JPH06281972A - Optical switch - Google Patents

Abstract

PURPOSE:To provide an optical switch capable of reducing the difficulty on adjusting the center of a waveguide and having no dependency on polarized wave in optical switching and securing a high coupling efficiency between an input and an output. CONSTITUTION:Optical fibers 5, 6, 7 are connected to the terminals 2, 3, 4 of an optical circulator 1. A switching means passing or reflecting a beam propagating therein responding to prescribed switching operation and outputting the beam from an incident beam waveguide 5 from any one of a first outgoing beam waveguide 6 or a second outgoing beam waveguide 7 is provided on a halfway part of an outgoing beam waveguide 6. As the switching means, for instance, a diffraction grating formation erasure part 8 is provided on the halfway part of the first outgoing beam waveguide 6, and an ultraviolet light source (not shown in the figure) for forming the diffraction grating, two waveguides 9, 10 leading two light waves lambda1, lambda2 outgoing from the light source to the diffraction grating formation erasure part 8 and one waveguide 11 leading the infrared beam lambda3 for erasing the diffraction grating in the vicinity of the diffraction grating formation erasure part 8 are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical switch for switching an optical line used for optical communication.

[0002]

2. Description of the Related Art In an optical communication system, an optical switch for switching an optical line is a basic component for constructing an optical switching system. Among optical switches, a so-called cross-type switch in which two optical waveguides are crossed and a reflection mechanism is provided at the crossing part to switch the output destination has been widely studied and put to practical use.

For example, two optical waveguides are crossed on a substrate having an electro-optical effect, and a voltage can be applied to the crossing portion. Since the refractive index of the electro-optic material in the portion to which the voltage is applied changes due to the electric field effect, the incident guided light undergoes total reflection at the interface, and the waveguide path is bent.
(Shimomura et al. 1992 IEICE Spring Conference C-
196, pp4-238, 1992).

[0004]

In the conventional cross type optical switch, the path of the light propagating through the incident optical waveguide is bent by the total reflection of the reflecting mirror formed at the crossing portion,
Since it has a structure that guides it to the output optical waveguide, it is necessary to align the two waveguides via a reflecting mirror, which increases manufacturing difficulties. Further, since the incident light is incident on the reflecting mirror at an angle smaller than 90 degrees, the reflectance has a polarization dependency, and when the polarization direction of the incident light changes, the light output propagates to the optical waveguide. This will cause variations in strength.

Further, when a diffraction grating is used as a reflecting mirror in such a cross type optical switch, the beam spot size of the reflected light becomes larger than that of the incident light, so that the beam shape changes. Therefore, when the waveguides having the same shape are used for the input optical waveguide and the output optical waveguide, there is a problem that the coupling efficiency between the input and the output is reduced.

The present invention has been made in order to solve the above problems, and reduces the difficulty in aligning the waveguide,
An object of the present invention is to provide an optical switch that does not have polarization dependency in optical switching and can secure high coupling efficiency.

[0007]

The optical switch of the present invention comprises:
A three-terminal optical component having three terminals, having a function of emitting light incident from the first terminal to the second terminal and emitting light incident from the second terminal to the third terminal; The incident optical waveguide connected to the terminal of the, the first and second output optical waveguides connected to the second and third terminals, respectively, and the first output optical waveguide which is emitted from the second terminal. By transmitting or reflecting the propagating light in response to a predetermined switching operation, the light incident from the incident optical waveguide is switched from one of the first and second emission optical waveguides and is output to the outside. And a switching means.

Here, the switching means emits from the second terminal and propagates in the first emission optical waveguide by forming or erasing a diffraction grating in the middle of the first emission optical waveguide. It may be a diffraction grating formation erasing means for reflecting or passing the light to be emitted, or a movable mirror that is movably installed in the gap formed in the middle of the first emission optical waveguide with respect to the first emission optical waveguide. It may be a moving means for moving vertically, or an aqueous solution containing metal ions having a smaller ionization tendency than hydrogen ions is placed in the gap formed in the middle of the first emission optical waveguide and its vicinity, and Means for forming a potential difference between the transparent electrode and the other electrode by immersing a transparent electrode perpendicularly intersecting the first emission optical waveguide and another electrode different from the transparent electrode It may be.

