JP3075218B2 - Optical waveguide and optical back wiring board for optical interconnection - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical back wiring for mounting a plurality of circuit boards including an optical circuit in a detachable manner and transmitting an electric signal and an optical signal from one circuit board to another circuit board. The present invention relates to a board and an optical waveguide thereof.

[0002]

2. Description of the Related Art The above-mentioned optical back wiring board (rear wiring board, hereinafter referred to as optical BWB) is composed of wiring for transmitting electric signals between circuit boards, an optical waveguide for transmitting optical signals, and
An electrical connector and an optical connector for connecting these wirings, the optical waveguide and each circuit board are provided.

In general, an optical fiber is used as an optical waveguide for connecting an optical circuit between a motherboard, a package, and the like, and a light emitting end and an incident end of the circuit are connected to an optical fiber by an optical connector. It is necessary to precisely align the optical axis with the fiber, and various connecting means for that purpose have been disclosed.

[0004] For example, as disclosed in Japanese Patent Application Laid-Open No. 58-12451, in signal transmission between a motherboard and a package mounted on the motherboard, a multiplexing circuit for multiplexing electric signals on the package, An electric / optical conversion circuit and a light emitting element for converting a multiplexed signal into an optical signal,
An optical-to-electrical conversion circuit and a light-receiving element for converting an optical signal to an electric signal, and a demultiplexing circuit for demultiplexing the electric signal converted by the optical-to-electrical conversion circuit, and forming an optical waveguide on a motherboard; A method of optically coupling a light emitting element and a light receiving element on a package with each other is known.

Japanese Patent Application Laid-Open No. 63-202723 discloses a light-emitting element, an optical waveguide for guiding light emission of the light-emitting element, and an optical waveguide attached to the optical waveguide for transmitting propagation light outside the waveguide. A light deflector that has a diffraction grating that emits light to the substrate, and deflects the angle of the emitted light by applying an electrical signal; and a light converging optical system that converges the emitted light to a light receiving element on a receiving substrate. An optical connection device is disclosed.

[0006]

However, the above-mentioned prior art 1 is a connection between a motherboard and a package mounted on the motherboard, but is a connection within the same substrate. A connection between circuit boards in the same board or in the same plane by a fiber or the like. In each case, a large space is required in an optical connector section as an optical BWB for mounting a plurality of circuit boards in parallel and connecting them to each other. There was a problem.

An object of the present invention is to provide a small-sized optical BWB on which a plurality of circuit boards having an optical interface are mounted and optical signals can be connected between the circuit boards, and an optical waveguide thereof.

[0008]

The optical waveguide for optical interconnection according to the present invention has a rectangular cross section having a thickness L between opposing surfaces, and a total reflection film is provided inside each side surface which is linearly extended in the longitudinal direction. A light-transmitting medium coated with an anti-reflection film on both end surfaces, an input window provided by removing a part of the total reflection film on one side in the longitudinal direction of the light-transmitting medium, and the same side as the input window above, and an output window which is provided by removing a total reflection film of the portion spaced integral m multiple intervals of unit length n from the input window, input Huy
On the same side between the window and the output window.
1 to (m-1) at intervals of an integer multiple of the order length n
The total reflection film at the position of the integer x is removed, and each of the predetermined reflection is performed.
X intermediate parts provided by coating a high percentage of permeable membranes
Window and the input window, the light incident perpendicularly to the side surface is incident at an angle θ = tan ⁻¹ (n
/ 2L) and provided in the output window and each of the intermediate windows in the light transmission medium and emitted in the longitudinal direction within the light transmission medium, and at an angle? An output prism that refracts the incident light and emits the light perpendicular to the side surface.

[0009] In particular, the coat
The transmittance of each of the permeable films to be coated is 1 / from the direction closer to the input window toward the output window.
From (x + 1) to 1/2, it is determined step by step ,
And Ru same prism and output prism to these intermediate windows are provided.

An optical BWB according to the present invention includes any one of the above optical interconnection optical waveguides, an electrical connector arranged at intervals of a unit length n and connected to a terminal of an electrical signal on a circuit board, and an input of the optical waveguide. An optical connector for connecting an optical interface unit of the circuit board to the window, the output window, and the intermediate output window;

[0011]

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

FIG. 1 is a longitudinal sectional view of one embodiment for explaining the basics of an optical waveguide for optical interconnection according to the present invention.

