JPH0443313A - Optical waveguide array and its manufacture - Google Patents

Abstract

PURPOSE:To improve the resolution of a latent image formed on a photosensitive body by molding a two-dimensional distribution refractive index lens integrally at a light projection part. CONSTITUTION:The optical waveguide array 1 is formed on a substrate 8 and a layer 2 which has a refractive index distribution is sandwiched between two clad layers 4 and 5 which are low in refractive index; and the optical waveguide array consists of the part A of a normal optical waveguide array and a part B where the refractive index is distributed in the scanning direction (y direction) of light. Then, the two-dimensional distribution refractive index lens 6 is formed integrally at the part B while having a projection surface 7 with length L. Projection light can, therefore, be converged in a (y) direction by the optical waveguide array 1. Consequently, the resolution of the latent image formed on the photosensitive drum can be improved only by using an inexpensive converging means which converges the light at right angles to the projection light and scanning direction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical waveguide array used in optical scanning devices and the like, and a method for manufacturing the same.

[Prior Art] Conventionally, as shown in FIG. 5, there is an optical scanning device that uses an optical waveguide array 95 and is installed in a laser printer or the like.

In this device, a laser beam from a semiconductor laser 91 passes through an imaging lens system 93 and is then deflected by a polygon mirror 94 that rotates at a constant speed.

The reflected light from the polygon mirror 94 enters from the entrance part 95A of the optical waveguide array 95, propagates through the optical waveguide part, exits from the exit part 95B, and is focused by the lens array 97, and is focused on the photoconductor rotating at a constant speed. The drum 96 is scanned along the direction of arrow E, which is parallel to its rotation axis. This lens array 97 focuses the light beams emitted from the emitting section 95B in the scanning direction and in a direction perpendicular to the scanning direction.

[Problems to be Solved by the Invention] However, if the lens array 97 is not provided in the above-mentioned optical scanning device, the light rays emitted from the emitting section 95B are determined by the numerical aperture NA of the optical waveguide, as shown in FIG. It spreads at an angle θc (= sin-” (NA)).

Therefore, the spot diameter of the optical signal applied to the surface of the photoreceptor drum becomes large, and the resolution of the latent image formed on the photoreceptor drum deteriorates. Therefore, in conventional optical scanning devices,
Output section 95B of optical waveguide array 95 and photosensitive drum 96
A lens array 97 is inserted between the optical waveguide array 9
However, since such a lens array 97 is very expensive, there is a problem in that it leads to a significant increase in the cost of the optical scanning device.

The present invention has been made in order to solve the above-mentioned problems, and can be formed on a photoreceptor drum by simply using an inexpensive focusing means that focuses light only in a direction perpendicular to the light emission direction and the scanning direction. An object of the present invention is to provide an optical waveguide array that can improve the resolution of a latent image and a method for manufacturing the same.

[Means for Solving the Problems] In order to achieve this object, the leading waveguide array of the present invention has the following features:
A plurality of optical waveguides each comprising an input section into which an optical signal is input, an output section through which the optical signal is output, and an optical waveguide section connecting them and through which the optical signal is propagated. A two-dimensional gradient index lens that focuses the optical signal emitted from the emitting section in the scanning direction is integrally formed with the emitting section.

Furthermore, in order to achieve this object, the method for manufacturing a leading waveguide array of the present invention includes a first material having a light-transmitting property and a flat plate shape, which has a property of changing the refractive index by a photopolymerization reaction. a step of placing a second material having a
A step of forming a first part having a refractive index larger than that of the first material and having a constant refractive index, and a second part having a two-dimensional distribution of refractive index by continuously changing the irradiated light irradiation energy. forming a waveguide pattern by continuously providing a portion of the second material from the first portion; It consists of a step of covering with three materials.

[Function] According to the present invention having the above configuration, since the two-dimensional gradient index lens that focuses the light emitted from the output part in the scanning direction is integrally provided in the output part, the optical waveguide array The light beam emitted from is focused in the scanning direction.

Therefore, if an optical scanning device is constructed by providing a focusing means between the output section and the photoreceptor for converging the light beams emitted from such an optical waveguide array in a direction perpendicular to the output direction and the scanning direction, the photoreceptor can be The spot system on the body surface can be made small, and a high-resolution latent image can be formed on the photoreceptor surface.

[Example] Hereinafter, an example embodying the present invention will be described with reference to the drawings.