[0009]

Since the optical switch of the present invention is constructed as described above, when the switching means is brought into a state of reflecting light by a predetermined switching operation, it is incident from the first terminal of the three-terminal optical component. The optical signal emitted from the second terminal toward the first outgoing optical waveguide is vertically incident on the reflection mechanism formed in the first outgoing optical waveguide and is reflected at a right angle to the second outgoing optical waveguide. It is output from the waveguide to the outside. Further, when the switching means is brought into a state of passing light by a predetermined switching operation,
The optical signal propagated from the second terminal to the first output optical waveguide passes through the first output optical waveguide as it is and is output to the outside. In this way, the optical signal emitted from the second terminal toward the first emission optical waveguide is passed or reflected by the switching means, and is output from the first or second emission optical waveguide. The optical switching function is realized by controlling the switching of routes.

Here, when the switching means of the optical switch is the diffraction grating forming and erasing means, when the optical signal incident on the incident optical waveguide is emitted from the second emission optical waveguide, the diffraction grating which is the reflection layer is It is formed in the middle of the first emission optical waveguide. Therefore, the optical signal propagated to the first emission optical waveguide is reflected at a right angle, changes its traveling direction, and is output from the second emission optical waveguide. Further, when the optical signal is emitted from the first emission optical waveguide, the diffraction grating is erased, and the propagated optical signal passes through the first emission optical waveguide as it is and is output.

Further, in the case where the switching means is provided with a movable mirror in a gap formed in the middle of the first emission optical waveguide to move the movable mirror in a direction perpendicular to the first emission optical waveguide, the optical signal Is output from the second output optical waveguide, the movable mirror is moved and installed perpendicularly to the first output optical waveguide, and the optical signal propagated to the first output optical waveguide is reflected at a right angle, It is output from the second emission optical waveguide. When the optical signal is output from the first output optical waveguide, the movable mirror is moved to a position that does not block the gap of the first output optical waveguide, and the optical signal propagated through the first output optical waveguide is As it is, it passes through the first emission optical waveguide and is output.

Further, when the switching means is provided with a transparent electrode capable of forming a reflecting mirror by a silver mirror reaction in the first outgoing optical waveguide, when outputting the optical signal input to the incoming optical waveguide to the second outgoing optical waveguide, A reflecting mirror is formed by setting the transparent electrode to a negative potential, and the optical signal emitted to the first emission optical waveguide is reflected at a right angle and output from the second emission optical waveguide. When the optical signal input to the incident optical waveguide is output from the first outgoing optical waveguide, the transparent electrode is set to a positive potential to erase the reflecting mirror, and the optical signal is allowed to pass through the first outgoing optical waveguide. Will be output.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description.

FIG. 1 is a block diagram of the optical switch of the first embodiment. An input optical waveguide 5, a first output optical waveguide 6 and a second output optical waveguide 7 each made of an optical fiber are connected to each of the terminals 2, 3 and 4 of the optical circulator 1, and in the middle of the first output optical waveguide 6. A diffraction grating forming / erasing portion 8 is interposed in the portion. Here, the optical circulator 1 has a function of emitting light incident from the terminal 2 to the terminal 3 and emitting light incident from the terminal 3 to the terminal 4. An ultraviolet light source (not shown) for forming a diffraction grating, two waveguides 9 and 10 for guiding two light waves λ 1 and λ 2 emitted from this light source to the vicinity of the diffraction grating forming and eliminating section 8, and a diffraction grating eliminating Infrared light source (not shown) and one optical waveguide 11 for guiding the light wave λ3 emitted from this light source to the vicinity of the diffraction grating formation / erasure unit 8 are installed, and these form a diffraction grating formation / erasure means. There is. That is, when an optical fiber is used as the optical waveguide 6, the material glass (for example, a silicon-based glass containing Ge) has many atomic defects that absorb light in the ultraviolet region. When such an atomic defect is irradiated with light of its absorption wavelength, the refractive index changes and it becomes possible to form a diffraction grating,
On the other hand, the refractive index is restored by heating or irradiation of infrared light, and the diffraction grating can be erased. The optical switch in which the diffraction grating forming / erasing means, that is, the switching means and the optical circulator are combined, operates as follows and fulfills the switching function.

FIG. 1A shows a flow of an optical signal when the optical signal input from the incident optical waveguide is reflected by the diffraction grating forming and erasing means and emitted to the second emitting optical waveguide 7. At this time, the diffraction grating is formed in the diffraction grating formation / erasure section 8.