Referring to FIG. 1, an optical waveguide 100 of this embodiment is shown.
Has a rectangular cross-section in which the antireflection film 10 is coated on both end surfaces 1 in the longitudinal direction extended in a straight line, and the total reflection film 12 is coated on each of the other longitudinal side surfaces. The input window 4 provided by removing the total reflection film 12 on a part of the one side surface 11 coated with the light transmission medium 3 and the total reflection film 12, and on the same side surface 11 as the input window 4, And the input window 4
1, is provided at the position of an output window 5 provided by removing the total reflection film 12 at positions spaced by an integer m times the unit length n, for example, 3 times in FIG.
The light perpendicularly incident on the side surface 11 is angled with respect to the normal θ = t
An input prism 6 refracted to an-1 (n / 2L) and emitted in the longitudinal direction in the light transmitting medium, and provided at the position of the output window 5, and enters the light transmitting medium at an angle [theta] with respect to the normal line. And an output prism 7 that refracts the emitted light and emits the light perpendicularly to the side surface 11.

By using the optical waveguide 100 having such a structure, an optical signal incident on the input window 4 and perpendicular to the side surface 11 is incident on the input prism 6 at an angle θ with respect to a normal line.
And is guided in the longitudinal direction in the optical waveguide 100. When the total reflection is repeated between the side surface 11 and the opposing surface at an angle θ with respect to the normal of 2m−1 times, that is, five times in the example of the drawing, and reaches the output window 5, the light is refracted by the output prism 7 and is output. 5 is emitted perpendicularly to the side surface 11. Therefore, an optical signal incident on the optical waveguide 100 from the circuit A disposed opposite to the input window 4 is:
Since the light is emitted in parallel to the circuit B disposed opposite the output window 5, the circuit A and the circuit B can be optically connected.

Next, a second embodiment of the optical waveguide for optical interconnection to which the present invention is actually applied will be described with reference to FIG .

As shown in FIG. 2, the optical waveguide 200 of the second embodiment has an interval of an integral multiple of the unit length n between the input window 4 and the output window 5 of the first embodiment. And at least one integer x up to m-1 (here, two places), the total reflection film is removed, and the transmittance becomes 1 / (x +
From 1) to 1/2, 1 / x, 1 / (x-1),. . .
, An intermediate window coated with a permeable film 13 that changes step by step (in the illustrated example, the transmittance is 1/3 and 1 /
Two intermediate windows 30 and 31) coated with two transmission films 13 are provided, and an output prism 7 similar to the output prism 7 is provided in each of these intermediate windows.

The optical signal incident from the input window 4 is totally reflected inside the optical waveguide 200 and first reaches the intermediate window 30. When the optical signal reaches the intermediate window 30, 1/3 of the incident light is refracted by the transmission film having the transmittance of 1/3. Then, the light is vertically emitted out of the optical waveguide from the intermediate window 30, and the remaining ２ is reflected into the optical waveguide 200. The optical signal reflected into the optical waveguide 200 is refracted in the next intermediate window 31 by 2/3 × 1/2 = 1/3 of the incident light due to the transmission film having the transmittance of て. From the optical waveguide 200, and the remaining 1/3 is reflected into the optical waveguide 200. The remaining 1/3 is vertically emitted from the last output window 5 to the outside of the optical waveguide 200.

That is, each intermediate window 30, 31
And 1/3 of the incident light are equally distributed and output from the output window 5.

The intermediate window has a unit length n on the side surface 11.
It is not always provided at each reflection point. The total reflection film 12 at the reflection point where the intermediate window is not provided is not removed, and the transmittance of the transmission film coated on each intermediate window is an input window represented by a multiple of the unit length n or an output window. Not the distance from the window,
It depends on the number x of arranged intermediate windows and the arrangement order.

Next, an optical BWB 300 using the above-described optical waveguide 100 will be described with reference to FIG.

The optical BWB 300 shown in FIG. 3 is composed of an optical waveguide for optical interconnection in which two optical waveguides 100 shown in FIG. 1 are arranged in parallel, and circuit boards 20a and 20b having both an optical interface and an electrical interface. Optical connectors 23a and 23b to which optical interfaces can be connected
And an electrical connector 2 to which electrical interfaces of the circuit boards 20a and 20b and other circuit boards (not shown) can be connected.
And 2.

The two optical waveguides 100 are arranged such that one input window 4 and the other output window 5 are arranged side by side.
Both ends are connected to either one of the optical connectors 23a and 23b, and when the circuit board 20a or 20b is mounted, both the one input window 4 and the other output window 5 are arranged on the optical interface of the circuit board. Connected at the same time.

The electrical connectors 22 are arranged in one or more rows in parallel with the optical waveguide 100 at intervals of a unit length n, and the electrical connectors are electrically wired on the optical BWB. In each row, up to m + 1 electrical connectors 22 including a circuit board having only an electrical interface without an optical interface can be attached.

