. At the same time, an in-liquid assisted etching method was also studied.

As a result, it has been found that ablation using an excimer laser is particularly effective for forming a ridge-type optical waveguide, and that a ridge-type optical waveguide can be manufactured with extremely high productivity. In addition, the obtained ridge-type optical waveguide exhibited remarkable stability in optical characteristics and shape stability.

The ridge-type optical waveguide obtained as described above shows that, when light is propagated, the ridge-type optical waveguide has good light absorption characteristics and extinction ratio characteristics, and that no modified layer is formed on the surface of the optical waveguide. Discovered and reached the present invention.

According to the present invention, the d / W of the ridge type optical waveguide or the d / W of the ridge portion (described later) can be set to an extremely large value (1 or more and 100 or less) as compared with the conventional art. understood. In particular, an elongated ridge type optical waveguide having a d / W of 2 or more cannot be formed by the ion etching method or the like for the above-described reason. In addition, it was confirmed that the ridge angle of this optical waveguide can be set to approximately 90 °.

The present inventor has further studied the reason why the above-mentioned effects are obtained. That is, regarding the stability of the optical characteristics, in the ablation processing, the material of the substrate is instantaneously decomposed and vaporized in the portion irradiated with light,
It is considered that there was almost no influence of heat, stress, and the like on the peripheral portion where the light did not directly hit, and therefore, no altered layer was formed on the side surface of the ridge-type optical waveguide at all. For example, when etching is performed by the RIE method, a damaged layer having a thickness of several μm is generated. Therefore, it is necessary to design a ridge-type optical waveguide in consideration of the portion of the damaged layer in advance, and furthermore, it is necessary to design optically Stability was low.

Regarding the shape stability of the ridge type optical waveguide, the side surface of the ridge type optical waveguide manufactured by the RIE method has an inclination of 70 to 80 degrees with respect to the main surface of the substrate. However, according to the present invention, the inclination of the side surface of the ridge-type optical waveguide with respect to the main surface of the substrate can be accurately controlled by adjusting the inclination of the lens of the laser light irradiation device to the optimum position.

As a light source for ablation processing, it is necessary to use light on the shorter wavelength side than the absorption edge of the material of the substrate. However, usually, light having a wavelength of 350 nm or less is preferred. In particular, when processing a substrate made of an oxide single crystal, by using light having a wavelength of 350 nm or less, light emitted to the substrate is absorbed in the extremely surface layer. It decomposes only the surface layer and does not damage the inside of the substrate.

Since the wavelength region suitable for such ablation processing varies depending on the position of the light absorption edge of the crystal to be processed, it cannot be uniformly defined. However, an oxide single crystal generally used for an optical waveguide is 350
It has a light absorption edge in a wavelength region of nm or less. Therefore, for example, when an argon laser having a wavelength of 512 nm was used, good ablation processing was not possible. The reason for this is that since the light has a longer wavelength than the absorption edge of the material of the substrate, the light is transmitted to the inside of the oxide single crystal, and ablation due to absorption on the surface hardly occurs.

The wavelength of light for ablation processing is 30
More preferably, it is 0 nm or less. However, from a practical viewpoint, the thickness is preferably 150 nm or more.
As actual light sources, in addition to excimer laser light sources, fourth harmonics of YAG (laser light of 266 nm),
Excimer lamps and the like are currently practical.

As a light irradiation apparatus for ablation processing, a so-called batch exposure type apparatus and a multiple reflection type apparatus are known. The multiple reflection method has a feature that the light utilization rate is high even when the aperture ratio of the mask is small. In the present invention, it is more preferable to use an ablation processing apparatus using a multiple reflection system,
As a result, a chip pattern formed over the entire wafer having a dimension of 1 inch or more can be processed in a short time.

Here, the excimer laser will be further described. An excimer laser is a pulse repetition oscillation laser of ultraviolet light, and has ArF (wavelength 193 nm), Kr
Ultraviolet light oscillated by a gaseous compound such as F (wavelength: 248 nm) and XeCl (wavelength: 308 nm) is extracted by using an optical resonator with uniform directionality. Since an excimer laser is a short-wavelength laser of ultraviolet light, it can decompose the bonds of atoms and molecules constituting a substance with the energy of photons, and applications based on this chemical action have been developed.

Ablation using an excimer laser is used to form holes for fine processing of, for example, polyimide, and it has been reported that fine holes with good shapes can be formed. As a literature on applied technology of excimer laser, "O plus E" 1
A special feature, “Excimer Laser Entering the Practical Use Period”, Nov. 995, pp. 64-108, can be mentioned.

In the present invention, the following three embodiments can be cited as a method for forming a ridge-type optical waveguide by using an excimer laser. (1) Spot scan processing. This is a method schematically shown in FIG. In FIG. 1, a spot-shaped light beam 5 is irradiated so that the optical axis of the laser is perpendicular to the main surface 1a of the substrate 1, and the light beam 5 is directed, for example, in the direction perpendicular to the side surface 1b by an arrow A. Proceed as follows. As a result,
A groove 2A having a rectangular cross section is formed in a portion where the light beam has passed. Similarly, groove 2B parallel to groove 2A
To form However, the broken line 4 indicates a portion to be processed. An elongated ridge type optical waveguide 3 is formed between the grooves 2A and 2B. The upper surface 3a of the optical waveguide 3 is parallel to the surface of the substrate, and the pair of side surfaces 3b are substantially perpendicular to the main surface of the substrate.

According to such a method, the processed deposited layer can be removed by etching after the processing. Further, since the groove pattern is formed by scanning the spot-shaped light beam 5, a ridge-type optical waveguide having an arbitrary planar shape can be formed.

(2) Batch transfer processing. This is a method schematically shown in FIG. 2 (the same parts as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted). A light beam that has passed through a mask having a predetermined transfer pattern in advance 6 is directly applied to the main surface 1a of the substrate 1 to form the ridge type optical waveguide 3 having a predetermined planar pattern without moving the light flux 6.

According to such a method, since the planar transfer pattern of the mask is collectively transferred onto the substrate, the processing efficiency is high, and the reproducibility of the planar shape of the ridge type optical waveguide is extremely good. . However, it is necessary to oscillate a large-area laser beam, and it is necessary to increase the manufacturing accuracy of a mask for transmitting the laser beam and the accuracy of the optical system.

(3) Slit scan processing. This is a method schematically shown in FIG. The laser is transmitted through a mask having slits of an elongated pattern to obtain a laser beam 7 having an elongated rectangular planar shape. The light beam 7 is irradiated on the main surface 1a of the substrate 1 and is moved in the direction of arrow B. According to this method, the shapes of the bottom surfaces of the grooves 2A and 2B formed by processing are particularly smooth. However, in this method, only a linear groove can be formed in a plan view, and therefore, only a linear ridge type optical waveguide can be formed. Further, the edge of the side surface of the ridge-type optical waveguide tends to be unclear.

The ridge type optical waveguide obtained according to the present invention may project directly from the substrate. In addition, a ridge protruding from the substrate is formed, the base of the ridge is formed of the same oxide single crystal as the substrate, and a ridge-type optical waveguide made of an epitaxial film is formed on the top of the ridge. it can. Thereby, for the reasons described below,
Distortion of light in the optical waveguide was eliminated, light propagation loss and coupling loss with the optical fiber were further reduced, and the extinction ratio was reduced.

Hereinafter, each optical waveguide device according to this aspect of the present invention will be described with reference to FIGS. In the optical waveguide substrate 11A of FIG. 4A, a ridge 12A is formed so as to protrude from the main surface 16a of the substrate 16. Here, 16b is the other main surface,
14d is a side surface. The base 15 of the ridge 12A is made of the same oxide single crystal as the material of the substrate 16. A ridge type optical waveguide 13 made of an epitaxial film is provided on the base 15.
Are formed. In this example, since the epitaxial film is used as the optical waveguide, the refractive index of the epitaxial film needs to be larger than the refractive index of the substrate 16.

In the optical waveguide substrate 11B shown in FIG. 4B, a ridge portion 12B is formed so as to protrude from the main surface 16a of the substrate 16. Base 15 of ridge 12B
Comprises an oxide single crystal constituting a substrate material 16, and an epitaxial film 17 and a ridge-type optical waveguide 13 are formed on a base 15.

By forming these ridge portions 12A and 12B by an ablation process, the ratio of d / W is 1 or more, particularly 2 or more, and the ridge angle is approximately 90%.
The optical waveguide or the ridge can be formed so as to have a degree of °.

In such an optical waveguide substrate, the cross-sectional shape of the light beam 14 propagating through the optical waveguide 13 is substantially circular, and the light beam is not distorted. This is because the light beam does not leak or diffuse toward the substrate 16 because the base 15 protrudes from the substrate 16 and the optical waveguide 13 is formed on the base 15. It is. Further, since the side surfaces 13b of the optical waveguide 13 are parallel to each other and the cross-sectional shape of the optical waveguide 13 is a square or a rectangle, the symmetry of the light beam 14 is high, and the propagation efficiency is highest. is there.

Using such an optical waveguide substrate, an optical switching element such as an optical modulator for modulating the intensity and phase of light can be manufactured. At this time, although the form of the electrode for modulating light is not particularly limited, for example, FIG.
It is preferable to form an electrode as shown in FIG. 6B and FIG. In the optical waveguide device of FIG. 5A, an electrode 20A is formed on the top surface or upper surface 13a of the optical waveguide 13 in the optical waveguide substrate 11B, and the electrode 20A is formed on the other main surface or bottom surface 16b of the substrate 16. And an electrode 20B opposed to. The pair of electrodes 20 </ b> A and 20 </ b> B are electrically connected to power supply means (preferably an AC power supply) 22 by electric wires 21. Thereby, with respect to the ridge portion 12B,
A voltage is applied substantially parallel to the length direction (height direction), and an electric field due to this is applied to the optical waveguide 13.

In the optical waveguide device of FIG. 5B, an electrode 20A is formed on the top surface 13a of the optical waveguide 13 of the optical waveguide substrate 11B, and extends over the surface 15a of the base 15 and the main surface 16a of the substrate 16. Next, the electrode 20C is formed. The pair of electrodes 20A and 20C
It is electrically connected to a power supply means 22 by an electric wire 21. Thereby, for the optical waveguide 13,
A voltage is applied in the height direction.

In the optical waveguide device shown in FIG. 6, of the optical waveguide 13 of the ridge portion 12B, the main surface 16 of the substrate 16 is formed.
An electrode 20D is formed on each of a pair of side surfaces 13b perpendicular to a, and each electrode 20D is electrically connected to the power supply means 22 by an electric wire 21. Thereby, a voltage is applied to the optical waveguide 13 by each electrode 20D.

It is needless to say that, even when the optical waveguide substrate 11A shown in FIG. 4A is used, the optical waveguide devices of the respective forms shown in FIGS. 5A, 5B and 6 can be manufactured. Of course, in the case of FIGS. 5A and 5B,
An electrode 20A is formed on the top surface 13a of the optical waveguide 13, and FIG.
In this case, the electrodes 20D are formed on the pair of side surfaces 13b of the optical waveguide 13, respectively.

FIG. 7 is a perspective view showing an optical waveguide device according to a first aspect of the present invention, in which the optical waveguide device is a second harmonic generation device having a quasi-phase matching type periodically poled structure. Indicated by This second harmonic generation device 26 is composed of the optical waveguide substrate 11B. In the optical waveguide 13, a periodically poled structure 25 is formed. That is, as schematically shown in FIG. 7, a large number of domain-inverted portions 25a and 25b are formed in the optical waveguide 13, and the adjacent domain-inverted portions 25a and 25b are
The direction of polarization is reversed.

To manufacture the second harmonic generation device 26, the substrate 16 is polarized in a certain direction (preferably in a direction perpendicular to the main surface 16a), and then an epitaxial film is formed on the substrate 16. Is formed, and the epitaxial film and a predetermined portion of the substrate 16 are ablated as described above. At this time, the polarization direction of the epitaxial film is opposite to the polarization direction of the substrate 16. Next, a periodically poled structure is formed in the optical waveguide according to a known method.

In the present invention, the material of the substrate may be one or more oxide single crystals selected from the group consisting of lithium niobate, lithium tantalate, and a lithium niobate-lithium tantalate solid solution, or lithium potassium niobate and tantalum. One or more oxide single crystals selected from the group consisting of lithium potassium oxide can be used.

The cross-sectional shape of the optical waveguide is not particularly limited, but is preferably substantially square in order to improve the symmetry of the light beam and minimize the light propagation loss. In addition, it is preferable that the d / W of the ridge portion is 2 or more, because the electric field applied to the optical waveguide in the ridge portion hardly spreads toward the substrate. In addition, d of the ridge portion
By setting / W to 100 or less, the handling of the optical waveguide substrate having the ridge portion is facilitated, and the ridge portion is less likely to be damaged during the handling of the substrate.

[0041]

EXAMPLES Example 1 A Z-cut 3-inch wafer LiNbO ₃ single crystal substrate (optical grade) was prepared. This dimension was 3 inches in diameter and 1 mm thick. On this substrate, a lithium niobate-lithium tantalate single crystal film was formed by a liquid phase epitaxial method. _{Specifically,} it was prepared LiNbO ₃ -LiTaO ₃ -LiVO ₃ pseudo ternary melt. The charge composition of this melt was LiNbO ₃ : LiTaO ₃ : LiVO ₃ = 4:
16:80. This melt was stirred at 1200 ° C. for 3 hours or more to obtain a sufficiently uniform liquid phase. Then, after cooling the melt to 950 ° C., it was kept for 12 hours or more. As a result, a supersaturated solid solution nucleated inside the melt, and a solid phase was deposited on the wall of the crucible.

Thereafter, the temperature of the melt was reduced from 950 ° C. to a film forming temperature of 940 ° C. Immediately, a lithium niobate single crystal substrate was brought into contact with the liquid phase portion to form a film. The resulting solid solution film was LiNb _0.70 Ta _0.30 O ₃
Having the following composition: The thickness of the film was 10 μm.

On this solid solution film, a lithium niobate film was formed by a liquid phase epitaxial method. _{Specifically,} it was prepared LiNbO ₃ -LiVO 3 pseudo-binary system melt. The charge composition of this melt was LiNbO3:
LiVO3 = 20: 80. 120
The mixture was stirred at 0 ° C. for 3 hours or longer to obtain a sufficiently uniform liquid phase. Thereafter, the melt was cooled to 905 ° C. and held for 12 hours or more.

Thereafter, the temperature of the melt was cooled from 905 ° C. to a film forming temperature of 900 ° C. Immediately, a lithium niobate single crystal substrate was brought into contact with the liquid phase portion to form a film. The thickness of the obtained lithium niobate single crystal film was about 10 μm.

Ablation processing was performed on the epitaxial film side of this substrate. Using a KrF excimer laser (wavelength: 248 nm) having a shorter wavelength than the absorption edge of lithium niobate single crystal as a light source, ablation was performed by the method shown in FIG. FIG. 8 shows the planar shape of the irradiated light beam. In FIG. 8, reference numeral 8 denotes an irradiated portion or spot, and reference numeral 9 denotes a gap between the two irradiated spots 8, which corresponds to a ridge-type optical waveguide. a was 200 μm, b was 10 μm, and c was 1.0 mm. The optical system was adjusted so that the irradiation energy density was 6 J / cm ² , the pulse width was 15 nsec, the pulse frequency was 600 Hz, and the scanning speed was 1.2 mm / sec. The time required to form the ridge type optical waveguide 3 having a length of 20 mm was 17 seconds.

When the cross-sectional shape of the manufactured ridge-type optical waveguide was observed with a scanning electron microscope, it was confirmed that the grooves 2A, 2A
The depth of B is 20 μm, the width is 10 μm, and the inclination angle of the side surface 3 b of the waveguide 3 with respect to the main surface 1 a is 88 to 9
It was 0 degrees. A TE wave having a wavelength of 1.55 μm was made incident on the ridge-type optical waveguide, and the waveguide characteristics were evaluated. As a result,
The guided light is single mode, and the propagation loss is 0.6 dB
/ Cm.

(Example 2) Z-cut size 30 mm ×
30 mm KLNT (composition K _3.0 Li _2.2 Nb
A KLN epitaxial film (composition K _3.0 Li _2.2 Nb _4.8 O ₁₂ ) having a thickness of 5 μm was formed on a _4.6 Ta _0.2 O ₁₂ ) single crystal substrate by a liquid phase epitaxial method. Ablation processing was performed on the epitaxial film side of this substrate. ArF excimer laser (wavelength 193n) having a shorter wavelength than the absorption edge of KLNT single crystal
m) was used as a light source, and ablation processing was performed by the method shown in FIG. The planar shape of this irradiated light beam is
As shown in FIG. Here, a is 200 μm and b is 5 μm
And c was set to 1.0 mm. Irradiation energy density is 6
The optical system was adjusted to J / cm ² , the pulse width was 15 nsec, the pulse frequency was 300 Hz, and the scanning speed was 1.2 mm / sec. The time required to form the ridge type optical waveguide 3 having a length of 7 mm was 6 seconds.

When the cross-sectional shape of the manufactured ridge-type optical waveguide was observed with a scanning electron microscope, the grooves 2A, 2A
B has a depth of 8 μm, a width of 5 μm, and a waveguide 3.
Of the side surface 3b with respect to the main surface 1a was 90 degrees. A TE wave having a wavelength of 0.85 μm was made incident on the ridge-type optical waveguide, and the waveguide characteristics were evaluated. As a result, the guided light was single mode, and the propagation loss was 0.8 dB / cm.

Comparative Example 1 In the same manner as in Example 1, a lithium niobate-lithium tantalate solid solution film and a lithium niobate film were sequentially formed on a substrate. By the lift-off method, the width of 10 μm and the thickness of 400 Å,
A titanium film mask was formed. Reactive ion etching was performed using C3F6 gas to form a ridge type optical waveguide having a depth of 10 μm and a thickness of 20 mm. The gas pressure was set to 0.01 Torr. Etching rate is 40nm
/ Min.

Observation of the cross-sectional shape of the thus obtained ridge-type optical waveguide with a scanning electron microscope revealed that the ridge-type optical waveguide had a trapezoidal shape, and the inclination angle of the side surface of the optical waveguide with respect to the main substrate surface was 60 to 70. Degree, the width of the top surface was 10 μm, and the width of the bottom surface was 22 μm. A TE wave having a wavelength of 1.55 μm was made incident on the ridge-type optical waveguide, and the waveguide characteristics were evaluated. As a result, the guided light became multimode, and the propagation loss was 1.9 dB / cm.

[0051]

As described above, according to the present invention, a ridge-type optical waveguide can be manufactured with extremely high productivity, and the obtained ridge-type optical waveguide has remarkable stability in optical characteristics and shape stability. And was obtained. The ridge-type optical waveguide thus obtained was observed by propagating light. As a result, it was found that the light absorption characteristics and the extinction ratio characteristics were good, and that no modified layer was formed on the surface of the optical waveguide. Moreover, the angle of the side surface of the ridge-type optical waveguide with respect to the main surface of the substrate could be freely controlled, and in particular, could be made vertical.

[Brief description of the drawings]

FIG. 1 shows a principal surface 1 of a substrate by a spot scan method.
It is a perspective view which shows typically the state which irradiates the spot-shaped light beam 5 with respect to a.

FIG. 2 is a perspective view schematically showing a state in which a light beam 6 is irradiated on a main surface 1a of the substrate by a batch transfer processing method.

FIG. 3 shows a main surface 1 of a substrate by a slit scan method.
It is a perspective view which shows typically the state which irradiates the slit-shaped light beam 7 with respect to a.

FIGS. 4A and 4B are front views schematically showing optical waveguide substrates 11A and 11B that can be manufactured according to the present invention.

FIGS. 5A and 5B are front views schematically showing an optical waveguide device that can be manufactured according to the present invention.

FIG. 6 is a front view schematically showing an optical waveguide device that can be manufactured by the present invention.

FIG. 7 is a perspective view schematically showing a second harmonic generation device based on quasi-phase matching and having a periodically poled structure, which can be manufactured according to the present invention.

FIG. 8 is a plan view showing the shape of a spot of an excimer laser used in an example of the present invention.

[Explanation of symbols]

1, 16 substrate 1a, 16a main surface of substrate 1b
Side surface of substrate 5 Spot-shaped luminous flux 2A, 2B
Grooves 3, 13 Ridge type optical waveguide 6 Light flux 6 7 that has passed through a mask having a predetermined transfer pattern in advance
Slit-shaped light beam 11A, 11B Optical waveguide substrate
12A, 12B Ridge part 15 Base part 14
Light Beam Propagating in Optical Waveguide 13 26 Second Harmonic Generation Device 25 Periodically Poled Structure 25
a, 25b Polarization inversion part

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Minoru 2-56, Sudacho, Mizuho-ku, Nagoya, Aichi Prefecture Inside Nihon Insulators Co., Ltd. (72) Inventor Kenji Kato 2, Sudacho, Mizuho-ku, Nagoya, Aichi Prefecture No. 56 Nippon Insulators Co., Ltd. (72) Inventor Takashi Oguchi No. 2-56, Suda-cho, Mizuho-ku, Nagoya-shi, Aichi F-term in Nippon Insulators Co., Ltd. 2H047 KA05 NA02 PA06 PA22 QA03 TA41 2K002 AB12 BA03 CA03 EA04 EA07 FA27 HA20 4G077 AA03 BC32 BC37 CG02 CG07 EA02 ED06 EF01 HA01 QA04 QA26

Claims (13)

[Claims] 1. A method of manufacturing an optical waveguide device comprising a substrate and a ridge-type optical waveguide projecting on a main surface of the substrate, wherein the optical waveguide device is a second harmonic generation device, The method for manufacturing an optical waveguide device, wherein the ridge-type optical waveguide has a quasi-phase-matching type periodically poled structure, and the ridge-type optical waveguide is formed by ablation processing. 2. A light source for the ablation processing, comprising:
2. The method of manufacturing an optical waveguide device according to claim 1, wherein light having a wavelength of 50 nm or less is used. 3. A light source for the ablation processing, wherein
The method for manufacturing an optical waveguide device according to claim 2, wherein light having a wavelength of 50 to 300 nm is used. 4. The method of manufacturing an optical waveguide device according to claim 1, wherein an oxide single crystal is used as a material of said substrate. 5. The method according to claim 1, wherein the oxide single crystal is at least one oxide single crystal selected from the group consisting of lithium niobate, lithium tantalate and a solid solution of lithium niobate-lithium tantalate. , Claim 4
A manufacturing method of the optical waveguide device according to the above. 6. The photoconductor according to claim 4, wherein at least one oxide single crystal selected from the group consisting of lithium potassium niobate and lithium potassium tantalate is used as said oxide single crystal. Manufacturing method of waveguide device. 7. The ridge portion includes a base made of an oxide single crystal, and an optical waveguide made of an oxide single crystal epitaxial film formed on the base. The method for manufacturing an optical waveguide device according to claim 1. 8. A ratio d / h of a height d and a width W of the ridge portion.
The method of manufacturing an optical waveguide device according to claim 7, wherein W is 2 or more and 100 or less. 9. A method for manufacturing an optical waveguide device comprising a substrate and a ridge-type optical waveguide projecting on a main surface of the substrate, wherein the substrate is made of lithium niobate or lithium tantalate. And one or more oxide single crystals selected from the group consisting of lithium niobate-lithium tantalate solid solution or one or more oxide single crystals selected from the group consisting of lithium potassium niobate and lithium potassium tantalate. Forming the ridge-type optical waveguide by an ablation method. 10. A light source for the ablation processing,
The method for manufacturing an optical waveguide device according to claim 9, wherein light having a wavelength of 350 nm or less is used. 11. A light source for the ablation processing,
The method for manufacturing an optical waveguide device according to claim 10, wherein light having a wavelength of 150 to 300 nm is used. 12. The method according to claim 1, wherein the ridge portion includes a base made of an oxide single crystal and an optical waveguide made of an oxide single crystal epitaxial film formed on the base. A method for manufacturing an optical waveguide device according to any one of claims 9 to 11. 13. A ratio d between a height d and a width W of the ridge portion.
The method for manufacturing an optical waveguide device according to claim 12, wherein / W is 2 or more and 100 or less.