JPS63194235A - Optical switch - Google Patents

Abstract

PURPOSE:To narrow a carrier injecting part by forming the optical waveguide structure of the passing part of an injection carrier of an optical branching part where an optical waveguide intersects and branches, to a ridge type. CONSTITUTION:A light wave made incident from an optical waveguide 1 travels straight in the optical waveguide, and usually emitted to an optical waveguide 10. In this state, when a carrier is injected to a carrier injecting part 2, and the refractive index of this part is lowered, the light wave is reflected by an optical branching part, and emitted to an optical waveguide 11. Subsequently, when a current is allowed to flow between a ridge upper face electrode 8 and a reverse side electrode 9 by using a ridge type optical waveguide structure and the carrier is injected, the injected carrier is narrowed and flows only to the inside of an optical waveguide 7 through which the light wave is propagated. In such a way, the steep narrowing of a carrier injecting area can be executed efficiently without providing a special current narrowing layer.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an optical switch that performs switching by changing the refractive index of an optical branch where an optical waveguide intersects and branches into two, by injecting carriers. This invention relates to controlling the carrier injection region by using an optical waveguide as a ridge-type optical waveguide.

[Conventional technology]

As an optical switch using the conventional carrier injection method,
A total internal reflection type optical switch is an optical path switching optical switch that utilizes refractive index changes, and Inoue et al.

Proceedings of the 1985 IEICE Semiconductor and Materials Division National Conference 57-4. and Inoue et al., Proceedings of the 1986 IEICE General National Conference 969. These optical switches have CS as an optical waveguide structure in the carrier injection part.
P (ChanneledSubstrata Pl
anar) type and B H (Rurr, 1adHeter
In order to reduce the switching current and improve the extinction ratio, structures of different conductivity types are created in the substrate and cladding layer, and the carrier injection part in the optical waveguide is narrowed.

[Problem that the invention seeks to solve]

In these optical switches, it is necessary to create structures of different conductivity types in the substrate and cladding layer, which increases the number of manufacturing steps and reduces yield. Furthermore, when the width of the optical waveguide is narrowed in order to make the optical waveguide into a single mode, the width of this constriction region must be correspondingly narrowed. In other words, it is manufactured with an accuracy of about 1 μm or less.

Achieving this goal was extremely difficult.

An object of the present invention is to realize constriction of the carrier injection section by using a ridge-type leading waveguide in the injection section, thereby reducing power consumption.

The objective is to easily produce a compact optical switch with excellent extinction ratio characteristics.

c.Means for solving problems] For the above purpose, the optical guide paths formed on the substrate intersect.

This is achieved by making the optical waveguide structure of the injected carrier path portion of the optical branch portion into a ridge type.

[Effect] The present invention will be explained using FIG. 1, FIG. 2, and FIG. 3.

FIG. 1 is a top view of a Y-type optical switch using the present invention, and FIG.
3 and 3 show cross-sectional views of the carrier injection section.

In FIG. 1, a light wave entering from an optical waveguide 1 travels straight through the optical waveguide and exits to a normal optical waveguide 10. As shown in FIG. When carriers are injected into the carrier injection part 2 to lower the refractive index of this part, the light wave is reflected by the optical branching part and output to the optical waveguide 11. Here, if the optical waveguide structure is a C8P type optical waveguide shown in FIG. 3 as in the conventional example, a current narrowing layer 12 is provided in the substrate 5 and the clad layer 13,
It is necessary to perform a constriction of the carrier inward. However, the second
As shown in the figure, when a current is passed between the ridge top electrode 8 and the back electrode 9 to inject carriers using a ridge-type optical waveguide structure, the injected carriers are transferred only into the optical waveguide 7 where the light wave propagates. The current flow is constricted, and a steep constriction of the carrier injection region can be efficiently achieved without providing a special current confinement layer. Furthermore, in the present invention, the same effect can be achieved even if the ridge-type optical waveguide shown in FIG. 2 is replaced with a buried-type optical waveguide structure in which the ridge-type optical waveguide shown in FIG. 2 is buried with an insulating material.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

Figure 1 is a top view of the optical switch, and Figure 2 is a point a in Figure 1.
FIG. 3 is a sectional view at section 3;

As the substrate 5, the carrier density is 2×1018 am-”
n-type InP was used. (2) Crystal growth of an InGaAsP layer 6 as an optical waveguide layer is performed on the substrate 5 using the PE method, and processed into the shape of the optical branch path shown in FIG. 1 using the dry etching method. After vapor-depositing, providing an electrode 8, and forming a carrier injection part 2, Au-Ge-Ni was vapor-deposited on the back surface of the substrate 5 to form an electrode 9, thereby completing an optical switch.

The optical switch has a wavelength of 1.3 μ in the leading waveguide 1 for light incidence.
The switching characteristics were evaluated by inputting a light wave of m. When no current is applied and carriers are not injected, the ratio (extinction ratio) Pt/Pz of the output Pz from the output side optical waveguide 10 and the output P2 from the output side optical waveguide 11 is 100/l6.
Next, a current of 15 mA was applied, and when carriers were injected, Pt/Pz was 1/90. This result is sufficient for practical use.

〔Effect of the invention〕

According to the present invention, a practical optical switch that is small and has a large extinction ratio can be provided easily and with a high yield, which facilitates the construction of optical transmission and communication systems and has the effect of expanding the market.

[Brief explanation of the drawing]

1 and 2 are diagrams showing an outline of the present invention, and FIG. 3 is a sectional view of a conventional example. 1.10.11... Optical waveguide, 2... Carrier injection part, 3... Position showing cross-sectional structure, 4... Optical branching part, 5... Substrate, 6... Optical waveguide Layer 7... Optical waveguide section, 8, 9... Electrode, 12... Current confinement layer.

Claims (1)

[Claims] 1. An optical switch that performs switching by changing the refractive index of at least a portion of an optical branching portion where optical waveguides formed on a semiconductor substrate intersect or branch, by injecting carriers. An optical switch characterized in that the optical waveguide structure of the path portion is a ridge type optical waveguide. 2. The optical switch according to claim 1, wherein the semiconductor is a compound semiconductor. 3. The optical switch according to claim 1, further comprising an electrode for injecting the carriers by current injection.