First, referring to FIG. 1(a) to FIG. 1(e),
The configuration of the leading waveguide array 1 of this embodiment will be explained. Here, the point concentration represents the refractive index distribution.

The guiding waveguide array 1 is formed on a substrate 8 and has a structure in which a layer 2 having a refractive index distribution is sandwiched between two cladding layers 4 and 5 having a low refractive index. The optical waveguide array 1 includes a part A of a normal optical waveguide array and a part B where the refractive index is distributed in the scanning direction of light (hereinafter referred to as the y direction).
It is composed of. The refractive index n (y) in the y direction of the core portion 6 in the portion B is distributed as follows. Here, α is a constant, y, , is the position of the center of each leading waveguide in the X direction, and n is. is the refractive index of the core of part A. The refractive index is constant in the direction perpendicular to the light scanning direction (hereinafter referred to as the X direction) and in the light emission direction (hereinafter referred to as two directions).

In this way, a two-dimensional gradient index lens is formed in the portion B. The two-dimensional gradient index lens portion B is formed by a length longer than the exit surface 7, and its length is as follows.
The meandering period of light in the two-dimensional gradient index lens B is between one quarter and one half of 2π/α, that is, between π/2α and π/α. At this time, the light incident from the interface between the normal guide waveguide section A and the two-dimensional gradient index lens section B is focused at a distance Zt from the output surface 7 of the guide waveguide array 1 to the focusing position.

As described above, the leading waveguide array 1 has the function of focusing the emitted light in the X direction.

Here, the refractive index distribution only needs to be a distribution that can be approximated by the above formula, and the length of the part of the two-dimensional gradient index lens B is set to the above length, inside the two-dimensional gradient index lens B. The length may be an integral multiple of the meandering period of the light.

Next, an optical scanning device using this optical waveguide array 1 will be explained.

FIG. 2 shows only the vicinity of the output surface 7 of the optical waveguide array 1, which is a part of the optical scanning device. The other parts are the same as those of the conventional technology, so the explanation will be omitted. In the optical scanning device, a photoreceptor drum 22 is arranged facing the output surface 7 of the optical waveguide array 1, and a cylindrical lens 21 serving as a focusing means is arranged between the output surface 7 and the photoreceptor drum 22. . This cylindrical lens 21
focuses the light in the X direction. The distance between the output surface 7 and the photoreceptor drum 22 is the above-mentioned Zf. Therefore, the light emitted from the output surface 7 forms an image on the surface of the photoreceptor drum 22 in the X direction due to the action of the two-dimensional gradient index lens portion B of the leading waveguide array 1 . Further, in the X direction, an image can be formed by the cylindrical lens 21.

As described above, with this optical scanning device, it is possible to focus light both in the X direction and in the X direction.

In the embodiments described so far, the optical waveguide array 1
A lens is configured for each optical waveguide, or one lens may be configured to correspond to a plurality of optical paths. However, in this case, the length of the two-dimensional gradient index lens part B is determined by the meandering period of the light within the two-dimensional gradient index lens B.
It shall be between three minutes. By doing so, the two-dimensional refractive index gradient lens section B forms an image in the X direction at the same position as the light beam at the incident section (interface between section A and section B). Z
In the direction, it is focused at the position Z mentioned above.

Therefore, by installing the photoreceptor drum at this position, a beam spot having the same size as the diameter of the core portion of portion A can be obtained on the surface of the photoreceptor.

Next, an example of a method for manufacturing the guiding waveguide array 1 used in this example will be explained with reference to FIG.

First, as shown in FIG. 3(a), PMMA is placed on the substrate 8.
A cladding layer 5 of (polymethyl methacrylate) is formed, and a layer of a resin whose refractive index can be changed by a photopolymerization reaction, for example, PMMA containing styrene, is formed thereon. Such changes in the refractive index of the resin due to the photopolymerization reaction can be controlled by the irradiation energy of ultraviolet rays.

Therefore, by changing the irradiation energy of ultraviolet rays, a desired refractive index distribution can be created.

Next, as shown in FIG. 3(b), ultraviolet rays are irradiated through a mask 31 having an opening 31a through which ultraviolet rays can pass only in a portion A, which is a normal leading waveguide. At this time, portion B, which will later become a two-dimensional gradient index lens, is also masked. As a result, a photopolymerization reaction is carried out only in the portion that will become a normal leading waveguide.

