JPS58211717A - Composite optical waveguide - Google Patents

Abstract

PURPOSE:To obtain functions which take advantage of a plannar type waveguide and a channel type waveguide without providing a lens, etc., specially by composing an optical waveguide of plural kinds of waveguides in combination and incorporating at least one kind of waveguide in other waveguides. CONSTITUTION:A composite optical waveguide is equipped with a plannar type waveguide 2 constituted on a substrate 1 of glass, etc., a semiplannar type waveguide 3 constituted as included in the plannar type waveguide 2, and a channel type waveguide 4 included in the waveguide 3. The waveguide 2 is formed of, for example, Li2NbO3, etc., and the waveguides 3 and 4 are formed with large refractive indexes by diffusing titanium, etc., thermally into prescribed areas in the waveguide 2. The waveguide 4 is parallel and tapered in the waveguide 3; a light signal is entered as shown by an arrow to spread into the waveguide 3 from a cut part 4', and then passed through a convex lens to have arcuate section 3', so that it is transmitted into the waveguide 2 as a wide flat beam.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical field of the invention The present invention relates to a composite optical waveguide, and in particular to a composite optical waveguide that utilizes the advantages of various types of optical waveguides by combining optical waveguides such as a Brener type and a channel type. Regarding the utilized composite optical waveguide.

(2) Background of the Technology Recently, optical integrated circuits in which various optical elements such as optical waveguides and optical switches are constructed on a substrate such as glass have been attracting attention. In such optical integrated circuits, the Irj properties of the optical waveguides that transmit light have a large influence on the entire optical integrated circuit, and therefore it is necessary to fully utilize the advantages of the optical waveguides.

(3) Prior art and problems Conventionally, optical waveguides used in optical integrated circuits include planar waveguides formed flat on a substrate such as glass, and linear waveguides formed on a substrate such as glass. A formed channel type waveguide was used.

Planar waveguides are suitable for transmitting light with a wide beam width, and are suitable for optical circuit elements that require light with a wide beam diameter, such as Bragg diffraction switches. In addition, the channel type can transmit optical signals with low loss like an optical fiber cable, and is used for optical circuit elements with a directional connector and a thin structure.

However, in the conventional optical integrated circuit, planar waveguides and channel waveguides are used separately, so when obtaining parallel light beams with a wide width in the lateral direction, for example, lenses, etc. I had to use parts. In other words, when obtaining a wide range of parallel rays,
The light from the channel waveguide is first diffused into the air, and then this diffused light is converted into a parallel beam with a wide cross-sectional area using a convex lens, etc., and by manually inputting such a parallel beam into the planar waveguide, it is possible to create a planar waveguide. I had a parallel beam. Therefore, since a functional element such as a convex lens is separately required, the structure of the apparatus becomes complicated and expensive.

(4) 4 Objects of the Invention In view of the problems with the conventional type described above, an object of the present invention is to provide a composite optical waveguide used for optical integrated circuits, etc., in which the optical waveguide is configured by a combination of a plurality of types of waveguides, and at least Based on the idea that one type of waveguide is included in another type of waveguide, the advantages of planar and channel type optical waveguides are fully exploited and separate functional elements are used. The object of the present invention is to make it possible to obtain various light beams without any interference.

(5) Structure and object of the invention According to the present invention, a linear channel type waveguide and a plate having a sufficiently wide width compared to the width of the optical signal.
It consists of a square waveguide and a semi-planar waveguide having a width intermediate between these two types of waveguides, and at least two of these three types of waveguides are configured such that one of them contains the other. This is achieved by providing a composite optical waveguide with a characteristic of

(6) Examples of the invention An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic perspective view showing the configuration of a composite optical waveguide according to an embodiment of the present invention. Further, FIG. 2 is a cross-sectional view of the composite optical waveguide of FIG. 1 taken along the line ■--■. As is clear from these figures, the composite guided waveguide according to one embodiment of the present invention includes a planar waveguide 2 configured on a substrate 1 such as glass, and a structure included in the planar waveguide 2. A semi-planar waveguide 3 configured as shown in FIG. The planar waveguide 2 is made of, for example, lithium niobate (tt2Nb o5 ), and the semi-planar waveguide 3 and the channel waveguide 4 are made by thermally diffusing, for example, titanium or the like in the required area within the planar waveguide 2. It is constructed by increasing the refractive index. Further, the planar waveguide 2 is configured in a plane on the substrate 1, and the channel type waveguide 4 is configured as a substantially linear waveguide with a narrow width.

