JPH10319264A - Manufacturing method of optical waveguide device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an optical waveguide element which can reduce the occurrence of chipping and flaws on the end face of the optical waveguide and improve the processing efficiency in the processing of the optical waveguide element. SOLUTION: A groove is formed from the surface of the substrate 1 while leaving a part of the back surface side of the substrate 1 on which the optical waveguide 2 is formed so that the end of the optical waveguide 2 of the branching interference type optical waveguide is present on the end face of the optical waveguide element. The side surface 4 of the groove formed and formed is subjected to optical polishing together with the grooving operation, and the part partially left by the grooving process is an optical waveguide that is cleaved and separated along the cleavage plane 5 of the substrate 1. Device manufacturing method.

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 such as an optical modulator or a sensor head of an optical electric field sensor, which utilizes an optical waveguide formed on a crystal substrate exhibiting an electro-optic effect. .

[0002]

2. Description of the Related Art A material exhibiting an electro-optical effect, such as lithium niobate crystal, is used for a substrate of an optical waveguide device used for an optical modulator, a sensor head of an optical electric field sensor, or the like.
The branch interference type optical waveguide of the optical waveguide device is formed by thermally diffusing Ti on a lithium niobate crystal substrate.

A sensor head of an optical electric field sensor is manufactured by forming a modulation electrode near a phase shift optical waveguide of a branch interference optical waveguide formed on a lithium niobate crystal substrate. In addition, in manufacturing the optical waveguide element, vapor deposition or sputtering technology, photolithography technology, fine processing technology, and the like are used.

FIG. 3 shows a configuration diagram of an optical electric field sensor using an optical waveguide element as a sensor head. In FIG.
The sensor head 8 is generally called a reflection type sensor head.

[0005] The sensor head 8 via the optical fiber 22
The light incident on the optical waveguide 2 is branched into two phase-shifted optical waveguides 9 and reflected by the reflection surface 6.

Since the electric field signal received by the beam antenna 21 is applied to the phase shift optical waveguide 9 through the modulation electrode 7, the reflected light is converted into an intensity-modulated optical signal. From the optical waveguide 2, exits to the optical fiber 22, and is transmitted to the photodetector 24 via the optical circulator 25.

Conventionally, in many cases, an optical waveguide element is formed by using a lithium niobate crystal wafer having a diameter of 3 inches or more as a substrate, forming a plurality of branch interference optical waveguides on the surface thereof, and then machining the individual waveguides. Device was cut.

The end surface of the cut optical waveguide element having the branch interference type optical waveguide end is subjected to a precision polishing process called optical polishing for forming a microscopic smooth surface. In the optical polishing, usually, in order to obtain a predetermined optical surface, a workpiece is bonded and fixed to a processing jig, and 1/4 μm diamond abrasive grains are suspended in water on a rotating tin platen. This is performed using an abrasive.

In the case of a reflection type waveguide element, an optical fiber is connected to an input / output optical waveguide end of the optically polished optical waveguide element end face as described above, and a film is connected to the other phase shift optical waveguide end. Or a film was formed by sputtering or the like to form a reflective surface. In the case of a transmission type waveguide element, it is realized by connecting optical fibers to both end surfaces of the optically polished optical waveguide element.

[0010]

However, chipping and flaws often occur on the end face of the optical waveguide element obtained by optical polishing, and if there is chipping or flaws at the end of the optical waveguide or in the vicinity thereof, the optical waveguide element may be damaged. The characteristics such as insertion loss and extinction ratio are inferior and cannot be used. This is one of the causes of the low yield of the optical waveguide element.

In addition, since the bonding and peeling of the optical waveguide element to and from the processing jig are performed under heating, the frequency of breakage due to thermal stress is high, and this is considered to be the main cause of the decrease in yield. Have been.

Further, the time required for bonding and peeling cannot be ignored, which is one of the reasons why the production of the optical waveguide element requires a long time.

As described above, when handling an optical waveguide element that is easily damaged, a careful operation is required, and a high level of skill is required for the operator. It was difficult.

According to the analysis of the present inventor, in the production of an optical waveguide device according to the prior art, by performing a cutting step and an optical polishing step separately, a low yield is caused, which causes unnecessary flaws, and It became clear that the whole production time was prolonged and extremely high proficiency in the work was required for the bonding and peeling steps.

Accordingly, an object of the present invention is to provide a method of manufacturing an optical waveguide device which can reduce the occurrence of chipping and flaws on the end face of the optical waveguide and improve the processing efficiency when processing the optical waveguide device.

