JPH01118821A - Waveguide type optical switch - Google Patents

Abstract

PURPOSE:To manufacture the optical waveguide type optical switch which has practical crosstalk characteristics at high yield by specifying the element length and coupling length. CONSTITUTION:When a voltage which places the waveguide optical switch 38 in a cross state to one light beam having large electrooptic effect is applied to control electrodes 32, 34, and 36 while the element length is L and the coupling length is lc, the element length L and coupling length lc are so specified that the L/lc to the other light beam with small electrooptic effect is a value at which the waveguide type optical switch 38 is put in a cross state to the other light beam. Thus, the element length L and the coupling length lc to the other light beam are set to make the operation point where the cross state is entered to the former light beam coincident with the operation point where the cross state is entered to the latter light beam. Consequently, the waveguide type optical switch which has the practical crosstalk characteristics is manufactured at high yield.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is a polarization-independent waveguide optical switch having crosstalk characteristics suitable for practical use, and which is manufactured under milder manufacturing conditions. Regarding the upcoming waveguide type optical switch.

(Prior Art) In recent years, research and development of waveguide optical switches without polarization dependence have been progressing, for example, in Document I "Optical Communication Systems Workshop (OCS-87101987°8.3L) J
A polarization-independent optical waveguide switch that operates at low voltage and low loss in θ has been proposed.

FIG. 9 is a plan view schematically showing the configuration of the waveguide type optical switch proposed in the above-mentioned literature.

In the figure, 10 is a two-cut LiNbO3 substrate, 12
is the coupling region where light interaction takes place, and 14 and 1
Reference numeral 6 indicates input and output waveguides that are parallel to each other in the coupling region, and input and output waveguides 14 and 16 are formed by diffusing Ti into the substrate 10. 18 and 20 indicate control electrodes, one control electrode 18 which is not divided into the coupling region 12 of the input/output waveguide 14, and the input/output waveguide 1.
One control electrode 20 that is not divided into 6 coupling regions 12 is provided, and the illustrated waveguide optical switch 22 is connected to these control electrodes +8.20! The configuration is such that ΔB in-phase drive is carried out.

In a waveguide optical switch having parallel input and output waveguides 14 and 16 in the coupling region 12, T
By adjusting the voltage applied to the control electrodes 18 and 20, the operating point at which the bar (8a r) state occurs for M waves and the operating point at which the bar state occurs for TE waves with a small electro-optic effect can be set. It is generally known that matching can be achieved. The ratio of the electro-optic coefficients γ, 3 and γ33 of the 2-capacity LiNbO3 substrate 12 is γ13/γ33 1/3.
．． 3, it is possible to match the first operating point at which the bar state occurs for the TM wave with the third operating point at which the bar state becomes the TE wave.

Furthermore, in a configuration in which ΔB in-phase drive is performed using undivided control electrodes 18 and 20, cross (Cro)
ss) state and Cross
In order to match the operating point that becomes the state, the TM wave and the TE
It was necessary to match the coupling coefficients for the waves.

Moreover, in this configuration, in order to obtain crosstalk suitable for practical use in the Cross state, it is necessary to make the coupling length for the TM wave match the element length, and to make the coupling length for the TE wave match the element length. Ta.

(Problems to be solved by the invention) However, in the above-mentioned conventional optical waveguide type optical switch,
The problem is that the production conditions (especially the production conditions for the Ti thin film for forming input/output waveguides) are very strict, making it impossible to produce optical waveguide type optical switches with crosstalk characteristics suitable for practical use with a high yield. There was a point.

That is, the TiE diffused waveguide is formed by diffusing Ti formed into a thin film on the substrate, but as mentioned above, in order to match the coupling coefficient and make the coupling length minus 8 to the element length, This Ti thin film is made so that the thickness of this thin film is within the production error range of the design value (design value x 4%).
must be formed. However, it has been extremely difficult to control the thickness of the Ti thin film within such an error range.

The purpose of this invention is to solve the above-mentioned conventional problems and to provide a waveguide type optical switch that has crosstalk characteristics suitable for practical use and is polarization-independent, and that can be manufactured under more relaxed manufacturing conditions. Our purpose is to provide optical switches.