The light waves λ1 and λ2 emitted from the ultraviolet light source are guided to the diffraction grating formation / erasure section 8 through the optical waveguides 9 and 10, and optical interference fringes in which interference occurs and the intensity changes periodically are generated, and are almost generated. A diffraction grating is formed that is a 100% efficient reflective layer. The optical signal input from the input end 2 a is incident on the terminal 2 of the optical circulator 1 via the incident optical waveguide 5. The optical signal incident on the terminal 2 is emitted to the terminal 3 and travels through the first emission optical waveguide 6. Output optical waveguide 6
The optical signal in progress is incident on the diffraction grating formed in the diffraction grating forming and erasing section 8 at a right angle and is reflected at a right angle, and travels backward through the emission optical waveguide 6 and is incident on the terminal 3 of the optical circulator 1. The optical signal incident on the terminal 3 is emitted to the terminal 4 and output from the output end 4 a via the second emitting optical waveguide 7. This diffraction grating remains in the diffraction grating formation / erasure section 8 as it is even if the irradiation of the lights λ1 and λ2 is stopped.

FIG. 1B shows the flow of the optical signal when the optical signal input from the incident optical waveguide passes through the diffraction grating forming / erasing means without being reflected and is emitted to the first outgoing optical waveguide 6. Is shown. At this time, the diffraction grating forming / erasing unit 8
No diffraction grating is formed (erased) in the.

The light wave λ3 emitted from the infrared light source is guided to the diffraction grating formation / erasure section 8 through the optical waveguide 11, and the diffraction grating formed in the diffraction grating formation / erasure section 8 is erased. The optical signal input to the input end 2 a travels through the incident optical waveguide 5 and is incident on the terminal 2 and emitted to the terminal 3. The optical signal passes through the diffraction grating formation / erasure section 8 in the middle of the emission optical waveguide 6 as it is, and is output from the output end 3a. In the optical switch of this embodiment, by turning on the ultraviolet light source and the infrared light source, the diffraction grating formation / erasure section 8 of the emission optical waveguide 6 forms and erases the diffraction grating to perform the switching function of the optical switch.

As described above, according to the optical switch in which the diffraction grating forming / erasing means which is the switching means and the optical circulator are combined, the diffraction grating is irradiated in the middle of the first emission optical waveguide with ultraviolet light or infrared light. Since it is only formed and erased, the difficulty in aligning the waveguide is reduced, and since the incident optical signal is incident vertically on the diffraction grating, there is no polarization dependence in optical switching, and the input and output are A high coupling efficiency between the two can be secured.

Next, the second embodiment of FIG. 2 will be described.
FIG. 2A is a configuration diagram of the optical switch of the second embodiment.
The incident optical waveguide 5, the first outgoing optical waveguide 6 and the second outgoing optical waveguide 7 are connected to the terminals 2, 3 and 4 of the optical circulator 1, and are connected in the middle of the second outgoing optical waveguide 6. Has a gap formed therein, and a movable mirror 12 having a reflectance of about 100% is movably installed. An electrostrictive element (not shown) is connected to the movable mirror 12 as a moving unit that moves the movable mirror 12 in a direction orthogonal to the axial direction of the first emission optical waveguide 6.

2 (b) and 2 (c) are perspective views showing the structure of the first emission optical waveguide 6 and the switching means provided in the middle thereof. 2B shows a state in which the movable mirror 12 is moved and installed perpendicularly to the emission optical waveguide 6 in a gap formed in the middle of the emission optical waveguide 6, and FIG. 2C shows the movable mirror. 12 shows a state in which it has been removed from the gap. These movable mirrors 12 are moved by applying a voltage to an electrostrictive element (not shown).

In the state shown in FIG. 2B, the input terminal 2a
The input optical signal enters the terminal 2 through the incident optical waveguide 5 and is output to the terminal 3. The optical signal propagated to the outgoing optical waveguide 6 is vertically incident on the movable mirror 12 and reflected at a right angle. The reflected optical signal travels backward through the output optical waveguide 6, enters the terminal 3, and is output to the terminal 4. The optical signal emitted to the terminal 4 is output to the outside from the output end 4 a via the emission optical waveguide 7. In the case of FIG. 2C, the optical signal emitted to the terminal 3 proceeds through the emission optical waveguide 6 as it is,
It is output from the output terminal 3a to the outside.

