JPH03141326A - Optical switch array - Google Patents

Abstract

PURPOSE:To provide the optical switch array with simple constitution by disposing a diffraction grating between a luminous flux exit part and a shutter array, splitting the light emitted from the luminous flux exit part by the diffraction grating to plural pieces and admitting the split light rays to the shutter array. CONSTITUTION:Light sources 1a to 1d, 2a to 2d, 3a to 3d, 4a to 4d are respectively connected to 1st to 4th terminals on a transmission side. The respective light sources emit light by having the function as one signal line. The diffraction grating 6 is utilized in order to distribute or join the light. Namely, the system is so constituted that the plural diffracted light rays generated by the inserted diffraction grating 6 to to the corresponding positions of an aperture mask 9 if an example is taken of the incident side. The incident part and exit part of the light are so constituted as to be adaptable thereto. The efficient optical switch array is obtd. with the simple constitution in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical switch array useful when connecting signal lines of communication networks, computers, etc. using light as a medium.

(Prior Art) Switch arrays have traditionally been indispensable devices in the fields of communications and computers, and crossbar switches in particular are extremely useful devices that take advantage of their characteristics. However, the crossbar switch array is difficult to manufacture when the number of connection terminals increases, and even if current semiconductor technology is used, it is not easy to manufacture a large-scale switch array. For this reason, optical switch arrays that perform connections by introducing optical technology have recently been attracting attention.

However, optical switch arrays do not simply mean replacing conventional electrical devices with light.
One drawback is required, such as reducing the number of shutter arrays. The inventor has proposed an optical switch array as shown in Japanese Patent Laid-Open No. 64-49019, focusing on the compatibility of connected signals.

FIG. 7 is a perspective view showing a conventionally known optical switch array. Iota, 10fb.

101cm・-, 104c, 104d are! The i7i type light emitting light source 5 is a shutter array, 106 is an open "J mask, 107a, 107b, 107c, --110c, 1
j-Od is a surface photodetector. Solid light sources 101a-d
are connected to the four signal lines of the first terminal on the transmitting side. Similarly f02a to d, 103a to d, 10
4a to 4d are respectively the second . It is connected to each of the four signal lines of the third and fourth terminals.

The light emission of the solid-state lights @ 101 a to 104 d is fii (controlled) according to human signals. The shutter 105 determines which terminal on the receiving side the signal manually inputted on the transmitting side is sent to. When the signal from the i-th terminal is sent to the j-th terminal on the receiving side, the shutter in the i-th row and j-column becomes transparent.Aperture mask 106
is an opening lined up almost diagonally to one shutter.
It represents the correlation between the connections between the signal lines on the transmitting side and the receiving side. That is, open [1 mask 10
Due to the regulation of the luminous flux by 6, the signal line numbered 1 on the transmitting side terminal is also connected to the signal line numbered L1 on the receiving terminal.

On the other hand, first to fourth terminals on the receiving side are connected in sequence to each of the four surface detectors 107a to 110d. 1
Four signal lines are connected to the two terminals, each of which corresponds in turn to the surface detectors 107a to 110d.

In FIG. 7, the shaded portions of the shutter array 105 and the aperture mask ioa indicate that they are in a transparent state. For example, consider a signal from the 3rd H signal line of the 4th terminal on the transmitting side. This signal line is connected to solid light source 104c. Solid light source 104c
The light flux from the shutter array illuminates the entire facing vertically elongated area. In FIG. 7, the shutter array 105
The second row, fourth column is in the transparent state. For this reason 104c
The light beam from the opening passes through this portion, then passes through the open L1 mask 106, and is received by the cylindrical photodetector 108C facing this opening.

108C is connected to the third signal line of the second terminal on the light receiving side. As a result, No. 13 from the third Shingetsu line of the fourth terminal on the transmitting side is sent to the third signal line of the second terminal on the receiving side. Such correspondence holds true for other signal lines as well.

Another configuration example that operates on the same principle as the optical switch array shown in FIG.
is shown. Among these methods, there is a method in which an anamorphic optical system is placed between the light source and the shutter array, and the light beam from the light source is spread in one direction and then incident on the shutter array. Open L1
A method is shown in which the exit end of the optical fiber is placed at the position of the shutter array corresponding to the opening of the mask.