(Means for Solving the Problem) In order to achieve this objective, the waveguide optical switch of the first invention of this application has two inputs parallel to each other in the coupling region where light interaction takes place. In a waveguide optical switch having an output waveguide and an inverted ΔB electrode type control electrode, the element length is L and the coupling length is 8ρ. In this case, when a voltage is applied to the control electrode to bring the operating state of the waveguide optical switch into a cross state for one light that has a large electro-optic effect,
L/ρ for the other light that has a small electro-optic effect. The element length and the coupling length β are such that the value of is such that the operating state of the waveguide optical switch with respect to the other light is in a cross state. It is characterized by being configured by setting.

Further, the waveguide optical switch of the second invention of this application has two input/output waveguides parallel to each other in the coupling region where light interaction occurs, and has an inverted Δβ electrode type control electrode. In a waveguide optical switch having an element length of L and a coupling length of lc, a voltage is applied to the control electrode to bring the operating state of the waveguide optical switch into a cross state for one light that has a large electro-optic effect. When applied,
L/β for the other light that has a small electro-optic effect. The element length and the coupling length β are such that the value of is such that the operating state of the waveguide optical switch with respect to the other light is a cross state. and an auxiliary control electrode for forming a vertical electric field and/or a horizontal electric field is provided in at least one input/output waveguide of the coupling region.

(Function) According to the waveguide optical switch of the first and second inventions of this application, two input/output waveguides parallel to each other are provided in the coupling region where light interaction occurs. In a waveguide optical switch having such parallel input and output waveguides,
For one light that has a large electro-optic effect, bar (Ba
By adjusting the voltage applied to the control electrode, it is possible to match the operating point at which the light is in the r) state and the operating point at which the other light, at which the electro-optical effect is small, becomes the Bar state.

Further, according to the waveguide optical switch of the first and second inventions of this application, a voltage is applied to the control electrodes to bring the operating state of the waveguide optical switch into a cross state with respect to one light having a large electro-optic effect. When applied to the other light, the electro-optic effect becomes small when L/β is applied to the other light. The element length and the value of ! for the other light are such that the operating state of the waveguide optical switch for the other light is a cross state. . Set. In this way, the element length and β-c for the other light
By setting Cross
It is possible to match the operating point at which the light enters the state and the operating point at which the other light becomes the Cross state.

Therefore, according to the first and second inventions, the operating points of the Bar state for one light and the other light are made to match, and the operating points of the Cross state for one light and the other light are made to match, so that the polarization dependence is reduced. You can perform movements that are not possible.

In general, the waveguide optical switch of the second invention includes an auxiliary control electrode for forming a vertical electric field and/or a horizontal electric field in at least one of the input/output waveguides in the coupling region. The vertical electric field and/or horizontal electric field in at least one input/output waveguide is ti/? By changing it to 2
The propagation constant of the input and output waveguides can be finely adjusted.

(Embodiments) Hereinafter, embodiments of the first and second inventions of this application will be described with reference to the drawings. It should be noted that the drawings are only schematic illustrations to the extent that the first and second inventions can be understood, and therefore, the dimensions, shapes, distribution ratios, forming materials, and number of each constituent component may differ from the illustrated examples. It should be understood that this is not a limitation.

DESCRIPTION OF THE FIRST INVENTION FIG. 1 is a perspective view schematically showing the structure of a first embodiment of the first invention. In the figure, 24 is a substrate made of a crystal material having an electro-optic effect, for example, a two-cut LiNbO3 substrate, 26 is a coupling region where light interaction takes place, and 2
8 and 30 indicate input and output waveguides parallel to each other in the coupling region. The two input/output waveguides 28 and 30 are formed, for example, by diffusing T1 into the substrate 24. When a two-cut LiNb○3 substrate is used as the substrate 24, one type of light that has a large electro-optic effect is a TM wave,
The other type of light with a small electro-optical effect is a TE wave.

The direction in which the electric field of the TM wave and the TE wave is captured is determined by the substrate 24.
The directions are perpendicular and horizontal to the substrate surface.

The input and output waveguides 28.30 are placed in close proximity such that optical interaction takes place at P81 of these waveguides 28.30 in the coupling 9N'4.26, and thus:
Light coupling can occur between the waveguides 28, 30 of the coupling region 26 to effect light switching. The input and output waveguides 28,30 constitute a directional coupler in the coupling region 26. The light passes through the input/output waveguide 28.3 in the direction along the crystal axis in the X-axis direction of the two-cut LiNb○3 substrate 24.
Propagates through 0.

