JPH01159615A - Optical changeover switch - Google Patents

Abstract

PURPOSE:To electrically and freely adjust the light quantity ratio of a branch optical path or to changing several kinds of branch waveguides which differ in branch ratio freely under mechanical control by using a liquid crystal reflecting mirror, and varying the orientation of liquid crystal by varying a voltage. CONSTITUTION:While no voltage is applied to an electrode, both P and S polarized light components of incident light from a 1st port 21 pass through an element 25 for varying the main axis direction of a polarized wave, but is reflected by the liquid crystal reflecting mirror 24 regardless of their rotations and enters a 2nd port 22. Then when a constant voltage is applied to the electrode, both P and S polarized light components of the light which is incident from the 1st port 21 pass through the element 25; and the S polarized component is reflected by the liquid crystal reflecting mirror 24 and propagated to the 2nd port and the P polarized light component is transmitted and propagated to a 3rd port 23. Further, the polarization axis at the time of the incidence can be changed by rotating the element 25. Consequently, a folded transmission line or branch optical path is formed at the time of optical path switching and the branch ratio of the branch transmission line is easily adjusted electrically or mechanically.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical changeover switch that is small and allows easy switching of optical paths and adjustment of the light quantity ratio in branched optical paths.

(Prior Art) To electrically connect two metal wires, it is sufficient to mechanically contact the two wires. Therefore, in the case of an electric changeover switch, the signal path can be easily switched by mechanical contact, except in cases where characteristics up to a high frequency region are a problem.

However, in order to optically connect or switch optical fibers, the light emitted from one optical fiber must enter the other optical fiber at a limited angle of incidence within a small core of several μm to 100 μm. It won't happen. Therefore, a mechanism is required to move the optical path to an optimal position with extremely high reproducibility.

First, as an example of a mechanical moving mechanism, FIG. 10 shows an optical switching method in which the optical fiber itself is moved.

In FIG. 10, 1, 2, 3. is optical fiber, 4゜5
．． 6, 7, 8.9 are optical fiber end faces. To explain the operation of this mechanism, light that enters the optical fiber end face 4 passes through the optical fiber 1, exits from the optical fiber end face 5, and enters the end face 6 of the optical fiber 2 arranged on the optical axis. , passes through the optical fiber 2 and is emitted to the optical fiber end face 7. Next, when switching to the optical fiber 3, by moving the end face 8 of the optical fiber 3 and bringing it onto the optical axis of the optical fiber 1, the light emitted from the end face 5 of the optical fiber l is transferred to the optical fiber 3. The light enters the end face 8 of the optical fiber, is propagated to the optical fiber 3, and exits from the optical fiber end face 9.

As another switching method, FIG. 11 shows a method using a reflecting mirror. In FIG. 11, 1.2.3 is an optical fiber,
10 is a switching device, 11, 12, 13 is a lens, and 14 is a reflecting mirror. Light that enters the switching device W10 from the optical fiber 1 side passes through lenses 11.12, is emitted to the optical fiber 2 side, and is guided to the optical fiber 2.

To change the propagation path of light, the reflecting mirror 14 is moved in the direction of the arrow in the figure and inserted into the optical path connecting the optical fibers 1 and 2. At this time, from the optical fiber 1 to the switching device l
After passing through the lens 11, the light incident on O passes through the reflecting mirror 1.
4, passes through the lens 13, and enters the optical fiber 3, completing the switching.

FIG. 12 shows a method of inserting and switching a prism in the light propagation path. In FIG. 12, 15, 16, and 17 are rod lenses, and 18 is a prism. First, if there is no prism on the optical axis connecting optical fiber 1 and optical fiber 2,
The light emitted from the optical fiber 1 passes through rod lenses 15 and 16.
and enters the optical fiber 2.

Here, when the prism 18 is inserted on the optical path, the light passing through the rod lens 15 from the optical fiber 1 side is transmitted through the prism 1.
8 and passes through the rod lens 17 to form the optical fiber 3.
side, and the optical path switching is completed.

Furthermore, as another light switching method, there is a method using an acousto-optic effect, an electro-optic effect, etc., and FIG. 13 shows a method of changing the traveling direction of light using an acousto-optic element.