(Problem to be Solved by the Invention) However, in the conventional example described above, a long and narrow light beam is obtained in one direction by using a cylindrical light source or an anamorphic optical system, so the light beam that passes through the aperture mask is only a small part of the whole. There was a drawback that the utilization efficiency of 5 customers was poor. As a result, the S/N ratio deteriorates, requiring a high-performance amplification circuit for the received signal, and the optical switch array becomes complicated and costs increase.

In addition, when using an optical fiber splitter, which is another conventional example, although the light utilization efficiency is good, the exit ends of a large number of fibers are arranged to match the position of the aperture mask. This is a time-consuming task, and has the drawback of making the optical switch array as a whole complicated and expensive.

(1st step to solve the problem) The present invention was developed in consideration of the inefficiency of conventional light usage and the complexity of the entire system. It is characterized by its use.

That is, in the present invention, taking the incident side as an example, the system is configured so that a plurality of diffracted lights generated by the inserted diffraction grating go to the corresponding position of the open [-1 mask, and the light is It is characterized by having an entrance section and an exit section, thereby realizing a highly efficient system with a simple configuration.

(Embodiment) FIG. 1 is a perspective view showing a first embodiment of the present invention. la
, lb, lc, . . . , 4d are light sources, such as LEDs or conductor lasers. light source! a~1d
, 2a to 2d 3a to 3d 4a to 4d are respectively feed 3
It is connected to the first to fourth terminals on the side, each of which functions as one signal line and emits light.

Next, 5 is a first lens, and 6 is a first diffraction grating. The diffraction grating itself can be produced by known means, such as by exposing and projecting a grating pattern onto a silver salt sensitive material or photoresist, or by forming and exposing a two-beam interference pattern with coherent light. Further, it is also possible to fabricate it by molding a plastic substrate using a technique such as injection. Considering that the diffraction efficiency is good, it is possible to construct an efficient system by using a so-called phase type diffraction grating which has a distribution of phase transmittance and has a constant amplitude transmittance.

7 is a second lens. 8 is a shutter array, which is a spatial light modulator using an electro-optic material such as liquid crystal, P L ZT, L i N b 03, or a magneto-optic material such as Bi-substituted YIG, or a shutter array using a transmittance A control type display, such as electrochromy, is used. If the shutter array 8 is configured to utilize the reflected light, a reflective spatial light modulator that changes the reflectance can also be used.

Reference numeral 9 denotes an aperture mask, which is provided in large numbers at the openings or over the entire surface.

The opening pattern is created by mechanically processing metal to make holes, or by depositing AI or Cr on a glass plate and etching it using photolithography. In FIG. 1, the shaded portions of the shutter array 8 and the open L1 mask 9 indicate portions through which light beams are transmitted.

Next, regarding the relationship between the shutter array 8 and the aperture mask 9, FIG. 2 shows the relative relationship between the two. Second
Figure (A) is a partially enlarged view of the shutter array 8, and Figure 2 (
B) is a partially enlarged view of the aperture mask 9, showing corresponding parts.

Also, as in the previous figures, the shaded area indicates the part through which the light beam passes. One shutter 8 of shutter array 8
In one section 9a of the aperture mask 9 corresponding to a, 4x4
= There are 16 segments. In the embodiment shown in FIG. 1, four diagonal segments are fixed as apertures (transmissive parts) in one section, and the aperture mask 9 is formed by repeating the 4×4=16 segment pattern over the entire area. It is configured.

Figure 1 shows the light source! A to 4d emit light in response to a transmission signal. FIG. 3 is a diagram showing the operation of the optical system of the first embodiment of the present invention shown in FIG. 1. To simplify the explanation, light source 3d is shown as a representative from among light sources 1a to 4d.

In the figure, numeral 11 indicates a light beam emitted from the light source 3d. 12 is the 0th order diffracted light, 13.14 is the +1st order and +2nd order diffracted light, and 15.16 is the 11th order and -2nd order diffracted light.