It is configured as a waveguide having an intermediate width among the half-grainer waveguide 3Fi, the planar waveguide 2, and the channel waveguide 4. The channel waveguide 4 is cut into a shape that gradually becomes thinner inside the semi-grainer waveguide 3. The semi-planar waveguide 3 is cut into an arc-shaped cross section within the planar waveguide 2. In addition, the refractive indexes of the substrate 1, Brehner groove waveguide 2, half-silver waveguide 3, and channel waveguide 4 are determined as FIB T fl! +t13 and n4, the following relationship holds true between these respective refractive indices.

n4) ns ) ns > ns In the above-mentioned composite optical waveguide, the fc optical signal inputted to the channel type waveguide 4 from the direction of arrow A passes through the channel type waveguide 4 and passes through the cut portion of the channel type waveguide 4. 41 into the semi-planar waveguide 3 while widening the beam width. In this case, since the cut portion 4' of the channel waveguide 4 is gradually tapered as described above, unnecessary reflections are reduced and the light beam is efficiently diffused. The light beam spread in the semi-solenar waveguide 3 in this way is acted as a convex lens at the arc-shaped cross section 3' of the semi-solena waveguide 3, and a wide parallel beam is formed in the planar waveguide 2. It is transmitted as The dotted line in FIG. 1 schematically shows how the light beam is transmitted. In this way, the composite optical waveguide shown in Figures 1 and 2 makes it possible to obtain a wide parallel beam without separately providing a convex lens, etc., and it is suitable for input into a Bragg switch using Bragg reflection. A suitable light beam can be obtained.

Note that the relationship between the refractive index of the substrate 1 and each waveguide 2, 3.4 is not limited to the above-mentioned one, but may be such that, for example, n4) nz) ns > ns. The cut surface 3' of the semi-grainer waveguide 3 in FIG. 1 is not a protruding shape as in FIG. 1, but has a concave arc-shaped cross section as shown in FIG. 3, thereby achieving the same function as the composite optical waveguide in FIG. 1. can have.

(7) Effects of the Invention As described above, according to the present invention, various optical functions can be realized by utilizing the advantages of the siplanar type and channel type waveguides with a simple configuration without providing a separate lens or the like. It becomes possible to construct a composite optical waveguide for

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the structure of a composite optical waveguide according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the composite optical waveguide of FIG. 1 taken along the line ■--■, and FIG. 3 is a schematic plan view showing a composite optical waveguide according to another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Brener type groove waveguide, 3... Semi-planar type waveguide, 3'+3'... Arc-shaped cross section,
4... Channel type waveguide, 4'... Cutting section. Patent applicant Fujitsu Limited Patent application ceremony Participating patent attorney Akira Aoki Patent attorney Kazuyuki Nishidate Patent attorney Yukio Uchida Patent attorney Akira Yamaguchi

Claims (1)

[Claims] 1. A diagonal channel-type cardiac waveguide, a planar waveguide whose width is sufficiently wider than the width of the optical signal, and a semi-planar waveguide having a width intermediate between these two types of waveguides. A composite optical waveguide comprising a waveguide, and at least two of these three types of waveguides are configured such that one encompasses the other. The semi-planar waveguide is contained within a semi-planar waveguide and is interrupted in the semi-planar waveguide to widen the light beam, the semi-planar waveguide having a waveguide cross-section that functions to process the widened light beam. A composite optical waveguide according to claim 1, characterized in that: