JPH026906A - Waveguide optical element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to waveguide optical elements.

[Prior Art] A waveguide optical system has been proposed in which light is confined in a waveguide and guided, and the guided light is refracted or diffracted by a waveguide optical system to condense the light. The use of such waveguide optical systems allows the optical system to be made smaller.

Since it can be made lightweight, its practical use has been strongly desired in recent years.

[Problem M to be Solved by the Invention] One of the problems that makes it difficult to put such waveguide optical elements into practical use is the problem of waveguide optical systems.

In other words, a waveguide optical system is an optical system for condensing guided light, but conventionally, the paper journal: Applied Physics Vol. 48, No. 3
Mode index lenses, Luneburg lenses, geodesic lenses, grating lenses, etc. shown on pages 241 and below are waveguide optics.

It is intended to be used as a system. Among these lenses,
Mode index lenses and Luneburg lenses require extremely high accuracy in the refractive index control required during their manufacturing process, but high-precision refractive index control is difficult with current technology and is difficult to achieve in terms of mass production. At this stage, it is difficult to put it into practical use. In addition, geodesic lenses are created by creating a waveguide lens by making a depression in the waveguide, and since the shape of the depression is aspherical, it is difficult to process and requires precision cutting followed by a polishing process. For this reason, mass production is difficult, and cost reduction is also difficult.

Although the lens is relatively easy to manufacture and can be realized at a low cost, its lens action depends on the wavelength of light, and as the wavelength of light changes, the focal length changes. However, semiconductor lasers are commonly used as light sources for waveguide optical devices. As is well known, there is a property of wavelength shift due to temperature change. Therefore, when using a G1 noting lens, it is necessary to perform extremely high-precision temperature control on the semiconductor laser, or to use a DFB semiconductor laser with no wavelength shift. This invention has been made in view of the above-mentioned circumstances, and its purpose is to It can be easily realized at low cost,
Moreover, the present invention aims to provide a novel waveguide optical element that can use an ordinary semiconductor laser as a light source.

[Means for creating and solving multiple problems] The present invention will be explained below.

The waveguide optical element of the present invention has a waveguide m provided on a substrate.
and an R-wave optical system.

The waveguide optical system is an optical system for focusing the guided light guided through the waveguide layer, and is a waveguide reflective optical system formed as an end face of the waveguide layer.

[Function] In the present invention, the waveguide optical system is a waveguide reflective optical system formed as the end face of the waveguide layer as described above, and the guided light guided through the waveguide layer is guided through this waveguide. It is reflected by the reflective optical system and focused on one point.

In this way, the waveguide light is focused by reflection rather than refraction, so even if the optical wavelength changes, the function of the waveguide reflective optical system does not change at all. Further, since the waveguide reflective optical system is formed as an end face of the waveguide layer, its fabrication is also easy.

[Example] A specific example will be described below with reference to the drawings.

In Example 1 shown in FIG. 1, reference numeral 5 indicates a waveguide optical element.

The waveguide optical element 5 is constructed by laminating a waveguide layer 52 on a transparent substrate 51.

The guided light guided through the waveguide layer 52 is focused by a waveguide reflection optical system, which will be described later.

FIG. 1 is a plan view of the waveguide optical element 5. FIG.

The transparent substrate 51 (see FIG. 2) of the waveguide optical element is a flat plate made of glass, quartz, etc., and one surface thereof is coated with a material having a higher refractive index than the transparent substrate 51, such as ZnS or ZnO.
, Ce01. SiN, 5iON, Koh, Ning 7095
glass etc.

The waveguide J152 is formed by forming a film by vacuum evaporation, sputtering, CVD, or the like.

In FIG. 1, the waveguide layer 52 is in a state where a part of the waveguide layer has been removed, and the part indicated by reference numeral 52A of the end face of this removed part has a parabolic shape as a waveguide reflective optical system. is formed. A waveguide reflective optical system 52A whose sectional view taken along the line A-A in FIG. 1 is shown in FIG. .

Nazu end face of waveguide layer 52, transparent substrate 51, waveguide layer 52
perpendicular to each surface of .

Such a vertical end face can be easily formed by etching the formed waveguide layer using a dry etching method such as ion beam etching or reactive ion beam etching.

As mentioned above, the shape of the waveguide reflective optical system 52A is a parabola when viewed from the top, and the focal point of this parabola is at the 12th point.
This is point E in the figure.

The parallel waveguide light propagating in the waveguide layer 52 is totally reflected by the waveguide reflection optical system 52A and condensed at point E. The isolateral refractive index of 52 is N1. the refractive index of air.

1, the angle of incidence on the waveguide reflective optical system is 0. is everywhere.

The shape of the reflecting surface may be determined so as to satisfy the following condition: OI≧5in-' (i/N+).

In the embodiment shown in FIG. 1, the end face of the waveguide layer constituting the waveguide reflective optical system has a shape that is perpendicular to the surfaces of the transparent substrate 51 and the waveguide layer 52, as shown in FIG. However, the end face of the waveguide layer constituting the waveguide reflective optical system may have a taper as shown in a cut end view in FIG.

In this case, it is desirable that the taper radius Δ is at least equal to or greater than the wavelength of the guided light. Methods for forming the end face of the waveguide layer with such a taper include wet etching or dry etching by diagonally irradiating with an ion beam, etc. Examples include an etching method, or a method of forming a film through a mask having an opening with a slight gap with respect to a transparent substrate during film formation of the waveguide layer. When using the tapered end face of the waveguide layer as a waveguide reflective optical system, as described above.

In order to utilize total internal reflection as shown in FIG.

θ, ≧5in-” (Nz/N+) All you have to do is satisfy the following.

Furthermore, as shown in FIG. 4, a low refractive index layer 5 is added to the part where the waveguide layer 52 is removed to form a waveguide reflective optical system.
9, the low refractive index layer 59 has a lower refractive index than the waveguide layer 52, and is made of, for example, SiO2 or resin, and also serves to protect the waveguide reflective optical system. Letting the isolateral refractive index of the layer 59 be N3, when N2≦N3, the incident angle θ is everywhere θ, ≧5in-' (N3/
N+), and when N z > N s, θ
Total reflection can be achieved by satisfying 1≧5in-'(N2/N+).

Of course, the low refractive index layer may be loaded onto a non-tapered end face perpendicular to the transparent substrate as shown in FIG. 2, and the conditions for total reflection in this case are as follows.

θ, ≧5in-’ (N3/N+) It is.

5 and 6 show only the characteristic parts of the second embodiment,
In Example 1 described above, the shape of the waveguide reflective optical system is a parabola, and is formed in a shape that totally reflects the guided light. In this second embodiment, normal reflection is used instead of total reflection. That is, as shown in FIG. 5, in this second embodiment, the waveguide optical element 5E has a waveguide reflection optical system 5
2F is formed as a waveguide and an end face of N52, which reflects the guided light toward the focal point F as a convergent light beam.

The waveguide reflection optical system 52F has a parabolic shape with the focal point at point F or a circular shape approximating the parabolic shape. The end face of the waveguide layer 52 constituting the waveguide reflection optical system 52F is perpendicular to the transparent substrate 51, as shown in FIG. Such an end face can be formed by dry etching as described above. In this Example 2, since the incident conditions to the waveguide reflection optical system do not satisfy the conditions for total reflection, the waveguide as a reflection surface is in contact with the end face of the waveguide/[52], as shown in FIG. Metals, such as A 1 p A g p A ut
High reflectance M590 such as Cu is formed. .

This metal layer can be formed by vapor deposition or the like.

In addition to metals, high reflectance N590 can also be applied to dielectric multilayer films,
Other materials with high reflectance may also be used.

[Effects of the Invention] As described above, according to the present invention, a novel waveguide optical element can be provided. As mentioned above, this element reflects and focuses the guided light propagating through the waveguide layer using the waveguide reflective optical system, so it is not affected by changes in the wavelength of the light from the light source.
In addition, the waveguide reflective optical system is formed as the end face of the waveguide layer, but this end face is easy to form, and its shape can be easily achieved using techniques such as phosphorography, so it can be easily formed into a highly accurate shape. You can expect good optical properties. Therefore, the problem of mass production, which has been a problem with conventional waveguide optical elements,
The problem with wavelength change is solved.

It becomes easier to put waveguide optical elements into practical use.

In the configuration example shown in FIG. 4, a low refractive index layer 59 is bonded to the end face of the waveguide M52 that forms the waveguide reflection optical system, and the incident conditions to the part that forms the waveguide reflection optical system are set. When the conditions for total reflection are not satisfied, a part of the guided light passes through the low refractive index layer 5.
9 is also guided. Therefore, in such a case, the low refractive index layer 59
can also be called a waveguide layer, but in this case, the end face of the waveguide layer forming the waveguide reflective optical system is just the waveguide layer 52.
If the low refractive index layer is also considered as a waveguide layer, the term "end face forming a waveguide reflective optical system" as used in the present invention should also be referred to as a discontinuous surface of the waveguide layer.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining one embodiment of the present invention, and FIG.
The figures are a plan view of the waveguide optical element of the embodiment shown in FIG.
The figure is a cross-sectional view of the waveguide optical element of the embodiment shown in FIG. 1, and FIG. 4 is a diagram for explaining the modification Sk of the waveguide optical element.
FIGS. 5 and 6 are diagrams for explaining other actual travel examples of the present invention. 51.7 Waveguide optical element, 52°7, Waveguide J-taku, 53A
,. . Guided wave F flood

Claims (1)

[Claims] The waveguide optical system comprises a waveguide layer provided on a substrate and a waveguide optical system for condensing guided light guided through the waveguide layer, the waveguide optical system comprising: a waveguide layer provided on a substrate; A waveguide optical element, characterized in that it is a waveguide reflective optical system formed as an end face of the waveguide layer.