The emitted light beam 11 from the light source 3d is made parallel by the first lens 5, and then enters the first diffraction grating 6. The second lens 7 serves to condense the light beam emitted from the first diffraction grating 6, and as a result, the light from the light @3d is imaged as a spot on the shutter array 8 and the aperture mask 9. Ru. At this time, a major feature of the present invention is that the incident light beam is divided into a plurality of pieces according to the order of diffraction due to the action of the first diffraction grating 6, and is spread out at the positions of the shutter array 8 and the aperture mask 9. That is, the 0th order diffracted light 12,
The +1st-order, +2nd-order, and -1st-order light beams 13, 14, and 15 form spots on the shutter array 8 and the aperture mask 9, respectively. This 1t means that the light flux from the light source 3d is distributed to four different locations.

On the other hand, since the light source 3d is not on the optical axis, -2nd order diffracted light 16
goes outside the system. Depending on the position of the light source and the order of diffraction, there may also be diffracted light that forms a spot away from the shutter array 8 and the open [-1 mask 9. Since such light has no contribution to signal transmission and results in a loss of light 1j1, it is desirable to reduce it as much as possible. The intensity of light of each diffraction order is determined by the complex transmittance distribution of the first diffraction grating 6. Therefore, once the desired number of distributions, the location of the ears 7, and the desired diffraction efficiency are determined, it is possible to design the diffraction grating 6 optimized for the specifications.

Now, let us assume that the pitch of the first diffraction grating 6 is p, the focal length of the second lens 7 is f, and the wavelength of the light beam is λ. is approximately expressed by the following formula.

d=fλ/p If the size of the shutter array 8 is 1 inch square and the number of signals to be distributed is 16, the spot interval d is 1
．． A value of about 6 mm is appropriate. The wavelength λ is 0.871m
, when the focal ratio 711f is 10 mm, the pitch p of the first diffraction grating is 5 μm from the above equation. That is, such a system can be constructed by preparing 200 diffraction gratings per Imrn.

The position where the 0th order diffracted light creates a spot is the first diffraction path f
This is the position where the image of the light source 3d is created by the first lens 5 and the second lens 7 when ``6'' is not present.The other diffracted light spots are based on the position of this 0th-order light. They are formed at intervals d apart from each other.

As shown in FIG. 1, the light sources 1a to 4d are arranged diagonally in groups of four. Therefore, shutter array 8
A group of spots of diffracted light generated on the aperture mask 9 are obtained by repeating the light sources 1a to 4d in the direction in which diffraction occurs while maintaining their shapes.

FIG. 4 is a diagram showing the distribution of diffracted light spots generated on the shutter array 8 and the aperture mask 90. 21 represents a group of diffracted light spots, and 22a to 22d show those created by the light source 3d among these diffracted light spots. It should be noted that the spot position is rotated by 180 degrees from the light source side due to image inversion accompanying imaging.

As can be seen from a comparison with FIG. 2(B), the distribution of this diffracted light spot is the same as the pattern of the opening 71 of the aperture mask 9, and it can be seen that this is due to light distribution or efficient JT. In particular, efficiency has been dramatically improved by being able to concentrate light at the aperture, which in the conventional example was uniformly spread out to areas not covered by anamorphic optical systems.

A group of spots generated by the same light source in the diffraction light spot 21 are arranged in a vertical line according to the directionality of the diffraction grating 6. The diffracted light spot created by the light source 3d occurs in the leftmost column of the second column of the shutter array 8Q. From a comparison with FIG. 3, the diffracted light spot 22a ~ angled by the light source 3d
22d correspond to the 11th-order, 0th-order, +1st-order, and +2nd-order diffracted lights 15.12 and 13.14, respectively. Although the aperture mask 9 is not necessarily necessary because the distribution of the diffracted light spots 21 is the same as the pattern of the apertures, it is preferable to insert it in order to reduce crosstalk caused by stray light and the like.

The above is an outline of the optical arrangement on the side that distributes incident light. It can be seen that the same operation as the conventional example using the planar light source of the optical switch array can be achieved easily and efficiently by using the diffraction grating.

FIG. 5 is a perspective view showing a light combining section following the light distribution section in the first embodiment of the present invention. In the figure, numeral 31 indicates a third lens, and numeral 32 indicates a second diffraction grating. The diffraction grating used at 32 in FIG. 5 is the same as the first diffraction grating 6, but
However, the direction of the grid is arranged perpendicular to 6.

