JPH07261135A - Optical waveguide device - Google Patents

Abstract

PURPOSE:To provide an optical waveguide device, such as optical modulator or optical switch, for optical communication system operating in an ultra-high speed region, which has good microwave characteristics with decreased noises and is suitable for long-distance communication. CONSTITUTION:A plane inclusive of progressive wave electrodes 16 on a modulator chip 1 at its top end or a shielding member 35 existing on this plane is formed on the side wall of a housing container 3 in this optical waveguide device. The side faces of this shielding member 35 face the side ends of the progressive wave electrodes 16 via microspacings 36.

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 such as an optical modulator and an optical switch for an optical communication system operating in an ultrahigh speed range, and particularly to a long-distance optical communication having an excellent microwave characteristic. And a structure of an optical waveguide device suitable for.

Optical modulators and optical switches that are driven by high frequency signals and operate in the ultra-high speed range are used in optical communication systems and the like. It is required that the noise superimposed on the characteristic is extremely small.

However, in the conventional optical waveguide device, the shielding effect of the container is insufficient, and a lot of noise is superimposed on the transmission characteristic and the reflection characteristic. Therefore, there is a demand for the development of an optical waveguide device which has good microwave characteristics with little noise and is suitable for long-distance optical communication.

[0004]

2. Description of the Related Art FIG. 5 is a perspective view showing a conventional optical modulator, and FIG. 6 is a view showing a microwave characteristic of the conventional optical modulator.

In FIG. 5, a conventional optical modulator comprises a modulator chip 1 and a metal container 2 for housing the modulator chip 1, and the modulator chip 1 is long on a rectangular substrate 11 made of LiNbO _3. It includes a Mach-Zehnder type optical waveguide 12 formed along the axis.

The Mach-Zehnder type optical waveguide 12 is formed by depositing Ti on the substrate 11, patterning it, and then performing a diffusion process. On the substrate 11, a metal thin film is formed via a buffer layer 13 made of SiO ₂ or the like. And a ground wave electrode 15 and a traveling wave electrode 16 are formed.

A single ground electrode 15 made of a thin metal film that extends linearly is formed in parallel with the optical waveguide 12 formed on the substrate 11, and is located on the optical waveguide 12 to generate a high-frequency signal from the optical waveguide 12. The traveling wave electrode 16 that controls the passing light is a ground electrode.
It is arranged on both sides of 15.

On the other hand, the storage container 2 has a rectangular space 21 in which the modulator chip 1 is placed in the center of the bottom face sandwiched between the side walls 22.
The pedestals 24 for fixing the ceramic plates 23 arranged at the four corners are formed between the sidewalls 22 and the vicinity of both ends of the modulator chip 1 in which the pedestals 24 are accommodated.

The ceramic plate 23 has a microstrip line 25 for supplying a high frequency signal to the traveling wave electrode 16 of the modulator chip 1, and the traveling wave electrode 16 and the microstrip line 25 on the modulator chip 1 are Au wires. It is connected via conductors such as or Au ribbon.

[0010]

The optical modulator used for long-distance communication is required to have less noise superimposed on the transmission characteristics and reflection characteristics of microwaves. A conventional optical modulator having a large gap therebetween cannot provide a sufficient shielding effect for the storage container.

As a result, as shown in FIG. 6, the microwave transmission characteristics and reflection characteristics have a plurality of resonances and an extremely large amount of noise is superposed thereon, so that the conventional structure has good microwave characteristics and long-distance communication. However, there is a problem in that it is impossible to realize an optical modulator that can be used.

An object of the present invention is to provide an optical waveguide device suitable for long-distance communication, which has good microwave characteristics with little noise.

[0013]

FIG. 1 is a perspective view showing the structure of an optical waveguide device according to the present invention. Note that the same object is denoted by the same symbol throughout the drawings.

