JP2766531B2 - 4-port optical switch - Google Patents

Description

The present invention relates to a four-port optical switch used in optical communication and the like.

2. Description of the Related Art An optical switch, for example, four optical ports P ₁ shown in FIG.
In the 2 × 2 optical switch having a to P _4, the light path,
Optical port P ₁ → optical port P ₃ , optical port P ₂ → optical port P ₄ , or optical port P ₁ → optical port P ₄ , optical port P ₂ → optical port
Is switched to P _3, with respect to one point optical ports, the number of optical ports of the optical ports switchable connection counterpart was only two.

In the case of such a 2 × 2 optical switch, the number of optical ports of one partner that can be connected by switching is limited to two, and in addition to the above connection state, the incident optical port P ₁ → none of them also has a function of switching the incident light port P _2. For this reason, in optical communication and the like, when switching optical paths to realize various communication states,
There are problems such as an increase in the number of optical switches and an increase in the size of a switch installed at a relay point or the like.

As a countermeasure against such a problem, the present inventors have developed an optical switch in which the number of optical ports that can be switched and connected to one optical port is set to three, and this has already been disclosed in Japanese Patent Application Laid-Open (JP-A) No. 2001-222,086. Filed as 1-137827.

In the optical switch proposed here, as shown in FIG. 8, four optical switches A, B, C, and D having a cross section where the optical waveguide crosses in an X-shape are arranged in a lattice shape. , Optical port A ₁ -optical port D ₁ , optical port D ₄ -optical port C ₁ , optical port A ₃ -optical port D ₂ , optical port D ₃ -optical port C ₃ , optical port
C ₂ -optical port B ₃ , optical port A ₄ -optical port B ₁ are connected to each other, and optical ports 1, 2, 3, and 4 are configured as outgoing / incident ports.

In this optical switch, four optical switches A, B, C,
By suitably using the switching operation and D, optical port 1 optical ports A ₂ - optical ports A ₃ - optical ports D ₂ - optical ports D ₃ - optical port C ₃ - optical port C ₂ - light port B ₃ - optical port B ₂ - optical port 2, or optical port 3 optical ports C ₄ - optical ports C ₁ - optical port D ₄ - optical ports D ₁ - optical port A ₁ - optical port A ₄ - optical ports B ₁ - optical port B ₄ - optical port 4, between the optical port 1 optical port 2 or the optical path connecting the optical port 3 optical port 4; optical port 1 optical ports a ₂ - optical ports a ₃ -
Optical port D ₂ -optical port D ₄ -optical port C ₁ -optical port C ₄ -optical port 3 or optical port 2 -optical port B ₂ -optical port B ₄
An optical path of the optical port 4 connecting the optical port 1 to the optical port 3 or the optical port 2 to the optical port 4; an optical port 1 to an optical port A ₂ -an optical port A ₄ -an optical port B ₁ -an optical port B ₄ - optical port 4, or optical port 2 optical port B ₂ - optical port B ₃ - optical port C ₂ - optical ports C ₄ - optical port 3, between the optical port 1 optical port 4 or optical ports 2- Optical path connecting the optical ports 3 can be formed.

(Problems to be Solved by the Invention) In the case of the optical switch having the above-described structure, for example, the optical port 1 to the optical port 2 and the optical port 3 to the optical port 4 are in the first switch state, and the optical port 1 to the optical port 3. When the optical port 2 and the optical port 4 are in the second switch state, and the optical port 1 and the optical port 4 and the optical port 2 and the optical port 3 are in the third switch state, respectively, In an optical path connecting port 1 to optical port 3, light passes through three optical switches, while light port 2 to optical port 4
Only pass through one optical switch.

For this reason, in the optical switch having the above structure, the connection states of the respective optical ports are not equivalent, and the inconvenience that a difference occurs between the states cannot be avoided.

The present invention solves the above-mentioned inconvenience, and in each switch state, for example, in the second switch state, the same number of optical switches are passed, so that there is no difference in the connection state of each optical switch. The purpose is to provide a switch.

(Means for Solving the Problems) In order to achieve the above object, in the present invention,
An optical switch group comprising two 1-input / 2-output optical switches (hereinafter referred to as 1 × 2 optical switches) having Y-branched optical ports is referred to as a 2-input / 2-output optical switch (hereinafter referred to as a 2 × 2 optical switch).
.Times.2 optical switch), each of which is connected to the input side and the output side of the optical switch group, wherein one of the branch-side optical ports of each of the 1.times.2 optical switches in each of the optical switch groups is connected to each other. A four-port optical switch is provided.

(Operation) In the optical switch of the present invention, even in the above-mentioned second switch state, the optical switches constituting the second switch and the optical paths connecting them are arranged point-symmetrically with each other. No difference occurs in the connection state.

Embodiment An optical switch according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic plan view showing a basic configuration example of an optical switch of the present invention having a semiconductor optical waveguide. In FIG. 1, a first optical switch group S ₁ and a second optical switch group S ₂
In each case, the schematic plan view of FIG. 2 and the IV-
It is composed of 1 × 2 optical switches s ₁ , s ₂ , s ₃ , s ₄ as shown in FIG. 3 which is a sectional view of the switch section along the IV line.