Next, 33 is a fourth lens, and 34a to 37d are photodetectors. As the photodetector, a bin photodiode, an avalanche photodiode, or the like is used. 34a~
37d has four pieces arranged diagonally as shown in Figure 5.
They are arranged vertically in groups of two. 34a-34
d, 35a-35d, 36a-36d, 37a-37
Four terminals d are connected to the first to fourth terminals on the receiving side, and each one is connected to the corresponding signal line.
The number of recipients is now sent one book at a time.

The light combining section shown in FIG. 5 is connected to the light distribution section shown in FIG. 1, thereby forming an optical switch array as a whole. The number 9 in the open mask shown in FIG. 5 is to clearly show the relationship with FIG. 1, and means that the two are the same.

Next, the operation of the system shown in FIG. 5 will be explained. The light beam emerging from the aperture 1-1 mask 9 is made parallel by the third lens 31, and then decomposed by the second diffraction grating 32 into diffracted light specific to the diffraction grating, in the same way as in the case of the first diffraction grating 6. Ru. The decomposed light is focused by the fourth lens 33. As is clear from the similarities between FIG. 5 and FIG. 1 and from FIG. 3, the system from the third lens 31 to the fourth lens 33
The light beams emerging from the two apertures are detected by the photodetectors 34a to 3.
7d, the diffracted light is distributed into one row of spots in the lateral force direction. The pitch of this spot row is the diffraction grating 32
is determined by the pitch of the lens and the focal length of the lens system.

FIG. 6 is an enlarged view of the portion where the diffracted light spot array is detected in the light receiving section. 38a to 38c are diffracted light spot rows created by the diffracted light spots 22a of the aperture mask 9-t. Also 39a-39c.

40a to 40e are diffracted light spot rows created by other diffracted light spots on the open L1 mask 9. 38a~
Reference numerals 38c denote diffracted light spots created by the 12th-order, -1st-order, and 0th-order diffraction generated by the second diffraction jPrf32, among which 38b or photodetector 37d receives the light.

Other spot lights detected by the photodetector 337d include 39b and 40b as shown in FIG. Due to the directionality of the diffraction grating 32, the diffracted light spreads in a horizontal line. Therefore, in the distribution of diffracted light spots in the aperture mask shown in FIG. 4, the diffracted light spot to the right of 22a forms spots 39a to 39c in FIG. 6, and the diffracted light spot to the left of 22a forms spots 39a-39c. Spots 40a to 40 in Figure 6
form c. In terms of diffraction orders, spots 39a to 3
9c is the 1st order, 0th order, +1 diffraction by the second diffraction grating
The spots 40a to 40c correspond to
It corresponds to the next and -1st orders.

In this way, the photodetectors 37d are 38b and 39b.

The ability to receive a diffraction spot light such as 40b means that the system configured in this example has a photosynthetic effect. Light detection: ≦37a~3
The same holds true for 7c. While the light distribution section shown in FIG. are laterally merged and guided to corresponding photodetectors 334c to 37d.The shutter array 8 selects this two-dimensional connection.

As an example of this, let us return to FIG. 1 again and consider how the light beam from the light source 3d is guided to the photodetector. 3
The light beam from d is transmitted to the shutter array 8 by the action of the diffraction grating 6.
A plurality of spots are formed by the aperture mask 9 and the aperture mask 9, but among them, only the spot 22a corresponding to the hatched transparent portion passes through the shutter and the aperture mask portion. The light that passes through the aperture mask and enters the system shown in FIG. 5 forms a plurality of spots in the horizontal direction by the action of the diffraction grating 32, and is guided to the photodetector 37d as shown in FIG. . This means that the signal from the fourth signal line of the third terminal on the transmitting side is sent to the fourth signal line of the fourth terminal on the receiving side.

When transmitting the light from the light source 3d to another terminal on the receiving side, the transmitting portions of the shutters in the second row Lt of the shutter array 8 may be changed. In that case, the diffracted light spots 22b, 22c, or 22d in FIG. 4 are selected by the shutter 8 and transmitted through the first part 9 and the corresponding photodetectors 36d and 35d.