The above problem is that a single earth electrode is formed on the surface of a substrate 11 having an electro-optical effect, and an optical waveguide 12 extending in the length direction of the substrate 11 is formed of a metal thin film and is arranged in the extending direction of the optical waveguide 12. 15, and traveling wave electrodes 16 arranged on both sides of the ground electrode 15 to control the light passing through the optical waveguide 12,
An optical waveguide device comprising a modulator chip (1) formed on a substrate (11) and a storage container (3) made of metal and containing the modulator chip (1), the upper end of which is on a plane including a traveling wave electrode (16) or on a plane. This is achieved by the optical waveguide device of the present invention in which the positioned shielding member 35 is formed on the side wall of the storage container 3, and the side surface of the shielding member 35 faces the side end of the traveling wave electrode 16 with a minute gap 36 therebetween.

[0015]

In the modulator chip shown in FIG. 1, the side surface of the shield member, which is formed on the side wall of the storage container and has the upper end located on or above the plane including the traveling wave electrode, is opposed to the signal electrode through a minute gap. It is possible to realize an optical waveguide device suitable for long-distance communication, in which the shielding effect of the storage container to be stored is improved and which has good microwave characteristics with little noise.

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 2 is a diagram showing a microwave characteristic in one embodiment of the present invention, FIG. 3 is a plan view showing another embodiment of the present invention, and FIG. 4 is a microwave characteristic in another embodiment of the present invention. FIG.

In FIG. 1, the optical modulator according to the present invention has a modulator chip 1 and a metal container 3 for housing the modulator chip 1. The modulator chip 1 is formed on a rectangular substrate 11 made of LiNbO _3. It has a Mach-Zehnder type optical waveguide 12 formed along the major axis.

The Mach-Zehnder type optical waveguide 12 is formed by depositing Ti on the substrate 11 to form a metal thin film having a thickness of about 1000 Å and patterning it, and then at 1050 ° C. in a wet oxygen atmosphere.
It is formed by performing diffusion processing for 10 hours and diffusing Ti into the substrate 11.

An optical waveguide whose surface extends in the longitudinal direction of the substrate 11.
A buffer layer 13 in which SiO ₂ is deposited is formed on the substrate 11 on which the 12 is formed. On the buffer layer 13, a ground electrode 15 made of a metal thin film and a traveling wave electrode for modulating the transmitted light of the optical waveguide 12 are formed. 16 and are formed.

The single ground electrode 15 made of a thin metal film extending linearly is formed in parallel with the optical waveguide 12 provided on the substrate 11, and is located on the optical waveguide 12 to generate a high frequency signal from the optical waveguide 12. The traveling wave electrode 16 that controls the passing light is a ground electrode.
It is arranged on both sides of 15.

On the other hand, the storage container 3 has a rectangular space 31 in which the modulator chip 1 is placed in the center of the bottom face sandwiched between the side walls 32.
Is formed between the side walls 32 and the vicinity of both ends of the modulator chip 1 in which the pedestals 34 for fixing the ceramic plates 33 arranged at the four corners are housed.

The ceramic plate 33 has a microstrip line 25 for supplying a high frequency signal to the traveling wave electrode 16 of the modulator chip 1, and the traveling wave electrode 16 and the microstrip line 25 on the modulator chip 1 are Au wires. It is connected via conductors such as or Au ribbon.

Unlike the conventional storage container, the storage container 3 has a shield member 35 whose upper end is flush with the upper surface of the traveling wave electrode 16 on the side wall 32, and the side surface of the shield member 35 is on the modulator chip 1 housed therein. It faces the side edge of the traveling wave electrode 16 via a minute gap 36 of 100 μm or less.

The transmission characteristic of microwaves in the optical modulator according to the present invention has a plurality of resonances as shown in FIG. 2 (a), but there is little noise, and the reflection characteristics of microwaves have a plurality of resonances as shown in FIG. 2 (b). Although it has resonance of, the noise is reduced in general and the curve is smooth.

As shown in FIG. 3A, in the above embodiment, the earth electrode 15 is the conductor 37 such as Au wire or Au ribbon and the ceramic plate 33.
The traveling wave electrode 16 is connected to the upper electrode, and is connected to the microstrip line 25 on the ceramic plate 33 by a conductor 38 such as an Au wire or an Au ribbon.