In FIG. 13, 19 is an acousto-optic element. The acousto-optic effect refers to the interaction between ultrasonic waves and light. When an ultrasonic wave propagates in a transparent medium, a photoelastic effect occurs in the medium, perpendicular to the direction of propagation of the sound wave, in synchronization with the wavelength of the sound wave. A change in the refractive index occurs. When light enters such a medium, depending on the relationship between the wavelengths of the light and the ultrasonic waves, the light may be diffracted or reflected, or the plane of deflection of the light may be rotated. Examples of acousto-optic element materials include PbMoO4, Tea
,and so on. First, when the acousto-optic device is not operated,
The light emitted from the optical fiber 1 passes through the rod lens 15 , the acousto-optic element 19 , the rod lens 16 , and then enters the optical fiber 2 . Here, the acousto-optic element 19
When electrical control is applied to the light, the light is deflected, enters the rod lens 17, and then propagates to the optical fiber 3 side,
Optical path switching is completed.

As a switching method, FIG. 14 shows a method using an optical branching coupler. In FIG. 14, 1'.

2' is an optical waveguide, 54 is a substrate, and 55 is a refractive index discontinuity. The branching coupler shown in FIG.
The end faces of the two are butted together, and the light incident from one side is
It emits light in the direction.

As described above, various methods for switching optical paths have been proposed in the prior art, and branching couplers have also been produced. No light switch was proposed that could do this.

(Problems to be Solved by the Invention) The present invention provides a low-loss optical path between ports 1 and 2, and a low-loss optical path from port 1 to ports 2 and 3 in an optical transmission line between ports 1, 2, and 3. It is an object of the present invention to provide an optical changeover switch that can form a branched optical path, switch between the two optical paths, and easily change the light quantity ratio of the branched optical paths.

(Means for Solving the Problems) The present invention provides a first optical path for optically directly connecting port 1 and port 2, and a port a second optical path for branching from port 1 to port 2 and port 3, one of the two optical paths can be inserted between port 1, port 2, and port 3; The second optical path is configured to be mutually switchable.

As mentioned above, the conventional technology discloses a technology for switching the direction of light propagation, but in the present invention, the orientation of the liquid crystal is changed by changing the voltage using a liquid crystal reflector. An optical selector switch between three points that can electrically freely adjust the light intensity ratio of branched optical paths, or freely change branching waveguides with different branching ratios by mechanical control. Clarify the technology.

(Embodiment) FIG. 1 is a configuration diagram of a first embodiment of the present invention, and shows two
1 is a first port, 22 is a second port, 23 is a third port, 24 is a liquid crystal reflector using nematic liquid crystal, 2
5 indicates an element for changing the principal axis direction of polarized waves.

FIG. 2 specifically shows the operating state of the liquid crystal reflector 24 when a voltage is applied.
This figure shows how the alignment direction of liquid crystal is perpendicular to the liquid crystal surface. In FIG. 2, 26 is a liquid crystal reflecting mirror 24.
27 is a nematic liquid crystal, 28 is an electrode section, and 29 is a power supply section.

FIG. 3(a) shows that when the applied voltage is off, both P and S polarized light components are reflected on the liquid crystal surface, and FIG. 3(b) shows that when the applied voltage is on, the P polarized light component is reflected by the liquid crystal reflector 24. Transparent,
This figure shows a state in which the S-polarized light component is reflected. In FIG. 3, the solid line indicates the P-polarized light component, and the broken line indicates the S-polarized light component. In FIG. 1, when no voltage is applied to the electrodes 28 attached to both ends of the liquid crystal reflector 24 (V=O), both the P and S polarization components of the incident light from the first port 21 are aligned with the main axis of polarization. It passes through the element 25 for changing the direction, but regardless of its rotation, it is reflected on the surface of the liquid crystal reflector 24,
It enters the second port 22. Next, when a constant voltage is applied to the electrodes 28 attached to both ends of the liquid crystal reflector 24, the first
Both the P and S polarization components of the light incident from the port 21 pass through an element 25 for changing the direction of the principal axis of polarization, and the S polarization component is reflected by the surface of the liquid crystal reflector 24 and propagates to the second port. , the P-polarized light component is transmitted and propagated to the third port 23.

Furthermore, by rotating this element, the polarization axis at the time of incidence can be changed, that is, the ratio of both P and S polarization components can be changed. The branching ratio of light propagating to the third port can be changed. As a method of rotating the element 25 to change the direction of the principal axis of polarization, there is a method of providing a screw connected to the outside and using a mechanism that can rotate the element 25 in a direction perpendicular to the optical axis by turning the screw.

As an element for changing the principal axis direction of polarized light, a 1/2 wavelength element or a 174 wavelength element can be used depending on whether the incident light is linearly polarized light or circularly polarized light. As described above, it becomes possible to appropriately select the light quantity ratio between the light reflected from the first port 21 to the second port 22 and the light transmitted to the third port 23.

FIG. 4 is a configuration diagram of a second embodiment of the present invention,
1 is a first port, 22 is a second port, 23 is a third port, and 30 is a reflecting mirror. The reflecting mirror 30 is a combination of a perfect reflecting mirror and several semi-transparent reflecting mirrors whose reflectance R is in the range of 0<R<1.

First, when light enters from the first port 21 toward the third port 23, a reflecting mirror 30 is placed in the middle, and when it is blocked by a perfect reflecting mirror (R=1), the light is It is completely reflected and proceeds to the second port 22. When this reflecting mirror 30 is mechanically moved to block the optical path with a semi-transparent reflecting mirror having an arbitrary reflectance R, the optical power corresponding to PXR is reflected when the incident optical power is P. port 2
2, the optical power corresponding to P×(1−R) is transmitted and proceeds to the third port 23. Therefore, by preparing several reflectors with different reflectances R and applying mechanical operations, the branching ratio of light can be changed between the first port 21, the second port 22, and the third port 23. becomes possible.

FIG. 5 is a perspective view of a third embodiment of the present invention,
1 is an optical component A, 32 is an optical component B1, 33 is an optical component Bz,
34 is a pin terminal, 35 is a bottle insertion hole, 36 is a guide line, 37 is a stopper, and 38 is an optical fiber end face.

FIG. 6(a) shows the internal structure of optical component B+, and FIG. 6(b) shows the internal structure of optical component B2. Figure 6 (a), (b
), 35 is a pin insertion hole, 39 is a branch waveguide, and 4
0 indicates an optical fiber guide, and 41 indicates a 0-shaped optical fiber.

To explain this operation, the first port 21 is placed on the optical component A side.
, a second port 22, and a third port 23 on the optical component B2 side, and the end surfaces of the optical component A31 and the optical component B132 or B233 are in butt contact.

First, when sending light from the first port 21 to the second port 22, the end surfaces of the optical component A 31 and the optical components B and 32 are butted together, and the light incident from the first port 21 is transmitted to the optical component B.
, 32 and propagates to the second port 22. Next, in order to separate the light from the first port 21 into the second port 22 and the third port 23, the optical component A3
By abutting the end faces of the optical component B233 and the optical component B233, the light from the first port 21 is split into two directions by the branching waveguide 39 built into the optical component B233. It propagates to port 23 of. Therefore, if you prepare several branching waveguides with different branching ratios,
By switching between these, it is also possible to adjust the amount of light entering each port.

FIG. 7 shows the configuration of a fourth embodiment of the present invention, in which 42 is an optical connector, 43 is an outer frame for mounting the optical connector, 44 is a branching waveguide, and 45 is an optical component B2 including the branching waveguide 44. It is. When light enters from the first port 21, the light is split into a second port 22 and a third port 23 and propagated in a branch optical waveguide 44 built into the optical component B245. Similarly, an optical component B1 including a straight waveguide section connecting the first port 1-21 and the second port 22 is prepared separately, and the optical connector is attached by sliding it against the outer frame 43 and butting the end surfaces. This allows the optical path to be switched.

FIG. 8 is a perspective view of a fifth embodiment of the present invention, with four
6 is an optical component A containing two optical fibers, 47 is an optical component A containing 3 internally.
Optical component B includes a branch waveguide 52 (see FIG. 9) and a 0-shaped optical fiber 48, 49 is an end face of the 3-branch waveguide, 50 is an end face of the 0-shaped optical fiber 48, and 51 is an optical component A 46, an optical component. A nut is used to connect B47, and 53 is an optical fiber. However, the optical component B realizes the functions of the optical component B and the optical component B2 in one component.

FIG. 9 shows the structure of the three-branch waveguide 52. The waveguide switching method is to rotate the optical component B47.
The end face of the three-branch waveguide end face 49 or the U-shaped optical fiber end face 50 is optically coupled to enable optical path switching.

(Effects of the Invention) The optical changeover switch of the present invention can form a return transmission line or a branch transmission line when switching an optical path, and furthermore, in the branch transmission line, the branching ratio can be easily adjusted electrically or mechanically. Therefore, when the present invention is used, it is possible to couple or release a terminal into an optical transmission line at a node in an optical LAN (optical campus YJ), etc.
Branch losses at unnecessary nodes can be eliminated. Therefore, it is possible to increase the number of nodes in the transmission path, and it is also possible to change the amount of light at the branch point.
Terminals of different grades can be combined, increasing flexibility.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of the first embodiment of the present invention, Figure 2 is a diagram showing the state when voltage is applied to the liquid crystal reflector, and Figures 3 (a) and (b) are the surfaces of the liquid crystal reflector. 4 is a configuration diagram of the second embodiment of the present invention, FIG. 5 is a perspective view of the third embodiment of the present invention, and FIGS. 6(a) and (b)
is the optical component B in the third embodiment of the present invention shown in FIG.
I, internal structure diagram of optical component B2, FIG. 7 is a configuration diagram of the fourth embodiment of the present invention, FIG. 8 is a perspective view of the fifth embodiment of the present invention, and FIG. 9 is a three-branch waveguide. A perspective view showing the structure, FIG. 10 is an explanatory diagram of a method for switching optical fiber end faces, FIG. 11 is an explanatory diagram of an optical path switching method using a reflecting mirror, and FIG. 12 is an explanatory diagram of an optical path switching method using a prism. , FIG. 13 is an explanatory diagram of an optical path switching method using an acousto-optic element, and FIG. 14 is an explanatory diagram of an optical path switching method using an optical branching coupler. L 2.3... Optical fiber 1', 2'... Optical waveguide 4, 5.6.7.8.9... Optical fiber end face 1
0... Switching device 11.12.13... Lens 14... Reflector 15, 16.17... Rod lens 18... Prism 19... Acousto-optic element 21... First Port 22...Second port 23...
...Third port 24...Liquid crystal reflecting mirror 25...Element 26 for changing the principal axis direction of polarized light...Glass
27...Liquid crystal 28...Electrode part 2
9...Power supply section 30...Reflector 31...
・Optical component A32...Optical component B, 33...
Optical component B234... Pin terminal 35... Pin insertion hole 3G... Guide line 37... Stopper 38... Optical fiber end surface 39... Branch waveguide 40... Optical fiber guide 41.・0-shaped optical fiber 42 ・Optical connector 43 ・Outer frame 44 for optical connector installation 44 ・Branch waveguide 45 ・Optical component B24
6... Optical component A 47... Optical component B48
...0-shaped optical fiber 49...3-branch waveguide end face 50...U-shaped optical fiber end face 51...Tighten with nut 52...3-branch waveguide 53.
...Optical fiber 54...Substrate 55...Refractive index discontinuity portion Patent applicant Nippon Telegraph and Telephone Corporation Figure 1 Figure 2 Figure 9 Figure 5 Ri Figure 1O/, 2.3---Ikko 7 fiba. 4.5, 6.7.8.9---1tf? Figure 11 Figure 12 f8 --- Ariz ° 4 Figure 13 Figure 14 Figure 1'

Claims (1)

[Claims] 1. In the three ports for inputting and outputting light, a first optical path for optically directly connecting port 1 and port 2, and a first optical path for branching from port 1 to port 2 and port 3. 2
It is characterized by having an optical path, one of the two optical paths can be inserted between port 1, port 2, and port 3, and the first and second optical paths can be mutually switched. Optical changeover switch. 2. Port 1 and port 3 as a means of switching the optical path
An element for changing the principal axis direction of polarized waves and a liquid crystal reflector are inserted on the optical path connecting the After passing through an element for changing the principal axis of the liquid crystal, both P and S polarized components are reflected on the surface of the liquid crystal reflector and propagated to port 2, and when a voltage is applied to the liquid crystal reflector to change the alignment direction of the liquid crystal. , Of both the P and S polarized light components that have passed through the element for changing the principal axis direction of the polarized light, the S polarized light component is reflected on the surface of the liquid crystal reflector, and the P polarized light component is transmitted. The light propagates separately into port 2 and port 3, and the ratio of the P-polarized light component can be changed depending on the amount of change in the principal axis direction of the polarized light, thereby changing the branching ratio. The optical changeover switch described in item 1. 3. As a means for switching the optical path, when light enters from port 1, a perfect reflecting mirror with a reflectance R of R=1 and one or more semi-transparent reflecting mirrors with a reflectance of 0<R<1 are used. , on the optical path from port 1 to port 3, when the fully reflective mirror and the semi-transparent mirror are mechanically moved and a fully reflective mirror with R=1 is used, all the light is on the surface of the fully reflective mirror. When the light is reflected and propagated to port 2, and a semi-transparent mirror with 0<R<1 is used, the light is reflected and transmitted on the surface of the semi-transparent mirror, and
Claim 1 characterized in that propagation is split into port 2 and port 3 to form a branched optical path.
Optical changeover switch described in section. 4. As a means for switching the optical path, a component A that includes an optical waveguide and a component B_1 that is capable of parallel or rotational movement while in contact with the end surface of the component determined by the end surface of the waveguide and that includes a folded optical waveguide. and a component B_2 including a branched waveguide, and the waveguides of both components B_1 and B_2 can be optically coupled to the waveguide end face of the component A by mechanical switching. An optical changeover switch according to claim 1.