Note that 28a and 28b indicate the input port and output port of the input/output waveguide 28, and 30a and 30b indicate the input port and output port of the input/output waveguide 30.

Reference numerals 32 and 34 indicate control electrodes provided on the input/output waveguides, and 36 indicates a control electrode provided on the substrate area outside the input/output waveguides.
are these control electrodes 3 constituting an inverted ΔB type control electrode.
2.34.36, and is driven by an inverse ΔB through the control electrodes 32.34.36.

In this embodiment, the control electrodes 32, 34 and 36 are divided into two electrode members 32a, 32b, two electrode members 34a, 34b and two electrode members 36a, 36b, respectively. It is composed of %. However, the electrode members 36a and 36b are connected to the input/output waveguide 2 so that the input/output waveguide 28 is sandwiched between the electrode members 36a and 36b.
It is provided on the substrate 24 at a distance from the left side edge of the substrate 8 . The electrode members 32a, 32b are these electrodes 32a, 32b.
The left side edge of the electrodes 32a and 32b coincide with the right side edge of the input/output waveguide 28, and the right side edges of these electrodes 32a and 32b correspond to the area of the substrate 24 between the right side edge of the input/output waveguide 28 and the left side edge of the input/output waveguide 30. It is extended so that it seems to be whining. The right edges of the electrode members 34a, 34b correspond to the left edge of the input/output waveguide 30, and the right edges of the electrodes 34a, 34b extend from the right edge of the input/output waveguide 28 to the substrate 24. It is provided so as to extend toward the right side edge.

Roughly, the input boat 2 of the electrode members 32aJ4a, 36a
The edges on the sides 8a and 30a are connected to the input boat 2 of the coupling area 26.
8a, 30a side edges X, and electrode members 32b, 34b, 36b (7) output boat 28b,
The edge on the 30b side is the output port 28 of the coupler tJ226.
b, is inserted so as to coincide with the edge Y on the 30b side.

Next, the first embodiment will be roughly described in detail with reference to FIGS. 2(A) and 2(B).

Figures 2 (A) and (B) are diagrams of the operating conditions of this embodiment ((
L#, )-(ΔBL/π) diagrams). In these figures, a region M shown with notching is a region M where the waveguide optical switch 38 crosses the TM wave and the TE wave.
It shows the region in which it operates in the s state and with a crosstalk of -20 dB or less. In addition, L is Motoko, β. is the bond length and Δ
B is the propagation constant difference. Hereinafter, the coupling length and propagation constant difference for the TM wave will be ff, (TM) and ΔB(TM), and the coupling length and propagation constant difference for the TE wave will be β. (TE)
and ΔB(TE).

As shown in FIG. 2(A), for example, L
/β. If the waveguide optical switch 38 is created so that (L/β.(TM)) is 1.1, Δ
BL/TI (ΔB (TM)L/TT) is a-
When a' takes a value within the range, the operating state of the waveguide optical switch for TM waves on the third day is the Cross state. 8β(TM)L/T[in such a range, for example, applying a voltage of any suitable magnitude having positive (+) polarity to electrode members 36a, 34a, and 32b and applying a voltage of any suitable magnitude to electrode members 32a, 36b, and 34b is obtained by applying a voltage of any suitable magnitude having negative (-) polarity to .

When voltage is applied in this way, ΔBL for the TE wave
/T[(8β(TE)L/TI) is the electro-optical constant γ,
Since the ratio of 3 and γ33 is γ13/γ33 1/3.3, the value is in the range bb'. At this time, the operating state of the waveguide optical switch 38 for the TE wave is changed to Cr, o
In order to obtain the s s state, L/u for the TE wave,
The value of (L/ρ.(TE)) may be set within the range of STE.

By setting the value of L/βe(TE) to a value within the STE range, the operating state for TM waves can be changed to Cr
When a voltage is applied to bring about the oss state, L/βc(TE
) can be set to a value that brings the operating state with respect to the TE wave to the Cross state.

That is, for example, L/β. (TM)=1.1 and L/
β. By setting the value of (■ε) to a value within the STE range, it is possible to obtain a cross state for TE waves and TM waves with the same voltage application state (operation that results in a cross state for TE waves and TM waves). points match).

Similarly, as shown in FIG. 2(B), for example, L/ρ. (
TM)=1.5, L/β.

By setting the value of (TE) to a value within the STE range, when a voltage is applied that changes the operating state for TM waves to the Cr0SS state, the value of L/u, (TE) changes to the operating state for TE waves. Condition Cr.