[0016]

SUMMARY OF THE INVENTION The present invention relates to a method for manufacturing an optical waveguide device comprising a branch interference type optical waveguide formed on a substrate of lithium niobate, lithium tantalate crystal or the like exhibiting an electro-optical effect. Grooves are formed from the surface of the substrate so that a part of the back surface side of the substrate on which the optical waveguide is formed is left so that the optical waveguide end of the branching interference type optical waveguide is present on the end face of the optical waveguide element. Is a method of manufacturing an optical waveguide device in which optical polishing is performed along with a grooving operation, and a part partially left by the grooving process is cleaved and separated along a cleavage plane of a substrate.

The present invention is a method for manufacturing an optical waveguide device, wherein lithium niobate is used for the substrate exhibiting the electro-optical effect.

According to the present invention, the main surface of the substrate is an X-plane,
The branch interference type optical waveguide is a method for manufacturing an optical waveguide element, wherein light is propagated in the Z direction on the substrate.

[0019]

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

FIG. 1 is an explanatory view of a method for manufacturing a reflection type optical waveguide device according to the present invention. FIG. 2 is a diagram showing a state in which a plurality of reflective waveguide elements are formed on a substrate.

In FIG. 1 and FIG. 2, a plurality of reflection type guides are formed on the X-plane of a substrate 3 of a lithium niobate crystal having a diameter of 3 inches and a thickness of 0.5 mm in which light propagates in the crystal axis Z direction (arrow). An optical waveguide 2 for a waveguide element is formed. Next, the substrate 1 on which the optical waveguide 2 is formed is cured by irradiation with ultraviolet light, and after being cured, is attached to an adhesive tape (not shown) that can be easily peeled off. The surface of the adhesive tape is sucked by a suction chuck to fix the substrate 1.

End face 10 of optical waveguide 2 on which reflection surface is formed
Part, and the end face 11 where the end of the optical waveguide 2 is formed,
Each side surface 4 becomes a groove 3 formed by grooving using a diamond blade. In this case, the grade of the abrasive grains of the diamond blade to be used is preferably # 6000 which is finer than the conventional one.

The groove 3 is formed by cutting a substrate 1 of lithium niobate crystal having a thickness of 0.5 mm to a depth of about 0.4 mm from the surface on which the optical waveguide 2 is formed. In the grooving process, the side surface 4 of the groove 3 is optically polished at the same time as the cut by the formation of the groove 3.

Next, the substrate 1 is cut along the longitudinal direction of each optical waveguide 2 using a # 600 diamond blade. This cutting operation does not require the action of optical polishing. Thereafter, the cut pieces are peeled from the adhesive tape at room temperature by irradiation with ultraviolet rays. Then, a bending force is applied to a part of the bottom of the groove 3 which has been reduced in thickness by the formation of the groove 3 and partially left, and is cut along the cleavage plane 5 of the crystal.

The lithium niobate crystal has a crystal plane of {10
In the case of a groove formed along the Z plane, which is easily cleaved along 2｝, the groove is chamfered after cleavage, and substantially no post-processing is required. Formation is possible.

According to the present invention, the yield is improved as a result of eliminating the cause of introducing defects such as chipping, flaws, breakage, etc. due to the simple process. The same applies to the manufacture of the transmission type optical waveguide device.

[0027]

As described above, according to the present invention, it is possible to reduce the occurrence of defects such as chipping, flaws, breakage and the like on the end face of an optical waveguide, and to manufacture an optical waveguide element capable of improving the processing efficiency. A method is obtained.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a method for manufacturing a reflective optical waveguide device according to the present invention.

FIG. 2 is a diagram showing a state in which a plurality of reflective waveguide elements are formed on a substrate.

FIG. 3 is a configuration diagram of an optical electric field sensor using an optical waveguide element as a sensor head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Optical waveguide 3 Groove 4 Groove side surface 5 Cleavage surface 6 Reflection surface 7 Modulation electrode 8 Sensor head 9 Phase shift optical waveguide 10 End surface (where a reflection surface is formed) 11 End surface (where an end of an optical waveguide is formed) Reference Signs List 21 beam antenna 22 optical fiber 23 light source 24 photodetector 25 optical circulator Y, Z arrows

Claims (3)

[Claims] 1. A method for manufacturing an optical waveguide device comprising a branch interference type optical waveguide formed on a substrate exhibiting an electro-optic effect, wherein an optical waveguide end of the branch interference type optical waveguide exists on an end surface of the optical waveguide device. Grooving from the surface of the substrate so as to leave a part of the back surface side of the substrate formed so that the side surface of the formed groove is subjected to optical polishing together with the grooving operation, and the grooving is performed. A method for manufacturing an optical waveguide element, wherein a part left by processing is cleaved along a cleavage plane of the substrate and separated. 2. The method of manufacturing an optical waveguide device according to claim 1, wherein lithium niobate is used for the substrate exhibiting the electro-optic effect. 3. The optical waveguide according to claim 2, wherein the main surface of the substrate is an X-plane, and the branch interference optical waveguide is formed so that light propagates in the Z direction on the substrate. Device manufacturing method.