Shielding member formed on the side wall 32 of the storage container 3
As shown in FIG. 3 (c), the upper end of 35 is flush with the traveling wave electrode of the modulator chip 1, and the shielding effect is improved by accommodating the modulator chip 1 in the storage container 3 having the shielding member 35. be able to.

On the other hand, another embodiment of the present invention is shown in FIG.
As shown in, the ground electrode 15 is connected to the electrode on the ceramic plate 33 by the conductor 37, and the traveling wave electrode 16 is similarly connected to the microstrip line 25 of the ceramic plate 33 by the conductor 38 such as Au wire or Au ribbon. .

The ground electrode 15 on the modulator chip 1 is connected to the shield member 35 in the vicinity of the tip via a conductor 39 such as an Au wire or Au ribbon, and the traveling wave electrode 16 on the modulator chip 1 and the upper part thereof are connected. It is insulated by a means such as interposing a space between the conductor 39 and the conductor 39 that traverses.

Shielding member formed on the side wall 32 of the storage container 3
As shown in FIG. 3 (d), the upper end of 35 is above the traveling-wave electrode of the modulator chip 1, and the upper end of the shielding member 35 is located several hundreds of μm above the upper surface of the traveling-wave electrode to further enhance the shielding effect. Can be improved.

As shown in FIG. 4 (a), the microwave transmission characteristic of another embodiment of the present invention is less noise than that of the above embodiment, and the microwave reflection characteristic thereof is also as shown in FIG. 4 (b). A smoother curve with less noise is drawn compared to the embodiment.

In this way, the side surface of the shield member, which is formed on the side wall of the storage container and whose upper end is located on the plane including the traveling wave electrode or on the plane, is opposed to the signal electrode through a minute gap to shield the storage container. It is possible to realize an optical waveguide device which is improved in effect and has good microwave characteristics with less noise and which is suitable for long-distance communication.

[0032]

As described above, according to the present invention, it is possible to provide an optical waveguide device which has good microwave characteristics with little noise and is suitable for long-distance communication.

[Brief description of drawings]

FIG. 1 is a perspective view showing a structure of an optical waveguide device according to the present invention.

FIG. 2 is a diagram showing a microwave characteristic in an example of the present invention.

FIG. 3 is a plan view showing another embodiment of the present invention.

FIG. 4 is a diagram showing a microwave characteristic in another example of the present invention.

FIG. 5 is a perspective view showing a conventional optical modulator.

FIG. 6 is a diagram showing a microwave characteristic of a conventional optical modulator.

[Explanation of symbols]

1 Modulator Chip 3 Storage Container 11 Substrate 12 Optical Waveguide 13 Buffer Layer 15 Earth Electrode 16 Traveling Wave Electrode 25 Microstrip Line 31 Space 32 Sidewall 33 Ceramic Plate 34 Pedestal 35 Shielding Member 36 Minute Spacing 37, 38, 39 Conductor

Claims (5)

[Claims] 1. An optical waveguide (12) is formed on the surface of a substrate (11) having an electro-optical effect and extends in the length direction of the substrate (11), and the optical waveguide (12) is formed of a metal thin film and extends in the extending direction. On the substrate (11), a ground electrode (15) arranged on the substrate (11), and traveling wave electrodes (16) arranged on both sides of the ground electrode (15) for controlling light passing through the optical waveguide (12). Formed Modulator Chip (1)
And a container (3) made of metal and containing the modulator chip (1), the upper end of which is located on the plane including the traveling wave electrode (16) or on the plane. The shielding member (35) is formed on the side wall of the storage container (3), and the side surface of the shielding member (35) faces the side end of the traveling wave electrode (16) through a minute gap (36). An optical waveguide device characterized by the above. 2. The ground electrode (15) on the modulator chip (1) and the shielding member (35) of the storage container (3) are electrically connected via a conductor (39). Optical waveguide device. 3. The optical waveguide device according to claim 1, wherein the minute interval (36) is 100 μm or less. 4. The optical waveguide device according to claim 1, 2, or 3, wherein the optical waveguide (12) is a Mach-Zehnder type optical waveguide. 5. A substrate (11) comprising LiNbO ₃
2. The optical waveguide device described in 2 and 3.