In the optical switch of this embodiment, the movable mirror 12 is moved into a gap formed in the middle of the emission optical waveguide 6 depending on whether or not the movable mirror 12 is moved to a position perpendicular to the emission optical waveguide 6. Realize the switching function. According to such an optical switch composed of the movable mirror and the means for moving the movable mirror, that is, the switching means and the optical circulator, only the gap is formed in the first outgoing optical waveguide to interpose the movable mirror. Since the incident light is vertically incident on the movable mirror, the optical switching has no polarization dependency and a high coupling ratio between the input and the output can be secured.

Next, a third embodiment will be described with reference to FIG. FIG. 3A is a configuration diagram of the optical switch of the third embodiment. The incident optical waveguide 5, the first outgoing optical waveguide 6, and the second outgoing optical waveguide 7 made of optical fibers are connected to the terminals 2, 3 and 4 of the optical circulator 1 and are formed in the middle of the outgoing optical waveguide 6. The transparent electrode 13 is installed in the gap. A mechanism (not shown) for forming and erasing a reflecting mirror on the transparent electrode 13 by a silver mirror reaction is installed near the transparent electrode 13.

FIG. 3B is a perspective view showing the structure of the emission optical waveguide 6 and the switching means provided in the middle thereof. A silver sulfate aqueous solution 15 having a smaller ionization tendency than hydrogen ions is arranged in a gap formed in the middle of the emission optical waveguide 6, and a transparent electrode is arranged in the aqueous solution 15 so as to intersect with the axial direction of the emission optical waveguide 6 perpendicularly. Install 13. The transparent electrode 13 is formed by vapor-depositing indium tin oxide on quartz glass, and the platinum electrode 14 is immersed in the silver sulfate aqueous solution 15 at a position apart from the transparent electrode 13. A battery (not shown) and an electric switch (not shown) are installed as a mechanism for generating a potential difference between the transparent electrode 13 and the electrode 14. An optical switch that combines a means for forming and erasing a reflecting mirror on the transparent electrode 13 by such a silver mirror reaction and an optical circulator operates as follows and fulfills a switching function.

When the electric switch is switched to set the transparent electrode 13 to a negative potential, metal ions in the silver sulfate aqueous solution 15 are deposited on the surface of the transparent electrode 13 (silver mirror reaction), and a reflecting mirror is formed. Therefore, the optical signal input from the input end 2a, incident on the terminal 2 and propagated from the terminal 3 to the outgoing optical waveguide 6 is vertically incident on the reflecting mirror and reflected at a right angle. The reflected optical signal enters the terminal 3, is emitted to the terminal 4, and is output to the outside from the output end 4 a via the emission optical waveguide 7.

By switching the electric switch in the opposite direction, the transparent electrode 13
When is set to a positive potential, the metal ions deposited on the surface of the transparent electrode 13 are dissolved again in the silver sulfate aqueous solution 15 to erase the reflecting mirror. Therefore, the input terminal 2a
The optical signal further incident and emitted to the terminal 3 travels through the emission optical waveguide 6 as it is, and is output to the outside from the output end 3a.

The optical switch of this embodiment performs the switching function by switching the potential of the transparent electrode 13 and forming or erasing a reflecting mirror on the transparent electrode 13. According to the optical switch including the means for forming and erasing the reflecting mirror on the transparent electrode 13 by the silver mirror reaction, that is, the switching means and the optical circulator, the transparent switch provided in the gap formed in the first outgoing optical waveguide is transparent. Since only the reflection mirror is formed and erased by the silver mirror reaction on the electrode, the difficulty in aligning the waveguide is reduced, and since the incident light enters the reflection mirror perpendicularly, there is no polarization dependence in the optical switching, Moreover, a high coupling efficiency between the input and the output can be secured.

The present invention is not limited to the above embodiment, but various modifications can be made.

For example, as a means for erasing the diffraction grating of the first embodiment, a heating element may be installed near the diffraction grating forming and erasing portion 8 of the outgoing optical waveguide 6 of FIG. 1 to heat it.
Further, a material having a photochromic effect, for example, fulgide can be used for the diffraction grating formation / erasure portion. Figure 4
Is an optical waveguide using a photochromic material for a part of the waveguide. The photochromic material 20 is covered by quartz 21. When this waveguide is used in the diffraction grating formation / erasure section 8 of FIG. 1, the diffraction grating is formed by irradiating the optical interference fringes, but when the irradiation is stopped, the diffraction grating is erased.
By turning on the ultraviolet light source, the diffraction grating is formed and erased, and the switching function of the optical switch is achieved. In addition, the diffraction grating forming / erasing portion 8 of the emission optical waveguide 6 is irradiated with the diffraction grating forming light through the slit to form a diffraction grating, while the diffraction grating forming / erasing portion 8 receives the diffraction grating forming / erasing light through the slit. The irradiation can erase the diffraction grating.

Further, the movable mirror 1 of FIG. 2A of the second embodiment.
As another example of No. 2, a portion having a reflectance of about 100% and a reflectance of about 0% in which a metal thin film is deposited on a portion of a glass substrate.
It is possible to use a movable mirror consisting of FIG. 5 is a perspective view showing the structure of the first emission optical waveguide 6 and this movable mirror installed in the middle thereof. A portion 12a having a reflectance of about 0% is provided at a position perpendicular to the axial direction of the emission optical waveguide 6 in a gap formed in the middle of the emission optical waveguide 6.
And a movable mirror 12 having a portion 12b having a reflectance of about 100% is set, and by sliding the movable mirror 12 in a direction orthogonal to the axial direction of the emission optical waveguide 6, the switching function of the optical switch is achieved.

[0032]

As described in detail above, according to the optical switch of the present invention, the optical signal is vertically incident on and reflected by the reflection mechanism by the switching means provided in the emission optical waveguide. Since the paths are switched, it is possible to alleviate the difficulty of aligning the waveguide, and to have high polarization efficiency in the optical switching and to secure high coupling efficiency between the input and the output.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an optical switch according to a first embodiment.

FIG. 2 is a configuration diagram of an optical switch according to a second embodiment.

FIG. 3 is a configuration diagram of an optical switch according to a third embodiment.

FIG. 4 is a diagram showing a waveguide used in a modification of the optical switch of the first embodiment.

FIG. 5 is a perspective view of a main part of a modification of the optical switch according to the second embodiment.

[Explanation of symbols]

1 ... 3-terminal optical component, 2, 3, 4 ... Terminal, 2a ... Input end,
3a, 4a ... Output end, 5 ... Incident optical waveguide, 6 ... First outgoing optical waveguide, 7 ... Second outgoing optical waveguide, 8 ... Diffraction grating formation erasing section, 9, 10, 11 ... Optical waveguide, 12 ... Movable mirror,
12a ... Reflectance approximately 100% portion, 12b ... Reflectance approximately 0% portion, 13 ... Transparent electrode, 14 ... Electrode, 15 ... Silver sulfate aqueous solution, 20 ... Photochromic material, 21 ... Quartz.

Claims (4)

[Claims] 1. A three-terminal optical component comprising three terminals, wherein light incident from a first terminal is emitted to a second terminal and light incident from the second terminal is emitted to a third terminal. An incident optical waveguide connected to the first terminal, first and second outgoing optical waveguides respectively connected to the second terminal and the third terminal, and outgoing from the second terminal By passing or reflecting the light propagating through the first output optical waveguide in response to a predetermined switching operation, the light incident from the input optical waveguide is transmitted through the first output optical waveguide. An optical switch having switching means for switching from one side and outputting to the outside. 2. The switching means, in response to the predetermined switching operation, in a middle part of the first emission optical waveguide,
A diffraction grating forming and erasing means for reflecting or passing light which is emitted from the second terminal and propagates in the first emission optical waveguide by forming or erasing a diffraction grating. 1. The optical switch described in 1. 3. The switching means includes a movable mirror movably installed in a gap formed in an intermediate portion of the first emission optical waveguide, and the movable mirror, which is responsive to the predetermined switching operation. The optical switch according to claim 1, further comprising a moving unit that moves the optical waveguide in a direction perpendicular to the one outgoing optical waveguide. 4. The switching means arranges an aqueous solution containing metal ions having a smaller ionization tendency than hydrogen ions in the gap formed in the middle of the first emission optical waveguide and in the vicinity thereof, and in the aqueous solution. A transparent electrode perpendicularly intersecting the first emission optical waveguide and another electrode different from the transparent electrode, and the predetermined switching is provided between the transparent electrode and the other electrode. The optical switch according to claim 1, wherein a potential difference is generated in response to an operation.