It can be set to a value that will cause the SS state.

Therefore, for example, by setting L/βe(TM) = 1,'5 and setting the value in the range of WaS□ of L/β, (TE), the cross state for the TE wave and TM wave can be created by applying the same voltage. You can get it.

As can be understood from FIGS. 2(A) and 2(B), since region P is steep, L/β. Even if the values of (TM) take different values, the ranges of STE where the operating points coincide in FIGS. 2(A) and 2(B) are almost the same. Control electrode 3
It is thought that by configuring 2.34.36 as an inverted ΔB type control electrode, the area ISP becomes steep.

Thus, for example, L/β. (TM) value is 1.1 to 1
．． 5, and the value of Katsushi/βc(TE) is S
If the waveguide type optical switch 38 is created under the manufacturing conditions such that the value falls within the range of □, Cr for TM waves and TE waves
It is possible to create a waveguide type optical switch 38 that has the same operating point in the oss state and operates with a crosstalk suitable for practical use of -20 dB or less. Although it is not necessarily possible to create only the waveguide optical switch 38 that has the same operating point and operates with crosstalk suitable for practical use, compared to the conventional case where it must be created under IIi-class manufacturing conditions. As a result, it is possible to manufacture a leading wave optical switch having a crosstalk characteristic suitable for practical use in a cross state under more relaxed manufacturing conditions and with a high yield.

On the other hand, in a waveguide optical switch that has two parallel input and output waveguides in the coupling region, Bar
It has been known for a long time that the operating point at which the state occurs and the operating point at which the TE wave becomes the Bar state can be matched by adjusting the voltage applied to the control electrode. Also in the waveguide type optical switch 38 having the waveguide 28, 30, the operating points of the Bar state for the TM wave and the TE wave can be matched by adjusting the voltage applied to the control electrode 32, 34, 36. . In this case, crosstalk suitable for practical use can be obtained. Therefore, the operating points can be matched by adjusting the applied voltage, so Bar
The creation conditions required to match the operating points of the states can be set to gentle conditions, and crosstalk suitable for practical use can be obtained under the relaxed creation conditions. B
In order to set the ar state, for example, the electrode member 36a-3
It is sufficient to apply a voltage of any suitable magnitude having positive (+) polarity to 4a-36bs34b and a voltage of any suitable magnitude having negative (-) polarity to the electrode members 32a and 32b.

Therefore, as can be understood from the above, Cr08
A waveguide optical switch 38 that operates with crosstalk suitable for practical use in both the S and Bar states can be manufactured under conditions that are gentler than those of the prior art and with a high yield. Also, Cr.

Since the operating points of the SS state and the Bar state coincide, a waveguide optical switch 38 without polarization dependence can be obtained.

FIG. 3 is an explanatory diagram of the production conditions, and the hatched area Q in the figure indicates an area where a crosstalk of -20 dB or less is obtained for the TM wave and the TE wave in the cross state.

The vertical axis is L/ff, (TE) and the horizontal axis is L/β, (
TM).

As shown in FIG. 3, L/β. (TE) and L/β, (
By creating the leading wave type optical switch 38 under manufacturing conditions such that TM) takes @ in the region Q, it is possible to obtain a crosstalk of -20 dB or less in the cross state.

Figures 4 (A) to (C) show TM waves and T waves in the Bar state.
Fig. 4 (A) is a crosstalk characteristic diagram between E waves.
is L/J2e(TE) = 1 and L/A, (TM)
= 1, Figure 4 (B) shows L/A, (TE
) = 1 and L/β. When (TM) = 1.25, Figure 4(C) shows the crosstalk characteristics when L/(le(TE) = 1 and L/βe(TM) = 1,5. The axis is ΔBL/T [(
ΔB(TM)L/π) and the vertical axis are crosstalk.

In these figures, the crosstalk characteristic curve A between the TM waves is shown as a solid line, and the crosstalk characteristic curve A between the TE waves is shown as a solid line.
B is shown by a broken line, and crosstalk related to TM waves and crosstalk related to TE waves when a voltage giving ΔB(TM)L/π on the horizontal axis is applied are plotted and shown as curves A and l, respectively. .

The ratio of electro-optic constants γ, 3 and γ33 is γ13/γ33~
Lenote at 1/3.3, Figure 4 (A) to (C) 1.
As shown in FIG. 1m, in the 8ar state, the first operating point for the TM wave and the third operating point for the TE wave can be completely defeated by adjusting the applied voltage.

Moreover, as can be understood from FIGS. 4(A) to (C), βJTE)=1 (const, ) and β. (T
Even if M) is changed to 1.1.25.1.5, the operating point will be defeated at the operating point where ΔB(TM)L/TI = 6, and neither the TM wave nor the TE wave A crosstalk of less than -20 dB can be obtained even for

FIG. 5 is a crosstalk characteristic diagram showing the change in crosstalk between TM waves when the crosstalk between TM waves and TE waves is at its minimum in the Bar state, and the horizontal axis shows L/TE waves.
β. (TM) and the crosstalk related to the TM wave is plotted on the vertical axis.

As can be understood from FIG. 5, the waveguide optical switch 38
Even if the value of ΔB(TM)/ΔB(TE) changes to 3.0.3.2.3.4.3.6 due to the creation error of When the value is in the range of .0 to 1.5, a crosstalk of -20 dB or less can be obtained.

FIG. 6 is a perspective view schematically showing the structure of the second embodiment. Regarding the components corresponding to the first example described above,
The same reference numerals are given and the detailed explanation thereof will be omitted.

In the figure, 40 and 42 indicate control electrodes provided on the input/output waveguide, and 44 indicates a control electrode provided on the substrate area outside the input/output waveguide, and the waveguide optical switch 46 of this first embodiment has these control electrodes 40, 42, 44 constituting an inverted ΔB type control electrode, and the control electrodes 40.
Inversion ΔB can be driven short through 42.44.

In this embodiment, the control electrode 40 is divided into three electrode members 40a, 40b, and 40CIFr.
2 divided into three electrode members 42a, 42b, 42c
Thus, the control electrode 44 is roughly constituted by three divided electrode members 44a, 44b, and 44c.

Furthermore, the electrode members 44a, 44b, and 44c are provided on the substrate 24 at a distance M from the left edge of the input/output waveguide 28 so that the input/output waveguide 28 is sandwiched between the electrode members 44a, 44b, and 44c. . The right edges of the electrode members 40a, 40b, 40c are connected to the input/output waveguide 2.
One loss to the right edge of 8, and these 40a, 40b, 40
so that the right edge of c is positioned in the area of the substrate 24 between the right edge of the input/output waveguide 28 and the right edge of the input/output waveguide 3o.
It is extended. Electrode members 42a, 42b
, 42c, the right edge of these 42a, 42b, 42c coincides with the left edge of the input/output waveguide 3o, but these 42
The right edge of a 142 b % 42 c is extended so that the right edge of the input/output waveguide 28 extends toward the right edge of the substrate 24 .

Roughly speaking, the edges of the electrode members 40a, 42as, 44a on the input port 28as 30a side meet the edge X, and the edges of the electrode members 40c, 42c, 44c on the output port 28b, 30b side, It is arranged so as to be flush with the edge Y.

Similarly to the first embodiment, the waveguide optical switch 46 of the second embodiment also has a value of L/ff, (TE) of T
Operating state ICr for E waves.

The two input/output waveguides 28 .
308 provided.

When the control electrode 40, 42, 44 is divided into three parts to form an inverted ΔB type control electrode, the electrode member 44 a% 42
a % 40 b −44c, 42c are positive (
Applying a voltage of any suitable magnitude having a polarity of +);
By applying voltages of arbitrary suitable magnitudes having negative (-) polarity to the electrode members 40a, 144b, 42b, and 40c, Cr can be removed for TM waves and TE waves.
It can be operated in oss state. Moreover, it can be operated with crosstalk suitable for practical use.

Moreover, electrode members 44a, 44b, 44c, 42a
, 42b, and 42c, respectively, with positive (+) polarity and an arbitrarily suitable voltage applied to the electrode member 40.
By applying voltages of arbitrary suitable magnitudes having negative (-) polarity to a, 40b, and 40c, respectively, it is possible to operate in a Bar state with respect to TM waves and TE waves.

Moreover, it can be operated with crosstalk suitable for practical use.

In this second embodiment, as in the first embodiment, a polarization-independent optical waveguide switch that operates with crosstalk suitable for practical use was fabricated under milder fabrication conditions than in the past, and at a higher yield. You can.

