JPS6025042Y2 - Tapered optical coupler - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for optically coupling an array of polymer light guide paths integrally formed in a sheet shape to an array of light receiving elements.

Conventionally, in this type of coupling between a light guide array and a light receiving element array, as shown in FIG.
Since the end surface 2a of the sheet 2 of the light guide path 1 and the light-receiving element array 3 are directly opposed and coupled, the end surface is wavy due to wrinkles in the sheet, etc., making it possible to hold both optically accurately and stably. It had some troublesome drawbacks.

The present invention has been made in order to solve the drawbacks of the prior art, and it prevents the sheet from waving and holds it rigidly at the end of the polymer light guide array formed integrally in the form of a sheet. By arranging a batten in a direction perpendicular to the light guide array and forming the end face of the light guide array to have a tapered surface at an appropriate angle, the light propagating within the light guide can be directed to the target direction. This device is characterized in that the light is reflected by a tapered end face to change its traveling direction, and is incident on a light-receiving element array arranged on a sheet, thereby optically and easily coupling the light guide path array and the light-receiving element array.

FIG. 2 is a schematic diagram of the principle of the present invention, and in the figure, parts having the same functions as those in FIG. 1 are designated with the same reference numerals as in FIG. 1.

As shown in FIG. 2, when the end face of the light guide sheet 2 is cut diagonally, the light guided inside the light guide will be directed to the inclined part of the end face.
It is totally reflected at point b and exits to the upper surface of the sheet as shown by the arrow.

Therefore, by arranging the light receiving element array 3 on the upper surface of the light guide sheet 2, the light propagating within the light guide 1 can be detected.

In this case, the inclination angle θ8 of the end face is determined by the refractive index of the core portion 1a of the light guide path 1 and the refractive index of the cladding portion 1b.

In order for all the light propagating in the light guide to be totally reflected by the inclined surface 2b and emitted to the upper surface of the sheet, the inclination angle θ8 needs to satisfy the following formula.

θ, (sin-” (diagnosis-5in-'(,;) θ within the range that satisfies the condition of the above formula.

If is extremely small, the light will be reflected over a wide angular range, and the width of the array of light-receiving elements for the reflected light will need to be widened, leading to an increase in the size and cost of the device.

Conversely, if the value on the right side of the above equation is smaller than 08, that is, the direction of the inequality sign is reversed, some light passes through the inclined surface 2b and the amount of light incident on the light receiving element decreases, so the overall efficiency decreases. decreases.

Therefore, the inclination angle θ satisfies the above formula and satisfies the characteristics of the light guide sheet material and the miniaturization of the device.

are selected by themselves.

In the present invention, it is appropriate to cut or polish the end surface 2b of the polymer light guide sheet 2 so that the angle of inclination is approximately 40 degrees.

By adhering and fixing the light-receiving element array to this inclined surface at a suitable position on the upper surface of the sheet in the direction in which light rays are emitted, optical coupling between the light-guiding path array and the light-receiving element array can be achieved.

In this case, the light-receiving element array is arranged directly on the top surface of the sheet, so it is easy to secure it to the sheet, and
Due to the synergistic effect, it is possible to prevent effects such as waving of the sheet.

Furthermore, each light guide path and each light receiving element are completely connected to each other.
Since it is technically difficult to achieve pair-to-one correspondence because it requires minute alignment, it is possible to improve the image quality by arranging the array of light receiving elements with a higher element array density than that of the light guide array. Optical coupling can be easily realized without missing parts, that is, without deteriorating definition.

FIG. 3 is a perspective view for explaining one embodiment of the present invention.
In the figure, 2 is a light guide sheet, 3 is a light receiving element array, 4 is a batten, and 2b is an inclined end surface.
A light guide array was used, which was prepared by arranging light guide paths at an arrangement density of 10 lines/rrrIn in a sheet of polycarbonate, which is a transparent polymer, by the method described in No. 2648, "Method for Manufacturing Optical Circuits."

A polymer batten 4 was adhered to the end face of this light guide sheet to facilitate polishing, and the end face was polished to an inclination angle of 40°.

In the light guide sheet of this example, the refractive index of the core portion is n.

f-1, 59, the refractive index n1 of the cladding part is 1.55 to 1
．． 58, therefore, the inclination angle θ8 was set to approximately 40°.

After that, when image sensors with an array density of 30/TIrIft were aligned and glued onto the sheet,
The image could be received by the light receiving element.

As explained above, the tapered optical coupling device according to the present invention has the end face of the array of polymeric light guides integrated in a sheet shape tapered at an angle of 40 to 50', thereby improving the propagation within the optical path. The structure is such that the light is reflected by the tapered end face and extracted from the top surface of the sheet, and this light is detected by the light receiving element array fixed on the sheet, so the light receiving element array is fixed to the light guide sheet.
It is easy to hold, and optical coupling can be performed simply and stably, so it has the advantage that it can be input to the light receiving element without impairing the definition of the image.

In addition, this optical coupling device according to the present invention can be used for image input terminals such as solid-state scanners in facsimile machines and for optical wiring between units of electronic computers, thereby easily converting optical signals from the light guide array into electrical signals. It has the advantage of being able to be converted into

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining an example of a conventional coupling device, FIG. 2 is a schematic diagram of the principle of an optical coupling device according to the present invention, and FIG. 3 is a perspective view for explaining an embodiment of the present invention. It is. 1... Light guide path, 1a... Core part of the light guide path, 1b... Clad part of the light guide path, 2...
...Light guide path row sheet, 2b... Slanted end surface, 3.
...Light-receiving element row, 4...Bracket.

Claims (1)

[Scope of utility model registration request] A batten that rigidly holds the sheet on which the light guide array is formed is disposed on one side of the end of the flexible polymer light guide array formed integrally in a sheet shape in a direction perpendicular to the light guide array. The end face of the light guide array is tapered at an angle of approximately 40°, and the light receiving array has a higher arrangement density than the light guide array on the surface where the batten of the sheet-like light guide array is not disposed. The element array is fixed in place and propagated through the light guide path,
A tapered optical coupling device characterized in that the light is reflected at the tapered end face and made to enter the light receiving element array.