JPH0363631A - Spatial optical matrix switching device - Google Patents

Abstract

PURPOSE:To improve characteristics by composing the device of a microlens array, an optical deflecting element array, a micro-hologram array, and coupling element arrays. CONSTITUTION:Light which is collimated by the microlens array 11 is deflected by the optical deflecting element array 12. Then the microhologram array 13 increases the angle of deflection of deflected light from the array 12 by diffraction to switch optical paths. Outgoing light whose optical path is switched by the array 13 is coupled selectively with an output optical element 23 by coupling element arrays 14 and 15. Thus, the device is composed of the microlens array, optical deflecting element array, microhologram array, and coupling element arrays and the optical paths can be switched at a large by increasing the deflection angle by the microhologram array. Consequently, secure optical switching becomes possible and excellent switch characteristics are obtained; and those are advantageous to the layout design of an output-side optical element, etc., and the small-sized device in thin structure is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to spatial optical matrix switch devices such as spatial light modulators and parallel optical switches used in fields such as optical communications and optical information processing systems.

2. Description of the Related Art Conventionally, there is a spatial optical matrix switch device of this type as disclosed in Japanese Patent Application Laid-Open No. 111019/1983. FIG. 4 shows its configuration, in which a diffraction grating (not shown) is formed on the photosensitive medium 1 using light interference, and the light emitted from the photoemitter circuit 2 is collimated through the collimating means 3. A diffraction grating formed on the photosensitive medium 1 is used to emit a light beam to a predetermined position on the photoreceptor circuit 4 to obtain optical coupling. In this device, by using a crystal that has both a photoconductive effect and an electro-optic effect, such as a BSO crystal, as the material of the photosensitive medium 1, the diffraction grating can be made variable and an arbitrary diffraction grating can be formed using the writing light. It becomes possible to arbitrarily select the optical coupling between the emitter circuit 2 and the photoreceptor circuit 4.

Problems to be Solved by the Invention However, such a spatial optical matrix switch device basically requires a writing system to form a diffraction grating, an optical system to separate the writing light and the signal light, etc. However, the element itself becomes large. Also,
Electro-optic crystals such as BSO generally have a small electro-optic effect, and the diffraction efficiency of the grating induced by the action of light is also small. Therefore, when used for optical path conversion or the like, the conversion may be insufficient, which may also be a factor in deteriorating switch characteristics.

Means for Solving the Problems A microlens array that collimates incident light, an optical deflection element array that deflects the collimated light from the microlens array by changing the refractive index based on an electro-optic effect, and A micro hologram array that switches the optical path by increasing the deflection angle of the polarized light by diffraction, and a coupling element array that selectively couples the emitted light whose optical path has been switched by the micro hologram array to an output side optical element are provided in this order.

The light collimated by the working microlens array is deflected by the optical deflection element array. At this time, the deflection angle is small due to the refractive index change using the electro-optic effect, but when it enters the next stage micro hologram array and undergoes a diffraction effect, the deflection angle increases and a large optical path switch occurs. It becomes possible.

Therefore, reliable optical switching becomes possible and good switching characteristics can be obtained. Furthermore, since optical path switching is possible with a large deflection angle, coupling to the output side optical element is possible even with a thin structure, resulting in a small device. Furthermore, since optical path switching can be accomplished by controlling the electric field in the optical deflection element array using the electro-optic effect, high-speed switching function can be maintained.

Embodiment An embodiment of the present invention will be described with reference to FIGS. 1 to 3. The spatial optical matrix switch device of this embodiment includes a collimating element 11 as a microlens array, a spatial deflection element 12 as an optical deflection element array, a deflection angle amplification element 13 as a micro hologram array, and an angle conversion element 14 as a coupling element array. and a coupling element 15 are sequentially stacked in the light propagation direction.

Here, the collimating element 11 has a refractive index distribution type microlens 16 formed in a two-dimensional array on the exit side surface to collimate the incident light. Spatial deflection element 12
is LiNb0. It is based on an electro-optic crystal 17 such as, and has electrode pairs 18 arranged in a two-dimensional array so that each lens 16 has an electrode pair 18, and the voltage applied between each electrode pair 18 (therefore, , the electric field between the electrode pair 18) to deflect the incident light in a predetermined direction (details will be described later).

The deflection angle amplification element 13 has a plurality of micro holograms 19 formed in an array in the deflection direction for each lens 16, which diffracts the incident light in a predetermined direction in an area as small as the beam diameter of the incident light. It is. The angle converting element 14 is also similar to the deflection angle amplifying element 13, and has micro holograms 20 corresponding to the micro holograms 19 formed in an array in the deflection direction. The coupling element 15 is similar to the collimating element 11, and has a refractive index distribution type microlens 21 formed in a two-dimensional array on the exit side surface and has a collimating function.

The minute holograms 19 and 20 can be formed in a high-density array with high accuracy on a glass substrate or the like by using a processing method such as an electron beam lithography method or a dry etching method. Further, the refractive index gradient microlenses 16.21 can be formed in an array with high accuracy on a glass substrate or the like by an ion exchange method or the like.

In such a device configuration, the operating principle is
This will be explained with reference to the figures. Here, the collimating element 11
An input optical fiber 22 is coupled to an input side position corresponding to the lens 16, and an output optical fiber 23 as an output side optical element is coupled to a position of the coupling element 15 corresponding to the lens 21.

First, light 24 entering from a certain input optical fiber 22a is collimated by the corresponding lens 16 of the collimating element 11 and enters the spatial deflection element 12. In the spatial deflection element 12, a predetermined electric field is applied between the corresponding electrode pairs 18, and the collimated light 24 passing between the electrode pairs 18 is deflected so as to be incident on a desired micro hologram 19.

The micro hologram 19 of the deflection angle amplification element 13 into which such polarized light 24 is incident is diffracted so as to be incident on a desired micro hologram 20 of the angle conversion element 14 at the next stage. Looking at this state, as can be seen from FIG. 2, the deflection using the electro-optic effect by the spatial deflection element 12 is further increased by the diffraction deflection by the minute hologram 19. Thereafter, the light is emitted by the micro hologram 2o to the corresponding lens 21 of the coupling element 15, condensed by the lens 21, optically coupled to the corresponding output optical fiber 23b, and emitted. Therefore, even if the length of the elements after the deflection angle amplifying element 13 is reduced, switching coupling to the output optical fibers 23a, 23b, etc. is possible.
The overall device is thinner and smaller.

In such an operation, the strength of the electric field applied between the electrode pair 18 in the spatial deflection element 12 is varied, and the deflection angle is changed to the state of the light 24 as shown by the broken line in FIG. If the micro holograms 19 and 20 of the amplification element 13 and the angle conversion element 14 are selected to have different diffraction directions and angles, they can be coupled to the output side, for example, to the output optical fiber 23a side. That is, switching selection of the output optical fibers 23a and 23b=optical switching becomes possible.

By the way, the structure and operation for exerting the deflection function by the spatial deflection element 12 will be explained with reference to FIG. When one element of this spatial deflection element 12 is extracted, a rectangular LiNb0. Electrode pairs 18 are formed facing each other on both sides in the Z-axis direction so as to apply an electric field in the Z-axis direction of the electro-optic crystal 17.

The electrode pair 18 is formed in a right triangular shape such that the boundary surface between the electric field application area and the non-applied area is oblique to the optical axis of the incident light 24. According to such a configuration, when no voltage is applied between the electrode pair 18 by the power source 25, no change in refractive index occurs in the entire electro-optic crystal 17;
When a voltage is applied between electrode pair 18, a refractive index change occurs due to the electro-optic effect in the area between electrode pair 18 where the electric field extends.
A difference in refractive index is generated between the region where no. now,
Let E2 be the electric field between the electrode pair 18 applied in the Z-axis direction,
If the refractive index when E and =O is n's, and the electro-optic constant of the electro-optic crystal 17 is γ, then the resulting refractive index change Δn2 becomes ΔnZ" 27 am n Z" EZ. That is,
A change in the refractive index occurs in proportion to the applied electric field E2. Then, the light 24 incident on the electro-optic crystal 17 is
The light is emitted after being deflected by the difference in refractive index between the area where the electrode pair 18 is present and the area where it is not, and by the boundary slope thereof (the broken line indicates the case where there is no deflection effect). The spatial deflection element 12 as a whole is formed by integrating such element structures into an array. For this purpose, for example, the same Li
Nb0. By forming holes for the electrode pairs 18 on the substrate by machining or etching, and pouring electrode material into the holes, it is possible to fabricate a monolithic structure like the spatial deflection element 12 shown in FIG. 1. This makes it possible to operate optical deflectors capable of high-speed operation in parallel at high density.

Note that when constructing the spatial optical matrix switch device of the present invention, the structure is not limited to that illustrated in FIG. 1; for example, a spatial deflection element array may be provided between the exit side lens and the micro hologram array element. By doing so, a bidirectional optical matrix switch may be constructed.

Effects of the Invention As described above, the present invention is composed of a microlens array, an optical deflection element array, a micro hologram array, and a coupling element array, so that the deflection angle can be increased by the micro hologram array and optical paths can be switched at a large angle. This makes it possible to perform reliable optical switching and obtain good switching characteristics. It is also advantageous for the layout design of output-side optical elements, etc., and the thin structure allows for miniaturization of devices. Furthermore, optical path switching can be done electrically. Electric field control in a light deflection element array using optical effects is sufficient.
It is possible to maintain high-speed switching function.

[Brief explanation of drawings]

1 to 3 show an embodiment of the present invention,
Fig. 1 is a schematic exploded perspective view, Fig. 2 is an explanatory diagram showing the principle of operation in a plan view, Fig. 3 is a perspective view of an l element showing the operation of the spatial deflection element, and Fig. 4 is a schematic diagram showing a conventional example. FIG.

Claims (1)

[Claims] A microlens array that collimates incident light, an optical deflection element array that deflects the collimated light from the microlens array by changing the refractive index based on the electro-optic effect, and diffracts the deflection angle of the polarized light from the optical deflection element array. A spatial optical matrix switch device comprising: a micro hologram array that switches the optical path by increasing the number of lights produced by the micro hologram array; and a coupling element array that selectively couples the emitted light whose optical path has been switched by the micro hologram array to an output side optical element. .