DESCRIPTION OF THE SECOND INVENTION> Private side FIG. 7 is a perspective view schematically showing the structure of an embodiment of the second invention. It should be noted that constituent components corresponding to the constituent components of the embodiment of the first invention described above are indicated with the same reference numerals,
A detailed explanation thereof will be omitted.

In the figure, 48 and 50 indicate control electrodes provided on the input/output waveguide, and 52 indicates a control electrode provided on the substrate area outside the input/output waveguide. These control electrodes 48.50.52 constitute an inverted ΔB type control electrode, and the control electrode 48.50
．． 52 and is driven by inverse ΔB.

The control electrode 52 is composed of one undivided electrode member, and has an input/output waveguide 28 between it and the input/output waveguide 30.
It is provided on the substrate 24 at a distance from the right edge of the input/output waveguide 2 so as to sandwich the input/output waveguide. The control electrode 48 is constituted by one undivided electrode member, and its right edge coincides with the right edge of the input/output waveguide 28 and its right edge coincides with the right edge of the input/output waveguide 28. It is provided so as to extend so as to be located in the area of the substrate 24 between the left edge of the output waveguide 30 and the left side edge of the output waveguide 30 .

The control electrode 50 is an electrode member 50a15 divided into two parts.
0b, the left edges of these 50a and 50b are connected to the left edge of the input/output waveguide 30, and these 50
A and 50b are extended so that their right edges coincide with the right edges of the input/output waveguide 28.

Roughly, the edges of the control electrode 48.52 and the electrode member 50a on the input port 28a, 30a side are aligned with the edge X, and the edge of the control electrode 48.52 and the electrode member 50b on the output port 28b, 30b side The edge of is arranged to coincide with edge Y.

Similarly to the first embodiment of the first invention, the waveguide optical switch 53 of this embodiment also has L/β when a voltage is applied to bring the operating state to the TM wave into the Cross state. The value of (TE) indicates the operating state for TE waves.

Two parallel input/output waveguides 28, 307 & are provided in the coupling region Vt26.

Therefore, similar to the first embodiment of the first invention, a polarization-independent waveguide optical switch that operates with crosstalk suitable for practical use in both Cr0SS and Bar cases can be created in a gentler manner than before. It can be produced under the same conditions and with a high yield.

The waveguide optical switch 53 is driven by inversion ΔB by applying voltages of arbitrary suitable magnitudes having arbitrary suitable polarities to the control electrodes 48, 50, 52, respectively.
It can be operated in S and Bar states.

54 is in at least one input/output waveguide of the coupling region,
3 shows auxiliary electrodes for creating vertical and/or horizontal electric fields; In this embodiment, the auxiliary electrode 54 is composed of, for example, two divided electrode members 54a and 54b, and these 54a and 54b are located between the right edge of the input/output waveguide 30 and the right edge of the substrate 24. An electrode member 50a is placed on the substrate 24 area of
, 50b.

FIG. 8 is a front view showing the configuration of the embodiment shown in FIG. 7.

As shown in the figure, in this embodiment, the control electrode 48.5
By forming an electric field in the direction shown by the arrow P through 0.52, for example, an electric field in the direction perpendicular to the surface of the substrate 24 (vertical electric field) is formed in the input/output waveguide 28,30. At the same time, an electric field is formed in the direction shown by the arrow Q, for example, through the auxiliary electrode 54 (thereby, an electric field (horizontal electric field) in a direction parallel to the substrate 24 surface is formed in one input/output waveguide 30. do.

Refractive index change Δn due to electric field for TM wave.

can be expressed by the following equation (1).

In addition, the refractive index change Δno due to the electric field for the TE wave is
It can be expressed by the following equation (2).

However, n: refractive index for TM waves n0: refractive index for TE waves γ13, γ2□, γ33: electro-optic coefficient Ev: intensity of vertical electric field formed in the input/output waveguide Eh =intensity of the vertical electric field formed in the input/output waveguide Strength of the horizontal electric field formed: Constant As can be understood from equations (1) and (2) above, Δn and Δno cannot be controlled independently with the vertical electric field (Ev) alone, but the vertical electric field (Ev) and horizontal electric field (El, )
According to the method, Δn and Δno can be independently controlled.

The waveguide type optical switch 53 changes the operating state for the TM wave to C.
When a voltage is applied to bring the ross state, L/β. (T
If the value of E) is created under conditions such that the operating state with respect to the TE wave is in the Cross state, it is suitable for practical use by operating the inverted Δe through the control electrodes 48, 50, 52. Cross with crosstalk
It is possible to operate without polarization dependence in the Bar state.

