JP2733121B2 - Optical space connection method between mounting boards - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an optical space connection method for transmitting and receiving signals between mounting boards (wiring boards) in an electronic device using a light beam propagating in space. In particular, the present invention relates to an optical space connection method between mounting substrates which aims at realizing a compact and large space optical space connection by reducing the number of light emitting elements and light receiving elements.

[Conventional technology]

Multiple boards (mounting boards) mounted in electronic devices
When signals need to be exchanged between these boards, it is necessary to provide a signal transmission / reception arrangement between these boards. Conventionally, such wiring between boards has been performed electrically. However, with an increase in the number of boards and an increase in the speed of transmission / reception signals due to an increase in the size of the device, inductance, stray capacitance, and electromagnetic induction caused by these electrical arrangements have become problems. As a wiring method to solve such problems of electrical wiring, an optical space connection method using a parallel light beam propagating in space as a signal transmission medium has been proposed (Noguchi, et al., “Multilayer Optical Wiring Board”, Japanese Patent Application 1963-20
No. 6473).

FIG. 6 shows an explanatory diagram disclosed in the above proposal,
This is an example in which connection between a plurality of (five in the illustrated example) boards is realized by an optical space connection method. In FIG. 6, reference numeral 1 denotes a light emitting element module which integrates a light emitting element and a lens, converts a signal generated on each of the mounting boards 11-1 to 11-5 into a parallel light beam, and radiates the light into space, and 2 denotes a light receiving element. The light receiving element module 3 with the integrated lens represents a window for passing a parallel light beam. That is, (N-1) light emitting elements and (N-
1) A plurality of light receiving elements are provided, and another third and fourth light emitting elements are provided between a board provided with an arbitrary light emitting element and a board provided with a light receiving element for receiving the light. And sometimes more than one board), this third,
By providing the fourth board with a window through which the light passes, signals can be exchanged between any two of the N boards.

[Problems to be solved by the invention]

In the optical space connection method according to the above proposed technique, it is necessary to arrange the same number of light emitting element modules and light receiving element modules on each board as the number of boards to be connected.
That is, assuming that the number of boards is N, N (N-1) light emitting element modules and N (N-1) light receiving element modules are required. Therefore, as the number of boards increases, the light-emitting module, light-receiving module,
And the number of opto-electrical conversion circuits connected to those modules also increases, and the power consumption of the optical space connection increases.
There are problems such as an increase in the proportion of the optical space connection portion in the board area.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in the prior art, reduce the number of light emitting elements and light receiving elements, increase the degree of freedom of connection, and reduce the size of the connection section. To provide an optical spatial connection method.

[Means for solving the problem]

In order to achieve the above object, the present invention employs an optical space connection method as described below. That is, in the optical space connection method in which signal transmission and reception between a plurality of N (N ≧ 2) mounting boards are performed using parallel light propagating in a space, an electric signal is formed on the surface of each mounting board by only a linear polarization component. One light-emitting element that converts the signal light into space and radiates it to the space and N-1 light-receiving elements that convert the incident signal light into an electric signal are provided on the path of the signal light from each light-emitting element. The polarization plane control element that rotates the polarization plane of the passing signal light by an arbitrary angle under external control, and the P-polarization component parallel to the plane formed by the incident signal light and the normal of the reflection surface at the incident point are: An S-polarized component, which is transmitted and reflected by changing the course of the perpendicular S-polarized component at right angles, has a reflection surface, and a polarization plane of the signal light traveling in a direction parallel to the radiated signal light in the optical path conversion device is 90 °. And rotate it back toward the reflective surface And a polarization plane control element are also arranged between each optical path conversion element. By controlling the rotation angle of the polarization plane by these polarization plane control elements, the signal from the light emitting element on an arbitrary mounting board is provided. First, the light path is changed by a right angle by the optical path conversion element for the self-mounting substrate, and is incident on the optical path conversion element for the other mounting substrate. Then, the light path is changed again by the right angle in the optical path conversion element that takes in the incident light. By radiating the light toward the light-receiving element of the mounting substrate to be connected, a method of spatially connecting the arbitrary mounting substrates with each other is adopted.

[Action]

The most significant feature of the present invention is that the optical path conversion function by polarization control is applied to the connection portion between the mounting boards, thereby reducing the number of light emitting elements and realizing a compact and flexible optical space connection. In this respect, it is clearly different from the prior art.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Embodiment 1 FIG. 1 is an explanatory view of an optical path according to a first embodiment of the present invention, and FIG. 2 is a three-dimensional perspective view. In FIG. 1, in order to facilitate the description of the optical path, the light emitting element and the light receiving element shown in FIG. 2 are rotated by a right angle so as to face the optical path conversion element. This embodiment is an example in which a connection between any two substrates between four mounting substrates is realized.
1-1 to 1-4 are light-emitting element modules that integrate a light-emitting element, a lens, and a polarizer and emit a single-polarized parallel light beam; 2-1 to 2-3, 3-1 to 3-3, 4, -1 to 4-3,5-1
5-3 is a light receiving element module integrating a light receiving element and a lens, 6-1 to 6-4 are polarization beam splitters, 7-1 to
Reference numeral 7-4 denotes a quarter-wave plate, and reference numerals 8-1 to 8-4 denote total reflection mirrors. The polarization beam splitter transmits a polarization component (P-polarization component) parallel to the plane formed by the normal to the reflection surface and the incident parallel light, and reflects a perpendicular component (S-polarization component) in a direction perpendicular to the incident light. Element. 9-1 to 9-
Reference numerals 4, 10-1 to 10-3 denote polarization plane control elements, specifically, liquid crystal switches, ferroelectric switches, and the like. 11-1 to 11-4 are mounting substrates, and 12 is mounting substrates 11-2 to 11-1.
An optical path for transmitting a signal to 1-4, 13 is a mounting board 11-3.
Respectively represent optical paths in the case of transmitting a signal from the optical path to the signal 11-1. The light emitting element modules and light receiving element modules on each mounting board are arranged one-dimensionally or two-dimensionally on the same plane, and the number thereof is one each when the total number of mounting boards is N, and (N-1). It is.

The operation of this embodiment will be described by taking as an example a case where a signal is transmitted from the mounting boards 11-2 to 11-4 and a case where a signal is transmitted from the mounting boards 11-3 to 11-1. First, a case where a signal is transmitted from the mounting boards 11-2 to 11-4 will be described. The electric signal output from the mounting board 11-2 is converted into a single-polarized parallel light beam 12 by the light emitting element module 1-2 and emitted to space. The parallel light beam 12 is converted into S-polarized light by the polarization plane control element 9-2 and enters the polarization beam splitter 6-2. Since the signal light 12 incident on the polarization beam splitter 6-2 has only the S-polarized light component, the signal light is converted at a right angle to the incident light, the light path is changed in the downward direction in the drawing, and is emitted, and is incident on the polarization plane control element 10-2. The polarization plane control element 10-2 is a signal light.
The 12 polarized lights are rotated by 90 degrees and emitted as P-polarized light. The signal light 12 converted to P-polarized light passes through the polarization beam splitter 6-3 as it is and enters the polarization plane control element 10-3. The polarization plane control element 10-3 rotates the polarization of the signal light again by 90 degrees,
Convert to polarized light. Therefore, the signal light 12 is reflected at right angles by the polarization beam splitter 6-4, and the polarization is rotated by 90 degrees through the quarter-wave plate 7-4, the reflection mirror 8-4, and the quarter-wave plate 7-4.
The light is converted into P-polarized light and is again incident on the polarization beam splitter 6-4. Since the signal light 12 has been converted to P-polarized light,
The light passes through the polarizing beam splitter 6-4 as it is and is emitted to the left in the drawing. The emitted signal light 12 is converted into an electric signal by the light receiving element module 5-2, and is mounted on the mounting substrate 11-.
It is led to 4. Next, a case where a signal is transmitted from the mounting boards 11-3 to 11-1 will be described. The electric signal output from the mounting board 11-3 is incident on the polarization beam splitter 6-3 as a P-polarized parallel light beam by the light emitting element module 1-3 and the polarization plane control element 9-3. Incident signal light
13 passes through the polarizing beam splitter 6-3, the quarter-wave plate 7-3, the reflecting mirror 8-3, and the quarter-wave plate 7-3, and is reflected by the polarizing beam splitter 6-3. The light is emitted upward. The polarization of the output signal light 13 is converted into P-polarized light by the polarization plane control element 10-2 and converted into S-polarized light by 10-1.
3 is reflected by the polarization beam splitter 6-1 and guided to the light receiving element module 2-2. Light receiving element module 2-2
Converts the signal light into an electric signal and outputs it to the mounting board 11-1. As described above, the signal light radiated from the light emitting element module can be arbitrarily processed by performing polarization plane control (switching between P-polarized light and S-polarized light) and path conversion depending on these polarization planes in the course of the path. It is possible to couple with the light receiving element module on the mounting board. Therefore, according to the present embodiment, it is possible to reduce the number of light emitting element modules and light emitting element driving electronic circuits to 1 / (N-1), respectively. The optical system will be downsized.