That is, in these 1 × 2 optical switches, n ⁺
A lower electrode 11 is formed of a material such as AuGeNi / Au on a lower surface of a semiconductor substrate 12 such as GaAs, and a lower cladding layer 1 made of a semiconductor such as n ⁺ AlGaAs is formed on the semiconductor substrate 12.
Core layer 14, made of a semiconductor such as 3, n ^- GaAs, and ridge-shaped upper cladding layer 15, n ^- G, made of a semiconductor such as n ^- AlGaAs
A cap layer 16 made of a semiconductor such as aAs is sequentially laminated, and the entire upper surface thereof is covered with an insulating thin film 17.

In the optical waveguide, as shown in FIG. 2, one optical port p is Y-branched into two branch-side optical ports q and r, and one of these optical ports q and r is one. The book has an upper electrode 19 for current injection or voltage application. This upper electrode 19 is formed by removing a part of the insulating thin film 17 to form a window 17a, diffusing Zn from this to form a Zn diffusion region 18, and then evaporating Cr / Au here, for example. be able to.

In this optical switch, when light enters from the optical port p in a state where current is not injected (or voltage is applied) from the upper electrode 19, the light goes straight and the branch-side optical port q
(OFF state). However, when a current is injected (or a voltage is applied) from the upper electrode 19, the refractive index of the core layer below the lower layer is reduced. And is emitted only from the branch-side optical port r (ON state).

In the optical switch of the present invention, the 2 × 2 optical switch S ₃
At both ends (input side and output side) of the optical switch group S ₁
S ₂ is connected with.

In this case, when the left side of the figure is the input side, each optical switch s ₁ and s ₂ of the optical switch group S ₁ functions as a 1 × 2 optical switch, and each optical switch of the optical switch group S ₂
Each of s ₃ and s ₄ is connected so as to function as a 2 × 1 optical switch (when the right side in the figure is the input side, each optical switch functions in reverse to the above).

Then, one of the optical ports s ₁ c of the optical switch s ₁ is an optical port S ₃ a of the optical switch S _3, the optical port S ₃ of one optical port s ₂ c of the optical switch s ₂ optical switch S ₃ b If, optical port S ₃ c of the optical switch S ₃ is the one of the optical ports s ₃ c of the optical switch s _3, the optical port S ₃ d of the optical switch S ₃ is one of the optical ports s ₄ c of the optical switch s ₄ When connected, respectively, also of the other optical switches s ₁ optical port s ₁ b and the optical switch s ₂ of the other optical port s ₂ b,
Other optical port s ₃ b and the other optical port s ₄ b of the optical switch s ₄ of the optical switch s ₃ are connected.

In this optical switch, the optical switch _{s 1, s 2, s 3} , s 4
If you also turned off the light switch S ₃ to the ON state of any of the optical path connecting the optical ports s ₁ a (optical port _{1) -s 1 b-s 2} b-s 2 a ( optical ports 2) and light port s ₃ a (optical port _{3) -s 3 b-s 4} b-s 4 a light path connecting the (optical port 4) is formed. When all of the optical switches s ₁ , s ₂ , s ₃ , and s ₄ are turned off and the optical switch S ₃ is turned off, the optical port s ₁ a (optical port 1) −the optical port s ₁ c - optical port S ₃ a- optical port S ₃ d-optical port s ₄ c- optical ports s ₄ a light path connecting the (optical port 4) and the optical port s ₂ a (optical port 2) - optical port s ₂ c - light path connecting the light port S ₃ b-optical port S ₃ c- optical port s ₃ c- optical port s ₃ a (optical port 3) is formed. Further, when all of the optical switches s ₁ , s ₂ , s ₃ , and s ₄ are turned off and the optical switch S ₃ is turned on, the optical port s ₁ a (optical port 1) −the optical port s ₁ c - optical port S ₃ a- optical port s ₃ c- optical port s ₃ c- optical port s ₃ a light path connecting the (optical port 3), and an optical port s ₂ a (optical port 2) - optical port s ₂ c - light path connecting the light port S ₃ b-optical port S ₃ d-optical port s ₄ c- optical ports s ₄ a (optical ports 4) is formed.

FIG. 4 is a schematic plan view showing another embodiment. In the case of this optical switch, in each of the optical switch groups S ₁ and S ₂ , the optical port s ₁ b and the optical port s ₂ b, the optical port s ₃ b and the optical port s ₄ b are:
Reflective portion R _1, are connected via a R _2, also the optical switch S ₃ is four 1 × 2 optical switch s _5, s ₆ shown in Figure 2,
By connecting s ₇ and s ₈ as shown in the figure, 2 × 2
It is an optical switch.

Here, in the reflection section R ₁ (R ₂ ), as shown in FIG. 5, the connection between the optical ports s ₁ b and s ₂ b forms a reflection surface. Light guided from the optical port s ₁ b (s ₂ b) can be totally reflected by the reflecting surface and guided in the direction of the optical port s ₂ b (s ₁ b).