However, in actual production, the produced waveguide optical switch may not satisfy the above-mentioned production conditions. In this case, for example, it becomes impossible to obtain crosstalk suitable for practical use, or it becomes impossible to operate in a cross state with respect to TE waves. Such inconvenience is caused by, for example, the input/output waveguide 2 for TM waves and TE waves.
This can be avoided by controlling the refractive index of 8 and the refractive index of the input/output waveguide 30 for TM waves and TE waves through the auxiliary electrodes 54, respectively. Auxiliary electrode 541
By using Fr, crosstalk can be reduced when the above-mentioned production conditions are not satisfied, and TM waves and T
The operating state for E waves can be electrically controlled. As a result, the second invention has an advantage over the first invention in that the yield can be improved.

When operating in the cross state, for example, the following procedure may be performed. First, the control electrodes 52 and 48 are grounded. At this time, for TM waves, the control electrode 50a
By applying a voltage of any suitable magnitude of positive (+) polarity to the control electrode 50b and negative (-) polarity to the control electrode 50b,
It can be operated with crosstalk suitable for practical use.

In addition, for TE waves, the auxiliary electrode member 54a has a positive (+
) or negative (-) polarity and the auxiliary electrode member 54b has negative (-) polarity.
By applying a voltage of any suitable magnitude with positive (+) or positive (=) polarity, it is possible to operate with a crosstalk suitable for practical use.

Further, when operating in the Bar state, the following may be performed, for example. First, the control electrode 48 and the control electrode member 5
0a and 50b are grounded. The control electrode is positive (+) on the 4th day.
) or negative (-) polarity of any suitable magnitude. Then, voltages of the same polarity and magnitude, and any suitable magnitude, are applied to the auxiliary electrode members 54a and 54b. As a result, it is possible to match the operating points for TM waves and TE waves, and to operate with crosstalk suitable for practical use.

The first and second inventions are not limited to the above-mentioned embodiments, but may arbitrarily suitably change the arrangement position, configuration, dimensions, forming material, numerical conditions, and other manufacturing conditions of each component. It's good. In addition, the polarity and amplitude of the voltage applied to the control electrode and/or the auxiliary electrode and other operating conditions, particularly in the second invention, the formation state of the vertical electric field and the horizontal electric field may be changed as desired.

For example, in the first invention and the second invention, the number and arrangement position of the control electrode of the inverted ΔB electrode type, the number of divided parts when the control electrode is divided, and the number of divided parts forming the control electrode. The dimensions of the electrode member can be set arbitrarily and suitably.

In addition, in the second invention, the formation state and formation method of the vertical electric field and/or horizontal electric field formed in the two input/output waveguides are not limited to the above-mentioned embodiments, but can be arbitrarily changed. good.

In addition, in the first and second inventions, the bond length β. (TM)
and AC(TE)! The operating voltage can be reduced by making the lengths approximately match the respective element lengths.

(Effects of the Invention) As is clear from the above description, according to the waveguide optical switch of the first and second inventions of this application, the operating state for one light having a large electro-optic effect is the Cross state. When a voltage is applied, the value of L/lc for the other light, which has a smaller electro-optic effect, changes the operating state for the other light to Cr.

Set it to a value that will bring it into the SS state. By creating a waveguide optical switch under these conditions,
The operating points of one light and the other light in the cross state can be matched. Furthermore, by creating a waveguide optical switch with a control electrode of the inverted ΔB electrode type under the above-mentioned manufacturing conditions, it is possible to create a waveguide optical switch that operates with a crosstalk suitable for practical use in the cross state, which is gentler than conventional ones. It can be manufactured with good yield under suitable manufacturing conditions.

On the other hand, in a waveguide optical switch that has two parallel input and output waveguides in the coupling region, by adjusting the applied voltage, it is possible to obtain crosstalk suitable for practical use when the waveguide is in the Bar state. The operating points of one light and the other light can be made to coincide with each other. Adjustment of Applied Voltage 1 Since the operating points can be made to match, the required production conditions can be set to be gentle conditions in order to make the operating points of the Bar state match.

Therefore, according to the first and second inventions, Cr.