Embodiment 2 FIG. 3 is an explanatory view of an optical path according to a second embodiment of the present invention. In the first embodiment of the present invention, the polarization plane control element is used as an S-polarized light switch and a P-polarized light switch to realize one-to-one connection between arbitrary mounting substrates. In the configuration of the first embodiment of the present invention, when the polarization plane control element has a function of rotating the polarization plane of the incident light by an arbitrary angle, a broadcast-type connection can be made with the same configuration as that of FIG. Arbitrary angle rotation of the polarization plane can be realized, for example, by adjusting the voltage applied to the strong dielectric switch. FIG. 3 shows a second embodiment of the present invention capable of broadcasting connection. The configuration is the same as that of FIG. 1, except that polarization plane control elements (22-1 to 22-4, 23-1 to 23-3) having a function of rotating the polarization plane of the incident light by an arbitrary angle are used. It is different from FIG. Numeral 24 indicates an optical path when a broadcast connection is made from the mounting board 11-2 to all other mounting boards.
The electric signal output from the mounting board 11-2 is converted into a single-polarized parallel light beam 24 by the light emitting element module 1-2 and emitted to space. The parallel light beam 24 is converted by the polarization plane control element 22-2 into a polarization plane having an angle of 30 degrees with the S polarization plane, and is incident on the polarization beam splitter 6-2. The signal light 24 incident on the polarization beam splitter 6-2 contains an S-polarized component and a P-polarized component in a ratio of 2: 1. The S-polarized component is in the downward direction in the figure, and the P-polarized component is in the upward direction in the figure. Is emitted. The signal light emitted upward is polarized light control element 23-1.
As a result, the plane of polarization is rotated so as to become S-polarized light, reflected by the polarizing beam splitter 6-1 and guided to the light receiving element module 2-1. The light emitted in the downward direction in the figure is converted by the polarization plane control element 23-2 so that its polarization plane is converted to an angle of 45 degrees with the S-polarized light. The converted signal light is P
It has a polarization component and an S-polarization component at a ratio of 1: 1. Accordingly, the polarization beam splitter 6-3 emits the P-polarized component of the incident light as it is in the downward direction in the figure, and guides the S-polarized component to the light receiving element 4-2. The light emitted from the polarization beam splitter 6-3 having only the P-polarized component is converted into S-polarized light by the polarization plane control element 23-3, and guided to the light-receiving element module 5-2. From the above, the signal light emitted from the light emitting element module 1-2 is coupled to all other light receiving element modules. In this way, using the configuration shown in FIG. 3, it is possible to realize a broadcast-type connection in which the output signal light from an arbitrary mounting substrate is coupled to the light receiving elements on all other mounting substrates. Of course, one-to-one connection between arbitrary mounting substrates is also possible using the configuration of this embodiment. Therefore, according to the present embodiment, the switching of the connection mode (one-to-one connection, broadcast type connection) and the switching of the connection terminals can be easily realized by external control, and the conventional optical space connection between the mounting boards can be realized. The degree of freedom in connection is greatly improved as compared with.

Embodiment 3 FIG. 4 is an explanatory view of an optical path according to a third embodiment of the present invention, and FIG. 5 is a three-dimensional perspective view. 14-1 to 14-4 are for light reception
1/4 wavelength plate, 15-1 to 15-4 are total reflection mirrors for light reception, 16-
1 to 16-4 are 1 wavelength plates for light emission, 17-1 to 17-4 are total reflection mirrors for light emission, 18-1 to 18-4 are condensing lenses, 19-1 to 19
-4 indicates a light receiving element. The positional relationship between these condenser lenses and light receiving elements is such that each light receiving element is arranged at a lens focal position on the optical axis of each condenser lens. Reference numeral 20 denotes an optical path for transmitting a signal from the light emitting element 1-2 to the light receiving element 19-4, and reference numeral 21 denotes an optical path for transmitting a signal from the light emitting element 1-3 to the light receiving element 19-1. In this embodiment, a reflection element composed of a quarter-wave plate and a total reflection mirror is separately arranged for light emitted from the light emitting element module and light incident on the light receiving element, and the light incident on the light receiving element is divided. The difference from the first embodiment is that light is coupled to one light receiving element via a condenser lens. In this embodiment, the same functions as those of the first and second embodiments of the present invention can be realized. In addition, the number of light emitting elements and the number of light receiving elements are set to N for the total number of mounting boards N. be able to. Therefore, in the optical space connection of this embodiment, the ratio of the optical space connection portion to the mounting substrate area can be significantly reduced.