In this optical switch, the optical switch _{s 1, s 2, s 3} , s 4
When all of the above are turned on and the other is turned off, an optical path connecting the optical port 1 to the optical port 2 and the optical port 3 to the optical port 4 is formed, and the optical switches s ₅ , s ₆ , and s ₇ are formed. , when the other to the oFF state is turned on to any of the s _8, optical port 1 optical port 4, the light path connecting the optical port 2 optical port 3 is formed. Further, when all the optical switches are turned off, the optical ports 1 to 3, the optical ports 2 to 4,
Are formed.

FIG. 6 is a schematic plan view showing another embodiment. In this case, the optical switch groups S ₁ and S ₂ are configured in the same manner as in FIG. 5, and the optical switch S ₃ is the same as FIG. The connection of each optical port is changed to 2 × 2 by using four 1 × 2 optical switches of FIG.
This is an optical switch.

In this optical switch, the optical switch _{s 1, s 2, s 3} , s 4
Are turned on and the other optical switches are turned off, so that the optical port 1-optical port 2, the optical port 3-
Two sets of optical paths connecting the optical ports 4 are formed, and all of the optical switches s ₁ , s ₂ , s ₃ , s ₄ are turned off, and any of the optical switches s ₅ , s ₆ , s ₇ , s ₈ Is turned on, two sets of optical paths connecting the optical port 1 to the optical port 3 and the optical port 2 to the optical port 4 are formed. Further, when all the optical switches are turned off, two sets of optical paths connecting the optical port 1 to the optical port 4 and the optical port 2 to the optical port 3 are formed.

 FIG. 7 is a schematic plan view showing still another embodiment.

In this case, the optical switch S ₃ is the same as the 2 × 2 optical switch and optical switch shown in FIG. 4, both the optical switch group is not provided with a reflective portion, each other directly connect one branch side optical ports It is of a structure with

In this optical switch, the optical switch _{s 1, s 2, s 3} , s 4
Are turned on and the other optical switches are turned off, two sets of optical paths connecting the optical port 1 to the optical port 2 and the optical port 3 to the optical port 4 are formed, and the optical switches s ₁ ,
s _2, s _3, the optical switch s ₅ is turned off any of s _4,
When any of s ₆ , s ₇ , and s ₈ is turned on, the optical port 1
-Two sets of optical paths connecting optical port 4, optical port 2 and optical port 3 are formed. Further, when all the optical switches are turned off, two sets of optical paths connecting the optical port 1 to the optical port 3 and the optical port 2 to the optical port 4 can be formed.

(Effects of the Invention) As is apparent from the above description, the four-port optical switch of the present invention includes an optical switch group including two 1 × 2 optical switches having Y-branched optical ports arranged side by side. A four-port optical switch connected to an input side and an output side of a two-optical switch, respectively, wherein one of the branch-side optical ports of each of the 1 × 2 optical switches in each of the optical switch groups is connected to each other. Because of the feature, even in the case of the second switch state, each optical switch and each optical port are arranged symmetrically with respect to each other, and as a result, there is no difference in the connection of each optical port, and the switching does not occur. The operation can be performed evenly.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing a basic configuration example of an optical switch of the present invention, FIG. 2 is a schematic plan view of an optical waveguide having an Y-branched optical port, and FIG. 3 is a view taken along line III-III in FIG. FIG. 4 is a schematic plan view showing another embodiment, FIG. 5 is a schematic plan view showing a reflecting portion of FIG. 4, FIG. 6 is a schematic plan view showing another embodiment, FIG. FIG. 8 is a schematic plan view showing still another embodiment, FIG. 8 is a schematic plan view of a conventional example, and FIG.
It is a schematic diagram of a * 2 optical switch. 1, 2, 3, 4 ... light port, S _1, S ₂ ... light switch group, s _1, s _2, s
_{3, s 4, s 5,} s 6, s 7, s 8 ... 1 × 2 optical switches, S ₃ ... 2 ×
2 optical _{switch, s 1 a, s 1 b} , s 1 c, s 1 d, s 2 a, s 2 b, s 2 c, s
_{2 d, s 3 a, s} 3 b, s 3 c, s 3 d, s 4 a, s 4 b, s 4 c, s 4 d, S 3 a, S
₃ b, S ₃ c, S ₃ d: optical port, p: optical port, r, q: branch-side optical port, R ₁ , R ₂ : reflector, 11: lower electrode, 12: n-type semiconductor substrate, 13 ... lower cladding layer, 14 ... core layer, 15 ... upper cladding layer, 16 ... cap layer, 17 ... insulating thin film, 17a ...
Window, 18 ... Zn diffusion zone, 19 ... Top electrode.

Claims (1)

(57) [Claims] An optical switch group comprising two 1-input / 2-output optical switches having Y-branched optical ports is connected to the input side and the output side of a 2-input / 2-output optical switch, respectively. A four-port optical switch, wherein one of the branch-side optical ports of each of the one-input and two-output optical switches in each of the optical switch groups is connected to each other.