A waveguide optical switch that operates with crosstalk suitable for practical use in both the SS and Bar states can be manufactured under conditions that are more relaxed than conventional ones and with a high yield. Also, the operating points in the Cross state match and B
Since the operating points in the ar state coincide, a waveguide optical switch without polarization dependence can be obtained.

In addition to this, according to the waveguide optical switch of the second invention,
An auxiliary control electrode is provided for forming a vertical electric field and/or a horizontal electric field in at least one of the input and output waveguides in the coupling region. Vertical electric field and/or horizontal electric field in at least one input/output waveguide +! '? By changing , the propagation constants of the two input/output waveguides for one and the other light can be finely adjusted. With this fine adjustment,
In addition to reducing crosstalk, it is possible to electrically control the operating state of one light and the other light.

If the created waveguide optical switch does not satisfy the above-mentioned creation conditions, for example, crosstalk suitable for practical use may not be obtained, or it may not be possible to operate in a cross state with respect to TE waves. However, by finely adjusting the propagation constant using an auxiliary electrode, it is possible to reduce crosstalk or to operate in a cross state with respect to the other light. As a result, the second invention has an advantage over the first invention in that the yield can be improved.

[Brief explanation of the drawing]

FIG. 1 is a perspective view schematically showing the configuration of the first embodiment of the first invention, FIG. 2 is an operating condition diagram for explaining the production conditions of the first embodiment of the first invention, and FIG. An explanatory diagram of the production conditions of the first embodiment of the first invention. Figures 4 and 5 are crosstalk characteristic diagrams of the first embodiment of the first invention. Figure 6 is the configuration of the second embodiment of the first invention. FIG. 7 is a perspective view schematically showing the configuration of the embodiment of the second invention, FIG. 8 is an explanatory diagram of the auxiliary electrode of the second invention, and FIG. 9 is a conventional waveguide. 1 is a perspective view schematically showing the configuration of a type optical switch. 26... Coupling region, 28.30... Input/output waveguide 32.34.36.40.42.44.48.50
．． 52-...Control electrode 38.46.53-...Waveguide type optical switch 54...Auxiliary electrode. Patent applicant Oki Electric Industry Co., Ltd. 24: Substrate 26: Coupling region 28.30: Input/output waveguide 32.34, 36: Control electrodes 32a, 32b, 34a, 34b, 36a, 36b: Electrode member 38: Waveguide type Optical switch Embodiment 1 of the first invention Figure 1
) Ω Δ13L/TT L/βc (TE) θq /, 0 1. f/, 2/, J 1.
4 1.5L/βc (TM) Explanatory diagram of creation conditions t, o t, t /, 2 t, y /4 t
, sL/i7c (TM) Crosstalk Characteristic Diagram Figure 5 40. 42, 44: Control electrodes 40a, 40b, 40c, 42a, 42b,
42c, 44a, 44b, 44c: electrode member 4
6: Conductive optical switch Second embodiment of the first invention Fig. 6 48.50.52: Control electrodes 50a, 50b, 54
a, 54b: Electrode member 53: Waveguide optical switch 54:
FIG. 7 Embodiment of the second invention of the auxiliary electrode

Claims (2)

[Claims] (1) In a waveguide optical switch that has two input/output waveguides parallel to each other in the coupling region where light interaction takes place and has an inverted ΔB electrode type control electrode, the element length is L and the coupling length is is l_c, when a voltage is applied to the control electrode to bring the operating state of the waveguide optical switch into a cross state for one light that has a large electro-optic effect, the other light that has a small electro-optic effect is applied to the control electrode. L for light
The element length L and the coupling length l_c are set such that the value of /l_c is such that the operating state of the waveguide optical switch with respect to the other light is a cross state. Waveguide type optical switch. (2) In a waveguide optical switch that has two input/output waveguides parallel to each other in the coupling region where light interaction occurs and has an inverted ΔB electrode type control electrode, the element length is L and the coupling length is is l_c, when a voltage is applied to the control electrode to bring the operating state of the waveguide optical switch into a cross state for one light that has a large electro-optic effect, the other light that has a small electro-optic effect is applied to the control electrode. L for light
The element length L and the coupling length l_c are set such that the value of /l_c is such that the operating state of the waveguide optical switch with respect to the other light is a cross state, and at least one of the coupling regions A waveguide type optical switch characterized in that an auxiliary control electrode for forming a vertical electric field and/or a horizontal electric field is provided in one input/output waveguide.