Next, mask 33
3(C), and move the mask 32 as shown in FIG.
irradiate ultraviolet light while moving in the direction of The mask 32 has an apex at the center of each optical waveguide, and has an ultraviolet transmitting aperture 34 of the model whose length is longer than the length of the portion B which becomes a two-dimensional gradient index lens. By irradiating ultraviolet rays while moving this in the direction of arrow M, the extension of the central part of the optical waveguide is irradiated for a long time, and the irradiation time becomes shorter as it moves away from there. The reduction in irradiation time at this time is determined by the shape of the irradiation port 34. Depending on the shape of the irradiation port 34, the irradiation time is set such that a desired refractive index can be obtained, taking into consideration the relationship between irradiation energy and refractive index change.

Thereafter, as shown in FIG. 3(d), unreacted monomers are removed by baking, and a PMMA cladding layer 4 is formed as shown in FIG. 3(e).

Through the above steps, the normal optical waveguide portion A and the two-dimensional gradient index lens portion B can be integrally molded.

The present invention is not limited to the embodiments detailed above, and various changes can be made without departing from the spirit thereof.

For example, the shape of the mask 32 used in the embodiments described above is not limited to the shape shown here, and any shape may be used as long as a desired irradiation time distribution is obtained.

Alternatively, a desired irradiation energy distribution may be obtained by scanning an intensity-modulated light beam without using a mask.

Furthermore, the materials of the substrate, core portion, and cladding portion are not limited to those described here.

Furthermore, as a focusing means for focusing light in the X direction, a second two-dimensional gradient index lens 23 having a square distribution of refractive index in the X direction may be used instead of the cylindrical lens 21.

[Effects of the Invention] As is clear from the detailed description above, according to the present invention, since the two-dimensional gradient index lens is integrally molded and provided in the light output section, the output direction and scanning direction can be changed. Industrially, it is possible to provide an optical waveguide array and its manufacturing method that can improve the resolution of a latent image formed on a photoconductor by simply using an inexpensive focusing means that focuses light only in a direction perpendicular to the direction of the photoreceptor. It has a remarkable effect.

[Brief explanation of the drawing]

1 to 3 show embodiments embodying the present invention. FIG. 1(a) is a top view of the optical waveguide array, and FIG. 1(b) is a top view of the optical waveguide array in the X direction. A graph showing the refractive index distribution, FIG. 1(C) is a graph showing the refractive index distribution in the X direction of the two-dimensional refractive index distribution lens portion, and FIG. 1(d) is a side view of the optical waveguide array. e) is a graph showing the refractive index distribution in the X direction of the optical waveguide array and the two-dimensional gradient index lens portion, FIG. 2 is a perspective view of the vicinity of the output part of the optical scanning device using the optical waveguide array, and FIG. a) to Figure 3 (
Figures up to e) are diagrams explaining the procedure for producing a guiding waveguide array, Figure 4 is a diagram explaining the spread of the output light emitted from the guiding waveguide when no lens array is used, and Figure 5 is a diagram showing a conventional optical waveguide. 1 is a diagram showing an example of an optical scanning device using an array. In the figure, 1 is an optical waveguide array, 2 is a core, 3,4°5 is a cladding, 6 is a two-dimensional gradient index lens portion, 7 is an exit surface, 22 is a photosensitive drum, 91 is a semiconductor laser, and 94 is a polygon. Mirror 95A is the incident surface. 1 sentence (d,) Figure 3 Cd)

Claims (1)

[Claims] 1. Consisting of an input section into which an optical signal is input, an output section through which the optical signal is output, and an optical waveguide section connecting them and through which the optical signal is propagated. An optical waveguide array comprising a plurality of optical waveguides, characterized in that a two-dimensional gradient index lens that focuses an optical signal emitted from the emitting section in the scanning direction is integrally formed in the emitting section. optical waveguide array. 2. On top of the flat plate-shaped first material that has light-transmitting properties,
a step of placing a second material whose refractive index is variable through a photopolymerization reaction; A step of forming a first portion having a larger refractive index and a constant refractive index; and a step of forming a second portion having a two-dimensional distribution of refractive index by continuously changing the irradiated light irradiation energy. forming a waveguide pattern by continuously providing a waveguide pattern from the first part; and forming a top surface of the second material with the first material or a third material having a refractive index similar to the first material. A method for manufacturing an optical waveguide array, comprising the step of coating.