In the method of the third embodiment, one light emitting element is provided for each mounting substrate, but the arrangement position in the one-dimensional direction needs to be sequentially shifted for each substrate as shown in the figure. In this regard, the number of mounting boards that can be interconnected is limited. On the other hand, the positions where the light emitting elements can be arranged are m × n two-dimensional matrices (m and n are each 1 or more and m + n is 3 or more). The light receiving element side is configured to receive the signal light to one light receiving element via the condenser lens, so that the total number of the light receiving elements is mx. Wiring between the n mounting boards becomes possible, and the degree of freedom of the wiring is greatly improved.

The two-dimensional arrangement described above is also applicable to the above-described first and second embodiments of the present invention. The two-dimensional arrangement can be applied to the mutual connection when the number of mounting boards is large, so that a great effect is exhibited. be able to.

The embodiments described above can be applied not only to the connection between mounting substrates but also to the connection between light surface input / output elements (surface emitting lasers, array light receiving elements, optical bistable elements, etc.).

〔The invention's effect〕

As described above, according to the present invention, the optical path conversion function based on the polarization plane rotation angle control is applied to the connection portion between the mounting substrates. According to the method of the first aspect of the present invention, it is necessary to provide -1 light emitting elements and N-1 light receiving elements on each mounting board, respectively. According to the second aspect of the present invention, the number of light receiving elements can be reduced to one for each mounting board, thereby reducing the size of the optical space connection portion and free connection. This has the effect of increasing the degree.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an optical path of the first embodiment of the present invention, FIG. 2 is a three-dimensional perspective view of the first embodiment, and FIG. 3 is an explanatory view of an optical path of the second embodiment of the present invention. FIGS. 4 and 5 are explanatory views of the optical path of the third embodiment of the present invention, FIG. 5 is a three-dimensional perspective view of the third embodiment, and FIG. 6 is a perspective view showing the prior art. <Description of Signs> 6 ... polarizing beam splitter 7 ... 1/4 wavelength plate, 8 ... total reflection mirror 9,10 ... polarization plane control element 11 ... mounting substrate 14 ... 1/4 wavelength plate for light reception 15: Total reflection mirror for light reception 16: Quarter-wave plate for light emission 17: Total reflection mirror for light emission 18: Condensing lens ○ mark: Light emitting element module

Claims (2)

(57) [Claims] In an optical space connection method in which signal transmission and reception between a plurality of N (N ≧ 2) mounting boards are performed using parallel light propagating in space, an electric signal is linearly polarized on a surface of each mounting board. One light emitting element that converts the signal light into only the component light and radiates it to the space, and N-1 light receiving elements that convert the incident signal light into the electric signal are provided, and the emission signal from each light emitting element is provided. A polarization control element that rotates the polarization plane of the passing signal light by an arbitrary angle under external control on the light path, and a plane parallel to the plane formed by the incident signal light and the normal of the reflection surface at the point of incidence. An optical path conversion element having a reflecting surface that transmits a polarized light component and reflects a vertical polarized light component while changing its course by a right angle, and a polarization of the signal light that has traveled in the optical path conversion element in a direction parallel to the radiation signal light. Rotate the surface 90 degrees and move backward toward the reflective surface Causing a reflection element is provided, respectively the plane of polarized light control element in between each of the optical path conversion elements each other,
The polarization plane rotation angle of these polarization plane control elements is controlled from the outside, and the signal light from any light emitting element is first changed by a right angle by the optical path conversion element for the self-mounting board, and the path is changed for other mounting boards. And then irradiates the incident light onto the light receiving element on the mounting board to be connected by changing the course again at a right angle in the optical path changing element. An optical space connection method between mounting boards, wherein the optical space connection is performed. 2. The light receiving element provided on the mounting substrate according to claim 1, wherein the number of light receiving elements is one for each mounting substrate, and the reflecting element receives signal light from a light emitting element and light incident on the light receiving element. And a light-reflecting portion, and a condenser lens is provided between the optical path conversion element and the light-receiving element, and each light-receiving element is disposed at a focal position on the optical axis of each condenser lens. The optical space connection method between mounting boards, which is provided.