JPS63191111A - Optical coupler - Google Patents

Abstract

PURPOSE:To prevent the radiation of light to the base side and returned light from the end face of a waveguide and to improve coupling efficiency by forming a reflection layer on one inclined face other than the one from which waveguide light is projected out of the inclined faces of a V-shaped groove formed asymmetrically about the right and left sides and more deeply than a core layer of an optical waveguide. CONSTITUTION:Light transmitted into the core layer 3 of the optical waveguide in an arrow direction reaches the projecting inclined face 5 of the V-groove, and since the inclined face 5 is set up to an angle suppressing the full reflection of the transmitted light, the light is refracted and projected from the inclined face 5 and reaches a high reflection factor layer 6. The light is reflected on the layer 6, radiated in the direction vertical to the base and coupled with a light receiving element 8. Since light is not radiated to the base side and return light is not generated on the projecting end face of the waveguide in the optical coupler, coupling efficiency with the light receiving element can be prevented from being dropped.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to an optical coupler between guided light of an optical waveguide on a substrate and a light receiving element.

[Conventional technology] The conventional technology will be explained using FIGS. 2 and 3.

FIG. 2 is a block diagram of a coupler between an optical waveguide and a light receiving element using a grating coupler. 1 is a substrate, 2 is an optical waveguide lower cladding layer, 3 is an optical waveguide core layer, 7 is a grating coupler portion, and 8 is a light receiving element. The light guided through the optical waveguide core layer 3 in the direction of the arrow in the figure is radiated onto the optical waveguide by the grating coupler section 7 and is coupled to the light receiving element 8 . The optical coupler having the configuration as shown in FIG. 2 has problems in terms of coupling efficiency because it is necessary to increase the grating length in order to improve the efficiency and the light is also radiated to the substrate 1 side.

FIG. 3 is a configuration diagram of a coupler between an optical waveguide and a light receiving element using a microreflector. 1 is a substrate, 2 is a lower cladding layer of an optical waveguide, 4 is an upper cladding layer of an optical waveguide, 3 is an optical waveguide core layer, 9 is a micro-reflector made of a glass block,
8 is a light receiving element. The light that has been guided through the optical waveguide core layer 3 is emitted from the end face of the optical waveguide core layer 3 and is connected to the substrate 45.
The light is reflected upward by a minute reflecting mirror 9 having an angle of .degree., and is coupled to the light receiving element 8. In a coupler configured as shown in Figure 3,
Since the reflecting mirrors are individually manufactured, it is difficult to process and mount the reflecting mirrors in alignment, and there is also the problem of return light from the end face of the waveguide.

[Problems to be Solved by the Invention] The purpose of the present invention is to solve the above-mentioned problems and to receive light without emitting light to the substrate side or without returning light from the end face of the waveguide. An object of the present invention is to provide an optical coupler between a waveguide and a light-receiving element, which has high coupling efficiency to the element and does not require assembly steps such as alignment.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an optical coupler having an optical waveguide and a light receiving element, in which a left-right asymmetric 7-character is formed deeper than the core layer of the optical waveguide. Of the slopes of the groove,
It is characterized in that a reflective layer is provided on a slope other than the slope from which the guided light is emitted.

[Function] The optical coupler of the present invention improves the coupling efficiency with the light receiving element because light is not radiated to the substrate side and no return light is generated from the end face of the waveguide.

[Example] The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view of an optical coupler according to an embodiment of the present invention.

In the figure, 1 is a substrate, 2 is a lower cladding layer of the optical waveguide, 3 is an optical waveguide core layer, 4 is an upper cladding layer of the optical waveguide, 5 is a guided light emission slope, and 6 is a layer having a high reflectance. A certain slope 8 is a light receiving element.

In this embodiment, a silicon wafer is used as the substrate 1,
The lower cladding layer 2 of the optical waveguide is made of 5i02 by thermal oxidation.
μm was formed. The optical waveguide core layer 3 was made of multicomponent glass manufactured by Corning Corporation, such as Corning 7059, and the optical waveguide upper cladding layer 4 was formed of SiO□ to a thickness of 1.2 μm and 2 μm, respectively, by sputtering.

The refractive index of the optical waveguide lower cladding layer 2 is 1.46, and the refractive index of the optical waveguide core layer 3 is 1.53.

In this example, a left-right asymmetrical V-groove deeper than the optical waveguide core layer was provided. The optical waveguide output slope 5 is set at an angle at which the propagating light is not totally reflected so as not to reduce the efficiency of the optical coupler, and the angle of the waveguide light output slope 5 with respect to the substrate is set at a high reflectance layer 6.
and the angle between the substrate 1 and the substrate 1.

Here, the asymmetrical V-shaped groove is formed by machining, the guided light emission slope 5 has an angle of 60°, the high reflectance layer 6 has an angle of 35°, and a depth of 6 μm, and the high reflectance layer 6 is made of gold. It was formed by vapor deposition. Other reactive ion beam etching methods can also be applied to form the 7-shaped groove.

The operation of this embodiment will be explained below.

The light propagating through the optical waveguide core layer 3 in the direction of the arrow in the figure reaches the exit slope 5 of the figure 7 groove.Since the exit slope 5 is set at an angle that prevents total reflection of the propagating light, the light passes through the exit slope. The light exits from 5 while being bent and reaches the high reflectance layer 6 . The light is reflected by the high reflectance layer 6, radiates in a direction perpendicular to the substrate, and is coupled to the light receiving element 8.

In this way, in the optical coupler of this embodiment, no light is emitted to the substrate side, and no return light is generated at the output end face of the waveguide, so that the coupling efficiency with the light receiving element does not decrease. Furthermore, since the optical waveguide and the 7-shaped groove are integrally constructed, the optical coupler can be made smaller.

Even when the optical waveguide is formed of materials with different refractive indexes, it is possible to emit light in a direction perpendicular to the light receiving element by appropriately selecting the angle of the slope of the 7-shaped groove.

[Effects of the Invention] As explained above, in the optical coupler of the present invention, the coupling efficiency with the light receiving element is improved because the light is not radiated to the substrate side and the return light from the waveguide end face is not generated. do.

Further, in the optical coupler of the present invention, since the optical waveguide and the 7-shaped groove for light reflection are integrally formed, steps such as alignment of the reflecting mirror are not required, and the coupling efficiency is increased, resulting in a small size.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an optical coupler according to an embodiment of the present invention, and FIGS. 2 and 3 are sectional views of conventional optical couplers, respectively. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Optical waveguide lower cladding layer, 3... Optical waveguide core layer, 4... Optical waveguide upper cladding layer, 5... Waveguide light emission slope, 6... High reflectance layer, 7... Grating coupler section, 8... Light receiving element, 9... Micro reflecting mirror.

Claims (1)

[Claims] In an optical coupler having an optical waveguide and a light receiving element, a reflective layer is provided on the slopes of the asymmetrical V-groove formed deeper than the core layer of the optical waveguide, other than the slopes from which the guided light is emitted. An optical coupler characterized by: