JP2001147337A - Optical waveguide element and method for manufacturing the optical waveguide element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form satisfactory light incident and exit end faces, which are free of chipping and edge drooping by polishing at an optical waveguide element having an optical waveguide layer, consisting of Pb1-xLax(ZryTi1-y)1-x/4O3, having a high optoelectric coefficient. SOLUTION: This laminate, including the optical waveguide consisting of the Pb1-xLax(ZryTi1-y)1-x/4O3 (0<x<0.3, 0<y<1.0) and a protective substrate are fixed by the adhesive and are polished integrally in this state under polishing pressure of 100 or higher to 350 or lower kPa, so that the light incident and exit end faces are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical waveguide device and a method for manufacturing an optical waveguide device, and more particularly, to a method for manufacturing an optical waveguide device in which a light input / output end face is formed by polishing, and a method for manufacturing the same. The present invention relates to an optical waveguide device.

[0002]

2. Description of the Related Art Among optical devices, in particular, waveguide type optical modulators.
Optical components such as optical modulators and optical switches propagate as guided light.
Has the role of controlling the optical signal
Corning 7059, BaO,
Nb_TwoO_Five, Ta_TwoO_Five, Al_TwoO_Three, Ion exchange glass, etc.
Quartz-based material, GaAs, GaAlAs, ZnS, ZnO
Such as compound semiconductors and organic materials such as PMMA and VTMS
Material, Ti thermal diffusion LiNbO _Three, Nb thermal diffusion LiTaO_Three,
Ion exchange LiNbO_ThreeSuch as ferroelectric materials
Have been. Among the above optical waveguide materials, oxide ferroelectrics
Body material has a particularly good acousto-optic or electro-optic effect
And an example thereof is LiNbO _Three, BaT
iO_Three, PbTiO_Three, Pb_1-xLa_xZr_yTi_1-y)
_{1-x / 4}O_Three(PZT, PLT, PL depending on the values of x and y
ZT), Pb (Mg_1/3Nb_2/3) O_Three, KNbO_Three, Li
TaO_Three, Sr_xBa_1-xNb_TwoO₆, Pb_xBa_1-xNb_TwoO
₆, Bi_FourTi_ThreeO₁₂, Pb_TwoKNb_FiveO_Fifteen, K_ThreeLi_TwoNb_Five
O_FifteenAnd the like.

As described above, there are various oxide ferroelectric materials.
However, most of the devices actually manufactured are LiNbO_ThreeAnd Li
TaO_ThreeUsing BaTiO_Three, Pb_1-xLa_x
(Zr _yTi_1-y)_{1-x / 4}O_ThreeEtc. are LiNbO_ThreeThan non
Always known as a material with a high electro-optic coefficient
In particular, PLZT (8/65/35: x = 8%, y =
65%, 1-y = 35%) The ceramic is LiNbO
_ThreeAlthough the electro-optic coefficient of the single crystal is 30.9 pm / V
On the other hand, it has a high electro-optic coefficient of 612 pm / V
Despite that, it is not used much.

[0004] Thus, LiNbO_ThreeBetter properties than
Despite the fact that many ferroelectrics have
Most of the devices are LiNbO_ThreeAnd LiTaO_ThreeUsing
The reason is that LiNbO_ThreeAnd LiTaO_ThreeAbout simple ties
Crystal growth technology and its diffusion to wafers and proton exchange
Optical waveguide forming technology has been established, but LiNbO _Three
And LiTaO_ThreeWhen using materials other than
A single crystal thin film must be formed by char growth,
Conventional thin-film optical waveguides of practical quality with the vapor phase growth method
The road could not be created.

[0005] In recent years, in order to solve the above-mentioned problem, a method for producing a thin film optical waveguide having a practical level of quality by solid phase epitaxial growth has been proposed. For example, JP-A-7
Japanese Patent Application Laid-Open No. 78508/1995 discloses that Pb _1-x La _x (Zr
It is described that a thin film optical waveguide having a practical level of quality can be produced even with a material such as _y Ti _1-y ) _{1-x / 4} O ₃ .

However, thin-film optical waveguide consisting of _{Pb 1-x La x (Zr} y Ti 1-y) 1-x / 4 O 3 by epitaxial growth is prepared, the propagation loss in the optical waveguide be greatly reduced If the optical fiber and the optical waveguide cannot be satisfactorily connected, the insertion loss increases, and the device cannot be actually used as an element. In order to reduce the insertion loss, the optical fiber and the optical waveguide must be accurately connected at the time of mounting, that is, reflection and scattering of light should not occur as much as possible at the interface between the optical fiber and the optical waveguide. Required. For this reason, the end face of the optical waveguide is polished to a mirror surface without chipping and scratching.

The end face of the optical waveguide is formed by bonding a protective substrate to an optical waveguide substrate obtained by laminating an optical waveguide material on a substrate, cutting the protective substrate into a desired size, and polishing the cut surface. "Edge" in which the edge of the optical waveguide substrate is polished deeply by the abrasive that has accumulated in the bonding part between the optical waveguide substrate and the protective substrate, "chipping" where a part of the surface is chipped, "scratch" that scratches the polished surface A defect called "who" may occur. Conventionally, in order to prevent such defects from occurring, various polishing methods, polishing agents, and polishing conditions suitable for the objects to be polished have been studied.

Various polishing methods have been proposed as polishing methods for optical devices, including lapping using free abrasive grains, grinding stone polishing using fixed abrasive grains, mechanical action by abrasive grains, and chemical action by acid and alkali. Chemomechanical polishing combined with mechanical action is mainly used.

[0009] For example, mirror polishing of a silicon wafer is usually performed by chemomechanical polishing, as described in an optical device precision machining handbook (Optronics Co., Ltd.). It is mirror-finished using silica at a polishing pressure of 20 kPa and a platen rotation speed of 60 rpm. Japanese Patent Application Laid-Open No. 8-323604 describes a method of polishing silicon carbide using a polishing liquid containing diamond abrasive grains having an average particle diameter of 1 to 3 mm at a polishing pressure of 66 kPa or less as a method for polishing silicon carbide. . In addition, a method for polishing a quartz wafer by using colloidal cerium and changing the processing pressure in a range of about 7 to 23 kPa is described on page 59 of the proceedings of the 1996 Autumn Meeting of Precision Optics Academic Lecture Meeting. In addition, the page 57 of the 1996 Autumn Meeting of the Japan Society of Precision Optics Academic Lectures shows that, for a MgO single crystal substrate used for an optical material such as a lens, ZrO ₂ is dispersed under a polishing pressure of about 44 kPa and pH is reduced. It is described that mirror polishing with good smoothness can be realized by using an abrasive having a particle size of 11.

As described above, silicon carbide, silicon, quartz,
Generally, the polishing pressure at the time of polishing an optical material such as a single crystal of MgO is different for each material.

[0011]

[SUMMARY OF THE INVENTION However, it produced by epitaxial growth _{Pb 1-x La x (Zr} y T
At present, there is no established method for forming an end face of an optical waveguide device having a thin film optical waveguide made of i _1-y ) _{1-x / 4} O ₃ .

Accordingly, the objective is to _{Pb 1-x La x (Zr} y Ti 1-y) 1-x / 4 O 3 optical waveguide element having an optical waveguide layer made of having a high electro-optic coefficient of the present invention, By polishing
It is an object of the present invention to provide a method of manufacturing an optical waveguide device that forms a good light input / output end face without chipping or edge droop.
Another object of the present invention has an optical waveguide layer made of _{Pb 1-x La x (Zr} y Ti 1-y) 1-x / 4 O 3 having a high electro-optic coefficient, the edge who no An object of the present invention is to provide an optical waveguide device having a good end face.

[0013]

In order to achieve the above object, a method for manufacturing an optical waveguide device according to the first aspect of the present invention comprises the steps of:
_{1-x La x (Zr y} Ti 1-y) 1-x / 4 O 3 (0 <x <0.3,
0 <y <1.0), the laminate including the optical waveguide layer composed of 0 <y <1.0) and the
The light input / output end face is formed by integrally polishing the laminate and the protective substrate at a polishing pressure of not less than a and not more than 350 kPa.

According to a second aspect of the present invention, in the method of the first aspect, the elastic modulus of the adhesive is:
It is characterized by being at least 1 GPa.

According to a third aspect of the present invention, there is provided the method of manufacturing an optical waveguide device according to the first or second aspect of the invention, wherein the polishing agent has a pH of 10 or more and SiO ₂ having an average particle size of 100 nm or less is dispersed. It is characterized by using.

An optical waveguide device according to a fourth aspect of the present invention is an optical waveguide device comprising SrT
the iO ₃ substrate or impurity-doped SrTiO _{3 substrate, Pb 1-x La x (} Zr y Ti 1-y) 1-x / 4 O 3 (0 <x <
An optical waveguide device having an optical waveguide layer formed of 0.3, 0 <y <1.0), wherein the curvature of the end face defined by the following equation is 4 ° or less.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optical waveguide device and a method of manufacturing the optical waveguide device according to the present invention will be described in detail.

The object of the polishing process in the present invention is shown in FIG.
As an example, Pb _{1-x is formed} on a single crystal substrate 11 as shown in FIG.
_{La x (Zr y Ti 1-} y) 1-x / 4 O 3 (0 <x <0.3,0
<Y <1.0) is a laminate (hereinafter referred to as “optical waveguide substrate”) 10 in which thin film optical waveguide layers 13 made of <y <1.0) are stacked, and a buffer layer 12, a cladding layer (not shown), and the like as necessary. Is provided. The method of forming the thin film optical waveguide layer and the material of the single crystal substrate will be described later.

In the present invention, as shown in FIG. 2, the optical waveguide substrate 10 and the protective substrate 14 are fixed with an adhesive 16 so that the protective substrate 14 overlaps the thin film optical waveguide layer 12, and the desired size is obtained. After cutting into pieces, the cut surface 18
Are integrally polished with the adhesive 16 in a state where the optical waveguide substrate 10 is fixed to the protective substrate 14, thereby forming a light input / output end face. Note that the optical waveguide substrate 10 is cut perpendicular to the lamination surface.

As the protective substrate, Pyrex, soda glass, fused quartz, Corning 7059, BaO, Nb
A known glass substrate such as ₂ O ₅ , Ta ₂ O ₅ , Al ₂ O ₃ , CeO ₂ , and TiO ₂ can be used.

As the adhesive, a known adhesive used for assembling optical components can be used, but it is preferable to use an adhesive having an elastic modulus of 1 GPa or more in order to prevent occurrence of edge dripping. When the elastic modulus is less than 1 GPa, under a high polishing pressure of 100 kPa or more, only the adhesive layer is liable to be selectively polished and edge dripping is likely to occur.

Specifically, Canadian balsam, unsaturated polyester resin-based adhesive, room temperature-curable or heat-curable epoxy resin-based adhesive, acrylic adhesive, cyanoacrylate-based instant adhesive, UV-curable adhesive, Silicone adhesives, etc. can be mentioned, but it is easy to adhere in a short time
UV curable adhesives are preferred. UV-curable adhesives include epoxy-based, acrylate-based, and vinyl-based UV-curable adhesives. Edge curling hardly occurs, and the protective substrate detaches even when an alkaline abrasive is used. Since there is no danger, a UV-curable adhesive made of an alkali-resistant decyclic epoxy resin is particularly preferably used.

As the polishing apparatus, for example, a polishing apparatus as shown in FIG. 3 can be used. The polishing apparatus shown in FIG. 3 includes a polishing pad 1 rotatably arranged and a polishing object 2.
, And a jig 3 on which a weight 4 for adjusting the polishing pressure to a predetermined pressure is placed. The abrasive tank 5 is provided with a nozzle 6 for supplying an abrasive.
And a polished surface of the object 2 to be polished. The object to be polished 2 is fixed by a jig 3 so that the surface to be polished is in contact with the polishing pad 1 at a predetermined pressure, and the surface to be polished is polished at a predetermined pressure by rotating the polishing pad 1 in the arrow direction. You. Further, the polishing portion is supplied with the polishing agent at predetermined time intervals from the nozzle 6 of the polishing agent tank 5 as needed.

Examples of the polishing method include lapping using free abrasive grains, grindstone polishing using fixed abrasive grains, and chemomechanical polishing using both mechanical action of abrasive grains and chemical action of acid and alkali.

In the present invention, in order to form a good end face free from chipping and scratching, 10
It is important to polish at a polishing pressure of 0 kPa to 340 kPa, and the polishing pressure is 170 kPa to 340 kPa.
Pa or less is preferable, and 200 kPa or more and 290 kPa or less are more preferable. In polishing pressure of less than 100 kPa, it is difficult to remove the _{Pb 1-x La x (Zr} y Ti 1-y) 1-x / 4 O 3 chipping and scratches in the end face of the optical waveguide, polishing of more than 340kPa Polishing with pressure is not preferable because edge dripping becomes remarkable. Edge edge can be evaluated by the curvature of the end face defined by the following equation.

[0026]

(Equation 2)

The curvature of the end face is set to 4 ° or less so that the connection with the fiber is hardly affected. More preferably, the curvature of the end face is 1 ° or less. When the curvature of the end face is 1 ° or less, almost no edge is observed even by microscopic observation.

As a polishing pad, for lapping,
A polishing pad made of a metal such as cast iron, copper, tin, and zinc can be used, and among them, a polishing pad made of copper or tin is preferable. Diamond, CaCO ₃ , Ba
CO ₃ , Fe ₂ O ₃ , CeO ₂ , Cr ₂ O ₃ , Al ₂ O ₃ , Si
A lapping grindstone such as C bonded with a binder such as phenolic resin, polyvinyl alcohol, or polyester can be used. On the other hand, for chemomechanical polishing, known polishers such as blown asphalt polisher, shellac impregnated felt polisher, and urethane polisher can be used, with urethane polisher being preferred.

The number of revolutions of the polishing pad at the time of polishing is preferably 50 rpm or more, more preferably 10 rpm, at the time of lapping or grinding of a grinding stone, in that the polishing efficiency becomes good.
0 rpm or more. The rotation speed during the chemomechanical polishing is preferably 70 rpm or less, particularly preferably 50 rpm or less.

The abrasive is obtained by dispersing an abrasive material in a liquid medium.
The abrasive material is diamond, Fe
_TwoO_Three, Fe_TwoO_Four,CeO_Two, ZrO_Two, TiO_Two, Sn
O_Two, Al_TwoO _Three, Cr_TwoO_Three, SiO_Two, TbO_Two, Mg
O, ZnO, CaCO_Three, MgCO_Three,, PbO, MnO
_Two, MnO, colloidal silica, fumed silica, pure
High purity silica, fumed alumina, high purity alumina
Any known one can be used. Distribute the abrasive material
Water or KOH solution, ammonia
Near solution, alkaline solution such as NaOH solution
You. Particularly, the pH of the alkaline solution is preferably from 10 to 12.

The average particle size of the abrasive material may be in the range of 0.1 mm to 100 mm for lapping, more preferably 0.5 mm to 10 mm. If the average particle diameter exceeds 100 mm, the roughness of the end face becomes large, and cracks are easily generated. On the other hand, if it is less than 0.1 mm, the polishing efficiency is undesirably reduced. For chemomechanical polishing, the thickness is preferably from 10 nm to 100 nm, more preferably from 10 nm to 50 nm.

Although lapping, grinding stone polishing, and chemomechanical polishing may be performed alone, these polishing methods may be used in combination. Above all, a method of performing rough polishing (lapping) with an aqueous solution containing diamond abrasive grains and then finish polishing (chemomechanical polishing) with an alkali solution containing colloidal silica abrasive grains is particularly preferable.

[0033] _{Pb 1-x La x (Zr} y Ti 1-y) 1-x / 4 O
₃ (0 <x <0.3, 0 <y <1.0) is a thin film optical waveguide layer formed by electron beam evaporation, flash evaporation, ion plating, Rf-magnetron sputtering, ion beam sputtering, Laser ablation, MBE, CVD, plasma CVD, MOC
VD and the like, solid phase epitaxial growth by heating after forming an amorphous thin film by the above-mentioned vapor phase growth, or solidification by heating of an amorphous thin film formed by a wet process such as a sol-gel method or a MOD method. It is produced by a phase epitaxial growth method. Among these methods, the solid-phase epitaxial growth method is more preferable in terms of waveguide quality, and an amorphization step in which a solution of a metal organic compound such as a metal alkoxide or an organic metal salt is applied to a substrate and the applied film is made amorphous by heating. And a crystallization step of crystallizing the amorphous thin film by heating. The solid-phase epitaxial growth method requires less equipment cost than various vapor-phase growth methods, has good crystal uniformity within the substrate surface,
The control of the refractive index, which is important for controlling the structures of the buffer layer, the thin film optical waveguide layer, and the cladding layer, can be easily performed with good reproducibility.

Single crystal substrate for providing a thin film optical waveguide layer
Has SrTiO_Three, BaTiO_Three, BaZrO_Three, La
AlO_Three, ZrO_Two, Y_TwoO_Three8% -ZrO_Two, MgO, M
gAl _TwoO_Four, LiNbO_Three, LiTaO_Three, Al_TwoO_Three, Z
Oxides such as nO and simple substances such as Si, Ge, and diamond
Semiconductor, AlAs, AlSb, AlP, GaAs, G
aSb, InP, InAs, InSb, AlGaP, A
1LnP, AlGaAs, AlInAs, AlAsS
b, GaInAs, GaInSb, GaAsSb, In
III-V group compound semiconductors such as AsSb, ZnS, Z
nSe, ZnTe, CaSe, Cdte, HgSe, H
Group II-VI compound semiconductors such as gTe and CdS
Oxide thin film photoconductive
Oxides, special features, are often advantageous for the film quality of the waveguide.
SrTiO_ThreeIt is preferable to use

The SrTiO ₃ substrate may be made semiconductive by doping impurities with the impurity, and may be used as the substrate. Elements that can be used as impurity dopants are Sr sites of SrTiO ₃ or Tr.
Any element having an ionic radius capable of substituting the i-site and having a valence different from that of Sr or Ti may be used. Sc, Lu, Yb, Tm, Er, H
o, Y, Dy, Tb, Bi, Gd, Na, Eu, Sm,
Zn, Nd, Pr, Ce, La, In, K, Tl, R
b, Cs, and the like are preferable, and Al, As,
V, Ni, Ga, Sb, Co, Fe, Ta, Rh, N
b, Cr, Mn, Bi, Ru, In, Sc, Sn, P
u, Np, Lu, Yb, U, Tm, Er, Pa, Ho,
Y, Dy, Tb, Tl, Gd, Eu, Sm, Pm, A
m, Nd, Pr, Ce, La, Th, Ac, and the like are preferable, and Sc, Y, La, and C, which are Group III elements of the periodic table, are used.
e, Pr, Nd, Pm, Sm, Eu, Gd, Tb, D
y, Ho, Er, Tm, Yb, Lu, Ac, Al, G
a, In, or V, Nb, Ta, P
Elements selected from a, As, Sb, and Bi are more preferable, and La and Nb are particularly preferable.

[0036]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples. Example 1 <Manufacture of Optical Waveguide Substrate> As shown in FIG.
₃ A PZT buffer layer 12 having a composition of Pb (Zr _0.95 Ti _0.05 ) O ₃ is laminated on the (100) single crystal substrate 11 by solid phase epitaxial growth to a thickness of 1430 nm.
Pb _0.91 La _0.09 (Zr _0.65 Ti _0.35 ) O ₃
The optical waveguide substrate 10 in which the PLZT optical waveguide layer 13 having the following composition was laminated with a thickness of 1500 nm was manufactured.

The details of the fabrication process are as follows. Anhydrous lead acetate Pb (CH ₃ COO) ₂ , zirconium isopropoxide Zr (OiC ₃ H ₇ ) ₄ , and titanium
As isopropoxide _{Ti (O-i-C 3} H 7) 4 starting material, 2-methoxy ethanol to dissolve, and distillation performed under reflux, eventually PZT buffer layer precursor of 0.6M in Pb concentration Obtain a solution. Next, the precursor solution is washed,
Spin coating is performed on the etched and dried SrTiO ₃ (100) single crystal substrate 11. The temperature is raised in an O ₂ atmosphere, maintained at 350 ° C., further maintained at 650 ° C., and then cooled. By repeating this, 143
A PZT buffer layer 12 having a thickness of 0 nm is grown by solid phase epitaxial growth. In addition, Pb _0.91 La
_A precursor solution for a PLZT optical waveguide layer, which becomes the PLZT optical waveguide layer 3 having a composition of _0.09 (Zr _0.65 Ti _0.35 ) O _3, is spin-coated, heated in an O ₂ atmosphere, kept at 350 ° C., and further heated to 650. After holding at ℃, cool. By repeating this, a PLZT having a thickness of 1500 nm is formed.
The optical waveguide layer 13 is grown by solid phase epitaxial growth.

As starting materials for the precursor solution for the PLZT optical waveguide layer, anhydrous lead acetate Pb (CH ₃ COO) ₂ , zirconium isopropoxide Zr (OiC ₃ H ₇ )
₄ 、 Titanium isopropoxide Ti (OiC
₃ H _{7) 4} in addition to lanthanum triisopropoxide La
Is used _{(O-i-C 3 H} 7) 3.

The crystallographic relationship is that of a single orientation PLZT (1
00) thin-film optical waveguide // PZT (100) buffer layer /
/ SrTiO ₃ (100) substrate, in-plane orientation PLZT [0
01] thin-film optical waveguide // PZT [001] buffer layer /
/ SrTiO ₃ [001] substrate structure is obtained. <Formation of End Surface of Optical Waveguide> Next, PLZT of an optical waveguide substrate
A quartz substrate was fixed on the upper surface of the optical waveguide layer with a UV-curable adhesive (elastic modulus: 1 GPa, de-ring epoxy resin).
The optical waveguide substrate to which the quartz substrate was bonded was fixed to a stainless steel jig with wax, and cut into a desired size with a wire saw. After cutting, the optical waveguide substrate was removed from the jig by heating.

Next, using a polishing apparatus having the same configuration as the polishing apparatus shown in FIG. 3, the optical waveguide substrate with the quartz substrate adhered is fixed to a jig so that the cut surface comes in contact with the polishing pad, and the polishing is performed. The pad was rotated and polished at a polishing pressure of 120 kPa. Polishing was performed in three stages using the following combinations of polishing agents and polishing pads. First, the average particle size is 10 m
The surface is polished for 50 minutes at a polishing rotation speed of 100 rpm with a combination of an abrasive made of a dispersion liquid of diamond and water and a copper pad, and then the average particle size is obtained under a polishing pressure of 120 kPa. Is polished with a combination of a polishing agent composed of a dispersion liquid of diamond and water of 0.5 mm and a pad made of tin for 40 minutes at 100 rpm, and finally, pH 10 in which 50 nm of colloidal silica is dispersed.
3 with combination of alkaline solution of epoxy and epoxy polisher
The chemomechanical polishing was performed at 50 rpm for 0 minutes.

The state of chipping and scratching of the input / output end face after polishing was observed with an optical microscope, and as shown in FIG.
Evaluation was made by measuring the ratio (a + b) / L of the length (a + b) of the chipping scratch to the length L of the end face (hereinafter, referred to as “end face defect rate”). The degree of edge droop was evaluated by observing with a laser displacement microscope and calculating the curvature of the above-described end face.

As a result of the evaluation of the obtained input / output end face, the end face defect rate was 1.6%, which was not a level affecting the optical evaluation, and the end face curvature was 0.02 °. (Example 2) Polishing was performed in exactly the same manner as in Example 1 except that the polishing pressure was 240 kPa. The evaluation result of the obtained incident / exit portion end face shows that the end face defect rate is 0.8
%, And the curvature of the end face was 0.35 °. (Example 3) Polishing was performed in exactly the same manner as in Example 1 except that the polishing pressure was 310 kPa. The evaluation results for the obtained incident / exit portion end face show that the end face defect rate is 0.3
% And the curvature of the end face was 3.51 °,
It was not at a level that affected the connection with the fiber. (Example 4) Polishing was performed in exactly the same manner as in Example 1 except that the polishing pressure was 110 kPa. The evaluation result of the obtained incident / exit portion end face shows that the end face defect rate is 2.5%.
%, And the curvature of the end face was 0.2 °, which was not a level affecting the connection with the fiber. Example 5 Polishing was performed in exactly the same manner as in Example 1 except that the chemomechanical polishing step using a combination of colloidal silica and epoxy polisher was omitted. As a result of the evaluation of the end face of the obtained input / output part, the end face defect rate was 2.3%, which was not a level affecting the optical evaluation, but the end face curvature was 0.02 °. (Example 6) Polishing was performed in exactly the same manner as in Example 1 except that an acrylic adhesive having an elastic modulus of 0.3 GPa was used as a UV adhesive for bonding a quartz substrate to the incident / exit end surface. The evaluation results for the obtained input / output section end faces are as follows:
The end face defect rate was 1.7%, which was not a level that would affect the optical evaluation, and the curvature of the end face was 3.03 °, but not a level that had a bad effect on the connection with the fiber. (Example 7) SrTiO ₃ doped with 0.5% of Nb
Polishing was performed in exactly the same manner as in Example 2 except that a (100) single crystal substrate was used. As a result of evaluation of the obtained end face of the incident / exit portion, the end face defect rate was as good as 0.6%, and the curvature of the end face was 0.05 °. (Embodiment 8) The PZT buffer layer 2 is made of Pb _0.91 La
PLZT having a composition of _0.09 (Zr _0.65 Ti _0.35 ) O ₃ ,
The PLZT optical waveguide layer 3 is made of Pb (Zr _0.52 Ti _0.48 ) O ₃
Polishing was performed in exactly the same manner as in Example 1 except that PZT having the composition of The evaluation result of the end face of the input / output part obtained was that the end face defect rate was 1.3%, which was not a level affecting the optical evaluation, but the end face curvature was 0.3%.
1 °. (Example 9) Polishing was performed in exactly the same manner as in Example 2 except that a MgO (100) single crystal substrate was used. As a result of the evaluation of the end face of the obtained input / output part, the end face defect rate was 1.1%, which was not a level affecting the optical evaluation, and the end face curvature was 0.26 °. Comparative Example 1 Polishing was performed in exactly the same manner as in Example 1 except that the polishing pressure was 60 kPa. The evaluation result of the obtained incident / exit portion end face shows that the curvature of the end face is 0.07.
°, but the end face defect rate was as high as 6.3%. Comparative Example 2 Polishing was performed in exactly the same manner as in Example 1 except that the polishing pressure was 380 kPa. The evaluation result of the obtained incident / exit portion end face shows that the end face defect rate is 0.2%.
%, But the curvature of the end face was 4.32 °,
The edge droop occurred over the range from the end of the protective substrate to the optical waveguide substrate. The evaluation result was evaluated as △ × 3 according to the following criteria
Table 1 shows the results displayed in stages. The evaluation criteria for the end face defect rate are as follows. Edge face defect rate of less than 1%: Edge face defect rate of 1% or more and less than 3%: Δ Edge face defect rate of 3% or more: × In addition, the evaluation criteria for edge droop are as follows. Curvature of end face less than 1 °: Curvature of end face not less than 1 ° and 4 ° or less: △ Exceeding curvature of end face of more than 4 °: × Comprehensive evaluation is one in which there is no x in the end face defect rate / edge edge evaluation However, those with x were marked as x.

[0043]

[Table 1]

From the above results, the polishing pressure was 100 kPa
It can be seen that when the polishing pressure is in the range of 350 kPa or less, chipping and edge dripping are significantly suppressed as compared with the case where the polishing pressure is out of this range.

[0045]

According to the manufacturing method of the optical waveguide element of the present invention, Pb _{1- x} La _x having a high electro-optic coefficient (Zr _y T
i _1-y ) By polishing, an optical waveguide element having an optical waveguide layer made of _{1-x / 4} O ₃ can form a good light input / output end face without chipping or edge dripping.

Furthermore, according to the present invention has an optical waveguide layer made of _{Pb 1-x La x (Zr} y Ti 1 -y) 1-x / 4 O 3 having a high electro-optic coefficient, the edge Who An optical waveguide device having no good end face is provided. If this optical waveguide element is used, the connection with the optical fiber is also improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a layer configuration of an optical waveguide substrate.

FIG. 2 is a schematic view showing a structure of a polishing object.

FIG. 3 is a schematic configuration diagram illustrating an example of a polishing apparatus used in the manufacturing method of the present invention.

FIG. 4 is an explanatory diagram for explaining a method of calculating an end face defect rate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Polishing pad 2 Polished object 3 Jig 4 Weight 5 Abrasive tank 6 Nozzle 10 Optical waveguide substrate 11 Single crystal substrate 12 Buffer layer 13 Optical waveguide layer 14 Protection substrate 16 Adhesive 18 Cutting surface

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H047 KA02 MA05 PA02 PA06 PA24 QA01 TA32 2H079 AA02 AA12 DA03 EA02 EA21 HA11 JA06 JA08

Claims (4)

[Claims] 1. A _{Pb 1-x La x (Zr} y Ti 1-y) 1-x / 4 O 3
(0 <x <0.3, 0 <y <1.0) The laminate including the optical waveguide layer composed of 0 <x <0.3 and 0 <y <1.0) and the protective substrate are fixed with an adhesive and the polishing pressure is 100 kPa or more and 350 kPa or less. A method for manufacturing an optical waveguide device, wherein a light input / output end face is formed by integrally polishing a laminate and the protective substrate. 2. The method according to claim 1, wherein the adhesive has an elastic modulus of 1 Gpa or more. 3. The pH is 10 or more and the average particle size is 1
3. The method for manufacturing an optical waveguide device according to claim 1, wherein an abrasive in which SiO _{2 of} not more than 00 nm is dispersed is used. 4. A SrTiO ₃ substrate doped with SrTiO ₃ substrate or _{impurities, Pb 1-x La x (} Zr y Ti
_1-y ) An optical waveguide element having an optical waveguide layer formed of _{1-x / 4} O ₃ (0 <x <0.3, 0 <y <1.0),
An optical waveguide element having a curvature of an end face defined by the following formula of 4 ° or less. (Equation 1)