The output is detected at 34d. The input signal is thus sent to the third, second and first terminals depending on the selection of the shutter 8. The same applies to signal transmission between other terminals and signal lines, and it can be seen that this system as a whole constitutes a crossbar switch.

Furthermore, as can be seen from the alignment of the spots on the detection surface in Figure 6, the diagonal arrangement of the light source section and the detection section within each terminal is optimized based on the correspondence between the connected signals. . On the other hand, there are a plurality of positions where the diffracted spot light shown in FIG. 6 is focused, depending on the order of the diffracted light. Since the Pth order of the diffraction grating used is known, the characteristics can be determined so that almost the same light reception (1) can be obtained anywhere.

In the above description, a system using a diffraction path f is employed in both the light distribution section and the light convergence section. Since the efficiency is significantly improved by the diffraction grating, it is of course possible to substitute one side of the system, for example, the light combining section, with a conventional anamorphic system.

It is also possible to construct a system by placing an array of optical fibers at the positions of the light source and photodetector. In this case, the exit end and the entrance end of the optical fiber are the light sources 18 to 4d and the photodetector 3.
They are arranged in the same way as the arrangement of 4a to 37d.

(Effects of the Invention) As explained above, in the present invention, a diffraction grating is used to distribute and combine light, and light input is performed by focusing on the characteristics of the diffracted light spot and the characteristics of the correspondence between the human output signal. By optimizing the arrangement of the optical switch section and the detection section, we have made it possible to realize an optical switch array with a simple configuration. This system maintains the feature of reducing the number of shutter arrays as described in the inventor's previous application, and is also inexpensive because the system is constructed without using any special element Y- other than the diffraction grating. realizable.

Further, in the present invention, the efficiency of the optical system is improved, so that the loss of light amount is reduced, and as a result, an improved S/N ratio can be realized. As a result, the electrical system becomes simple, and there is also the advantage that the system can be constructed at low cost.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a light distribution section according to a first embodiment of the present invention;
FIG. 2(A) is a diagram showing the shutter array 8, FIG. 2(B) is a diagram showing the relative relationship between the two, and FIG. 3 is a diagram showing the operation of the optical system of the first embodiment of the present invention. FIG. 4 is a diagram showing the distribution of diffracted light spots on the shutter array 8, and FIG.
The figure is a perspective view showing the light convergence section of the first embodiment of the present invention,
The figure is a partially enlarged view of the light receiving section of the first embodiment of the present invention, and FIG. 7 is a perspective view showing a conventional optical switch array. In the figure, 1a to 4d: light source, 6: first diffraction path r-18:
Shutter array, 9: aperture mask, 12: 0th order diffracted light, 13: +1st order diffracted light, 14: +2nd order diffracted light, 1
5 Ni-first-order diffracted light, 16 Ni-second-order diffracted light, 21:
Diffraction light spots, 22a to 22d: Diffraction light spots created on the shutter array by light source 3d, 32: Second diffraction path f-534a to 37d: Photodetector, 38a
~38C: Spot created on the light receiving surface by the diffracted light spot 22a, 101a~104d: Surface light source, 101
a to 104d: Indicates a surface type photodetector. Figure 1 (B) Figure 6 Figure 9d Uc1 9b Ub :5υC UC Figure

Claims (3)

[Claims] (1) A light beam emitting section arranged in a predetermined repeating pattern, a light detecting section arranged in a predetermined repeating pattern,
In the optical switch array having a shutter array having a switching function between the light beam emitting section and the photodetecting section, a diffraction grating is disposed between the light beam emitting section and the shutter array, and the diffraction grating allows the An optical switch array characterized in that light emitted from a light beam emitting part is divided into a plurality of parts and enters the shutter array. (2) A second diffraction grating is disposed between the shutter array and the light detection section, and the second diffraction grating divides the light emitted from the shutter array section into a plurality of pieces, and the light The optical switch array according to claim 1, wherein the light is received by a detection section. (3) The optical switch array according to claim 2, wherein the grating directions of the first diffraction grating and the second diffraction grating are substantially perpendicular to each other.