[0024]

Optical interconnection optical waveguide of the present invention as described above according to the present invention is Rutotomoni provided the input and output of the window cross-section having an input prism and an output prism light transmission medium which is extended in a straight line with a square Refracts the optical signal incident on the input window and propagates it to the output window
At least one at an interval of an integral multiple of the unit length n
A position of an integer x up to (m-1), that is, a light transmitting medium
X reflection points in the inside are coated with a predetermined transmittance.
Established intermediate window, like the output window
By emitting an optical signal also from these intermediate windows, an optical signal incident from one circuit board can be converted into one optical signal.
Waveguides can be distributed to multiple circuit boards,
Therefore, there is an effect that the apparatus can be downsized .

In addition, each intermediate window is coated with a coating.
The transmittance of the permeable membrane is output from the one closer to the input window.
By gradually increasing toward the window,
The emitted optical signal is divided into each intermediate window and output window.
Has the effect of being equally distributed .

The optical back wiring board of the present invention has the effect of reducing the size and weight of the device and reducing power consumption by embedding the above-described optical waveguide in the board.

[Brief description of the drawings]

FIG. 1 shows an optical waveguide 1 for optical interconnection according to the present invention.
It is a longitudinal section of an example.

FIG. 2 is a longitudinal sectional view of another embodiment of the optical waveguide for optical interconnection of the present invention.

FIG. 3 is a perspective view of one embodiment of an optical back wiring board (optical BWB) of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 End surface 3 Light transmission medium 4, 5, 30, 31 Window 6 Input prism 7 Output prism 10 Non-reflection film 11 Side surface 12 Total reflection film 13 Transmission film 20a, 20b Circuit board 22 Electrical connector 23a, 23b Optical connector 100, 200 Light Optical waveguide for interconnection 300 Optical back wiring board, (optical BW
B)

Claims (2)

(57) [Claims] (1) The cross section is rectangular, and the thickness (L) between one opposing surfaces is determined.
Has a full counter inside each side that is linearly extended in the longitudinal direction.
Coated with anti-reflective coating on both end surfaces
Light-transmitting medium, and a longitudinal direction of the light-transmitting medium.
Input window provided by removing a part of the total reflection film on one side
Window, on the same side as the input window, and
An interval of integer m times the unit length n is placed from the input window.
Output window provided by removing the total reflection film of the part
And provided on the input window and perpendicular to the side surface.
Is the arctangent of (n / 2L) with respect to the normal.
Refracted at an angle θ and emitted in the longitudinal direction in the light transmitting medium
An input prism, and provided in the output window,
From the light transmission medium at the angle θ with respect to the normal line.
Output prism that refracts the reflected light and emits it perpendicular to the side surface
And one optical circuit connected between the optical circuit boards.
An optical interface that transmits an optical signal from the board to the other optical circuit board
In the optical waveguide for connection, on the same side surface between the input window and the output window, a total reflection film of one or more integers x and up to m-1 is provided at intervals of integer multiples of the unit length n. And from 1 / (x + 1) to 1 / x, 1
/ (X−1),... And x intermediate windows coated with a permeable film that changes in a stepwise manner up to 1/2 are provided, and each intermediate window has an output prism similar to the output prism. <br/> optical interconnections optical waveguide, characterized in that is provided. 2. A rectangular section having a thickness L between opposed surfaces,
A total reflection film covers the inside of each side extended linearly in the hand direction.
Coated on both sides with anti-reflective coating
Light transmitting medium, and one side surface in the longitudinal direction of the light transmitting medium.
Input window provided by removing some of the total reflection film
And on the same side as the input window, and
A part spaced from the force window by an integer m times the unit length n
Output window provided by removing the total reflection film of
It is provided in the part of the input window and is perpendicular to the side.
Is the arctangent of (n / 2L) with respect to the normal.
Refracted at an angle θ and emitted in the longitudinal direction in the light transmitting medium
Input prism and the output window
At an angle θ with respect to a normal from within the light transmitting medium.
An output plate that refracts incident light and emits it perpendicular to the side surface.
A rhythm and an interval equal to the unit length n;
Wiring for connection between circuit boards and electrical interface of each circuit board
An electrical connector to be connected to the input
Dow and output window and optical interface of each circuit board
And an optical connector to be connected to each
Wiring to make circuit connections between circuit boards
In the board, on the same side surface between the input window and the output window, the total reflection film at one or more integer-m locations x is removed at intervals of an integral multiple of the unit length n. Then, from 1 / (x + 1) to 1 / x, 1 from the side whose transmittance is closer to the input window toward the output window.
/ (X−1),... And 1/2, x intermediate windows provided with an output prism similar to the output prism and coated with a transmission film that changes stepwise in order, that it has an optical connector that window and the optical interface of each circuit board are connected
Characteristic optical back wiring board.